Gigemags05

I am getting the error code 41 in my 92 4.0. I have researched as much as I can online and haven't found anything really conclusive.

What I have already done:
1.) replaced alternator (and checked it twice to make sure its good)
2.) replaced battery
3.) checked all connections
4.) as far as I can tell, all wiring looks good, no nicks or cuts

The volt gauge is showing maximum of 11 volts. When I drive the jeep, the battery runs out after about 10 minutes of driving. Headlights, stereo, everything loses all power.

Any ideas on what to look for next?

I found the link below and have run steps one and two of the first test. I am not sure where to place the probes to check resistance in step three and the 2nd test. Can anyone explain where to place these?

https://www.justanswer.com/car/10jco...-replaced.html


Any help is greatly appreciated, as I have spent quite a few hours chasing this down.

PatHenry

The field terminals on the alternator are the two little posts that have the weird connector across them at the bottom of the alt IIRC.

It's unclear if the diagram in your link is indicating that pin 20 is the test pin, or that it's not present. I'd pull the PCM connector off and look. If there's a dark green wire connected to 20, I'd guess that's the test point. If it's empty, then I'd try to find a more helpful diagnostic test.

Gigemags05

I thought those were the terminals. However, When I put one probe on each of the terminals there was no OHM reading. I will give terminal 20 a look and see if that is my test terminal.

I am struggling to find any other diagnostics tests. I have a feeling it could be the ECM, but I don't want to pay the money for a new one if that doesn't solve the problem. I am just not sure what else it could be.

Gigemags05

I checked that pin #20 and it is the dark green wire for the alternator. I ran the test and it was inconclusive. The resistance was bouncing around. One time I'd test it and the resistance would be in the 1.5-3.5 range. The next time it would be 18-20 range. I checked all the connections and all up and down that wire and do not see anything wrong.

It seems like the issue has to be with one of the following:

1.) alternator
2.) battery
3.) wiring from ECM to alt
4.) ECM

I checked the first three multiple times and they test out good. Is my only real possibility to replace the ECM?

Gigemags05

One last bump.

I disconnected all other electrical components with no change to the battery voltage on the gauge.

Any ideas??

PatHenry

It is definitely possible that the voltage regulator in the computer is bad. Unfortunately a couple hundred bucks for a reman computer is a lot of money to guess on, but I can't think of anything else that could be malfunctioning. I'd check the local junkyard and see if you can find a computer with the same part number and see if they'll let you swap it out in the parking lot to "make sure it works before buying it" and see if you get better results.

Gigemags05

Thanks for the input. That's kind of what I was thinking regarding the junk yard. If I can't find one there, I wonder if Auto zone would let me do the same thing in their parking lot. I would be up front with them and let them know my plans before doing it.

PatHenry

Autozone may not have the computer in stock, it's probably special order. I would just take it home and try it and if it doesn't work just return it like any other return. IIRC you can order online and return/core exchange in store.

Gigemags05