Overview:
The Fuller Advantage transmission is equipped with an auto-neutral function. This function shifts the transmission to neutral when the vehicle is brought to a complete stop while the transmission is in gear and the park brake is set. Fault Code 21 indicates a problem with the Auto-Neutral Park Brake Switch circuit.

Detection:
The TECU has two options that can be configured depending on component setup. For a TECU configured for a Hard-Wired Park Brake Switch, this fault can be detected anytime the ignition key is on. For a TECU configured for a J1939 Park Brake Switch input, the fault can be detected anytime the J1939 communicates to the TECU from a chassis module (e.g., Cab Controller, Engine, etc).

Conditions to Set Fault Code Active:
FMI 14 – Special Instructions: Park Brake Switch is set and one of the following are true:
• Vehicle is moving 11 MPH or greater for more than 9 seconds.
• Hard-wired Park Brake Switch and J1939 Park Brake Switch values do not match for more than 3 seconds.

Note: The fault can also set anytime the Park Brake Switch status remains released for five consecutive power-up and power-down cycles.

Fallback:
FMI 14
• Remote Throttle and Split Shaft PTO (if equipped) may be inoperative if the TECU cannot determine if the park brake is set.

Conditions to Set Fault Code Inactive:
FMI 14: Park Brake Switch circuit operates normally for 6 seconds or after a power cycle.

Possible Causes:
FMI 14
1) Park Brake Switch
– Normally open park brake switch installed on chassis (Normally closed is required)
– Internal failure
2) Park Brake Switch Configuration
– Incorrect configuration setting
3) Vehicle Harness
– Wiring shorted to ground, shorted to power or open
– Bent, spread, corroded or loose terminals
4) J1939 Data Link
– Wiring shorted to ground, shorted to power or open
– Bent, spread, corroded or loose terminals
5) Operator Influence
– Not setting Park Brake Switch