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Ask Jerry Your Own Question
Jerry, Master Mechanic
Category: Dodge
Satisfied Customers: 1754
Experience:  ASE Master tech, 30 years exp. troubleshooter, driveability tech
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Cummins 1993 3/4 Ton. Alternator will not charge battery.

Customer Question

Cummins 1993 3/4 Ton. Alternator will not charge battery. Problem first thought to be in voltage regulator on computer. Could not locate a replacement computer. Alternator with a voltage regulator installed. Still charging rate is only 11.5 volts. Speedometer will not work probably due to low voltage. HELP!!!
JA: Have you checked all the fuses? Do you have a wiring diagram?
Customer: Truck is in hands of a mechanic and I doubt he has a diagram. I suppose he has checked all fuses, but don't know for sure.
JA: What is the model of your '93 Dodge?
Customer: 3/4 ton 2500(?) with only 100,000 miles on it.
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: Speedometer quit working so I took it to a local garage where is has been for 3 weeks.
JA: Anything else you want the mechanic to know before I connect you?
Customer: Nothing except I love my Dodge which was used to pull our 32 foot camper all over west in 1995.
Submitted: 10 months ago.
Category: Dodge
Expert:  Chad Farhat replied 10 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Expert:  Chad Farhat replied 10 months ago.

what engine you have in it so i can look up right diagram?

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Expert:  Chad Farhat replied 10 months ago.

5.9 dsl , 5.2 or 5.9 liter gas?

Customer: replied 10 months ago.
Engine is 5.9 Cummins Diesel
Expert:  Chad Farhat replied 10 months ago.

ok thanks be right bsack

Expert:  Chad Farhat replied 10 months ago.

I have sent you all the circuit diagram need for the mechanic to trouble shoot the circuit , there is a fusible link on the inner fender needs checking

and also all the grounds , the pcm connector inspected for any backed out pins making poor connection and als pcm location

most like if the battery & alternator and grounds and pcm connector is good & wiring , for the year of the truck, it will the pcm that control the charging rate is bad internally causing the no charge condition

The Power Train Control Module (PCM), is located in the engine compartment, on the left inner fender behind the left headlight assembly.

The dark green wire goes to the PCM (computer ) & Dark brown wire goes to the pcm , he need to follow these wires and od a continuity test

if wires are good replace PCM .

The main components of the alternator are the rotor, stator, rectifier, end shields and drive pulley. Direct current is available at the output "B+" terminal. Alternator output is controlled by voltage regulator circuitry contained within the power and logic modules of the Engine Controller.

Please let me know if you need anything else on it, just reply back and we will continue

A 5 Star Rating is much Appreciated

Please keep in mind that when you rate me , it does not end our conversation.

you can always come back to this conversation and ask me any follow up question you may have on this issue

(you can copy this link page & paste it in your browser when ready and it will open up our conversation again)

Thank You
Chad Farhat
ASE Certified Technician