P0121

(P0121) APPS 5-VOLT SUPPLY CIRCUIT






When Monitored and Set Condition
^ When Monitored: Ignition on.
^ Set Condition: When the PCM recognizes the APPS 5-Volt Supply circuit voltage is below 1.0 volt or higher than 5.2 volts.

POSSIBLE CAUSES
ACCELERATOR PEDAL POSITION SENSOR 5-VOLT SUPPLY SHORTED TO (B+)
ACCELERATOR PEDAL POSITION SENSOR 5-VOLT SUPPLY SHORTED TO GROUND
ACCELERATOR PEDAL POSITION SENSOR 5-VOLT SUPPLY CIRCUIT OPEN
ACCELERATOR PEDAL POSITION SENSOR
POWERTRAIN CONTROL MODULE

Diagnostic Test
1. CHECK FOR CURRENT DTC





Note: If the PCM detects and stores a DTC, the PCM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the DRB III at the same time the DTC is displayed.

Note: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for a DTC. Turn the ignition on. With the DRB III, erase PCM DTCs.

Note: It maybe necessary to road test the vehicle for this DTC to set. With the DRB III, read the PCM DTCs.

Did this DTC set again?
Yes>> Go To 2
No>> Go To 6

2. APPS 5-VOLT SUPPLY SHORTED TO GROUND





Turn the ignition off. Disconnect the PCM harness connectors. Disconnect the APPS Sensor.

Note: Check connectors-Clean/repair as necessary. Measure the resistance between ground and the APPS 5-Volt Supply circuit.

Is the resistance below 100 ohms?
Yes>> Repair the short to ground in the APPS 5-Volt Supply circuit.
Perform Powertrain Verification Test - Ver 2
No>> Go To 3

3. APPS 5-VOLT SUPPLY SHORTED TO (B+)





Turn the ignition on.
Measure the voltage between ground and the APPS 5-Volt Supply circuit
at the APPS harness connector.
Is the voltage above 5.2 volts?
Yes>> Repair the APPS 5-Volt Supply circuit short to B(+).
Perform Powertrain Verification Test - Ver 2
No>> Go To 4

4. OPEN APPS 5-VOLT SUPPLY





Turn the ignition off.
Measure the resistance of the APPS 5-Volt Supply circuit from the APPS
harness connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
Yes>> Go To 5
No>> Repair the APPS 5-Volt Supply circuit for an open.
Perform Powertrain Verification Test - Ver 2

5. APPS





With the ignition off.
Connect the PCM harness connectors.
Turn the ignition on.
Measure the voltage between ground and the APPS 5-Volt Supply circuit
Signal circuit at the APPS harness connector.
Is the voltage above 4.6 volts?
Yes>> Replace the APPS.
Perform Powertrain Verification Test - Ver 2
No>> Replace and program the Powertrain Control Module.
Perform Powertrain Verification Test - Ver 2

6. INTERMITTENT WIRING AND CONNECTORS
The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.

Note: Check connectors-Clean/repair as necessary. Poor pin to terminal connections can set DTC's.

Note: Check for any Technical Service Bulletins that may apply. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors specific to this DTC. Wiggle the wires while checking for shorts and open circuits.

Were there any problems found?
Yes>> Repair as necessary.
Perform Powertrain Verification Test - Ver 2
No>> The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.