Volvo Gen 2 Electrical Schematics

[SuiteSuccess]

Anyone have access to a 2006 Volvo 780 electrical schematic?  I just got my truck out of the shop replacing ECM and reprogramming. Discovered I have no power to cigarette lighters or CB radio.  Checked fuse and it was good at panel. Also checked fuses at battery and they are good. Isn’t that power direct from battery?

[NeverEasy]

Cal,

Check your email.  Sent 3 pdf files.  Will have to send the rest later.  I don't spend much time in the Gen 2 arena so I am not sure which files to send.  I have to run off to a truck repair shop to put my 2001 in for brakes and clutch.

They are large.  Might not make it through the mail servers

Chet

Edited July 11, 2023 by NeverEasy

[RickW]

Carl,

If I remember correctly from my '04, the same fuse box & wiring harness are installed in all trucks.  The ECM programming is what turns the circuit on/off.  If I was a betting man, I would bet when they programmed the ECM they did not turn those two options back on.

--Rick 

[SuiteSuccess]

Thanks Chet and Rick. 

[SuiteSuccess]

2 hours ago, NeverEasy said:

Cal,

Check your email.  Sent 3 pdf files.  Will have to send the rest later.  I don't spend much time in the Gen 2 arena so I am not sure which files to send.  I have to run off to a truck repair shop to put my 2001 in for brakes and clutch.

They are large.  Might not make it through the mail servers

Chet

They are coming through. 

[SuiteSuccess]

Chet was kind enough to send me several schematics. Unfortunately they aren’t for my truck. Fuses and relays don’t fit what’s on my panel legend. Anyone have schematics for 2006 Volvo VNL 780?  Specifically tracing no power to cigarette lighters and CB studs. Or if anyone knows where I can purchase would appreciate it.

Should mention Resource Guide Schematics are what Chet sent. I don’t have a relay 29 which is supposed to control power. 

This is my fuse panel legend. 

Edited July 13, 2023 by SuiteSuccess

[DanZemke]

I googled:  pdf 2006 Volvo 780 electrical schematic

and received this as the first link:

https://www.volvotrainingsupport.com/-/media/vtna/files/shared/body-builder/wiring-diagrams/april-2017-p6605-modular-22622040_05_1.pdf

Like most Volvo service manuals, it doesn't indicate clearly which years it covers. 

Good luck!

[rickeieio]

I never would have thought to put "pdf" in the search line.  Good detective work Dan!!!

[SuiteSuccess]

Thanks Dan. 

[SuiteSuccess]

Think I’ve narrowed my search down to a bad relay.  Sent pictures to my “expert “ and awaiting his opinion.  Thanks to everyone’s help and lots of Google and YouTube seems the battery protection relay modulates power to cigar/12 volt sockets on dash and overhead, CB power studs, and dome/door lights…all things not working in my truck.  Took this and several relays home for testing.  It is a Volvo specific five pin relay and stands taller than the others and mine has a yellow sticker with part number.  It’s expensive at over $100 to replace, hence, waiting on second opinion.  This relay has lettered pins not the usual numbers (and typical proprietary goods) NO diagram on it.  I even peeled back the yellow sticker.  However, it looks like a typical five pin configuration with A (85?), B (30?), C (86?), D (87?), and E (87a?).  When I tested resistance across what I think is 85/86 got no reading.  My understanding is the coil and resistor should give between 50-150 ohms.  Additionally 30/87 and 30/87a both read 75 ohms while 87/87a read 142 ohms.  Not sure I understand that.  Would seem if it was “normally closed” in either 87/30 or 87a/30 there should be minimal to no resistance. Also the 87/87a reading points to both being close with some type of resistor in those circuits.  I’m not smart enough to figure this out so any help is appreciated.

[SuiteSuccess]

Pins are lettered clockwise from red probe A,B,C,D, and E center.  Will be testing socket on fuse board tomorrow to see which positions are energized.

Edited July 14, 2023 by SuiteSuccess

[NeverEasy]

Carl, Start at the socket, not the relay.

Pin 30 is 12 VDC supply on the socket.  Try this with the key on and off.   If 12 VDC is not there, it is a problem before the relay.  

I would think that the relay is there to only provide power when the key is on.  Therefore, the normally closed contact (87A) is not used.  

If there is 12DC there, put a 10 amp fuse in-line with a piece of electrical wire.  16 AWG is good enough.  With 12VDC on pin 30, touch pin 87 (the normally open contact) and see if your systems work.  If not, touch to pin 87A (normally closed) and see if that works.  

This test does not rely on ground on the relay but to be sure the relay is good, test for 12vdc on either 85 or 86 with the ignition switch on and off.  Ever which one has 12VDC is the trigger.  The other pin has to have ground to provide a path for current to ground when the trigger is applied.

[SuiteSuccess]

1 hour ago, NeverEasy said:

Carl, Start at the socket, not the relay.

Pin 30 is 12 VDC supply on the socket.  Try this with the key on and off.   If 12 VDC is not there, it is a problem before the relay.  

I would think that the relay is there to only provide power when the key is on.  Therefore, the normally closed contact (87A) is not used.  

If there is 12DC there, put a 10 amp fuse in-line with a piece of electrical wire.  16 AWG is good enough.  With 12VDC on pin 30, touch pin 87 (the normally open contact) and see if your systems work.  If not, touch to pin 87A (normally closed) and see if that works.  

This test does not rely on ground on the relay but to be sure the relay is good, test for 12vdc on either 85 or 86 with the ignition switch on and off.  Ever which one has 12VDC is the trigger.  The other pin has to have ground to provide a path for current to ground when the trigger is applied.

Ok going back to truck tomorrow.  I used a 12 volt battery at home across A & C (which I think is 85,86) and got nothing.  No clicks and no energizing 30, 87, or 87a.  That makes me think the coil is bad.  Normally my cigar/12 volt power sockets are energized even with the truck turned off so I was thinking that this was a normally closed circuit between 30 and 87a and that since it was battery protection, as voltage dropped, something would trigger 85,86 to shed the 30/87a load which is the sockets, cb, dome and door lights.   Am I thinking wrong?  I can use the same battery and will put 12 volt on 30 and should measure it on 87a correct?  If my hypothesis is correct then energizing 85,86 should make that 12 volts disappear? So I can also energize 85,86 to test.  

Edited July 14, 2023 by SuiteSuccess

[rickeieio]

I ask this because I don't know.....  Would it potentially harm anything to put in a regular relay?  Could something worse than a blown fuse become of it?

Reason I ask is \because John Deere does the same silly stuff, using special proprietary parts that far cheaper elsewhere.  Only difference is the markings on the cover.

[NeverEasy]

Carl, Call me before you head out to your truck. 

Major change to my post last night if you read it.  I got into the schematics that are on the Resource Guide.  There are two that specifically say they are for a 2006.

Do not attempt to replace the relay with a standard automotive relay.  The one in your hand is wired internally different and externally connected nothing like a standard relay function.

 

Note:  Volvo uses sheet positions to locate components.  The first digit is the horizontal number at the top or bottom.  The second digit is the vertical letter at the left or right.

The Wiring Diagrams are by alphabetical reference.  Easiest way to find one is to use the FIND TEXT Tool and type in the Wiring Diagram listing.  Ex:  AA takes you to the very beginning of the 12VDC system.  

The schematic that Dan sent a link to is not like the 2006 schematics on the Resource Guide.

One more thing:  Testing the relay with 12 VDC is  not a good idea at this point.  

You still need to go to the truck and check the voltage on the relay socket.  This may prove that the schematic and relay are as I expect them to be.  We can move forward if they agree.  I believe that you will find that 12VDC is on Pin D (87) rather than the usual Pin 30.  

Do not attempt to jumper anything on the relay as discussed earlier!!!

Here is what I have found so far:

PV776-20043814_ElectricalSchematic_V2_1105.pdf  Page 4 of this pdf says it is for 2006 Volvo
PV776-20175317_ElectricalSchematic_V2_0605.pdf  is also for a 2006 Volvo.  The circuitry appears the same as in the above pdf.

PV776-20047693_IllustrationIndex_V2_1105.pdf is the 2006 component location.

Use the Find Text Search button in Acrobat to enter search criteria for F79 and F48

F79
CB Power Studs
{AA 0 D} Fig. 1: AA page 7
{IF 3 A} Fig. 69: IF page 75

F48 
Batt. Prot./Beacon LPS 
{AA 1 C} Fig. 1: AA page 7
{HB 1 A} Fig. 58: HB page 64
{GI 3 A} Fig. 54: GI page 60

Note that on Page 75 (Wiring Diagram IF), the CB studs via Fuse F79 are direct connect to the BATT bus.  The BATT bus may be controlled by the "Power Relay Battery", RLY21.  I have not found a tie from the bus to the battery.

Note that on Page 64, F48 feeds the Battery Protection Relay (RLY44)and that relay shows both the ABCDE relay contacts as well as the 30,85,86,87,87A and the way it is wired and internally connected is far different from what the usual setup is. 

 #1  BATT comes in on Pin D (87) of the relay.  
 #2  Internally, there appears to be two coils that are interconnected such that 12 VDC is feed to both the coils.
 #3  Those coils are controlled by the Lighting Environment Control Module by putting a ground on Pins B or E.
 #4  Pin A (86) of Relay RLY44 is a ground trigger feed to pin 85 of RLY21, Power Relay Battery,  on Wiring Diagram AA (page 7). 

 

 

Edited July 15, 2023 by NeverEasy
Complete change in trouble shooting!

[SuiteSuccess]

Update:  Problem solved after much needed and appreciated help from Chet.  Turns out I could get my truck specific schematics from Volvo eMedia for free.  The setup to give power to cigar lighter, cab, cb,  and door/dome lights involves the battery low voltage protection system and two relays.  Working together they shed load to make sure you can still start the truck.  In my case, the R44 which is an expensive, double coiled relay was bad but my friend, Chet, had one in his stash of old scavenged electrical parts.  HOWEVER, after replacing the relay, still had no power.  Turns out in dissecting the schematics a fuse 52 allowed power to one side of R21.  I had previously checked all my fuses inside and at battery so was stumped but when I re-examined panel I found F52 missing.  Apparently the dealership in trying to diagnose my ECM problems had removed it (why?) and not replaced it.  New 5amp fuse and everything back to normal.

[NeverEasy]

Carl was amazingly patient.  Troubleshooting over the net is difficult at best.  I think he learned a lot about reading schematics and using a Digital Voltmeter.  In the end, he found the missing F52 on his own while doing some voltage and resistance checks.

The schematic we used that seemed to fit his truck best was on the Resource Guide.  I think the Gen 2 schematics were posted by Mark Bruss.  Thanks Mark.  That was schematic PV776-20175317_ElectricalSchematic_V2_0605.  That schematic was for a build date (June 2004) but further down it said it was for a 2006 Volvo.  

Cheers!  Chet

 

 

Edited July 21, 2023 by NeverEasy
Typo

[lappir]

Well done Carl. 

 

Rod