QuestionQUESTION: Is there any way to check the BCM in a 91 plymouth voyager 2.5l. Now when starting the fuel pump will SOMETIMES work. The gauges still will not work, also when starting in the cold you must keep it running by reving it up or it will stall if it is not warm; also when you restart the car after its warm you must put the gas all the way to the floor once it starts after you let the pedal all the way up it has a really high idle (id say it is about 3/4 pedal if I made it rev that high) that lasts for 10 or so seconds. When driving it is not shifting into overdrive. I'm 100% postive it is a electrical problem, I have tried a new ignition,gauge cluster, computer,and checked all electrical wires/grounds and everything points to the BCM. This van has been taken care of fluids where changed at regular intervals and this has never been beaten on, this is why it has 245,000 miles with the orgional engine and tranny. Any help with checking th BCM or if you know of any places that can do it would be great.I live in Westport,MA Thanks.
ANSWER: Hi Jesse,
I believe you are really more interested in the powertrain control module (pcm) not the body control module (bcm). The best thing to do is use the ignition key to get any fault codes that might be stored in its memory:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light, which remains 'on', to see it begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat the process to be sure you have the flash counts accurately. Then let me know the flash counts in the order that they appeared. Once we have fault codes we can move on to solve the problems. The last two sets of flashes will always be 5 in each as that is the code for "end of readout".
Roland
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QUESTION: I tried to use the ignition but when i did it the light did not flash at all I tried it 3 different times. One day about a month ago I started it all the gauges worked and the check engine light was on then all of a sudden while driving all of the gauges died and the check engine light went out too.I do have a code reader but i can not get the van to start because the fuel pump will not work(its temperamental it only works when it wants to). Should I bypass the relay and run power to the pump and then try to start it and then use the code reader? I also looked for a PCM on a 91 voyager online and I found no results I only found them for newer models, is the PCM the same as the BCM? Thanks for all of the help.
ANSWER: Do the left and right turn signal warning lights in the 'warning light center work? If not, check the ground (black/orange) wire from the warning lights to the ground point on the left side kick panel, to the left of the driver left leg. We need to get that check engine light back on, maybe change out the bulb for it. It is energized by pin 56 of the engine computer under the hood so you could put a pin in that wire (gray/pink) and measure between that pin and ground and that count the 'flashes' that you would other wise see if the bulb worked. The bcm is the body computer and is not the pcm which is the powertrain computer. You don't have to run the engine to read the codes. Just have the ignition switch in the run position if that is the instruction for the code reader; just follow the reader instructions. Have you checked fuse #15 which is needed to power the body computer?
Roland
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QUESTION: When I turn the ignition on all of the idiot lights work even the check engine,after i cycle the ingnition and leave it in the "run" position only the brake,airbag, and oil light turn on. When I try to start the van all of the lights turn off execpt for the airbag that flashes then turns off.So im gussing it may be a computer not relaying a code/flash to the bulb.I already used a different good computer from another van and I still have the same problems.This all hapened when the spedometer quit and over time it got worse this is the order these problems occured in:
1.gauges stopped 2. fuel pump sometimes worked 3. Rough idle until warm/hard to start in hot weather if motor was warm 4.overdrive not working 5. Random stumble while driving This took place over a couple of months.
Where do you get your manuals from they seem really detailed?
I will see if I can post s youtube video of it and I will give you the url.
Thank You so much Jesse
AnswerHi Jesse,
There is no problem to jump the fuel pump relay for service/diagnostic purposes, so long as it runs ok, and of course you have to remove it to shut it off when you are done, and to not have any fuel leaks which would cause a fire. I also wouldn't drive it around like that regularly because if you have an accident it will keep running and that is a fire hazard. That is the purpose of the autoshutdown system so you don't want to defeat that on an on-going basis.
The check engine light, in contrast to the other lights which are powered by fuse 15 and go to various sensors/switches and thus will continue to work, gets its sole power from the pcm pin 56 on a gray/pink wire. I still don't understand the check engine light: it should go off while you are trying to start it, but then when it won't start it should stay 'on' while in the key is in the run position. If that is not happening, and then I assume that if you turn the key off and back to run it will come on, correct? And what happens if you cycle the switch "on-off-on-off-on and leave on" in less than 5 seconds elapsed time? Either you aren't doing the switching fast enough or there is a problem with the ignition switch not reliably powering the pcm, or the pcm is bad. The pcm is of course the computer in the engine compartment, the bcm is in the cabin and likely over on the right side kick panel?
I don't think I need to see a video...but if you want to go to that trouble it is ok.
I have the '91 fsm wiring diagram manual put out by Chrysler. Unfortunately, I don't have the rest of the manuals for that year, but I do have them for the cars of that year and the design is pretty consistent across all models with some minor exceptions. I get my factory manuals off eBay (search: Chrysler service manuals) but only buy from individual owners, not dealer in general because they think they are worth too much for my wallet.
Roland
