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-   -   ABS code C1233 R F Speed Sensor open or shorted with ABS and TRAC OFF lights on dash (https://www.gmforum.com/buick-172/abs-code-c1233-r-f-speed-sensor-open-shorted-abs-trac-off-lights-dash-309409/)

bighank Jul 19, 2015 04:04 PM

ABS code C1233 R F Speed Sensor open or shorted with ABS and TRAC OFF lights on dash
 
Have a CURRENT code of C1233 showing problems with the right front sensor. Also have following history codes:
C1216
C1222
C1226
C1233
C1275
C1298

The ABS warning light and the TRAC OFF light are lit on the dash and pressing the button on the console does nothing.

What is wrong and what do I do to fix it?

REGAL GUY Jul 19, 2015 07:26 PM

Take the RF wheel off and you'll easily see the wires coming from the wheel hub assembly. Check this wire to insure its connected at the car properly and look for broken, chafed or shorted wires to the frame. Check the connector itself to insure its got clean contacts and so on. No, the hub is not rebuildable but you can get a high quality new one from AutoZone by Tiemkin. Good price and they work great if you need one.

REGAL GUY Jul 19, 2015 07:28 PM

You could even plug the new one in before you remove the old hub to see if the lights go out

Tech II Jul 20, 2015 11:12 AM

But even though the harness looks good, it could still be the harness......when you have water intrusion(remove the harness from end of sensor and shake the harness, and see if water comes out), you usually have to replace both...

2kg4u Jul 20, 2015 12:54 PM

Most likely can be fixed by replacing front right wheel hub/bearing, but if the problem turns out to be in the wiring you can run redundant wires from the connector at the wheel bearing to the connector at the electronic brake control module. You just have to know which of the two connections in the large connector at the EBCM are for the right front wheel sensor. The recommendation of a Timken bearing from Rockauto is the best you will get.

2kg4u Jul 20, 2015 12:57 PM


Originally Posted by REGAL GUY (Post 1614125)
You could even plug the new one in before you remove the old hub to see if the lights go out


Uhmm, no. The system works by detecting differences between opposite sensors (RF vs. LF). Simply plugging a new bearing into the connector at the wheel will not reset the DTC's, and if you reset the DTC's with a scanner you don't know if the problem has gone away until you drive with the new hub installed.

Mike Jul 20, 2015 04:02 PM

I agree.

bighank Jul 20, 2015 06:18 PM

Pulled R F wheel. Sensor not shorted or open
 
Pulled R F wheel and disconnected ABS sensor. It measures 1005 ohms across the pins and neither pin is shorted to chassis ground. Not sure what resistance should be. On one post I believe the poster said about 1500 ohms.


Did same in connecting cable. The cable at this wheel looks OK. Not shorted to chassis ground. When ignition is turned on I measured 4 + volts from one wire to chassis ground. Across the two wires with ignition on measures about one volt. One of the TSBs say it could be shorted on the other side of the car and could chafe where the transmission is near the cable.

Was too hot to stay out and crawl under the car to look for the routing of the cable. Does anyone know what the resistance should be? See that this hub is used in Ventures, Montanas, Impalas, Pontiacs so someone must have some experience with the hub and cable. Not sure where the cable winds up. Hate to replace the hub and have no fix.

Tech II Jul 20, 2015 09:06 PM

Sensor resistance could be anywhere from 800 to 1400 ohms......for comparison, check the the R of the opposite side....

Can also check A-C voltage output by spinning the bearing...vary from 100 to 1000 mv, the faster you spin....

to check the wire harness, you would disconnect the main harness at the at the abs controller and attach an ohm meter at the two correct connectors.....take a jumper and attach to the end of the harness...should read zero ohms.......now start flexing the harness...if it goes OL it's the harness....the wiring on the the harness is SPECIAL, not hard wiring.....

bighank Jul 21, 2015 01:19 PM

Where do the ABS harnesses fron the wheels terminate?
 

Originally Posted by Tech II (Post 1614136)
Sensor resistance could be anywhere from 800 to 1400 ohms......for comparison, check the the R of the opposite side....

Can also check A-C voltage output by spinning the bearing...vary from 100 to 1000 mv, the faster you spin....

to check the wire harness, you would disconnect the main harness at the at the abs controller and attach an ohm meter at the two correct connectors.....take a jumper and attach to the end of the harness...should read zero ohms.......now start flexing the harness...if it goes OL it's the harness....the wiring on the the harness is SPECIAL, not hard wiring.....


See the harness going under the engine. Where should I look to find the connector where it terminates? Car is new to me and I don't have any shop manuals or wiring diagrams.


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