Electrical issue

[nikos]

The other day all of a sudden I see that my "check guages" alert is on and that my voltometer is ready very low. I am not getting any juice either from the alternator or from whatever else is going on. I take the alternator out and have it inspected and it is faulty so they say. I have it rebuilt and I put it in again, with the same result; no power, no charging. What should I check for? What else could be wrong? Are there any fuses I should check? Thanks.

[aw12345]

If the power wire is good and the wiring to the alternator is ok it could very well have to do with the ecm seems like newer Jeeps have the ecm control the alternator

[RAT]

Nikos,
Art is correct. The ECM controls the charging circuit. I fried mine a while back and had the same symptoms you are describing. I hop eyou find it's something else; the ECM ain't cheap and you have to have it programmed to your Jeep and also the key code has to be programmed. Big $$$

[nikos]

Nikos,
Art is correct. The ECM controls the charging circuit. I fried mine a while back and had the same symptoms you are describing. I hop eyou find it's something else; the ECM ain't cheap and you have to have it programmed to your Jeep and also the key code has to be programmed. Big $$$

I've exhausted all other possibilities. I think it's the ecu. You exactly the same symptoms?any check engine lights though? I don't have any. Ecu for 124 programmer doesn't sound too much. Is there a cheapy one or all the same? Any info on your jeeps circumstances could help me much thanks

[aw12345]

You could try swapping an ecm of one of your buddies see if the problem goes away or take the one of yours stick it on another Jeep and see if it stops charging

[Jerry Bransford]

Such problems are often nothing more than a loose or corroded battery connector. Have you physically removed both battery connectors, cleaned them, and reconnected them so they are tight around each battery post?

The connectors can also wear and loosen over time so the connector's bolt can't tighten it enough around the battery post. Taking a Dremel cutting wheel or hacksaw to widen the connector's gap that gets sqeezed together by the connector bolt will restore the required tightness if the connector is loose & can't be tightened enough.

[RAT]

I've exhausted all other possibilities. I think it's the ecu. You exactly the same symptoms?any check engine lights though? I don't have any. Ecu for 124 programmer doesn't sound too much. Is there a cheapy one or all the same? Any info on your jeeps circumstances could help me much thanks

Nikos,
Jerry Bransford posted some good info here as well. If you haven't tried those things, I would do that first. I grounded the battery lug on the alternator to the air cleaner box during a trip up Bronco Peak last year (busted engine mount on driver side). It shorted the charging circuit of the ECM, so no charging. Check engine light never lit up but the charging gauge slowly crept over to 0 after a few hours of driving with the lights on. Jeep went dead just North of Temecula at midnight. IIRC, the ECM was about $800+, and another $200.00 to get it programmed to my Jeep. But I got the ECM through a contact; it was used, but I have not had another issue since then.

[bails85]

i had tjis problem a while back in my ford. turned out to be my battery all together. i put a charger on it and it help well until i put a load on it. all the lights would work and everything. i took it to autozone and they did a test on it and sure enough it was it. i had it tested 3 time by other mechanics and even the dealer got kinda stumpped on this problem. just an idea to try also trace ur main wire to ur starter ther are times that teh zip ties or whatever can snap or get cut and the main wire gets rubbed by the tire or burns on the exhaust or something really stupid. better to check the simple things before u go shit out a gold brick for the ecu.

[nikos]

Nikos,
Jerry Bransford posted some good info here as well. If you haven't tried those things, I would do that first. I grounded the battery lug on the alternator to the air cleaner box during a trip up Bronco Peak last year (busted engine mount on driver side). It shorted the charging circuit of the ECM, so no charging. Check engine light never lit up but the charging gauge slowly crept over to 0 after a few hours of driving with the lights on. Jeep went dead just North of Temecula at midnight. IIRC, the ECM was about $800+, and another $200.00 to get it programmed to my Jeep. But I got the ECM through a contact; it was used, but I have not had another issue since then.

Ya, I've done all that. It seems ecu. I sent it in and should have it back in a week. Only cost me 125, not so bad. Thanks. 1000 bucks, whoh, crazy.

[nikos]

They just called me telling me they could not fix my original one. Something to do with there being some type of hole in the internals. Its pretty busted up. What could have caused that? Bad alternator maybe fried the computer. They want 225 shipped and one year warranty. I think thats fair. Its 75 just for a new core.

[aw12345]

Well at least you located the problem, don't you love all this integrated circuitry. The alternator overcharging could have caused it or anything in the electrical that spiked the ecm. Might be a good idea to ask which circuit bit the dust. Did you have the original alternator tested?

[nikos]

Well at least you located the problem, don't you love all this integrated circuitry. The alternator overcharging could have caused it or anything in the electrical that spiked the ecm. Might be a good idea to ask which circuit bit the dust. Did you have the original alternator tested?

Ya I found it, thats the good part. The alternator was bad and I had it rebuilt. Its a mean green 200 amp for powering up my UFO. So I think the alt took a sh..t and surged the ecu. I'll ask them anyway. Thanks.

[Jeri Lyn]

Where did you buy your replacement ecm from?