ABS Light + Horrible Grinding? The $5 Wire That Took Down A Van

Wiring is the central nervous system of an automobile. Almost every vehicle component requires an electrical connection to function properly. Late-model vehicles have upwards of 5,000 feet of wiring running through the body and chassis. When there is an issue with a vehicle’s wiring, any number of problems can arise. What about one wire? How much damage can one wire do? Stay tuned to find out.

A 2018 Ram Promaster 2500 was brought into the shop. The ABS light was on, and a loud grinding noise was coming from the rear wheels. This van was a delivery vehicle, and it was clear it had lived a hard, thankless life: multiple drivers, limited maintenance, and plenty of dents and dings. Road testing this Ram was out of the question; just getting it inside the shop was hard enough. The right rear wheel sounded like it was about to fall off.

Image 52 - Abs Light + Horrible Grinding? The $5 Wire That Took Down A Van

I began the inspection with a fault scan, which revealed a C003A code for a Right Rear Speed Sensor: General Electrical Failure. With the correct height adapters installed on the lift arms, the van was raised off the ground. However, due to the high roof, it could only be lifted a few feet off the ground.

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Before even removing the rear wheels, it was clear there was a serious issue. The plastic center cap was melted, and the steel wheel was discolored on the right rear wheel. Once the wheels were removed, the picture became even bleaker. The right rear rotor and brake pads were discolored due to severe overheating, and the wheel bearing disintegrated when the hub nut was removed. The cause of the ABS light was also quickly determined. The end of the wheel speed sensor had melted because either the right rear caliper had locked up or the parking brake was stuck on.

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I wrote up a list of parts I would need for this repair and submitted it to my shop’s service writer. After receiving approval, the parts were sourced and ordered. Most of the brake parts arrived the following morning, except for the parking brake cable retaining clips, which were on backorder.

2018 Ram Promaster2 - Abs Light + Horrible Grinding? The $5 Wire That Took Down A Van

After the back-ordered brake cable clip arrived, reassembly could finally be finished. Installation was uneventful, and as the torque wrench clicked to 145 ft-lbs on the final wheel bolt, the van was ready to be road-tested.

The road test was also uneventful. There were no brake or bearing noises. An infrared temperature gun was used to check the rear wheels, and they were within a few degrees of each other, indicating the brakes were not locking up or dragging.

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There was still the nagging question of why. Why did the right rear wheel get hot enough to melt the plastic center cap? That answer was soon discovered.

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While verifying the parking brake operation, the red BRAKE light did not turn on in the instrument cluster. We decided to investigate further. The parking brake on this van was operated by a pull handle to the left of the driver’s seat. Pulling back the plastic cover at the base of the seat, we found that the wire for the switch on the ratcheting mechanism was disconnected. The driver of the van must have driven with the parking brake on without even realizing it.

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Back to my original question: how much damage can one wire cause? All told, this van got new rear brake pads, calipers, and rotors. A new wheel hub and bearing, new parking brake shoes and cables, and a new ABS wheel speed sensor. A single 18-gauge wire, comprising 16 copper strands, was ultimately responsible for the catastrophic damage this Promaster endured. The wire was reconnected to the parking brake switch, and now the red BRAKE light worked as intended; the repair was now fully complete.