99 SLT 4x4 V-8
ABS and red Brake light on dash are on. I got the codes read last month and it called out the right front and rear diff sensors as bad.
Replaced the rear diff speed censor, the brake light is still on.
What would be a place to look next?

 

Is the ABS lite still on?

 

Yes both are still on, I expected the ABS light to stay on because I did not change out the front sensor.

 

Yes, I expected that the ABS would stay on since I have the faulty sensor in the front.

 

This works on Silverados for the brake light, may work on yours. Assuming here that the fluid level is not low, which would be a legitimate red light alarm. See the wire plugged in under the reservoir on the master cylinder on the top picture? Unplug that and see if the light goes out. If it does, replace the sensor that the wire was plugged into. On the side opposite the plug, use pliers or a screwdriver to squeeze the clip holding the sensor in place, and slide it out. The images are for a 99-04 Dakota, and you can see what needs to be squeezed together on the bottom pic. I just linked them because they're pretty big pictures.

https://images.carid.com/cardone/rep.../13-2967-2.jpg

https://am-ebay-images-items.s3.amaz...-184756985.jpg

 

Vimes, thanks I will give it a try.

 

@Vimes I do not have a sensor there. I removed the two wire plug from the block just outside the master cylinder and read 10 vdc with the ignition in the on position, if that has any bearing. From what I can tell there is no low level sensor in the fluid tank, I am going to assume there is just a pressure sensor.

 

Update

I used a code reader at Orielly's auto, it read right front sensor circuit malfunction/ right front sensor signal missing/ rear sensor signal erratic. Cleared the code for the rear sensor, the red brake light went out, now the ABS is flashing. Drove the truck for about 10 miles in the city so stop and go, no problems with the brakes and the light is still out. Speedometer is tracking fine (which was not a problem with the light on), but is about 5 mph slower than actual vehicle speed verified by the WAZE app. This was a problem before I did any work to the truck, probably the tires are the wrong size from original build.