Y DTC C1246, C1248

NOTE: Refer to the PINPOINT TEST section of the Flow of Diagnosis before beginning this pinpoint test. Flow of Diagnosis

NORMAL OPERATION:
The anti-lock brake control module conducts a valve function test every time the vehicle is keyed "ON", and the wheels exceed 6.4 km/h (4 mph) for the first time. If valve function is verified, the anti-lock control system is enabled. During normal driving, B+ is applied to all of the valve solenoid coils by the anti-lock relay whenever valve activity may be required. A passive check for open or shorted valve solenoids is conducted at this time.

FAULT DESCRIPTION:
Diagnostic trouble code (DTC) C1246 (open RR dump valve solenoid) is generated when the anti-lock brake control module detects low dump valve solenoid feedback voltage when it is expected to be high (B+). DTC C1248 (shorted RR dump valve solenoid) is generated when the anti-lock brake control module detects high (B+) dump valve solenoid feedback voltage when the solenoid is supposed to be energized.

POSSIBLE CONTRIBUTING CONDITIONS:
- Open/shorted RR dump valve solenoid.
- Open/shorted RR dump valve solenoid circuit 923 (GY/R) between the hydraulic anti-lock actuator and the anti-lock brake control module.
- Defective circuit within the anti-lock brake control module.
- Circuit 923 (GY/R) shorted to power.

Y1- Check Fault Repeatability
- Turn ignition switch to "OFF".
- Connect scan tool to Data Link Connector (DLC).
- Turn ignition switch to "RUN".
- Clear all DTC's using the scan tool.
- Perform the Drive Cycle Test. Refer To Inspection and Verification.
- Retrieve DTC's from ABS memory using the scan tool.
- Is a DTC retrieved?
YES - DTC C1246 is retrieved, go to Y2.
- DTC C1248 is retrieved, go to Y5.
- If a different DTC is retrieved, return to DTC Index.
NO - If System Pass is obtained, go to Y7.

Y2- Check RR Dump Valve Solenoid Resistance
- Disconnect connector C386 from anti-lock control module and connect breakout box and adapter.
- Measure the resistance between breakout box pin 25 and pin 28.
- Is the resistance between 3 and 6 ohms?
YES - Go to Y5.
NO - Go to Y3.

Y3- Isolate Resistance Fault
- Disconnect 12-pin connector from Hydraulic anti-lock actuator.

ABS HCU Circuit Test. RR Dump Valve:

- Measure the resistance between each of the following terminals on the hydraulic anti-lock actuator and pin 10.
- 3, 4, 5
- 12
- Were all resistances between 3 and 6 ohms?
YES - Go to Y4.
NO - Replace the hydraulic anti-lock actuator and go to Y7.

Y4- Check Circuit Between ABS Control Module and Hydraulic Actuator

ABS HCU Circuit Test. Circuit 923:

- Measure the resistance between breakout box pin 28 and hydraulic anti-lock actuator 12-pin connector pin 10, circuit 923 (GY/R).
- Measure the resistance between breakout box pin 28 and pin 1.
- Is the resistance less than 5 ohms between breakout box pin 28 and the HCU pin 10 and greater that 10,000 ohms between breakout box pin 28 and pin 1?
YES - Replace the anti-lock brake control module and go to Y7.
NO - Repair circuit 923 (GY/R) and go to Y7.

Y5- Check for RR Dump Valve Solenoid Short to Ground
- Disconnect connector C386 from anti-lock control module and connect breakout box and adapter.
- Measure the resistance between breakout box pin 28 and pin 1.
- Is continuity indicated?
YES - Repair circuit 923 (GY/R) and go to Y6.
NO - Replace the anti-lock brake control module and go to Y7.

Y6- Check Circuit Between ABS Control Module and Hydraulic Actuator
- Turn ignition switch to "RUN".
- Measure the voltage between breakout box pin 28 and pin 1.
- Turn ignition switch to "OFF".
- Was the voltage greater than 0 volts?
YES - Repair circuit 923 (GY/R) and go to Y7.
NO - Replace the anti-lock brake control module and go to Y7.

Y7- Verify repair
- Restore vehicle. Reconnect all components.
- Clear all DTC's using the scan tool.
- Repeat the Drive Cycle Test.
- Retrieve DTC's using the scan tool.
- Is System Pass obtained?
YES - Stop. Repair is complete.
NO - If original code is retrieved, repeat this Pinpoint Test.
- If a different DTC is retrieved, return to DTC Index.