electrical ? problems

oleksy_1oleksy_1 Member Posts: 6
edited March 2019 in Chrysler
Trying to fix that for some 5+ years, 96 Concorde LXi 3.5 L, 145 000 km, ocasionally engine stalls, needlessly checked/replaced everything except PCM (replaced PCM with factory new unit at 60 000 km - reason: cooling fans were continusly on even with A/C off) , have factory repair manual, the only code 12 (do not tell me to clean up battery terminals - done that), 3 different mechanics could not find the problem. Chrysler dealer checked for latest software - O.K. Starts up within 1/2 sec, regardless of the weather, temperature, air moisture etc. About 20 000 km ago when started up at night, the head lights went very bright than the engine stalled, shortly after that I had to replace head light bulbs - I know the alternator regulator is inside the PCM.

Question: any clues why this happens ? Or is it faulty PCM ?


  • oleksy_1oleksy_1 Member Posts: 6
    additional info from originator of the post:
    when engine is cold and runs at idle, it usually dies after 10-15 sec. When I keep idle at about 2000 rpm for one minut (or so), sometime it "hickups" with CHECK ENGINE ligth blinks during the "hickup". When engine is warm and waiting at the red light, after some 10 sec the engine starts very light, irregular"shaking" like if some cylinder once in a few seconds did not fire, sometime it has "hickup" with CHECK ENGINE blinks during the "hickup", sometime it dies and CHECK ENGINE light comes on. Again, the only code I get is 12 (and 55, end of codes) - and the battery has not been disconnected during the last 50 start ups.
  • oleksy_1oleksy_1 Member Posts: 6
    additional info from originator of the post:
    at start up - I turn the ignition key from OFF to RUN and wait, the bulbs, including CHECK ENGINE, go thru bulb test and go out, than I turn the key to START - at that time some time CHECK ENGINE light comes on again and than goes out.
    Is that normal ? Why would the CHECK ENGINE light come on again during START ? I speculate this causes the code 12 to be stored - for some reason the PCM thinks the battery is/was disconnected ? BTW, after I replaced the PCM at 60 000 km (see earlier note) I had checked occasionally for codes (using "key dancing" routine) and I had no codes except 55 (no more codes). The car battery is 3 years old, I had the same symptoms with the previous battery...
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    If I were you, I'd find someone with an oscilloscope to monitor the ignition system in real time, as the stall or misfire occurs. You apparently have an OBD-1 system, which is unfortunate in terms of diagnostics.
  • oleksy_1oleksy_1 Member Posts: 6
    Mr_Shiftright wrote: "... or misfire occurs" .. Hm ... I forgot what the misfire codes are (will have to look up into Chrysler repair manual) but there are NO codes except 12 and 55. BTW, I have replaced plugs (checked gaps before installation) and ignition wires (quality ones).
    Thanks for the suggestion anyway.
  • oleksy_1oleksy_1 Member Posts: 6
    Does the Body Control Module (BCM) communicates with the Powertrain Control Module (PCM) and vice versa ? I am asking this question because out of the blue BCM sometime locks my doors while I am driving (I am driving with all four doors unlocked) - sometime once every two weeks, some time twice a day within 10 minutes of driving. Recently it got worse - I can only lock the doors using the door rocker switch, can not unlock any doors. There is some faint noise coming out from the door actuators but the doors would not unlock. In the past I always had to visually check all the door buttons after locking/unlocking the car (using the door rocker switch, never used remote) - about 50% of the cases one sometime two door locks were not locked. The same with the unlock procedure. I replaced both lock and unlock relays on the side panel (where the fuses are) and I am still having the same lock/unlock problems. I also removed both relays and used jumpers - the door would lock/unlock perfectly which suggest the door actuators are O.K. ? Also, when both relays were taken out and I moved up and down the lock/unlock rocker switch, the door actuators obviously were quiet BUT I could hear some other relay located somewhere under the dash clicking - BUT the Chrysler factory repair manual electric schematics (section 8W-61) do not show any other relays except the two I have removed ??? Recently I also had one or two cases after getting into the car and unlocking the door with rocker switch the door would unlock than immediately lock.
    Could it be that BCM is toasted or having bad ground or rusty wire connections resulting in the weird behaviour and more - if the BCM communicates with the PCM confusing the PCM causing the problems I described at my first few posts ?
    BTW, some time ago I greased all pins on the PCM with electrical dialectric (colorless) grease and made sure the two 40-pin connectors were seated well. The same done to all fuses and had them checked with Ohm meter before reinstalling.

    Any clues ?
  • oleksy_1oleksy_1 Member Posts: 6
    Is it possible to have a "marginal" (particularly with cold engine) oxygen sensor AND no code set in the PCM ?
Sign In or Register to comment.