alternator not charging

[WadePatton]

Alt and reg check out okay off truck. No charge when installed on 90 model. Not my truck, trying to live up to my Diesel Guru status.



Ham radio guy with two CTD's. I'll get him on here eventually--quicker if we fix his problem.

 

[paccool]

Sounds like a wiring problem if they both check out ok off the truck. Is there any thing else that is NOT working?



Stan

 

[sparks57]

Check your crank position sensor. Don't know if that truck has one, mine does... and it went out causing my alternator to shut off.

 

[DKasper]

Almost for not this, but may be worth ruling out -- the alternator is also one of the PCM outputs. But I'm guessing you would probably see other things not working, like speedo or OD(auto).

good luck!

 

[WadePatton]

Thanks fellas, will advise.

 

[JBournes]

Alt.

Just something to check, i had a problem with the same thing on a 54 pickup i use to own, My problem i found out was that the hot wire that needs to go to the alt from the battery. It had come loose and was not sending any juice to the alt. The alt needs juice to make more. They arent like the old generators that would make it when it was running. Just a thought.

 

[Philip]

This sounds like an old stye charging setup with a extrernal regulator. So that means no computer control.



I would check the wires from the regulator to the alt to see if one is broken. Us a multi meter for this. These wires are small in dia and can get brittle with age.



Check the ground on the regulator. See if it is grounded to the body good. If it looses the ground it will not control properly. On Older Dodge gassers they had a ground strap that went from the engine block to the regulator just for this reason. If you lost body ground the charging system would work.

 

[Greenleaf]

I have a bus here at the school. Alt will not charge Cummins 12 valver. I worked three weeks on it, off and on, attempting to locate problem. I did everything known to man. No luck BOTH new alternators I installed tested good on the bench test. New batteries too!



So,,,,,,,,I drive it to the dealership [Bluebird] there they tell me that the alternator won't charge and I have a dead battery No,,Really??? They replaced the alternator [third one] and I have to buy a battery. :-{}



Scott

 

[phoekema]

Ditto on the crank pos sensor (front of engine, top side of pulley). I had rust built up on my '93 and that fooled the computer into thinking the engine wasn't running. I did not have to replace it, just clean off the rust.

 

[Philip]

Crank sensors didn't come into use till 91. 5. Wade is talking about a 90 model here. This one is old tech. No computer to mention. No overdrive on it to need a crank sensor.



Here is a diagram for the wiring.



http://e-toolbox.com/ads/rq.cfm





Everyone bookmark this site I posted the link to. Very good site to have in a hurry. I found this on another website a little while ago.