ABS wheel speed sensor GM service bulletin #PIT4683F ABS wheel speed sensor codes
GM has issued a service bulletin #PIT4683F to provide additional testing instructions to diagnose and fix these trouble codes related to ABS wheel speed sensor issues on the vehicles listed below: C0035 C0040 C0045 C0050 C0245 P0609
Warning about testing active wheel speed sensors
An active wheel speed sensor requires power from the Electronic Brake Control Module (EBCM). When testing the sensor, you may find that the 12-volt supply voltage isn’t present and make the mistaken assumption that the EBCM is faulty. It may not be. When the EBCM diagnosis a fault with a wheel speed sensor, it intentionally SHUTS OFF THE SUPPLY VOLTAGE TO THAT SENSOR. Do not mistake that feature for a bad EBCM.
Proper pre-testing technique for ABS wheel speed sensors
If you have any of these trouble codes; C0035 C0040 C0045 C0050 C0245 P0609, chances are the EBCM has shut off power to the wheel speed sensor. You must perform these tasks before attempting any further tests. These steps don’t apply to GM vans or heavy-duty pickups
1) Turn IGN to OFF and remove the key
2) Open and then close the driver’s door and wait for at least 60-secs before proceeding
3) Disconnect the suspected wheel speed sensor
4) Using your multimeter set to DC volts and the range to 40-60-volts, touch the probes to the supply voltage and signal circuits from the EBCM
5) Then turn the IGN to ON. You’ll see a quick 12-volt pulse on the meter. The EBCM sends this pulse every time the EBCM is powered up after it has been in sleep mode. This power pulse checks wheel speed sensor integrity.
6) If you see the 12-volt pulse, you can proceed with the normal wheel speed sensor tests.
7) If you don’t see the 12-volt pulse, check the wiring harness between the wheel speed sensor and the EBCM. If the harness tests good, check the terminals in the EBCM connector make sure no terminals are corroded or backed out of place. If everything checks out, then suspect a bad EBCM.
Next, test the active wheel speed sensors
Warning: this procedure is polarity sensitive. If you reverse polarity, you can damage the wheel speed sensor.
1) With the IGN OFF, connect a 3A fused jumper from B+ to the wheel speed sensor Supply Voltage terminal.
2) Connect a jumper with a 100Ω resistor in series to the negative
3) Set DVOM to the DC Milliamp scale
4) The reading should be between 4-8mA for a low reading and 11-16mA for the high reading as you turn the wheel slowly (just a few degrees rotation at a time).
5) If the reading is not within spec, replace the wheel speed sensor.
Vehicles affected by GM service bulletin #PIT4683F
2008 – 2013 Buick Enclave
2007 – 2013 Cadillac Escalade, Escalade ESV, Escalade EXT 2009 Cadillac XLR
2007 – 2013 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2008 – 2012 Chevrolet Express
2010 – 2013 Chevrolet Camaro
2009 – 2013 Chevrolet Corvette, Traverse
2007 – 2013 GMC Acadia, Sierra, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL
2008 – 2013 GMC Savana
2008 – 2009 Pontiac G8
2007 – 2010 Saturn Outlook
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