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ABS & Brake Light on Dash

The truck is an 01 Dodge Ram 1500 with 5.2L a/t with approx. 92K miles. Since I’ve owned it, whenever I’m cruising down the Interstate between 65 & 75 MPH the ABS & brake light come on. It does NOT do it while cruising in local traffic. I just replaced the center speed sensor on the differencial and am experiencing the same problem. I’m stumped!! Any suggestions?

Anytime the primary brake warning light comes on, the ABS warning light will automatically come on.

The ABS system is telling you that it’s not going to function as long as there’s a problem with the primary brake system.

So, that’s where I’d focus.


Start by checking for stored codes. Your ECU does store failure codes for the ABS system.

The center speed sensor in the differential is not the speed sensor that might cause your symptoms. Each wheel will have its own speed sensor, and the computer will compare the wheel speeds and activate the system in one isn’t turning as it should be when compared to the others. The differential sensor cannot tell if different wheels are operating at different speeds.

In your case, as tester said, you probably have a problem with the brake system overall that’s also triggering the ABS sensor as a second-order effect. Start by checking the brake fluid level, although if that’s low I would expect the brake warning to be illuminating at low speeds rather than at highway speeds, only because agitated fluids rise in level.

Check the fluid level, check for stored codes, and post back.

This happened twice on my 95 Dodge Dakota with Rear Wheel Anti-Lock (RAWL). The first time the dealer replaced the sensor in the differential was under warranty. The second time was out of warranty. I ended up replace the wiring harness connecting the sensor to the wiring harness on the frame rail.

Ed B.

The truck came standard with only RWAL. The first thing I did when I bought the truck was do a complete brake job… Pads, rotors. hardware kit, bearings, brake hoses, flushed brake fluid, complete lower control arms, ball joints, and new shocks on all four corners. I will try changing the ABS Wheel Speed Sensor Connector and hope for the best. Figured I’d also change the differential fluid.