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Thought I'd try the experts here...
I have a 2004 XC90 that has suffered an intermittent electrical problem for years, and Volvo never was able to figure it out while it was under warrantee, despite numerous trips to the dealer and wholesale replacement of modules in a seemingly random attempt to fix the problem. I’ll try to describe the problem the best I can, but the video here probably shows it best - http://youtu.be/cfcUr2LCdo4
I used to only have the problem on longer drives (several hours), but now it happens within 30 min or so, making the car almost unusable. Since it’s no longer covered under warrantee, I am looking at trying a few things myself to see if I can fix it and want to run it past the experts here.
Here’s the problem. The engine, lights, dash – almost everything – will “glitch” – that is, turn off then on quickly. You can hear many relays click when this happens. Once it does it once, it will do it again within a few minutes and eventually (within 4-5 min) the car will go into limp mode – no lights work (except headlights, perhaps brake lights, unsure) and you have to pull over, shut down and wait 10-15 min for it to cool down before it works again. The only thing that stays lit is the AC quadrant in the center console (see video for progression). Volvo believes it’s a module on the CAN bus that’s hanging up the bus causing other modules to “reset”, but was unable to figure it out.
Within the past month this has gotten worse, and twice has “locked-up” the car to the point that I had to disconnect the battery to get it back (nothing operational; locks, windows, starter, etc).
Some observations after living with this for years… It appears to be heat related, it happens more frequently when it’s hot, or when the engine is working hard, producing more heat. Because of this, I think it’s a module in the engine compartment, perhaps the ECU? Not sure what other CAN bus connected modules there are in the engine compartment. I am trying to figure out a plan of action, I am thinking of installing a remote thermometer in the ECU housing to track the internal temperature and see if the problem happens at a particular temp. If so, I’ll look at some ways to cool the box – perhaps a thermoelectric chiller installed in the cover? Is there already passive cooling that is perhaps clogged?
More drastic would be to pull the boards and inspect for bad capacitors (there were many around that timeframe), or perhaps do a hot oven PCB reflow of the solder if I suspect bad solder joints. I am an electronic hobbyist and have built my own PCB’s for microcontroller projects, so I am comfortable doing this.
Or, maybe I buy/build a CAN bus analyzer and sit it on the bus recording activity and find the smoking gun that way? I am leaning towards solving the heat problem since that’s what it appears to be...
Suggestions? Is this a known problem? Is there ECU cooling that I should look at first? Or perhaps I am looking in the wrong area? Any help appreciated!
SteveL
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