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Where do I get a electrical troubleshooting manual for a W1A64T?

I have had some ground issues and wiring problems in my truck over the last couple of weeks. In fact, it is in the shop this morning due to a ground issue keeping it from starting with the ignition key. We are suspecting the wiring, after troubleshooting the alternator, starter and batteries.

Here are some of the issues I am having, in addition to the truck not starting: My bunk HVAC has completely died and the cab air conditioner keeps cutting in and out when I go over bumps. I am getting static and error messages on my Cobra 29 LX CB radio and my AM/FM radio when the A/C is on and the engine is running. The voltmeter intermittently drops to 11.9 when accessories and headlights are running (needs to be 12.6).

I am suspecting a bad ground, but it's being a pain to find... and I would like to get a wiring diagram for this model of tractor. I can't find info other than a basic service manual on Volvo's web site. Should I contact a dealer about this?

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UPDATE: Found another wiring problem with this truck.. the Red wires going to the A terminal inside the fuse panel easily get pinched by the panel itself. Make sure when troubleshooting this model of truck that if you have problems with the volt meter and/or gauges, you check ALL the wires in the dash and fuse panel, make sure all the connections are tight and no wires have been bent or pinched.

I will likely be getting a new fuse panel wiring harness (or possibly a new fuse panel or a newer, supported model used truck (perhaps a 2000 Pete 378, 1997 Freightliner FLD or a late-model Volvo VN)) if this problem can't be resolved this weekend.

If I end up getting a different truck, the old red "sleigh" will surely be missed... yeah right!


Found the pinched wire... It was the red one going from the ignition key switch to the A terminal in the box. The connection was also loose, so the wire was replaced, the connection was re-tightened, the wires were re-routed and the rest of the wires near the fuse panel passed the inspection with "flying colors." I also re-spliced some wires in the dash, installed a new Volvo washer pump and new load lights on the back of the cab during this service. Once the electrical inspection was complete, I replaced any blown fuses with new ones and reset the circuit breakers. I had a helper assist me with the inspection (both the ignition switch wire and load lights were a 2-man job).


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'''I don't have access to the wiring diagram that you are looking for but I have worked on several trucks from different manufacturers that have had some of these issues and I will say that you can never have enough ground straps. First I would look down the frame rail and try and locate some of these grounds, if you find them take them loose and sand or grind the frame and the grounding lug so that you have a good connection and after bolting it down tight shoot it good with some primer or paint for protection.

Ground straps that you may not have but will help you system operate more efficiently. Run a 8 or 10 gauge ground wire from the alternator ground post around the engine to the ground post on your starter, run a ground wire from the same alternator ground post straight to the frame rail. Run a ground strap from the ground post on the engine starter to the frame rail. Run a battery size ground cable from your negative side of your batteries to the frame rail, if your batteries are split up into two groups one on each side of the truck ground both sides.

I would also look for grounding straps from the cab to the frame if you can't locate them add a ground strap from the cab and the sleeper to the frame rail.

With all of these components properly grounded your system will operate more efficiently. Remember you can't have too many ground straps. 'italic text''

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I got the shop to re-run the dash to frame ground, re-tighten the other dash ground at the ECM and re-tighten some screws in the fuse panel. That, combined with a defective solenoid/starter relay was the root cause and has been resolved. I also have asked the boss to order and operators manual and shop manual for this model if it's available from Volvo.


Blackwood, you are also right about ground straps- you can never have too many of those.


Blackwood, you have been very helpful on this issue. I was able to get a helper along with a wiring diagram and someone with experience with this exact problem/truck over the weekend. Found another pinched wire, and 1 loose connection, which were both fixed... for good.


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Zachary will be eternally grateful.
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