2007 1500 SLT Electrical Issues

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Lequarius

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Oct 23, 2013
Posts
6
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Ram Year
2007
Engine
Hemi 5.7
Hi Folks,

Having a bunch of problems arising with instruments and sensors. I suspect the wiring harness/loom but can find no diagrams detailing routing and placement.

The brake and abs trouble lights blink on/off on a fairly regular basis, the speedometer loses speed signal and drops to zero then returns, drops, then back to speed. The cruise control indicator light on dash shows system active but does not hold speed and front bank left (1) oxygen sensor regularly indicates a failure but benchtests good.

I suspect a branch of the wiring harness running up from the transmission well has chafed/deteriorated or had oil spilled onto it damaging the wiring insulation, or perhaps a bad connection on a common branch to the firewall? I'm not familiar with the wiring harness enough to be able to determine definitively.

Any trouble shooting tips or suggestions as to how to proceed would be appreciated.

I'm seriously hoping it's not the MCU as that would really suck.

Has anyone with this generation of Ram had this issue?

Thanks Folks
 

Roadhouse71

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Dec 21, 2017
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Location
Kentucky
Ram Year
1997
Engine
5.9L
1st i'd check your battery, terminals and strength.
2nd look at the connectors on the ecu and bcm look for corrosion and bent or compromised connections and apply dielect grease.
3rd scan for any history
thats where i would start
 
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Lequarius

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Ram Year
2007
Engine
Hemi 5.7
Thanks for your info.

Brand new Battery and terminals so they're good.

Not sure where those connections would be. Been looking for a wiring diagram that shows location/routing and what systems/wires are in each harness/branch. Figure that info would be the most useful if I can get my hands on it. Been having zero luck so far, if you don't count the $300 the dealer wants for the three page drawing (yeah like I'm going to pay that!)

No Electrical history as I'm second owner and was mint when purchased. These are new issues starting to crop up over the last one of eight years.
 
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Lequarius

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Posts
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Ram Year
2007
Engine
Hemi 5.7
Hi,

I don't think its the tipm module as I haven't had a single listed symptom that is common to tipm's. On any lists of symptoms I can find.

It does bear considering though so thanks for the tip.
 
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Lequarius

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Posts
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Ram Year
2007
Engine
Hemi 5.7
UPDATE

This turned out to be a bad main ground wire. Wire looked good on the outside, but after metering through system, found very high resistance through main negative cable. Wire was completely corroded inside insulation. Never seen anything like it.

Truck is running great now, and these intermittent electrical issues are all gone.

So if anyone else encounters a similar situation, make sure to check the condition of your main wiring. Might save you a bundle of cash and time.
 

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