Engine/Transmission (1994 - 1998) Altenator troubles

[ndurbin]

Well I felt like a dumb@$$ this afternoon. I was working on my truck Monday and left the key on ACC until this afternoon (I haven't driven it since sunday). Well when I started it up today (which surprised the hell outta me) the alt. guage stuck right at 12 volts and the check engine light was on. I attempted to ready the codes but I wasn't real sure how to do it. The check engine light blinked on/off as following 3 quick pause 4 pause 1 pause 5 pause 5 pause, does that sound right? I checked the wires going to the alt. and the looked ok (nothing disconnected or frayed/broken).



I plan on doing a search to see if I can turn up anything, but thought I 'd see if somebody had a quick answer first.



TIA

Nathan

 

[bmoeller]

Dependnig on what you were doing on the truck, you may have blown the 120amp alternator fuse in the power distribution center (PDC) under the hood. There are 2 screws holding it in place.

 

[ndurbin]

I just had the CD player on while I was moving my CB. The only electrical thing I did was disconnect the dome lights and run a power wire from the battery to the CB.



Nathan

 

[ndurbin]

Ok I think I got the code reading figured out. Do the numbers 12, 41, and 55 ring a bell with anyone.



I checked the 120 amp fuse. It was good.



Thanks

Nathan

 

[ndurbin]

Ok heres an update. Still haven't solved the problem. Codes 12 and 55 are battery disconnect codes. Code 41 is generator field not switching. Which according to the dealership I use from time to time means the alt. is bad. So I had took the alt. and had it tested. The alt. tested fine, so I started checking wires and stuff. All the wires seemed okay.



I'm stumped, code 41 means alt. is bad but when tested it works fine.



TIA

Nathan



PS I am to young to loose much more hair over this.

 

[crabman]

nd,

Pull both batteries out of the vehicle and have them load tested.

Clean ALL battery terminals/cables and grounds.

Remove Alt. and have it bench checked.

Clean C/S speed sensor connections. If the C/S is not working correctly then the alt. will not charge. (use diaelectric grease on connections)

Try all the above and if it does not correct the problem then post again.

crabman

 

[Texas Diesel]

The voltage regulator is built into the PCM and you have a "dumb" alternator. If the problem persists the dealer can check the PCM to see if it is putting out a voltage to the alternator.

 

[ndurbin]

I charged both batteries and load test em outside of the turck and they were fine. The terminals and grounds are in good shape (no corrosion). It has a new alt. now since when I opened up the orginal the brushes and shaft were pretty well worn.



Could I put another regulator on and cut the PCM completely outta the loop?



I discussed prices of a new PCM with the parts guy and he said somewhere in the ball park of $225.



Thanks

Nathan

 

[K5IP]

Nathan,

There was a very good discussion about two weeks ago on charging system problems.

The PCM needs to sink current for the field and the shutdown relay. I think the problem was an input to the PCM, in this case the engine speed sensor. If you did a search take time to read that discussion well. I am not sure if your 94 has the speed sensor (does it have a tach)? If it does, that provides a quick first check of the speed sensor.

Good luck

Rog

 

[K5IP]

Nathan,

The good post/discussion (see last post), was in the 911 group originally posted by KOwens on 10-26.

Do a search under KOwens and you should find some lgood info.

 

[ndurbin]

Thanks for the info on the post I'll check it out.



Nathan

 

[ndurbin]

I found the culprit, I shorted the 120 amp fuse out when I was putting the alt. back on. It sparked against something when I was hooking the harness up (my fault I should of had the battery disconnected).



I found it by going back over everything again. Was checking the alt. for voltage and it was putting out anything, so it I went back over and checked the 120 amp fuse. Sure enough the spark when hooking up the harness blew it. Now just have to wait until tomorrow to get a new one.



Thanks for everyones input.

Nathan

 

[K5IP]

Glad you found it! If you had mentioned the spark, about a hunderd of us would have zeroed in on you!!!

Rog