Test 26A - Rear Reset Switch Closed (Code 63)

Test 26A: Repairing Code (63) Rear Reset Switch Closed (Part 1 Of 2):

Test 26A: Repairing Code (63) Rear Reset Switch Closed (Part 2 Of 2):

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:
Left Front Reset Switch Closed

CONDITION:
The following criteria must be met for this fault to be detected.
1. Controller Antilock Brake (CAB) not in the antilock pressure control mode.
2. Vehicle speed exceeded 8 mph once since ignition turned on.
3. Reset switch voltage low.
4. Criteria 1 and 2 satisfied for over 400 consecutive controller checks spaced 5 ms apart.

THEORY OF OPERATION:
The reset switches are designed to shuttle for either of two hydraulic trouble conditions:
1. Hydraulic pressure difference between the inlet and outlet of each conventional braking circuit through the hydraulic system (caused by an unacceptable restriction).
2. Hydraulic pressure built up in a low pressure accumulator by enough fluid leaking into it to push the accumulator piston full stroke to a hard stop and causing accumulator pressure to exceed 200 psi.

POSSIBLE CAUSES:
- Anything that keeps the reset switch voltage low when not in the antilock mode
- Isolation orifice blocked during conventional braking
- Dump seat leaking during conventional braking
- Any other hydraulic leak from the conventional braking circuit into one of the low pressure accumulators
- A solenoid valve energized when not in the antilock mode may indicate a defective CAB
- Stuck reset switch
- Reset switch feedback circuit shorted to ground

Controller-Antilock Brake Connector: