Can’t get rid of ABS code C1233(RF sensor shorted)

[Nathan]

I’m working on a 2002 Chevy Impala with ABS + traction control lights on. After scanning it, it comes up with these:

History codes:
C1218 (pump motor circuit short to voltage or motor ground open)
C1222 (RF wheel speed sensor input signal is 0)
C1226 (Excessive wheel speed variation)
C1233 (RF wheel speed sensor circuit open or shorted)

Current codes:
C1233 (RF wheel speed sensor circuit open or shorted)

So clearly a problem with the ABS module and RF wheel sensor. I disconnect the harness from the module and clean it with electrical cleaner and let it dry. After reconnecting it I rescan the C1218 is gone so I reclear and rescan. Now it seems all I have is the C1233. I check for a complete circuit at the sensor and one sees ground and the other is open. Thinking it was probably the bearing I just went ahead and removed it. Using a multimeter, I read 1.2m ohms. I saw some corrosion on one of the pins and cleaned it as well. I now read about 1.4k. I then checked AC current and spun the bearing. Read about .3mV and the faster I spun, the high the voltage, so I concluded the bearing must be good and it was simply a bad connection. I reassembled only to see the code remained. After inspecting the wires in the harness I saw a butt connector a severed wire.

Thinking that’s definitely my problem, I reconnect the wires and check again. This time only the traction light turned off for 3 seconds and came back on again. I check for continuity at the module and the sensor and see none for each wire though they’re seeing ground. I think it’s shorted somehow so I decide it’d be easier just to run brand new wire. The old wire was black on the inside. I soldered, heatshrinked, flextubed, and zip tied the entire thing and ran it with the factory harness so I’m positive it’s making a good connection. Unbelievably, still a C1233. I clear the codes again and drive around for 20 minutes and it’s still on.

I’m completely lost now. It’s hard to believe there’s a problem inside the module itself but I’ve pretty much ruled out a connection issue and the bearing was reading correctly when I bench tested it. Before I make my buddy buy a new ABS module, I’d like a second opinion. Is it still somehow possible the bearing is the issue? When I ran all new wire, I compared the wire colors at the sensor and the module and when I did my cutting + reconnecting, the codes didn’t change, so I’m sure it’s the correct wires. If they weren’t the would have thrown another code. The wires were then reading ground but I wasn’t actually able to rotate the tires to see the readings with it assembled but it is directly wired from the working bearing so could it be shorted internally?

Topic

[Ole Eggers]

If you are going to throw parts at it, throw the cheapest ones first 🙂

The bearing is probably the cheapest to start with. I take it, that the sensor is integrated in the bearing / hub ? Some cars are like that, others you can replace the sensor itself.

[Nathan]

Well I don’t really want to throw parts at it. I’ve been trying to test everything but everything should be good now. And yes, the sensor is part of the bearing. It’s $90 for a replacement. Considering it’s reading out okay, I don’t know if it would be wise to replace it.

[Author]

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