Recently my van has no power locks, interior lights, HVAC controls, rear wiper.. etc. Seems to be BCM related to me. I looked at the power harness of the BCM and found all B+ voltages to be there. But I noticed according to the schematics (I have a haynes manual) that it sends an "ignition output (RUN)" signal to the HVAC.... which tells me that it should somehow know when I turn my key to RUN. But the schematic doesn't show this.... any idea how the BCM knows this? (I.E. anyone know which wire tells the BCM my key is in RUN)
Coupla comments: (1) I don't have the factory schematics of your van, but did you check (according to *factory* schematics - not fuse panel labels or aftermarket schematics, both of which are often incomplete or plain wrong) what fuses and circuit breakers power those things, and if there are some commonalities there? (2) Aftermarket (Haynes/Chilton) manual "typical" schematics are near worthless. Either a schematic is of your vehicle's system and is useful, or it is not an accurate and complete representation of your system and is worthless - in the same way a "typical" map - say, showing how to get from LA to Seattle, - would be worthless - say, for driving from Miami to Wheeling.
Let me suggest that, if you don't want to spend the $90 or so for a factory shop manual (FSM), spend the $25 for a one-year on-line
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subscription. With that, you will get on-line access to
100% complete factory schematics for the vehicle (along with some of the informational and procedural stuff out of the FSM and full TSB's specific to the vehicle). Even if this is the only time you use the information, would it not be worth $25 to you? (compare that to the cost of paying someone to troubleshoot and fix this problem for you)
Again, once you have some schematics that you can have some confidence in, I'd check power and ground common to the non-working systems first. THEN look at other things controlling them (like your ignition switch 'run' wire and BCM.
IMO...
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
Forget about the manuals right now and don't start unplugging things that will cause more problems. The first thing to do would be check the BCM for fault codes. A code reader will not do this, you will need a scan tool. You may find a fault code for a PANEL DIMMING SHORT. If so the BCM will need to be reflashed to correct this problem. Have you tried to reset the BCM by disconnecting the battery?
Yep... I disconnected the battery for a few minutes and while it was disconnected I shorted the pos and neg leads to discharge any decoupling caps that may be holding a charge in the BCM (or elsewhere)
Sounds like I should get it to a place that can read the codes out before I bring it in to the dealer in case it's something other than a total BCM failure.
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