Shift Interlock System
The shift interlock system prevents shifting from PARK unless the brake pedal is depressed. The shift interlock system consists of a shift lock actuator mounted at the base of the steering column or on the floor shifter mechanism. If the ignition switch is in the RUN position, the shift lock actuator is ON unless the brake pedal is depressed.
Symptom Chart
Symptom Chart
Condition
Possible Sources
Action
- The shift interlock system does not release/lock correctly
- Circuitry.
- Fuse(s):
- Shift lock actuator.
- Brake pedal position switch.
PINPOINT TEST D: THE SHIFT INTERLOCK SYSTEM DOES NOT RELEASE/LOCK CORRECTLY
Test Step
Result / Action to Take
D1 TEST THE BRAKE LIGHTS
- Apply brake pedal and view brake lights.
- Do the brake lights illuminate?
Yes
GO to D7 .
No
GO to D2 .
D2 TEST FUSE F1.5 (7.5A)
- Check fuse: Fuse F1.5 (7.5A).
- Measure the resistance of fuse F1.5 (7.5A).
- Is the resistance less than 5 ohms?
Yes
GO to D4 .
No
GO to D3 .
D3 TEST CIRCUIT 729 (RD/WH) FOR A SHORT TO GROUND
- Disconnect: Brake Pedal Position Switch C278.
- Measure the resistance of circuit 729 (RD/WH) at brake pedal position switch C278-5.
- Is the resistance greater than 10,000 ohms?
Yes
GO to D4 .
No
SERVICE circuit 729 (RD/WH) for short to ground. TEST the system for normal operation.
D4 TEST CIRCUIT 729 (RD/WH) FOR AN OPEN
- Measure the resistance between the output side of fuse F1.5 (7.5A) and brake pedal position switch C278-5, circuit 729 (RD/WH).
- Is resistance less than 5 ohms?
Yes
GO to D5 .
No
SERVICE circuit 729 (RD/WH) for open. RETEST the system.
D5 TEST THE BRAKE PEDAL POSITION SWITCH
- Measure the resistance of brake pedal position switch (C278) while open (OFF) and closed (ON).
- Is the resistance of the switch greater than 10,000 ohms while OFF and less than 5 ohms while ON?
Yes
GO to D6 .
No
INSTALL a new brake pedal position switch. TEST the system for normal operation.
D6 CHECK CIRCUIT 810 (RD/LG) FOR A SHORT TO GROUND
- Disconnect: Shift Lock Actuator C2008.
- Measure the resistance of circuit 810 (RD/LG), shift lock actuator C2096-1.
- Is the resistance greater than 10,000 ohms?
Yes
GO to D7 .
No
SERVICE circuit 810 (RD/LG) for short to ground. TEST the system for normal operation.
D7 CHECK CIRCUIT 810 (RD/LG) FOR AN OPEN
- Measure the resistance of circuit 810 (RD/LG) between shift lock actuator C2096-1 and brake pedal position switch C278-6.
- Is the resistance less than 5 ohms?
Yes
GO to D8 .
No
SERVICE circuit 810 (RD/LG) for open. TEST the system for normal operation.
D8 TEST FOR VOLTAGE ON CIRCUIT 1003 (GY/YE)
- Measure the voltage at shift lock actuator C2096-2, circuit 1003 (GY/YE).
- Is voltage greater than 10 volts?
Yes
GO to D12 .
No
GO to D9 .
D9 TEST FUSE F1.27 (5A)
- Check fuse: Fuse F1.27 (5A).
- Is the resistance less than 5 ohms?
Yes
GO to D11 .
No
GO to D10 .
D10 TEST CIRCUIT 1003 (GY/YE) FOR A SHORT TO GROUND
- Measure the resistance at shift lock actuator C2096-2, circuit 1003 (GY/YE).
- Is the resistance greater than 10,000 ohms?
Yes
GO to D11 .
No
SERVICE circuit 1003 (GY/YE) for short to ground. TEST the system for normal operation.
D11 TEST CIRCUIT 1003 (GY/YE) FOR AN OPEN
- Measure the resistance of circuit 1003 (GY/YE) between output side of fuse F1.27 (5A) and shift lock actuator C2096-2.
- Is the resistance less than 5 ohms?
Yes
GO to D12 .
No
SERVICE circuit 1003 (GY/YE) for open. TEST the system for normal operation.
D12 TEST CIRCUIT 57 (BK) FOR AN OPEN
- Measure the resistance of shift lock actuator C2096-6, circuit 57 (BK).
- Is the resistance less than 5 ohms?
Yes
INSTALL a new shift lock actuator. TEST the system for normal operation.
No
SERVICE circuit 57 (BK) for open. TEST the system for normal operation.