2006 Ram 2500 4X4 Diesel 370K miles.

[Ken Bagwell]

Truck went into 4wd and had a dash light that said service 4wd. After a week of trouble shooting, found that the wiring harness that runs down the side of the engine, near the oil filter, was shorting out, causing the fault. From years of oil changes dripping on the harness, the insulation became brittle and fell off. Had to rewire the entire harness.

 

[Fast69Mopar]

Truck went into 4wd and had a dash light that said service 4wd. After a week of trouble shooting, found that the wiring harness that runs down the side of the engine, near the oil filter, was shorting out, causing the fault. From years of oil changes dripping on the harness, the insulation became brittle and fell off. Had to rewire the entire harness.

I have experienced this particular issue with one of my trucks and plenty of my customers trucks. When I have a customer with this complaint the first thing I inspect the wiring harness you are referring to.

What I have done to alleviate this problem is pretty simple. I get a new section of wire loom or convoluted tubing and cover the section that keeps getting oil spilled on it. Then, I seal the ends of the wire loom with RTV to help prevent oil from getting inside.