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Join Date: May 2017
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Dodge Ram Electrical Problem

05/07/2017 12:44 PM

Dodge Ram 1998 2500 diesel. When the ignition is off and I turn the lights on the ac/heater fan comes on. How do I go about finding the electrical problem? Did not know what to do. Has to be a self repair. Everything works otherwise. Anyone else have this problem?

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#1

Re: terrie

05/07/2017 1:24 PM
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#2

Re: Dodge Ram Electrical Problem

05/08/2017 9:13 AM

You might want to check all earth connections regarding the lights and the AC/Heater.

A rusty/bad contact earth can cause some really strange (to understand!) problems.....

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#3

Re: Dodge Ram Electrical Problem

05/08/2017 10:32 AM

I've seen problems where after-market fog/driving lights have been installed and they've been spliced into the wrong wires (it's not that hard to get the wrong wire). What happens is that when you turn on the lights, there is some current/voltage feedback to the wrong wires which then power the fan at a reduced capacity. And the fan switch itself doesn't necessarily have to be on. Even if you didn't install any lights, there still could be a feedback problem for some other reason.

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#4

Re: Dodge Ram Electrical Problem

05/08/2017 11:31 AM

Do not cut the blue wire!

Try cleaning some contacts first. Bad ground seems a plausible root cause to me.

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#5

Re: Dodge Ram Electrical Problem

05/08/2017 6:04 PM

Which lights start the fan?

Did this just start all of a sudden, with no electrical modifications or adjustments? Change oil, exhaust system, hit a curb, etc?

Does the fan stop if you pull the fuse for the fan?

Does the fan start with the heater mode in off?

Can you change the speed of the fan?

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#6
In reply to #5

Re: Dodge Ram Electrical Problem

05/09/2017 4:14 AM

All good and sensible questions, even the curb one, which might have stove something in and "changed" wiring, possibly......

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#7

Re: Dodge Ram Electrical Problem

05/10/2017 12:19 AM

First thing I would I would buy is a factory service manual, the cost is not that much when you add in the ability​ of them to help lead you to your problem.

Not knowing your vehicle, I would take a look at each Switch, connections, relays.

The service manual will provide the correct path in diagnosing your system.If

you have ran the system procedures, let us Know​ where you are at, then it will help us know how to help you continue.

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