Jlk111205

i gotta 1994 cherokee xj. recently my check engine light came on and the volts went down to around 10v. on my battery gauge. the jeep starts fine everytime. runs fine. low dim headlights wipers take long to go bac and forth. sometimes wen driving down the rd the voltage on the gauge will go up to 13-14v. brand new batterynew cables. new alternator and starter. swapped out pcm and still same issue,. i am currently checking wires connections etc. the code for the check engine light is saying short somewhere kinda pointing at the alternator and charging system. i do not understand. i work for jeep currently and we cannot find a diagnosis. earlier today i was tinkering with it and while the jeep was running disconnected the battery and the whole jeep shut off. some say that means its alternator related. the alternator has been checked and tested out of the jeep(was removed and tested). anyone gotta any ideas?

Turbo X_J

It's a really bad idea to disconnect the battery while the engine is running.

Jlk111205

usually vehicles dnt shut off with battery being disconnected. but i was checking a ground wire and it came loose resulting in the battery being disconnected causing the vehicle to shut off. so it wasnt intentional.

cmartin2112

Check your grounds with the engine off and make sure they are clean and tight. After that check your battery with a volt/ohms meter while the engine is running... If its any lower then I think 13v (someone correct me if Im wrong) the alternator is bad. Also go to the auto parts store and borrow their OBD tool write down the codes and post them up here if you need help.

tjwalker

Gotta follow the codes. Always, always.

What is the exact code number (not just a description). The fact that you have a code and a symptom is not likely coincidental.

Have you freshened (actually removed and cleaned and reconnected) every single engine ground?

Turbo X_J

Old timey breaker point/pre digital vehicles maybe.

What is the OBD code that indicates a short, sounds like that could really wreak havoc on the entire electrical system. Should not be that hard to locate.

Jlk111205

Its obd1 pre 96 model i cant remember the code number. We scanned it at work . Ill have to rescan it .

Jlk111205

Ive never heard of a alternator throwin check engine light off

freegdr

41 is alternator feild switch .

justin92xj

Yes if the alternator voltage is low it will throw a code. You don't need a scan tool to pull codes on the obd1 xj's. Turn the key on, off, on, off, on and the check engine light will flash. Count how many times it flashes and that's your code. Code 41 is the alternator code.

Jlk111205

Ok i counted and recounted. I got 18 blinks. Total

justin92xj

Sorry I should have explained it a little better. For example if it was code 23 it would be indicated by two flashes, then a pause (about 1 or 2 seconds) followed by three flashes. If there is more than one code the pause between codes is about 3 or 4 seconds. Hope this helps.

Jlk111205

Yea ill have redo it. Im used to just scanning the vehicle lol

Jlk111205

Nothin like waking up at 5am eastern time to tinker with the jeep to decide if my wife and i need to share a car. Long story short. I smacked the back of (not real hard. More like a good tap) with a wrench heard the alternator actually turn on and make the little hmming sound. Everything started working correctly and also back to the 14v range.... With that bein said. I kno 1 i may needa new alt. 2could still have bad wire somewhere. Id be very unhappy to go threw trouble of replacing it to still have same prob. I kno its not hard to replace but fact in general

Jlk111205

Yep i went to lunch stsrted it up low volts. Popped hood. Smacked the back of the alternator wit a wrench. It turned on.