Test 20A - Rear Isolation Solenoid Open (Code 51)

Test 20A: Repairing Code (51) Rear Isolation Solenoid Open:

NOTE: When connecting or disconnecting connectors and inspecting connectors clean and repair as necessary.

NOTE: After completion of a repair or test then perform Verification Test. Verification Test VER-1A - ABS

NAME OF CODE:
Rear Isolation Solenoid Open

SET CONDITION:
The following criteria must be met For this code to be detected.
1. Ignition key turned on for at least 3.4 seconds
2. ABS power relay closed
3. Valve command for a particular solenoid not present.
4. Low feedback voltage from low side of solenoid.
5. Criteria 1 - 4 satisfied for over 20 consecutive controller checks spaced 5 ms apart.

THEORY OF OPERATION:
Vehicle battery voltage is applied to the high side of the six solenoid coils in the hydraulic assembly by the ABS power relay whenever valve activity may be required. Each solenoid is energized by the Controller Antilock Brake CAB shorting the low side of the coil to ground.

POSSIBLE CAUSE:
- 0pen solenoid
- 0pen circuit between relay and solenoid
- Shorted CAB solenoid control circuit
- Short to ground in the solenoid feedback to CAB circuit
- Anything that keeps solenoid feedback voltage low when it is expected to be high (solenoid energized)

ABS Main Relay Connector/Socket:

Rear Valve Body (RWAL) Connector:

Rear Valve Body (RWAL):

Controller Antilock Brake Connector: