Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the brake master cylinder piston position sensor.
- Ignition OFF, test for less than 5 ohm between the low reference circuit terminal 4 and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.
- If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
- If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the EBCM.
- Verify the scan tool BMC Primary Piston Position Sensor A parameter is less than 1 volt.
- If greater than the specified range, test the signal circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the EBCM.
- Install a 3A fused jumper wire between the signal circuit terminal 1 and the 5-volt reference circuit terminal 2. Verify the scan tool BMC Primary Piston Position Sensor A parameter is greater than 4.5 volts.
- If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
- Verify the scan tool BMC Primary Piston Position Sensor B parameter is less than 1 volt.
- If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the EBCM.
- Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 2. Verify the scan tool BMC Primary Piston Position Sensor B parameter is greater than 4.5 volts.
- If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
- If all circuits test normal, replace the brake master cylinder piston position sensor.