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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/)

2kg4u Jul 21, 2015 02:57 PM

Open the hood and look for the block where all the brake lines terminate ... should be in front of the brake booster and lower down in the engine bay. Piggy backed to that block on the outboard side is the electronic brake control module. On the side of the EBCM will be a large electric connector (I think there are something like 36 wires in it). There is a lever on that connector you slide to a position where you can then remove the connector from the EBCM. Now you come to the point where you need an electrical schematic to know which of the 36 (24?) terminals in that large connector are the two that go to the RH wheel speed sensor.

REGAL GUY Jul 22, 2015 09:56 AM

I guess we forgot the jack up the car with the tire on grab the tire at 12 pm
and 6 pm and feel for movement in the hub bearing assembly test. That 90% of
the time is the problem.

2kg4u Jul 22, 2015 02:24 PM


Originally Posted by REGAL GUY (Post 1614150)
I guess we forgot the jack up the car with the tire on grab the tire at 12 pm
and 6 pm and feel for movement in the hub bearing assembly test. That 90% of
the time is the problem.


Covered that in post #5 when I stated "Most likely can be fixed by replacing front right wheel hub/bearing". Fix the obvious stuff first.

bighank Jul 22, 2015 05:01 PM

How do you remove the large black connector after sliding the red locking tab?
 

Originally Posted by 2kg4u (Post 1614141)
Open the hood and look for the block where all the brake lines terminate ... should be in front of the brake booster and lower down in the engine bay. Piggy backed to that block on the outboard side is the electronic brake control module. On the side of the EBCM will be a large electric connector (I think there are something like 36 wires in it). There is a lever on that connector you slide to a position where you can then remove the connector from the EBCM. Now you come to the point where you need an electrical schematic to know which of the 36 (24?) terminals in that large connector are the two that go to the RH wheel speed sensor.

Found the ECBM and the large black connector with wires going in to the left side. Slid the red tab to the right about 1/2" See some indentations on the right side like where you might pull on the connector. Tryed to move the connector using my fingers and also several secrwdrivers. It does not seem to move. How do I remove the connector to get access to the wire terminals?

Looked at some schematics on the Autozone.com website which show the R F sensor connected to either pins A9 ans A10 or pins 21 and 20 on a "C" connector. Have an ohmmeter and would like to test each sensor for resistance and also look for AC voltage by spinning each wheel.

Need to get the connector off without destroying it first.
How do I do this?

REGAL GUY Jul 22, 2015 11:31 PM

Well actual in post 2 I said to get a high quality new one from AutoZone by Tiemkin.
and I did not see anyone telling him how to check the wheel hub.

2kg4u Jul 23, 2015 08:44 AM


Originally Posted by REGAL GUY (Post 1614159)
Well actual in post 2 I said to get a high quality new one from AutoZone by Tiemkin.
and I did not see anyone telling him how to check the wheel hub.

You are assuming a bad wheel sensor can be detected by diagnosing a bad bearing, and that is not the case. The bearing could be perfectly fine, and wheel sensor has failed and/or has become contaminated.

REGAL GUY Jul 23, 2015 09:20 AM

A bad wheel bearing will destroy the ABS sensor and no one told him how to check the wheel bearing. That should have been the first thing checked not ripping apart wiring harness's

2kg4u Jul 23, 2015 11:08 AM


Originally Posted by bighank (Post 1614154)
Found the ECBM and the large black connector with wires going in to the left side. Slid the red tab to the right about 1/2" See some indentations on the right side like where you might pull on the connector. Tryed to move the connector using my fingers and also several secrwdrivers. It does not seem to move. How do I remove the connector to get access to the wire terminals?

Looked at some schematics on the Autozone.com website which show the R F sensor connected to either pins A9 ans A10 or pins 21 and 20 on a "C" connector. Have an ohmmeter and would like to test each sensor for resistance and also look for AC voltage by spinning each wheel.

Need to get the connector off without destroying it first.
How do I do this?


There is a red (possibly grey) release tab with a plastic tether on it you have to pull out in order to remove the connector. This tab is restricting the lever you found to not being able to move enough to release the connector. If you can't find it, post a picture of the connector and I will point it out to you.

I am a little concerned you are not heeding our advice. I am telling you from personal experience on my own cars and from having been involved with this forum for a few years that 99% of these failures are resolved by replacing the hub/bearing. Its great you are exploring and learning about your car, and I am interested to hear what your continuity tests reveal, but please don't dive into rewiring the system as a first step.

bighank Jul 23, 2015 02:46 PM

Thanks for the info
 

Originally Posted by 2kg4u (Post 1614185)
There is a red (possibly grey) release tab with a plastic tether on it you have to pull out in order to remove the connector. This tab is restricting the lever you found to not being able to move enough to release the connector. If you can't find it, post a picture of the connector and I will point it out to you.

I am a little concerned you are not heeding our advice. I am telling you from personal experience on my own cars and from having been involved with this forum for a few years that 99% of these failures are resolved by replacing the hub/bearing. Its great you are exploring and learning about your car, and I am interested to hear what your continuity tests reveal, but please don't dive into rewiring the system as a first step.

I have worked on cars for over 50 years. Skilled in electronics and a ham radio operator. Before changing a hub I would like to do some simple resistance and voltage checks with a DVM. Not unable to change the hub but want to see if the wheel sensor is sending out AC voltage and compare it with the other sensor on the other side.
Slid the red locking tab over but did not want to ruin it. If it has to be removed I will do that.

2kg4u Jul 23, 2015 03:35 PM


Originally Posted by bighank (Post 1614188)
I have worked on cars for over 50 years. Skilled in electronics and a ham radio operator. Before changing a hub I would like to do some simple resistance and voltage checks with a DVM. Not unable to change the hub but want to see if the wheel sensor is sending out AC voltage and compare it with the other sensor on the other side.
Slid the red locking tab over but did not want to ruin it. If it has to be removed I will do that.


The locking tab does not slide over, you extract it completely ... other than it is still held on by the tether. Once you remove the tab the locking lever will be free to move to the unlock position.

Your response reminds me of a joke about a guy looking for his contact lens on the road at night underneath a street light. His buddy asked if he was sure he was looking in the right area, to which he responded he dropped the lens a ways down the street, but the light was better here.


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