i have a 94 yj and i just replaced the ecm in it and now the check engine light is on and it is over charging... it was running at 14 and now it is almost to 19 if i dont run the heater and lights..... can anyone lend me a hand....thanks
check and see what code you have. but if it wasnt over charging before you replaced the pcm you probly
got a bum one. the voltage regulator is in the pcm on these. other possiblity is a shorted to ground field wire
Hope this helped.
That is no joke. You are full fielding the alternator and it is dangerous.You can boil the battery and it can explode. Do not drive it unless you totally disconnect the alternator!
You either have a bad ECU or a short in the control line from the ECU to the alternator.
Here is a link to pic of the charging system laybackman posted. Disconnect the battery and check the resistance of that wire going from the ecu to the alternator to ground and see if its shorted If it is then pull the ecu connector and see if it is still shorted.
thanks for the tips..... i thought there were 2 voltage regs.... 1 in the ecm and 1 in the alternator..... i am pulling the alt and having it checked... im also going to do the tests that Que89 suggested
So the ecm was just grounding the alternator control? The voltage regulator was a problem on the SMEC modules that Chrysler put in the cars in the 80's. I'm glad to here it's all good now. In my testing I've seen the batteries blow apart from full fielding. Where did you get the regulator from?
I am having a overcharging problem with a 86 Cherokee with a 2.5. I have replaced the battery and the alternator with no change. Now that it is overcharging the engine will spit spuder then die. If i pull the field wire off it runs perfect. Will the above suggestions checking the resistance on the fielding wire or replacing the ECM be the same for this vehicle or is there something i am overlooking?
I was trying to gather as much info and parts possible. The jeep belongs to my grandfather who lives more then an hour away from any parts stores up in the mountains. With all the info from the good people on this site we went through everything again and it ended up being the ecm. Runs great again!