My truck is pissing me off. I had my alternator tested and batteries tested and they are both good. Then I thought the volt regulator went bad so I replaced my PCM and then I figured out all I did was blow my alternator fuse. Now it is acting up, but at least it is driveable. When I crank it up the battery charge gauge or whatever is always real low and the check gauges light comes on. Then when I get going it gets back up to 15. And sometimes when I let it idle it goes down to like 13 or so. Is something draining it? I have no idea. What do yall think?<br>

 

Have you put a voltage tester on the truck to varify that the Alt is actually charging correctly?<br><br>Also, check for bad or broken ground wires.<br><br>Good luck.<br><br>Rich

 

When I bought my truck &quot;used&quot; it was acting up also. I had the batteries checked at a auto parts store but they did not dissconect the two batteries. They said my alternator was bad. So I took it off and had the local alternator rebuild shop rebuild it. The brushes were worn out, but this didn't fix my problem. Then I took the batteries off and had them checked, one had a bad cell in it. This fixxed my problem hope you get it straightened out. This was a pain in the a...s for me also.

 

Check your crankshaft position sensor wiring and connections, also the sensor and check for excessive grease or oil on it. To adjust it you will need a brass feeler gauge.

 

Do you mean my crank speed sensor? My rpms and speedometer gauge act up every once in a while. I might need to replace this, but I just replaced my rear wheel speed sensor. So I will probably replace this crank sensor too I guess.

 

Thats it usually a bad connection or wire sometimes full of crud from seeping gaskets and seals sometimes needs adjustment.

 

Just reading this thread- it's not the exact problem that I have but close! Over last 3 months replaced both batteries and now the alternator. Truck is not hitting more than 13.10 to 13.5 (on a Snapon/Bluepoint meter), mostly it's around the high 12s. I have the meter wired to the cigar plug and sitting on the seat next to me while I drive. It's strange because I'm seeing the highest volts in the AM when I head out for work!? Turning on headlights/fan etc dont make a dent in the volts- it holds steady with the extra load!? Strange?

BTW the dashboard voltmeter is completly off compared to the Snapon meter. Whats with the PCM- manual says to not touch it- nothing about trouble shooting it. HELP!

 

I had the same problem on my 96. I rebuilt the alternator replaced the rectifer and replaced the brushes as well. There is a problem with the rectifer ground. I you look at the back of the alt there is a aluminum cover that is held on by 3 nuts. Remove and drill out the hole were the the rectifer ground stud is so you can get a good connection with the nut on the rectifer ground terminal then install the cover and the two nuts to hold it on. I also tested my batteries they seemed ok but I changed them out at the same time.Now every thing is ok, I have super bright lights and it is charging at 13.5 with eveything on.

 

Jack- Thanks- But I replaced the alternator with a new rebuilt unit from NAPA. Today (with the new altr installed) I saw volts go all the way to 13.8! The mechanic at work said it was the PCM that was at fault- he said to give it two days to "relearn" with the new alternator, that seemed like good news untill... tonight driving home with the headlights on I saw the volts crash down to the low 12s! I think I was lucky to make it back home- the lights were getting real dim and the GEN warning light came on!

Unless you guys have another idea I guess I'm headed to the dealer...the mechanic said they (the dealer) would have to service PCM.

BTW mine is a 1997 2500 CTD (4X4)

 

How old are your batteries? Have you had trouble starting in the morning. like I said earlier I also changed my batteries as well. I had the same problem as you.

 

possible defective alt,i know it's a rebuilt but,anything can happen.More than likely voltage reg in computer is on the bum.If i remember corectly hauling has a fix for that.Just my .02
Luc

 

You may be able to wire in a external voltage regulator from a 1st gen instead of replacing the pcm

 

Yes you can wire up an external voltage reg. Yes it was haulin in dixie who posted the how to (thanks!) Here is the post:

https://www.dieseltruckresource.com/...=36421#newpost


https://www.dieseltruckresource.com/...5&pagenumber=1


Here is another post that may be of help:

http://www.turbodieselregister.com/f...threadid=41593

Good luck, Kevin

 

Hats off to 1st Cumnz! Not only was the NAPA rebuilt bad- it WAS A DISASTER! While driving on the highway Thurs morn (second day with the new one) I lost all alternator output- then the temp gauge pegged all the way over...the fault...the pully on the "new" alternator started to come off the alternator- it then threw the belt causing the truck to overheat (lost the water pump)!

So a BIG WARNING to everyone- check those new or rebuilt parts- they may not be what they seem!!!!!