Re: Electrical Stuff (archive)

Kurt,
My personal feeling is not to jump to conclusions with ANY part of the electrical system in the E-31. The E-31 electronics are highly integrated between all systems: engine, ignition, transmission, stability and traction control, brakes, etc. Any of the fail safe modes (Limp Home, Transmission) can occur due to a wide variety of reasons, which is what makes electrical troubleshooting so difficult with our beasts. If you go into a fail safe mode, don't assume anything (remember that the definition of assume is making an ass out of u and me!). The best (and probably only) way to properly diagnose electrical problems is with the mechanic's plug-in test machine usually called a Modic (sp?). There are now three versions I, II, & III - each is more sophisticated in it's abilities. The original Modic I can perform basic tests and readout error codes, the Modic II can also separately activate any subsystem within the car, and I'm not sure about the specs on the Modic III as they have just recently come out and I've only heard about them once. The dealers will have them, but if you use an independent, make sure they have one. I was given to understand that they are around $8-10K US each.

As far as locating items:
1) If you follow the air hoses from the air filter box, they attach to the throttle bodies. The large black cylindrical item that sits at right angles to the throttle body and looks like a sealed electric motor... is the DK motor. There's a large electrical plug attached to it. Unless you know what you're doing with stepper motors, don't try to take the DK's apart. There was a post many moons ago about someone who rebuilds these, but I can't recall any details. You can clean the throttle bodies by spraying carburator cleaner into the throat while the engine is running. You have to start the car prior to removing the air hose from the throttle body. (We went through this on the board, use the search for details).

2) Pulse senders are located in front of the timing case cover, to the right side (alternator side as you look at the front of the block) of the main gear. There is a pulley between the main gear and the alternator, and the sensors are above and below this pulley. There is a test procedure in the repair manual for checking sensors - checking resistance and shielding and using an oscilliscope to check timing. Replacement involves a fair amount of work involving removing the fan, loosening the power steering pump console and moving hoses and lines out of the way to get at them (at least that's the details in the manual).

Again, I do not recommend just replacing items (which is usually the dealer's method) and take the time to run proper diagnostics. Also, mechanics with good experience on 750's can go a long way toward helping, even if they are not as familiar with the 8's.

Regards,
Stan C.

Follow Ups:

Thanks Stan & Steve, so much to learn Kurt.G 13:11 11/07/2000 (0)

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