tyh24

Hi all, hoping for some help diagnosing an electrical problem in my daughter's 2004 WJ.

She first noticed the gauge indicating it wasn't charging properly. I went ahead and replaced the alternator after confirming it wasn't charging. Manually charged the battery overnight and all seemed fine. She drove it the next day and the fuel injector fuse blew (#26). Got it home, replaced the fuse, checked things over and did not appear the new alternator was charging either. Took it to O'Reilly to have it checked. They said it was working.

Started doing some research, learned about the two wires going from the ECM to the alternator and checked them for voltage. No voltage at all going to the alternator. Alternator not getting signal to properly charge apparently. There is continuity between the ECM harness and the plug at the alternator so I can't find any problem there. Now I'm thinking the alternator is fine...

I've looked over the grounds, wiring harness (especially the area around the back of the head where it can rub through) and haven't found any shorts. Read through lots of threads about bad grounds and shorted wires, etc causing problems. I haven't been able to find anything there. So I went ahead and replaced the ECM. Same issues after replacing it.

In checking voltage to all the fuses in the block, there is no power going to fuse #28 (TCM).

I'm also getting P0753, P1765, and P1495 codes. (Thinking that's b/c there's no power to the TCM)

I've replaced the fuel injector fuse several times, it will start and run (on battery power) but inevitably blows the fuse again.

I'm at a loss as to where to go next... Any and all help is appreciated.

Thanks.

97grand4.0

Well? This is where it helps a lot to have some cursory knowledge of what you are doing in order to repair your own vehicle.

Noah911

I am being very quick with my response..

If your battery is charged, remove the wires to the alternator and isolate them ( taking the alt. out of any circuit) see if it still blows the fuse. If it doesnt its probably the alternator. Was the old alternator the reason IDK? Did they sell you the right alternator?

A bad fuel injector may be the cause too. See what the multimeter tells you.

97grand4.0

what is a multimeter?

Noah911

an instrument designed to measure electric current, voltage, and usually resistance, typically over several ranges of value.

BlueRidgeMark

Please elaborate. Which grounds, and how did you "look them over". A bad ground is often not visible unless it's taken apart, in which case you might as well clean them while you are in there.