281Thunder

Continuing to work to get my dad's old truck back up to great condition in preparation to sell it, and I'm at my last big hurdle...the ABS system. I've done a lot of reading, but nothing that really nails down whatever I have going on.

When I started troubleshooting the ABS light, it had a number of codes that I didn't know if they were valid...dad drove the truck for years with the ABS light on and never cared. Some of the codes I assume were related to low voltage due to the battery being dead for a few months. A couple of the codes were related to the front speed sensors. I don't think they'd ever been replaced and they were cheap enough, so I threw a few new sensors into it. After replacing those and clearing the codes, I got the following codes back:

C1145 - Right Front Wheel Speed Sensor Input Circuit Failure
C1155 - Left Front Wheel Speed Sensor Input Circuit Failure
C1233 - Left Front Wheel Speed Sensor Input Signal Missing
C1158 - Left Front Wheel Speed Sensor Input Signal Erratic

I started reading more about wiring issues or possible bad ABS module, but kept troubleshooting. At the plugs for the sensors on both sides, I have 5v at each plug, which from what I can tell is accurate. I also checked and have resistance through each sensor. To me, that all seems right.

I focused my attention elsewhere on the truck for a bit to fix some other small things, then cleared all the codes again. Now, it seems only the C1233 is consistently coming back.

Today I decided to check the tone rings on the hubs, so I pulled off the driver side wheel and brakes, and pulled the sensor out. Looking down in the hole at the tone ring, it looks intact and clean outside of a little bit of bearing grease here and there. Everything seems tight and proper as well. Then looking at the tone ring, something dawned on me. I tried to take a picture the best I can...




Should the tone ring be offset like that? Looking straight down the hole, only about half of the 'teeth' of the tone ring are below the sensor. I know he replaced the front hubs a few years back, perhaps the replacements aren't right? Can anyone confirm how the tone ring should look in the hole?