Controlling engine fan with adjustable thermostat and relay kit

[Parrformance]

For those that have rewired your engine fan to kick on either from a switch on the dash for a thermostat, can you share what method you used

I would like to use a thermostat the switch the fan on at the appropriate temperature so that I don't have to think about it or switch it on from a switch on the dash

[spindrift]

Shouldn't your cut-in and cut-out range already be programmed into your ECM?

[Darryl&Rita]

The automatic function should be already there, manual is just a switch to activate the solenoid involved. If yours isn't working automatically, fix that first.

[Parrformance]

Replaced the ECM with a used one.

The used one had this issue on startup.

I plan to add an adjustable fan controller until I figure out the issue.

Diesel Computer says wiring or relay.

I can jump 12v to the solenoid and turn the fan off.

With the fan controller I ordered, it looks like I can swap a normally closed relay in place of the normally open one.

This will power the solenoid when the fan doesn't need to be on.

Edited September 19, 2021 by Parrformance
Add info

[TD1]

Pre ECM trucks did this. Horton N.O. 205 degree (normally Open) switch installed in the water manifold. Power or ground going in and out when coolant temp reaches 205 depending on your thermostat usually 10 or 15 degrees higher than your thermostat. Turns off at 200  The wires  go to your fan solenoid. You run a ground or power to the N.O. switch on the engine to your dash switch for manual overide. You must also run a signal wire from your A/C high pressure switch to turn the fan on when your A/C is on. Make sure you wire in all three many times guys would try to run it with just a switch and would end up forgetting to turn it on. Overheating the engine or blowing the A/C high pressure relief. The wiring schematic was included with the Horton fan solenoids and temperature switches. Some used switched power most used switched ground with 12 volts constant power at the fan solenoid.  The water switch will have 2 screw terminals on one side you will have 1 wire on the other 3 a wire to the solenoid, a wire from the A/C switch and a wire from your dash over ride switch all will engage the air solenoid turning on the fan

[Parrformance]

For those that know, is there a difference between Electronic fan drive, and the air activated fan drive?

I suspect that the used ECU that I purchased, nay have been on a truck with a variable speed electronic fan.

My truck has an electrically activated air solenoid, normally closed for fan control.

I assume these parameters may be adjustable in the ECM?

I do have access to a Diesel Laptops computer.  We used the computer to reset the Max speed parameters. 

[RandyA]

On 9/19/2021 at 2:48 PM, Parrformance said:

For those that have rewired your engine fan to kick on either from a switch on the dash for a thermostat, can you share what method you used

I would like to use a thermostat the switch the fan on at the appropriate temperature so that I don't have to think about it or switch it on from a switch on the dash

I had to do that on my '04 Volvo.  The air solenoid block sprung a leak and the fan was staying on all the time.  I tried retaining the signal from the ECM to the new solenoid but something was wrong there too.  This robbed me of at least 30 hp and was very noisy.  My fix was a thermostat from Amazon             with the sensor in the radiator fins and using a Bosch relay wired as the broken pneumatic block was to control the solenoid.  I had several single air solenoids I bought on eBay and tapped into an air line on the firewall used (I think) for the long ago removed hitch slider release. This was maybe 5 years ago.  It is still working fine.

[Parrformance]

Thank you Randy, this is what I was looking for.  I realized I needed no volts for fan on and 12 volts for fan off.

I did a little research and realized I could use a double throw relay to accomplish what I needed.

I ran out of time last night, but it seems as though I have 5 volts on the ground leg of the fan solenoid circuit.

I also have no pre heater function, and the pre heat relays and fan solenoid share power from fuse 70.

I had hoped for an issue with this leg, but continuity and voltage are all good from fuse to solenoid.

Will check the ground side from ECM to solenoid next.  Hoping to find the phantom voltage there.  I think I will check the EM connector next for green crusties.

Both the 12v leg and ground leg pass through this connector.

Thanks RandyA

[podwerkz]

There should be a fuse (marked FAN or FAN CLUTCH) on the firewall (under the hood) that when pulled, will default the fan clutch to ON. If you wired in a thermostat, relay, or switch, in series with that fuse, you should be able to manually control the fan clutch if you (or someone) wants that ability.

But the ECM should be able to activate the fan clutch (on and off) automatically as needed, based on various temperature sensors.

 

Edited September 22, 2021 by podwerkz

[Parrformance]

I am pouring over multiple schematics.

More importantly component location diagrams.  The VED12d engine in my 2006 Volvo, manufactured 07/2005 is supposed to have a fan speed sensor on the front of the block near the fan clutch.

Perhaps someone can explain why I do not see a sensor near the fan clutch, nor any wire looms near it either.  

I am getting a fan speed error on the display, AND a pre heat error.

The fan solenoid Y35 and the Engine pre heat relay RLY42 share 12Volts from fuse 70 leg B through Splice SP592B.

Ground leg out comes from ECM connector B pin 49 through Connector EM pin 11

[Parrformance]

 

[Parrformance]

[RandyA]

I apologize for not offering more detail about my conversion.  I was just released from the hospital today after surgery to remove my prostrate (cancer).  As soon as I am able I will pull my schematic to share with you so that you have more detail.  I too had some errors appear on the DID but they simply disappeared.  I guess the EECM got tired of posting them 😉.  Anyway, from what I can see you are on the right track.  Unfortunately, the fuse podwerkz referenced on the firewall hadn't been included on my 2004 D12. 

[Parrformance]

I hope you recover soon.  I had to take a break on the truck diagnosis to install a mini split in my son's garage. Oh and fix the drier, and replace the faucet in the camper and.....

I hope to get back at it tomorrow.

I would need to understand the tying into the high pressure switch for the AC.

Edited September 25, 2021 by Parrformance
spelling

[Parrformance]

For those of you who are more experienced in wiring relay circuits.

I would like to use a Painless Adjustable fan controller.  I would splice the 12Volts from the original Volvo pigtail at the air solenoid to the pin 30 on the relay. I would splice the other half to the 87a terminal, to allow for 12 volts to the air solenoid to shut off the fan until the thermostat trips the relay, if I have that right. (Normally Closed).

I would expect as to the thermostat reaches set temp it would trigger the relay to open 87a and close 87 removing 12 volts from 87a and turning the fan on.

If this all seems kosher, where and how should I add a wire to the high side switch on the AC?

[Parrformance]

So....got the adjustable thermostat and relay wired up, fans coming on around 160°F.

Just need to know if I should tie into the high pressure side of the AC, and where to connect it in the relay.

[Darryl&Rita]

Parallel with the temp switch. You want either switch to turn on the fan.

[Parrformance]

 Thanks Darryl, so just piggy back the high pressure leg and piggyback the lead going from the adjustable resistor to the relay?

Not sure how the high pressure switch works, will it provide ground to the relay and kick the fan off, I'm getting confused?

 

 

[Darryl&Rita]

I'm too lazy to look up the wiring diagrams, but basically you want the high pressure switch to do the same thing as the temp switch. If the temp switch has +12 v on one side, and switched power to the relay, you want +12 v to the high pressure switch, and switched power to the same terminal of the relay. Other side of relay to ground. If Volvo, like Paccar, switches grounds, then ground to the switches, then out to the relay. Other side of relay gets the +12 v.

[rickeieio]

2 hours ago, Parrformance said:

So....got the adjustable thermostat and relay wired up, fans coming on around 160°F.

Are you sure you want it to come on so low?  I would think somewhere around 210-220 would be correct.

We just had this discussion with a topic posted by "sculptor".

[Parrformance]

3 hours ago, Darryl&Rita said:

I'm too lazy to look up the wiring diagrams, but basically you want the high pressure switch to do the same thing as the temp switch. If the temp switch has +12 v on one side, and switched power to the relay, you want +12 v to the high pressure switch, and switched power to the same terminal of the relay. Other side of relay to ground. If Volvo, like Paccar, switches grounds, then ground to the switches, then out to the relay. Other side of relay gets the +12 v.

Ok, I will try and make heads or tails of this and attempt to wire it in.

I set the fan to start at a lower temp until I can get the AC high pressure switch figured out.

Seems as though I may need to purchase the trinary switch.

[Parrformance]

Nope, the Trinary switch is not what is needed. I don't need the fan on whenever the AC is on.

More research tomorrow.

[Stan Wright]

Here's what I did:  http://hdt.eurekaboy.com/fanswitch.htm

 

[Jim & Wilma]

6 hours ago, Stan Wright said:

Here's what I did:  http://hdt.eurekaboy.com/fanswitch.htm

 

Good write up Stan.
Question, do you know what production years the pin assignment is applicable?

[Stan Wright]

I do not.  The article with this information was from 2015, and my truck is a 2004.