Archived alternator quit charging

[hottapper1]

i have a 94 dodge and the alternator wont charge. the tach and a/c quit all at the same time. i put in a new alternator, batteries, and cleaned the terminals and the alternator still wont charge. could there be a computer problem or electrical. where do i go from here. i really need help.

 

[RAJohnson]

Not to sound stupid but what is the condition of the belt (clean) (any oil on it), and is it routed correctly?

 

[RAJohnson]

When you say it wont charge are you going off the gauge on the dash or are you using a Meter like a fluke. On the batteries you should read 14. 2VDC with a Fluke or Simpson.

 

[hottapper1]

I put on a new belt . iam going off the guage and the headlights if you leave overnight

i have to jump start to get it to run.

 

[RAJohnson]

Then it sounds like a bad relay or fuse. Have you checked those?

 

[hottapper1]

i've checked all the fuses relays. IT is strange becuase it all happend at once.

but keepem coming.

 

[RAJohnson]

OK, I would then go after all the grounds on the Engine and the body. Remove, clean and re-install.

 

[hottapper1]

thats what i'll do next thanks for the response

 

[CArnold]

I would check the crankshaft sensor connector for corrosion, make sure the wires arent cut or damaged. That sensor tells the pcm that the engine is running and its ok to charge, run a/c and tach.

 

[DRadzierez]

It is most likely the crank sensor. If you dont have a wait to start light go out and unplug the crank sensor(the plug is to the left of the oil fill ). If you get the wait to start light after you unplug it then it is the crank sensor.

 

[JApol]

I don't know of this helps but a guy with a '96 had a similar problem. I think his fix is on the third page. https://www.turbodieselregister.com/forums/showthread.php?t=141477&highlight=low+voltage

 

[K5IP]

What was the final fix?

Rog

 

[jd5373]

I had the same problem -- Alternator, AC and Cruise control all quit. The serpentine belt had lost an 1/8 or so and in the process had cut the crank sensor (though I didn't know at the time that was what it was called) wires. I put on a new belt and repaired the three small wires. Everything works just fine.

 

[Gene Arnold]

On the link cited above, the fix was as follows:



ITS THE TRANS RELAY CIRCUIT!!!!!!!!!!!

I was experimenting with differnt combinations and got the ALT to charge and all of the lights work properly.



The 20 AMP fuse link feeds the trans relay circuit. The relay itself is ok... ... means that there is either a short at the selinoid, the selinoid itself or I hope not the ground path at the PCM. If you leave all the relays in place at the PDC, as soon as you turn the key you blow the 20 AMP fuse link in the RUN position. Take the TRANS relay out, replace the 20 AMP fuse link and you will get charging, guages and tach back.



All I did before all this happened was change the trans filter. Could the selinoid be jammed shut??



Cant beleive this circuit can cause so many problems!!!!!!!!!!



At least the tach, guages and charging (13. 7v) circuit work. Does anyone know what would happen if I would drive the truck with the trans relay pulled out of the PCM. I have an 47RE auto, I am assuming the OD wont work.



Also, asyone with a jumpy tach and ammeter, the following combination of relay/fuse failures will giver you said condition.



Blown 20 amp fuse link with out trans relay in PDC.