R DTC C1198, C1200

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) C1198 (open LF isolation [ISO] valve solenoid) is generated when the anti-lock brake control module detects low LF ISO valve solenoid feedback voltage when it is expected to be high (B+). DTC C1200 (shorted LF ISO valve solenoid) is generated when the anti-lock brake control module detects high (B+) LF ISO valve solenoid feedback voltage when the solenoid is supposed to be energized.

POSSIBLE CONTRIBUTING CONDITIONS:
- Open/shorted LF ISO valve solenoid.
- Open/shorted LF ISO valve solenoid circuit 902 (BR) between the hydraulic anti-lock actuator and the anti-lock brake control module.
- Defective circuit within the anti-lock brake control module.
- Circuit 902 (BR) shorted to power.

R1- 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 DTC C1198 or C1200 retrieved?
YES - DTC 1198 go to R2.
- DTC 1200 go to R5.
- If a different DTC is retrieved, return to DTC Index.
NO - If System Pass is obtained, go to R7.

R2- Check LF ISO 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 36.
- Is the resistance between 3 and 6 ohms?
YES - Go to R5.
NO - Go to R3.

R3- Isolate Resistance Fault
- Disconnect 12-pin connector from Hydraulic anti-lock actuator.

ABS HCU Circuit Test. LF ISO Solenoid:

- Measure the resistance between each of the following terminals on the hydraulic anti-lock actuator and pin 8.
- 3, 4, 5
- 12
- Were all resistances between 3 and 6 ohms?
YES - Go to R4.
NO - Replace the hydraulic anti-lock actuator and go to R7.

R4- Check Circuit Between ABS Control Module and Hydraulic Actuator

ABS HCU Circuit Test. Circuit 902:

- Measure the resistance between breakout box pin 36 and hydraulic anti-lock actuator 12-pin connector pin 8, circuit 902 (BR).
- Measure the resistance between breakout box pin 36 and pin 1.
- Is the resistance less than 5 ohms between breakout box pin 36 and the HCU pin 8 and greater that 10,000 ohms between breakout box pin 36 and pin 1?
YES - Replace the anti-lock brake control module and go to R7.
NO - Repair circuit 902 (BR) and go to R7.

R5- Check for LF ISO 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 36 and pin 1.
- Is continuity indicated?
YES - Repair circuit 902 (BR) and go to R6.
NO - Replace the anti-lock brake control module and go to R7.

R6- Check Circuit Between ABS Control Module and Hydraulic Actuator
- Turn ignition switch to "RUN".
- Measure the voltage between breakout box pin 36 and pin 1.
- Turn ignition switch to "OFF".
- Was the voltage greater than 0 volts?
YES - Repair circuit 902 (BR) and go to R7.
NO - Replace the anti-lock brake control module and go to R7.

R7- 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.