Archived Brake and ABS light came on

[MullinsM]

Both my brake and ABS light came on AND STAYED ON today when I hit a bump in the road. Should I be looking for something loose or what? Any suggestions appreciated.



99 24v 3/4 ton 4x4 auto.

 

[p-Bar]

Is your speedo wacking out? That is usually based off the speedo sensor in the rear end. You could pull it out and wipe off the metal shavings. I had to replace mine. See if you gett anybody else to chime in. Also that was on my 99.

 

[DavidC]

If you have a brake controller remove the plug at the hitch for a while. I have had 2 instances where the abs and brake light have come on between 45 and 50 mph. Removing the plug from the hitch for a while and then replugging it back in cures the problem. Unplugging the controller under the dash may also reset things but I have not tried that one yet.



Dave

 

[AndrewKing]

Check the brake fluid level in the master cylinder... . MIne has a slight leak and when it gets low the light will come on as a warning..... I will be replacing the mast cys soon... .

Hope this helps you

Andrew

 

[MullinsM]

p-Bar you hit my head on a nail!!! That was going to be another thread in the non-911. It is not working until I get to ~30mph. Then it kicks in and starts working. You say the speedo pickup is in the rear axle?

DavidC-- do have the brake controller and will try it also but am going to do one at a time to try and pinpoint.

AndrewKing -- no leak as of now but thanks anyway.

 

[DavidC]

p-Bar you hit my head on a nail!!! That was going to be another thread in the non-911. It is not working until I get to ~30mph. Then it kicks in and starts working. You say the speedo pickup is in the rear axle?

DavidC-- do have the brake controller and will try it also but am going to do one at a time to try and pinpoint.

AndrewKing -- no leak as of now but thanks anyway.

No speedo until 20-30 mph and ABS Brake light is definately the rear sensor or wiring. Unplug the rear sensor it should ohm somewhere in the vicinity of 1800 ohms. They cost somewhere around $45. 00.



Dave

 

[MullinsM]

Is the 1800 ohms good or bad? And that is measuring across the sensor correct?

 

[DavidC]

Is the 1800 ohms good or bad? And that is measuring across the sensor correct?

1800 is measured across the 2 pins of the sensor. A bad sensor will usually read extremely low resistance. There have been cases where the wiring gets chafed where the harness goes from the frame to the axle if the sensor checks ok. It is usually easier to remove the sensor (1 bolt) than trying to be a contortionist trying to ohm it out.



Dave

 

[MullinsM]

Thanks Dave. Will give it a try and let you know how it comes out.

 

[MullinsM]

Changed out the rear axle speed sensor today and everything works fine now. Score another one for TDR and the members who aren't afraid to help others.



Thanks

Mike