Onan Generator Start due to no power

[Utah Paul]

My 2001 Roadtrek Onan generator does not seem to get any electrical power.

The engine start button inside the van and on the generator frame does not result in any action.

Is this a power supply problem that can be easily resolved?

Thanks! 

[Darryl&Rita]

Do you have 12 volts at the solenoid? does the solenoid pass power to the starter? Let's start there.

[Utah Paul]

I will check that, but there are things I must disassemble to gain access to the top of the generator where the solenoid is mounted.

Thanks

[Kirk W]

The generator starter normally gets power from the coach battery. If you hear a click when pushing the start switch on the generator but no starter cranking, that probably means low voltage to the starter from the coach battery. You may want to try starting the chassis engine and allow it to run a few minutes and then try starting the generator again as that will add power from the chassis alternator to the available battery power. If your coach battery is pretty old it may not have the power capability to crank the starter any longer. How old is the coach battery? Have you measured the available voltage from the coach battery with an accurate meter? It probably needs at least 11V in order to crank. 

 

Edited August 19, 2019 by Kirk W

[Twotoes]

Agree with Kirk. Start your motor, maybe even drive a few miles and let the house batteries charge. Then try again. Or if you can hook up somewhere, that may also be another option. 

[oldjohnt]

Low voltage among other things may be the problem. In the typical set up (not all) EITHER plugging to shore power will power your Converter/Charger to charge the house battery OR depending on how wired starting the vehicles engine may provide some charge to the house battery. TRY BOTH.

If you have a good volt meter read the house battery voltage. A full charged 12 volt battery at rest and stabilized should read around 12.6 volts. If its too low that may be the problem....

In the event the house battery is good and full charged (assuming it feeds the genset) but still no cranking we have to look at the switch and solenoid issues.

Other causes may be a poor or corroded ground or battery or solenoid cable connection. Check connections and grounds.

Is there an onboard start/stop switch in addition to the remote ?? If so does it act the same there ???   From your post it sounds like NEITHER works but had to ask.

John T

 

[Kirk W]

6 hours ago, oldjohnt said:

Is there an onboard start/stop switch in addition to the remote ?? If so does it act the same there ???   From your post it sounds like NEITHER works but had to ask.

 

23 hours ago, Utah Paul said:

The engine start button inside the van and on the generator frame does not result in any action.

 

[oldjohnt]

9 hours ago, Kirk W said:

The engine start button inside the van and on the generator frame does not result in any action.

That's what I took from the posting IE NEITHER switch (on genset or inside remote)  makes her crank, so I'm still back to possibly low voltage and if plugging to shore power with a working and connected Converter/Charger doesn't help, then I would suspect possible starter solenoid or switch or power to the switch issues. In 49 years of RV ownership it's been more then once I have had to replace a faulty starter solenoid on a genset.

I have seen bad solenoids that fail to crank the genset act in two ways:  1) It clicks/engages BUT the contacts are bad (or even a bad starter) so there's no cranking  2) It fails to even click which can be a bad solenoid (activation coil bad/open) or perhaps the switch is bad (or has no 12 VDC input power) and isn't sending 12 volts to activate the solenoid ???????? These issues aren't hard to troubleshoot with a volt meter or even a 12 volt test lamp. If you put a meter or lamp on the starter solenoids small activation terminal see if it lights when the starter switch is depressed ??? IT SHOULD !!!!!!!!!!! If not the solenoid cant close to power the starter.. The solenoid also needs the other ground connection in place to work, there's yet another possible cause  ???   

NOTE most RV gensets use the house battery to crank the genset while a few have their own onboard battery. My discussion above concerns house battery for genset power.  

 While its the most headache and expense I've also seen bad control boards cause issues grrrrrrrrrrrrrrrrrrrr

John T 

[WILDSIDE]

I have a 2008 Onan 4KY version K 33amp 120 Hz GenSet that will not turn over. Indications are that the solenoid will activate when pushing the local start switch and after about two - three seconds of activating (clicking), the solenoid stops. A measurement of the battery measured 3VDC and the solenoid does nothing. But then, almost like a charging capacitor, the battery voltage increases back to 12.5VDC. I have to disconnect the positive lead from the solenoid to reset the solenoid.

 

At the start of it, the battery measures 12.9VDC at the solenoid battery stud. Resistance between GenSet ground and negative battery post read 250 Megaohm so I cleaned the ground stud that's welded to the camper frame and now resistance measures 30 ohms. The GenSet ground is clean.
I replaced the solenoid with an OEM solenoid and have the same indications. I connected an external battery to the ground and starter lead and the GenSet will crank. I dont know if the GenSet will shutoff when the battery is disconnected so I did not continue to see if the GenSet would actually start.
 

By the way, which contact is the "I" and which is the "S" on the 307-2586 solenoid? Picture attached...
Any troubleshooting suggestions?

[oldjohnt]

12 hours ago, WILDSIDE said:

By the way, which contact is the "I" and which is the "S" on the 307-2586 solenoid?

  If the solenoid you have is like many of the older often referred to a "Ford type" solenoids which used the case/frame as ground, the S (solenoid) is the activation terminal while the I (Ignition) is hot ONLY when the solenoid is engaged (can be used to by pass an ignition ballast resistor while cranking). If you apply hot 12 volts to the S the solenoid (and case/frame as ground) should engage but NOT if you apply it to the I.

  However, I have seen solenoids (gensets or lawn mowers or RV's or many cars) that appear similar to the "Ford type" EXCEPT instead of the case/frame being the ground return the coil is located between the two small terminals and the case/frame is isolated.

I HAVE NO IDEA if the solenoid you have is like the old "Ford type" which used the case/frame for ground and had S & I terminals orrrrrrrrrrrrrrrrrr the coil is between the two small terminals and the case/frame not used for ground ???? On a genset or lawn mower etc there's likely NOT any requirement for S and I terminals, just a coil between those two small terminals... 

Maybe take a 12 volt battery and some light jumpers and see which of the two small terminals causes it to engage and the one that does is the "S" Ima thinking ???   IF ITS AN OLD FORD TYPE or perhaps use an ohm meter as the solenoids coil (S terminal) will show coil continuity to the case/frame ground...

If its NOT a Ford type and does NOT use the case/frame ground, an ohm meter across the two small terminals will read the coil resistance and 12 volts applied across it will engage the solenoid.

OTHER ISSUES  

  That 30 ohms resistance IS NOT A GOOD GROUND it should read near zero. Its hard to get accurate low ohms readings on a cheap ohm meter. If the ground (or any connection) has some carbon resistance, once it conducts current it heats up and can open or become more resistive and drop more voltage.    

  Those 3 volt readings (subject to where measured) could be a BAD or dead battery orrrrrrrrrrrr there's a bad connection (including a bad ground) dropping all the voltage!!!!!!!! It (if bad battery) either needs a good charge or it may be totally shot. While a good charger should revive it, there's a chance its completely shot. Have a shop load test it 

 The low voltage which suddenly rises could be a bad connection that heats up and opens or increases in resistance...

  Since the substitute battery made it work fine, I question the existing battery orrrrrrrrrrrr else a poor resistive connection or poor resistive ground may be the cause. If the battery is just discharged but good otherwise the Converter/Charger when plugged to shore power should raise its voltage does it?? A full charged lead acid battery at rest and stabilized should read around 12.6 volts and when connected to a good working charger it should eventually rise to 13 to 14 volts.

 I would have the battery load tested just to be sure its NOT the problem,,,,,,,,,,Remove, clean and wire brush shiny each and every battery and ground connection (including any to frame) from battery to solenoid, you could even have a faulty cable not apparent just by looking. If the battery negative attaches to the RV frame so its used as the ground return current path and the genset ground connection also relies on the RV frame, any of those connections could be the problem. Check all the ground cables !!!

FIX THAT 30 OHM "GROUND" AND  CHECK THE BATTERY

John T   

Edited January 10, 2020 by oldjohnt

[Kirk W]

Like John, I think that your starting battery is very suspect and suggest that you take it to a battery store and ask them to load test it. Most places will do this with no charge. What you describe is typical of a very old and sulfated battery. I would also emphasize the point he made about that 30Ω resistance to ground is better, but still poor unless you have a meter that is not accurate. Resistance to ground should measure 5Ω or less. It could be either a bad connection or perhaps a bad cable between the solenoid and the ground post. I would try measuring the cable for resistance.

[oldjohnt]

  Yo Kirk, mind sharing  your opinion on his solenoid question??? On most of the RV, Genset, or lawn mower or many later cars I've seen that used the type of solenoid in his picture, those two small terminals POWER THE COIL and there was no case/frame ground circuit used NOR any S (solenoid activation) or I (Ignition resistor by pass) functions like the older Ford cars that had a ballast resistor and by passed it when cranking. I've slept since I worked on those lol. Of course EITHER type of solenoid could be made to work to power up and crank the genset.

 I agree it doesn't take much resistance in the ground return path to yield a substantial I x R Voltage Drop when you're passing maybe 40 or more amps.....Id hope for and expect a cheap meter to indicate perhaps near zero ohms.   

John T    Live from exhibiting (housed on site in my 29 Ft Class C) at the Florida Flywheelers Antique Tractor Show in Fort Meade Florida woooooooo hoooooooooooo 80 degrees

Edited January 10, 2020 by oldjohnt

[rickeieio]

Back to basics.....  We don't know for sure if the genny uses the coach battery to start.  We do know that a jump battery will crank genny, but he didn't start it.  So, before buying a battery, would it not make sense to take the suspect battery out and jump it like he did previously?  This might show whether he has a poor battery, or more likely, a bad ground.

In 50+ years of fixing farm equipment, it's usually the ground.

[Kirk W]

6 hours ago, oldjohnt said:

Yo Kirk, mind sharing  your opinion on his solenoid question???

My memory is a little sketchy on this too, but I did help a neighbor to put a very similar one into his lawn tractor but the spade connectors on his were stamped with an S & an I. In searching I was able to find this picture that may help. It isn't the same starter, but I suspect that the connections are the same. 

4 hours ago, rickeieio said:

We don't know for sure if the genny uses the coach battery to start.

While that may be true, I have never seen one connected any other way. There is good reason for that on a motorhome as it means that by using the cross connect you can start the generator to help if the chassis battery is discharged or visa versa. 

Edited January 11, 2020 by Kirk W

[Ray,IN]

To  both posters with starting problems. The very first step is to insure ALL wiring connections associated with the genset are clean and tight. FWIW, over 80% of 12V wiring issues are the result of a poor or missing ground.

After that free step is completed, then begin with the more complicated stuff, solenoids, switches, faulty equipment, etc.

I have seen battery cables that appear like new, cut away the insulation and the copper wires are green/corroded. Found a battery terminal clamp that was very corroded inside the crimp on the wires. The ohmmeter is your friend. 

Edited January 11, 2020 by Ray,IN

[WILDSIDE]

oldjohnt, Kirk W, Ray,IN, and rickeieio,

 

Thank you for all of y'alls suggestions. Thanks oldjohnt for the write up on the Ford type and non Ford type of solenoids. Kirk W thanks for the diagram. Both posts were highly informative. I'll see if I can get the solenoid to actuate using jumpers and one of my batteries from my charging station.

My plan is to bypass the RV (toyhauler) wiring and go from the existing batteries to the solenoid like what I did with the jump battery that previously turned over the genset. Then I'll see if I can half step it and add parts of the existing wiring until I can identify the ground / voltage drop issue. I'll swing by O'reilly's and have them load test the original batts Saturday morning when I pick up the cabling at the salvage yard. They've got battery cabling by the spools. I love that place...

Do y'all know where I can get wiring diagrams of the trailers 12V and 120V systems?

rickeieio - I'm running two batteries (875cca) in parallel. These run the 12VDC circuits such as the lighting, radio, water pump, heater blower and fridge as well as provide the spark for the genset. The internal 12VDC circuits are fully operational and battery drain is what I've come to expect which is that the batteries will run the heater fan all night in the 30° SoCal desert and still crank my extremely loud, yet operational 8KW genny that I've been hauling around with me this winter... So batteries may not be the issue...

I've got a bit of electrical experience but that was mainly with shipboard power which was 3 phase and 400Hz and checking continuity on various types of cabling. I do recall DC circuits from BEE(p) school... chasing grounds regardless of current type is a challenge. Thanks for reminding me of the importance of having minimal resistance - especially with grounds. The whole frame is a common ground. Continuity on this short of a run (frame ground front of the trailer to frame ground at rear) should be less than an ohm. The 30Ω reading from the genset gnd to the ground stud is excessive. I see that now. I apparently didn't clean the frame stud well enough. Either that or I have a combination of what some of you have mentioned; multiple gnd related issues. I'll inspect the battery terminals and cabling for corrosion and look under the insulation for hidden corrosion.  It might be time to replace the battery cables again.

Kirk - As I understand it, the solenoid is grounded to the frame at the bolting point. The S contact is the ignition switch. The opposite terminal of the battery connection (12.6 - 14VDC) goes to the starter. Does the I contact and starter terminal voltage levels remain at 0VDC until the S contact receives 12VDC? Once the genset starts running, the S level goes to 0VDC as I've released the start sw.  What happens to the voltage on the I and the starter terminal when the S post returns to 0VDC? I would expect that the I post would remain hot as it provides the battery voltage to the ignition coil but the starter post would go to 0VDC as I don't believe the starter would remain engaged with the fly wheel while the motor is running. Does the I contact stay hot until the kill (gnd?) signal is received? Is the kill signal generated from the processor board? Is it as simple as closing a ground on the ignition coil? 

I'll y'all know what I find this weekend. I want to get this fixed so I am not out at the "self-imposed" outer ring of the camping circle next weekend due my periodically running of my behemoth 8KW genny...

Edited January 11, 2020 by WILDSIDE

[oldjohnt]

Wildside, thanks for the feedback...….I don't think I successfully explained how the old "Ford Type" solenoids function and what the S and I terminals do, so I apologize (NOT a GOOD TEACHER LOL) and let me try again.

NOTE its still my opinion many (NOT saying all) lawn mowers or Gensets or RV applications DO NOT use the Ford Type solenoids with S and I terminals and where the case serves as the ground current return path,,,,,,,,,, but instead,,,,,,,,,,The coil is located between the two small terminals and the case IS NOT used as a current return ground....They look like Ford solenoids but THEY ARE NOT

                                                                                          Ford Type Solenoids with S and I terminals

  If 12 VDC is applied to S when a start button or key start position is engaged and the case is bonded to the frame, current passes through the coil and the high current relay closes so the motor cranks BUT ONLY SO LONG AS  the start button/switch is depressed. When  its released, voltage on S (as well as I) returns to ZERO......… Again the case is the ground current return path and the coil is located between S and case...……...  

 ONLY WHEN voltage is applied to S does the I terminal also have voltage. Its used to feed battery voltage direct to a coil so as to eliminate and by pass any ignition ballast resistor LOOK AT THE DIAGRAM KIRK POSTED this is how older Ford solenoids with S and I terminals operates and YES the case serves as a conductive path.  BUT it may NOT be how your solenoid operates !!!!!!!!!!!! (see below)

NOTE Voltage on I DOES NOT remain hot so as to power up the ignition coil on older Fords, the coil continues to receive voltage as long as the key is in ON/RUN (NOT talking State here) position,,,,,,, its just ONLY when cranking the ignition ballast resistor is by passed because I feeds the coil direct ONLY WHEN CRANKING.  But when its removed the coil still has voltage via the series ballast resistor and ignition switch being On/Run.... The Control board kills the genset NOTTTTTTTTTTTT by using the solenoids I terminal   

HOWEVER if the solenoid has no S and I terminals but instead places the coil between the two small terminals and DOES NOT use the case as a conductor, if you apply 12 volts to the two small coil terminals the relay closes and if voltage is removed the relay opens.

EITHER solenoid type can be easily wired and operate to crank the genset BUT ON MANY MOWERS AND GENSETS AND OTHER APPLICATIONS the Ford type S and I solenoids that use the case as a conductor ARE NOT REQUIRED.  

 

GROUND PROBLEM  If there's any resistance in the ground current return path, which may be a cable or cable end or termination the I x R Voltage Drop can cause the genset or other load to fail BIG TIME. Look, V = I x R...…….If the genset starter more drew say 40 AMPS and there was as little as say a 0.1 Ohms of resistance, V = I x R = 40 x 0.1 = 4 Volts and if you only have 12 to start with 8 left for the genset is NOT ENOUGH.  That' why 30 ohms or 5 ohms or even one tenth of an ohm in the ground (cable or cable end or termination) IS NOT WORKABLE  However a cheap ohm meter cant measure low resistance very accurate, a cheap meter may well read near 0 ohms which is what Id hope for and maybe expect.

BOTTOM LINE if its NOTTTTTTTTTTTT any battery problem I suspect a faulty resistive ground. Remove clean and wire brush shiny each and every connector and bond and frame and cable connection. Cables can look fine to the eye BUT STILL BE BAD.........If a cable is connected to frame and the frame is used as current path, dirt or rust or water or crud or paint can yield voltage dropping resistance and as little a one then of an ohm IS TOO MUCH

 Try a new substitute ground cable and connections from battery direct to the genset !!!!!!!!!!!!!!!!!!!!!! 

Whewwwwwwwww nuff said, but hey I try my best

Let me know what you find

John T

 

[Kirk W]

2 hours ago, oldjohnt said:

HOWEVER if the solenoid has no S and I terminals but instead places the coil between the two small terminals and DOES NOT use the case as a conductor, if you apply 12 volts to the two small coil terminals the relay closes and if voltage is removed the relay opens.

Since your present terminals are not marked for s & I, it would be my guess that you have what John is describing here. If the previous solenoid had S & I terminals then you probably should replace it with one of that type. 

9 hours ago, WILDSIDE said:

As I understand it, the solenoid is grounded to the frame at the bolting point.

That is only true for solenoids that use the S & I terminals. If yours will engage by applying 12V across the two small terminals, that means that you don't have the S & I type of setup. If the solenoid uses a case ground then it should engage with +12V applied to the S terminal and the negative connected to the mounting case. If you use an ohm meter you can determine which you have because you will read a very low resistance between the two small terminals and open between either one and the case, if you have the type without any S & I terminals. 

[WILDSIDE]

1 hour ago, Kirk W said:

Since your present terminals are not marked for s & I, it would be my guess that you have what John is describing here. If the previous solenoid had S & I terminals then you probably should replace it with one of that type. 

That is only true for solenoids that use the S & I terminals. If yours will engage by applying 12V across the two small terminals, that means that you don't have the S & I type of setup. If the solenoid uses a case ground then it should engage with +12V applied to the S terminal and the negative connected to the mounting case. If you use an ohm meter you can determine which you have because you will read a very low resistance between the two small terminals and open between either one and the case, if you have the type without any S & I terminals. 

I measured 4Ω between the two tabs on both the original and OEM replacement solenoid.

 

[WILDSIDE]

40 minutes ago, WILDSIDE said:

I measured 4Ω between the two tabs on both the original and OEM replacement solenoid.

 

I tested the solenoid this a.m. with it mounted in a vice which is isolated from ground - its mounted to a wooden bench... I connected the positive 12V from the positive battery terminal to the input terminal and the negative battery terminal to the frame / mounting point / vice. I then grounded the right small post (don't know if it is the I or S post) to the same potential as the negative battery connection. When a ground (same potential as negative terminal) on the left small terminal, nothing happened. Then I applied 12.3VDC to the left small post and measured 11.9 - 12.1V at the starter terminal of the solenoid. I'm curious to the cause of the voltage drop...

I removed the ground from the right small post and applied 12.3VDC to the right small post and measured 11.9 - 12.1V. I'm still curious as to the 0.2 - 0.4VDC drop...

This is what I measured:

1. 4Ω between the two small posts

2. O.L between batt post and starter post with nothing terminated to the small posts

3. 12.3V on the batt between the + and - terminals

4. 11.9 - 12.1VDC with a ground on either small post and 12.3VDC applied to either of the opposite small posts

Observations

1. With S grounded and 12VDC applied to I, the post that is not grounded, the solenoid relay closes and allows voltage on the starter terminal and current to flow to the starter. I don't know which post is S or I so I conducted the same test and swapped + and - and observed the same indications when the opposite post was grounded and 12V was applied to the other post.

2. Nothing happens if both S and I posts are grounded

3. Nothing happens if both S and I posts are tied to 12V.

4. I tested both the original and replacement (OEM) solenoids and observed the same measurements and voltage drop with  a ground on either post and 12V on the opposite post.

 

Take aways:

1. Both the original and replacement solenoids provide similar results.

2. Both solenoids appear to be operational - taking into consideration the voltage drop as being acceptable.

Assumptions

1. I have a ground related issue on my trailer that is impacting the genset 12v circuit.

2. Batteries are still suspect and will be tested today.

 

 

 

[oldjohnt]

3 hours ago, WILDSIDE said:

I measured 4Ω between the two tabs on both the original and OEM replacement solenoid.

Wildside  4 Ohms between the two terminals is reasonable and at 12 volts would draw 3 Amps SOUNDS FINE AND WHAT ID EXPECT...

So, if you review my post above:

 

8 hours ago, oldjohnt said:

Ford Type Solenoids with S and I terminals

  If 12 VDC is applied to S when a start button or key start position is engaged and the case is bonded to the frame, current passes through the coil and the high current relay closes so the motor cranks BUT ONLY SO LONG AS  the start button/switch is depressed. When  its released, voltage on S (as well as I) returns to ZERO......… Again the case is the ground current return path and the coil is located between S and case...……...  

 ONLY WHEN voltage is applied to S does the I terminal also have voltage. Its used to feed battery voltage direct to a coil so as to eliminate and by pass any ignition ballast resistor LOOK AT THE DIAGRAM KIRK POSTED this is how older Ford solenoids with S and I terminals operates and YES the case serves as a conductive path.  BUT it may NOT be how your solenoid operates !!!!!!!!!!!! (see below)

HOWEVER if the solenoid has no S and I terminals but instead places the coil between the two small terminals and DOES NOT use the case as a conductor, if you apply 12 volts to the two small coil terminals the relay closes and if voltage is removed the relay opens.

 You can easily determine

  a) Ifffffffff its an old "Ford type" of solenoid with the S and I terminals, the coil (4 ohms) is between the S terminal and the case...…... 

  b) Iffffffffffff its like many lawn mower or genset solenoids that are NOT "Ford type" the 4 Ohm coil is between the two unmarked terminals ONLY and the case IS NOT used as a conductor. The same NON "Ford type" would measure an open circuit from EITHER small terminals to case.  

   NOTE if your solenoids two small terminals are unmarked and it measures 4 ohms one to the other and an open circuit from either to case YOU DONT HAVE AN OLD FORD TYPE SOLENOID  !!!!!!!!!!!!!!!!!!!!!!!!!!!!

  When you said you measured 4 ohms between two tabs,  my guess is two UNMARKED tabs and NOT any S or I marked correct ???? And 12 volts across those two tabs will engage the solenoid to crank the genset yayyyyyyyyyyyyyy

 YOU STILL NEED A GOOD EXTREME LOW RESISTANCE GROUND PATH FROM BATTERY TO GENERATOR so work on that per my advice above, let us know what happens and post back any questions. Its not uncommon for one of the ground cables or its frame connection (battery to frame OR genset to frame) to be faulty and resistive CHECK THEM for rust or corrosion or crud or paint   

Best wishes and God Bless, hope this answers any solenoid questions

John T

Edited January 11, 2020 by oldjohnt

[oldjohnt]

2 hours ago, WILDSIDE said:

Take aways:

1. Both the original and replacement solenoids provide similar results.

2. Both solenoids appear to be operational - taking into consideration the voltage drop as being acceptable.

Assumptions

1. I have a ground related issue on my trailer that is impacting the genset 12v circuit.

2. Batteries are still suspect and will be tested today.

Wikdside, thanks for the update  FWIW      I LIKE YOUR TWO ASSUMPTIONS      (but add to them a third possible faulty  HOT cable or connection as the problem)

   Try a temporary big cable ran from battery Neg direct to gensets frame and see what happens ????????? Iffffffff she's fine that way but NOT otherwise, then suspect a bad ground cable itself (may still look okay)  orrrrrrrrrr a faulty resistive (loose or corroded or burned) battery neg cable to frame ground connection orrrrrrrrrrr a faulty genset to frame ground connection. Been there done that myself and they can look okay but still be bad. Remove, clean, grind and wire brush shiny can help cure the problem. Of course, even where the cable attaches to the gensets frame can be bad.

NOTE Even the connections at the battery (Pos and Neg) may be the problem, check them all also... 

NOTE Even the HOT cable or its connections can be the cause as well as ground !!!!!!!!!! The same above applies to all the hot circuit cables and connections including the battery

PS its possible a solenoid can still function but carbon pitting or burning on the contacts can still yield a small I x R voltage drop

Best wishes, post back your findings. There may be OTHER possible problems besides these I mentioned, and if so hopefully the other good gents can add them to this...…………... 

John T

Edited January 11, 2020 by oldjohnt

[WILDSIDE]

10 hours ago, oldjohnt said:

Wildside  4 Ohms between the two terminals is reasonable and at 12 volts would draw 3 Amps SOUNDS FINE AND WHAT ID EXPECT...

So, if you review my post above:

 

 You can easily determine

  a) Ifffffffff its an old "Ford type" of solenoid with the S and I terminals, the coil (4 ohms) is between the S terminal and the case...…... 

  b) Iffffffffffff its like many lawn mower or genset solenoids that are NOT "Ford type" the 4 Ohm coil is between the two unmarked terminals ONLY and the case IS NOT used as a conductor. The same NON "Ford type" would measure an open circuit from EITHER small terminals to case.  

   NOTE if your solenoids two small terminals are unmarked and it measures 4 ohms one to the other and an open circuit from either to case YOU DONT HAVE AN OLD FORD TYPE SOLENOID  !!!!!!!!!!!!!!!!!!!!!!!!!!!!

  When you said you measured 4 ohms between two tabs,  my guess is two UNMARKED tabs and NOT any S or I marked correct ???? And 12 volts across those two tabs will engage the solenoid to crank the genset yayyyyyyyyyyyyyy

 YOU STILL NEED A GOOD EXTREME LOW RESISTANCE GROUND PATH FROM BATTERY TO GENERATOR so work on that per my advice above, let us know what happens and post back any questions. Its not uncommon for one of the ground cables or its frame connection (battery to frame OR genset to frame) to be faulty and resistive CHECK THEM for rust or corrosion or crud or paint   

Best wishes and God Bless, hope this answers any solenoid questions

John T

Both of the two small posts are unmarked. Both are open between the frame and post. The 4Ω measurement is only between the two small posts that are not labeled as S or I.

 

[WILDSIDE]

10 hours ago, oldjohnt said:

Wikdside, thanks for the update  FWIW      I LIKE YOUR TWO ASSUMPTIONS      (but add to them a third possible faulty  HOT cable or connection as the problem)

   Try a temporary big cable ran from battery Neg direct to gensets frame and see what happens ????????? Iffffffff she's fine that way but NOT otherwise, then suspect a bad ground cable itself (may still look okay)  orrrrrrrrrr a faulty resistive (loose or corroded or burned) battery neg cable to frame ground connection orrrrrrrrrrr a faulty genset to frame ground connection. Been there done that myself and they can look okay but still be bad. Remove, clean, grind and wire brush shiny can help cure the problem. Of course, even where the cable attaches to the gensets frame can be bad.

NOTE Even the connections at the battery (Pos and Neg) may be the problem, check them all also... 

NOTE Even the HOT cable or its connections can be the cause as well as ground !!!!!!!!!! The same above applies to all the hot circuit cables and connections including the battery

PS its possible a solenoid can still function but carbon pitting or burning on the contacts can still yield a small I x R voltage drop

Best wishes, post back your findings. There may be OTHER possible problems besides these I mentioned, and if so hopefully the other good gents can add them to this...…………... 

John T

I took the batteries in and both checked out good under load.

I had to order the battery cables as my salvage yard had a clean out and no longer carries cables. They should be here early next week. I'll use my jumper cables to continue troubleshooting what I am accepting as a ground issue. I'll focus on terminations and closer inspect the battery cables between batteries, the frame gnd, and the genset gnd.

[WILDSIDE]

11 hours ago, oldjohnt said:

Wikdside, thanks for the update  FWIW      I LIKE YOUR TWO ASSUMPTIONS      (but add to them a third possible faulty  HOT cable or connection as the problem)

   Try a temporary big cable ran from battery Neg direct to gensets frame and see what happens ????????? Iffffffff she's fine that way but NOT otherwise, then suspect a bad ground cable itself (may still look okay)  orrrrrrrrrr a faulty resistive (loose or corroded or burned) battery neg cable to frame ground connection orrrrrrrrrrr a faulty genset to frame ground connection. Been there done that myself and they can look okay but still be bad. Remove, clean, grind and wire brush shiny can help cure the problem. Of course, even where the cable attaches to the gensets frame can be bad.

NOTE Even the connections at the battery (Pos and Neg) may be the problem, check them all also... 

NOTE Even the HOT cable or its connections can be the cause as well as ground !!!!!!!!!! The same above applies to all the hot circuit cables and connections including the battery

PS its possible a solenoid can still function but carbon pitting or burning on the contacts can still yield a small I x R voltage drop

Best wishes, post back your findings. There may be OTHER possible problems besides these I mentioned, and if so hopefully the other good gents can add them to this...…………... 

John T

What's a hot cable? Are you referring to the positive side of the 12V ckt?