Katmandu

FINALLY!!! SUCCESS !!!!!!! My truck is back on the road !!!!!!!

All due to a bad (shorted out) CPS !!

The PCM and alternator were NOT damaged at all!!

Hopefully, others will learn from this experience.

I'd like to thank all of you who gave me very valuable information (and moral support!) !!

vzdude

Good deal! Finally got up to almost freezing here yesterday, I figured you were working on it! Unfortunately, I've been shown how gut instict isn't always spot on! Hopefully you can get rid of that pcm!

Katmandu

It was around (22) degrees here and I cohered my buddy into helping me with the stupid serpentine belt.

We're both 3rd shifters so we were at it around 7:30AM.

I had some real (Dodge) experts miss the diagnosis as well.

Did **** me off that my (old) local mechanic misdiagnosed my alternator due to LAZINESS! I told the dumbass that I already did the wiring check and the post check while it was ON the truck already. I took it to him (due to lack of my time), to yank it off and get it bench tested. He just redid the wiring/post check (like I already did) and claimed the alternator was SHOT! Too bad for him he lost a GOOD customer and anyone else that I get a hold of !

Guess maybe I'll EBay the other good PCM.

Katmandu

[quote=sweeney186;1909071]Correctomundo Mr.Sweeney!

Now we do know for a FACT that a bad (shorted out) CPS will cause ALL the gauges to stay down (to the left), shut current off to the (exciter wire) alternator show it as 0 volts output, show "NO PCM" from the OBD-II scan port and cause random idiot lights to come on/off.

Hope this info help some else down the road! Hopefully by using the SEARCH window!

machine2

i have a similar problem. my truck was running fine then all of a sudden the rpms went to zero, speed went to zero, ac turned off and alternator turned off. i restarted the truck and it was fine but then it did it again and again until finally it wouldnt even last one second and now there is nothing. the truck will run fine but everything shows the truck not running other then volt meter, oil and temp. i installed a voltage regulator in order to drive the thing but then i got a new pcm put it in and no difference. at the pcm i have ground, battery and ignition but no voltage coming out for crank position sensor. any ideas? all wires look fine.
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patdaly

Check fuse #9 if I remember correctly.

machine2

fuse is good

patdaly

Then you need to look at the Crankshaft Sensor circuit. From your description, it sounds like you lost it.

This is assuming your truck is a 94-94 12V.

manureman

I am having the exact same issues, but in addition, no headlights, no radio, and no air heater. Either PCM or CPS? Any ideas on which one to sheck? Alternator and batteries already checked out as being fine.

AlpineRAM

@manureman-this sounds more like a ground issue to me.

Just had a 2nd gen where one of the main splices for the grounds was corroded- the one behind the drivers side headlight.
The truck started the windshield wipers with turn signal left and some other rubbish.
On the 12V the crankshaft sensor is often overlooked- no signal means no charging, no AC, no tach.
Short to ground on the +5V means that the PCM does not work- sometimes up to a point where the truck won't shift right. (47RE)
Another point to check is the wiring loom above the tranny to the PCM-a short or a broken cable there leads to some weird issues too.

@ machine2-
Yours sounds like the classic +5V sensor supply shorted to ground. The PCM will only deliver a certain amperage on this circuit and then shut down the 5V supply. Take a shop manual and measure all the sensors for resistance against ground. You can find the pins on the PCM plugs that are for these sensors, and a good ground, measure Ohms - none should be at low ohms.

HTH

AlpineRAM

Dodgeoilburner

I just had the exact problem you described and after hearing what you wrote i'm sooooo happy i'm not going out to buy a new pcm........Thanks to everyone who contributed to this forum!