Subject: | Additional Diagnostics For DTCs C0035-C0052 |
Models: | 2003-2007 Chevrolet Kodiak C4500-5500 Conventional Series |
| 2003-2007 GMC TopKick C4500-5500 Conventional Series |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Before replacing an EBCM or a Wheel Speed Sensor the following diagnostic checks must be performed. These additional diagnostics can help for any of the following DTCs: C0035, C0036, C0037, C0040, C0041, C0042, C0046, C0047, C0051, C0052.
Recommendation/Instructions:
Note: WSS = Wheel Speed Sensor, EBCM = Electronic Brake Control Module / ABS Module
- Check all portions of the WSS intermediate harness for short to ground or open. Use of an audible tone on an ohmmeter during this process is essential. Unplug the EBCM, and unplug the WSS in question, then perform the following tests:
• | Check WSS pins of EBCM harness for short to ground (repeat for both pins which go to WSS in question): Connect meter between pin & ground. Shake all portions of harness by hand. There should be no continuity to ground from either
pin. Audible tone indicates a short to ground somewhere in the harness which must be repaired. |
• | Check WSS intermediate harness for open circuit: Connect ohmmeter to WSS pins on opposite ends of intermediate harness. There should always be continuity (repeat for both wires that go from the EBCM connector to the WSS connector), if an audible
tone is intermittent, there is a broken wire somewhere in the harness which must be repaired. |
- WSS replacement is warranted only when one of the following conditions are met:
• | WSS resistance is out of range. Normal reading will be between 1800-2200ohms measured at WSS pigtail pins. (NOTE: Do not test connector pins with oversized probe as damage may result in loose pins) |
• | Sensor leads show signs of intermittent conditions. |
- | Wiggle WSS wiring during resistance measurements. |
- | If readings fluctuate, problem is in WSS pigtail. |
• | If one of the above conditions are met: |
- Additional checks:
• | Chaffed wiring harnesses. Check all wiring between sensor tip and EBCM. |
• | Corrosion or water in WSS, or EBCM connector. Clean and seal using dielectric grease. |
• | Broken wire at connector pin. Repair wire. |
• | Connector pin backed out of connector. Repair connector & pin. |
• | Bent connector pin. Straighten or replace pin. |
• | Loose connector pin (poor pin drag using probe same size as EBCM pin ). Replace connector pin. |
• | Corroded or loose electrical system ground (see eSI for ground locations) |
• | Incorrect tire size programmed into EBCM...go to "special functions" on diagnostic tool[mldr ]view current settings and update if incorrect. |
- Finding loose or damaged wiring can be very challenging, especially when it is intermittent. A wiring harness which appears undamaged may still have an internal short to voltage, ground, or open circuit.
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.