Thats not enough. That sounds like battery voltage and not charging voltage. Where did you get your alt? Make sure all you plugs are good and all connections are good and snug. If so, time to have the checked at the place you bought it.

 

Ok, didn't want to resort to changing parts, but, bit the bullet today, and installed 2 new batteries..and still the battery light stays on all the time...
is there anything elese i sould check?
peter

 

I was sure hoping for a problem found post from you, but I guess not yet. Is it holding a charge, drive it around with the lights on for a while and park it and leave the lights on for a half an hour or so then and see if it still starts. If the alternator is doing its' job you must have a bare wire somewhere touching something and you just have not found it yet. If it really bugs you and all is working well you can do my pig pals method of getting rid of idiot lights, put a piece of black tape over it..........LOL

 

There is a fusible link in the system that you need to check. It is actually a pair of wires in to a single ring terminal that connect to a junction block on the passenger side inner fender well.



If you need to replace that fusible link, I can send you the wire. It's 12ga wire and you can find it at NAPA in a 6' spool but you'll only need 10" (2 pieces @ 5" each) if I remember correctly. So I've got 5' extra in my toolbox right now. Here's a parts list:

8ga butt-splice connector (~$3 at NAPA)
8ga ring terminal
heat shrink tubing
dielectric grease
2 pieces of 12ga fusible link wire, 5" long each (re-measure to be sure!!)
rosin core solder

Here's how I did it. Please note that getting the stock one off is a major PITA!!! That said...

1. Strip 1/4" (or so) of insulation from the fusible link wire and twist the ends together tightly.
2. If the 8ga butt-splice has a plastic cover on it, take it off. Same for the ring terminal.
3. Crimp on the ring terminal.
4. Solder that connection by heating the INTERIOR portion of the crimp, and letting the heat PULL the solder through. Use rosin core solder!!
5. Let it cool off completely. Take your time.
6. coverthe connection thoroughly with dielectric grease. You want a bit to ooze out.
7. Cut a section of heat shrink tube to fit, slide it over top the grease, and heat it.
8. Wipe off the excess grease.
9. Repeat steps 3-8 for the butt-splice connection (soldering that one was..fun?)

Be sure to use the grease & shrink tube to ensure your connections are sealed from the elements.


Now, the really fun part. Find out what grounded out to blow your fusible link. That setup will hold ~300A!!! The cause of mine was an incorrectly wired AIH. I've got more pics in my Gallery "Broke stuff" if you want to see what I'm talking about.

 

Ok.after..2- alternators , and many hrs of tinkering, the problem is solved...It was the orange/blue wire in the main harness, broken from rubbing on the drivers valve cover, just as someone suggested early on....spliced a piece of new wire in, sealed it with shrink cover and electrical tape, and bingo..alternator gave out 14.4 volts, and battery light stayed off...whew.. this was a hard one, and hope this info saves someone from the aggravation that I have been through

 

Thanks, it will help someone else, or better yet, hang around and you can help them yourself.

 

I know this thread is a little older, but I just had to sign up and give you guys some mad props for all the helpful info here.

I had the cantankerous intermittent battery light problem. I'm leaving for a fishing trip on Wednesday, and had a pretty much dead truck when I tried to go to the carwash this afternoon.

I found the same problem as pgf50. The wire wraps had worn through by the driver's side manifold and shorted out. A little electrical tape and a quick charge has my baby hummin away again. I'm going to run it to work tomorrow to be sure all is well, but I can tell already because the light hasn't come on once and the dash & head lights are much brighter.

Thanks again! I know where I'll be coming for future info and to post any discoveries I may make.

 

Welcome aboard and hang around. There is a bunch of smart people here to help.

 

Thanks zx250,

I plan to hang around. Hopefully I can add a little piece of knowledge one day, rather than just leeching from you guys.

 

When you say manifold, do you mean the driver's side valve cover where the wires were rubbing??

 

I've heard a lot about that wiring harness since buying my truck, even from the dealer. Are there any preventive measure to take that will extend the life of the harness? Anyone wrap it extra well, or insulate it somehow???

 

Correct, it is rubbing on a bracket near the valve cover. Sorry for the confusion. I can't get much more specific as I was working on it in the dark last night. I have to get a closer look this afternoon. I think it may have rubbed both wires in there bare, because the problem hasn't completely disappeared. I'll have to tear into it further this afternoon.

 

Well in JPTrapshooter case, the main wire harness sometimes lays right on top of the driver's side valve cover and rubbed.. You need only to readjust the harness and maybe add some protection to protect the wires..
The other problem the engine has, is under the valve covers.. the harness may rub the rocker arms/push rods.. Again, you just have to adjust the harness away from moving parts.
Also the 9 pin connector can work it's way loose and disconnect your injectors/glow plugs.. Alot of us have added a shim behind the plastic connector locking tabs to prevent the connector from separating.. (modify a 25 cent coin by grinding about 1/4 of it and use it for a shim.. ) Mine came loose at 69K and caused a P1316 code, a SES light and a very rough running engine.

 

I HAVE BEEN CHASING THIS SAME PROBLEM FOR A FEW DAYS NOW. IF I USE A VOLT METER AND GO -GROND THEN TO + BACK OF MY NEW ALT. THAT JUST TESTED GOOD AT THE PART STORE , I ONLY SEE 11.8 THAT SEEMS LOW. I HAVE POWER AY THE SMALL PLUG ON THE ALT. ( BOTH HAVE 12V /W THE KEY ON AND ONLY ONE HAS POWER WHEN KEY IS OFF) I ASUME THAT PLUG IS WORKING. I WAS THINKING OF ELECT. TAPE... A SMALL PIECE OVER THE BATT. LIGHT HAHA

 

Thanks for the posts. Went thru 3 alternators. Different sources for each. Battery light was always on in the morning when idling to warm up. After a few miles it would go off. Alternator sometimes tested 14.4 sometimes 12.2. So weird. Fuses fine. Wires all seemed fine. No chaffing. Plugs all tight. While plugging in the new OE alternator this morning i found the orange wire was loose inside/at the connector. I could physically move it back and forth 1/8th inch or so where the wire enters the connector. The pin is loose inside the connector! Closer inspection shows the inside of the plug is fouled with soot at the orange connector pin! Sooooo thhhhhaaattts the problem. Just one more thing to check. Just thought i would share.