97 abs problem

[kahjdh]

The RF wheel sensor on my brother's car is bad and causing the abs pump to kick in during regular stopping. Since we dont have the tim to put a bearing in this week what can I unplug to stop the pump?

[GTP Dad]

Personally I wouldn't disconnect anything as it shouldn't hurt anything for it to kick in during normal braking. If you have to disconnect it look for the ABS fuse and disconnect the power to the system. This should take car of the system until you can get the bearing replaced.

[kahjdh]

I pulled the fuses. When ever it would kick in the would not stop and I had to pump the brakes. I ran the codes and it said RF erratic, no response.

[GTP Dad]

It sounds like you may have some ABS computer issues as well as a bad bearing. Also if you don't have an ABS capable scanner you will need to get it scanned with one. I would replace the bearing first just to save some money in case that is what is causing your whole problem.

[BNaylor]

That would depend on which scan tool was used Lynn. Based on my experiences unless it is a Tech II which will properly read out GM ABS codes the translation may not come out properly and the wrong component may get replaced. The wheel sensor output can be checked with a meter (DMM) and you can ohm out the wheel sensor at the electrical connector. Look for approximately 1K ohms. Also wiring from the hub to the EBTCM module is a common problem as is the EBTCM.

[kahjdh]

I used a snap-on solus scanner. The only other code the wasn't RF related was brake switch open. I dont know if that is for the lights or like a pressure switch?

[BNaylor]

Post the specific DTCs and we can cross reference with the FSM for validity.

[kahjdh]

C1222, C1226, C1233, C1291, C1293. Those were the five codes.

[BNaylor]

According to the GM ABS VI diagnostics section of the '97 FSM:

C1222 - Right Front Wheel Speed Sensor Input Signal Equals Zero

C1226 - Right Front Wheel Speed Sensor Excessive Variation

C1233 - Right Front Wheel Speed Sensor Circuit Open or Shorted

C1291 - Open Brakelight Switch Circuit During Deceleration

C1293 - CTC 1291 or 1292 Set in Current or Previous Ignition Cycle

[kahjdh]

Thats what the scanner said leading me to diagnose a RF hub w/ sensor replacement. I have access to a tech I and II at work its just the car is my brothers and he lives two hours away so he is here on weekends which is why I have to wait a week before I do it. I was just wondering where the realy was because it wasnt in the fuse panels and it was single digits last weekend. Thanks for the code check though.

[BNaylor]

Based on the DTCs the respective wheel sensor is a strong possibility but it is best to be sure. As I mentioned earlier easiest thing to do is ohm out the wheel sensor. Go across the two contacts hub side and see if you get around 1K ohms. Based on the multiple DTCs if the wheel sensor was really that bad this check may help you make a decision. Other possibilities is the electrical connector and wiring along the lower control arm. To check wheel sensor output you can check the Hi reference signal from the ABS module/EBTCM module and then with DMM on AC volts scale check the wheel sensor output Lo reference signal. It will read in a range of greater than or equal to 100 millivolts as you move the wheel.