ABS Light On With EBCM DTCs C0035 C0040 C0220 And/Or C0221 - keywords brake indicator light sensor speed wheel

This PI was superseded to update model years. Please discard PIT3460K.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

ABS and/or Brake light may illuminate at times and DTC C0035, C0040, C0220 and /or C0221 may be stored. The SI diagnostics used for these wheel speed DTCs do not effectively isolate the concern. Please follow the instruction below to repair the vehicle.

1. Use the Tech 2 and check for DTCs
2. Using the door sticker or GMVIS, document the build date of the vehicle.
3. If built prior to September 9th 2005 or prior to VIN last 8 of 68157082. Use Line 5 data and the chart below to determine which wheel speed senor(s) to replace. After the Line 5 data is obtained, unplug the EBCM connector and both left and right front wheel speed sensor connectors. While unplugged, replace the hub/bearing wheel speed sensor assembly with current SPO stock. Only replace the hub/bearing wheel speed sensor assembly as indicated in the chart below. Once replaced, reconnect all connections.
4. If built after September 9th 2005 or after VIN last 8 of 68157082, unplug the EBCM connector and both front wheels speed sensor connections. Leave disconnected for three minutes and then reconnect all three connections. If the vehicle is a repeat concern and is built after September 9th 2005, Use Line 5 data and the chart below to determine which wheel speed senor(s) to replace. Unplug the EBCM connector and both left and right front wheel speed sensor connectors. While unplugged, replace the hub/bearing wheel speed sensor assembly with current SPO stock. Only replace the hub/bearing wheel speed sensor assembly as indicated in the chart below. Once replaced, reconnect all connections.

Obtaining Line 5 Data:

Using the tech 2, please check the module information prior to replacing any parts. To get the module information within the Tech 2, go under chassis, then select ABS. Once ABS is chosen, choose F4 "Module Information". Scroll down to Event History Cal Data 1-5. Review "Event History Cal Data 5" ONLY. Perform the appropriate action for each digit listed. A vehicle that has no problems will display "00000000" (8 zeros). A vehicle with a concern can have any digit between 0 and 7 displayed. Associate the digit(s) from "Event History Cal Data 5" with the chart below.

Example: "Event History Cal Data 5" reads 00200001. Digit "1" and a digit "2" are both displayed after the Cal Data 5. The correct action would be to replace the FR hub and bearing for digit 1 and FL hub and bearing for digit 2 based on the chart below.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.