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Ron, ASE Certified Technician
Category: Dodge
Satisfied Customers: 36069
Experience:  ASE Certs
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Have a 2004 ram 2500 ,5.9 cummins ,, the voltage is going up

Customer Question

hello Jerry , have a 2004 ram 2500 ,5.9 cummins ,, the voltage is going up and down as i warm up the truck 15.8 high and 12.2 low lights get bright then dim every few seconds ,, does this truck have a voltage regulator , or is it incorporated into the altinator .. ? thanks
JA: Just to clarify, what are the exact lights you're talking about?
Customer: the cab lights
JA: Are you fixing your Ram yourself? What have you tried so far?
Customer: yes i will ,, nothing so far ..
JA: Anything else you want the mechanic to know before I connect you?
Customer: i had a tuner installed by a shop,, but the problem was there before that was done ... on the tuner are gages, thats how i could see thechange in the voltage ,,, just want to fix it before damage is done
Submitted: 11 months ago.
Category: Dodge
Expert:  Ron replied 11 months ago.

Hello. My name is ***** ***** I am happy to assist you today. Give me just a moment to review your post, and I'll be right back with the help you need.

Expert:  Ron replied 11 months ago.

The charging system control rate on your 5.9 is controlled by the duty cycle from the ECM (engine control module) . In most cases if the system is over charging as your appears to be the problem is usually with the ECM. See the wiring diagram in the link below for testing reference. In most case the computer will set and store a fault code as well when there is a charging system fault. If you can have the computer system scanned and post back with any fault codes we can work from there .

Customer: replied 11 months ago.
Ron, i was afraid of that thanks