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Eric
Eric, Automotive Repair Shop Manager
Category: Dodge
Satisfied Customers: 30830
Experience:  20+ yrs. experience as repair shop manager and technician.
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Why does the ABS light and brake light stay on?

Customer Question

My ABS and parking brake light stay on. I checked the manual and it said 1 of 2 things could be wrong: low brake fluid, or an issue with the hydraulic brake system. I checked the brake reservoir and it was very low, so I added some. But still the lights stay one. The next day, I noticed my speedometer wasn't working until I hit 15 miles per hour. The needle drops when I slow down to 15 and below as well. Are these issues connected?

Submitted: 4 years ago.
Category: Dodge
Expert:  Eric replied 4 years ago.

Hi,
Ok, first, toss the owner's manual when it comes to Airbag, Check Engine and ABS lights. They only tell you 1 or 2 of hundreds of possible causes. And in doing so, only lead to further owner frustration when they find out otherwise.
Ok, while it is true that low brake fluid can cause both lights to come on, there are also dozens of ABS faults - wheel speed sensor(3), wheel speed sensor reluctor/tone ring, short in their respective wiring harnesses, ABS control module, ABS hydraulic unit...
Now, the most common reason for these 2 warning lights coming on in conjunction with malfunctioning speedometer is the speed sensor located atop the rear differentialgraphic
Sensor costs $25 and takes 15 minutes to replace and just need a 10mm socket.

Customer: replied 4 years ago.

Is this a job I can do by simply jacking up my car a little? Or would I need to take it in to put it on blocks?

Expert:  Eric replied 4 years ago.

Hi,
Honestly, you can do it without jacking it up at all. Crawl underneath in front of either rear tire to the rear differential and you will see the sensor atop the differential pumpkin as shown in diagram. I have gone to people's houses and done them in the driveway in about 15 minutes. Use a 10mm deepwell socket and ratchet.

Expert:  Eric replied 4 years ago.

Honestly, you can do it without jacking it up at all. crawl underneath in front of either rear tire to the rear differential and you will see the sensor atop the differential pumpkin as shown in diagram. I have gone to people's houses and done them in the driveway in about 15 minutes. Use a 10mm deepwell socket and ratchet.