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P0121






P0121 - APPS 5-volt SUPPLY CIRCUIT





When Monitored and Set Condition

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







Diagnostic Test

1. PRE-DIAGNOSTIC CHECK OUT





NOTE: Always perform diagnostics with a fully charged battery.

NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs.

NOTE: Check for applicable TSBs related to the problem.

Turn the ignition on.

With the DRB III(R), read PCM DTCs.

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Repair as necessary.

Perform this procedure prior to symptom diagnosis.

Continue

- Go To 2

2. 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(R) 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(R), clear PCM DTCs.

NOTE: It maybe necessary to road test the vehicle for this DTC to set.

With the DRB III(R), read PCM DTCs.

Did this DTC set again?

Yes

- Go To 3

No

- Go To 11

3. CHECK THE APP SENSOR 5-volt SUPPLY CIRCUIT VOLTAGE





Turn the ignition off.

Disconnect the APP Sensor harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Turn the ignition on.

Measure the voltage of the APP Sensor 5-volt Supply circuit at the APP Sensor harness connector.

Is the voltage between 4.7 and 5.2 volts?

Yes

- Go To 4

No

- If the voltage is above 5.2 volts, Go To 5
- If the voltage is below 4.7 volts, Go To 7

4. CHECK THE APPS





With the ignition on.

With the DRB III(R), clear PCM DTCs.

NOTE: It maybe necessary to road test the vehicle for this DTC to set.

With the DRB III(R), read the PCM DTCs.

Did this DTC set again?

Yes

- Go To 9

No

- Replace the Accelerator Pedal Position Sensor.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

5. CHECK THE APP SENSOR 5-volt SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE





Turn the ignition off.

Disconnect the PCM C4 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Turn the ignition on.

Measure the voltage of the APP Sensor 5-volt Supply circuit at the APP Sensor harness connector.

Is the voltage below 1.0 volt?

Yes

- Go To 6

No

- Repair the APP Sensor 5-volt Supply circuit for a short to voltage.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

6. CHECK THE TP SENSOR 5-volt SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE





Turn the ignition off.

Disconnect the PCM C3 harness connector.

Disconnect the Throttle Body harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Turn the ignition on.

Measure the voltage of the 5-volt Supply circuit at the Throttle Body harness connector.

Is the voltage below 1.0 volt?

Yes

- Replace and program the Powertrain Control Module.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

No

- Repair the 5-volt Supply circuit for a short to voltage.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

7. MEASURE THE RESISTANCE BETWEEN GROUND AND THE TP SENSOR 5-volt SUPPLY CIRCUIT





Turn the ignition off.

Disconnect the PCM C3 harness connector.

Disconnect the Throttle Body harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between ground and the 5-volt Supply circuit at the Throttle Body harness connector.

Is the resistance above 100 kohms?

Yes

- Go To 8

No

- Repair the 5-volt Supply circuit for a short to ground.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

8. MEASURE RESISTANCE BETWEEN THE TP SENSOR 5-volt SUPPLY CIRCUIT AND SENSOR GROUND CIRCUITS





With the ignition off.

Measure the resistance between the 5-volt Supply circuit and all Sensor Ground circuits in the PCM C3 harness connector.

Is the resistance above 100 kohms for all measurements?

Yes

- Go To 9

No

- Repair the 5-volt Supply circuit for a short to the Sensor Ground circuit that measured below 100 kohms.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

9. MEASURE THE RESISTANCE BETWEEN GROUND AND THE APP SENSOR 5-volt SUPPLY CIRCUIT





With the ignition off.

Disconnect the PCM C4 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between ground and the APP Sensor 5-volt Supply circuit at the PCM C4 harness connector.

Is the resistance above 100 kohms?

Yes

- Go To 10

No

- Repair the APP Sensor 5-volt Supply circuit for a short to ground.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

10. MEASURE RESISTANCE BETWEEN THE APP SENSOR 5-volt SUPPLY CIRCUIT AND SENSOR GROUND CIRCUITS





With the ignition off.

Measure the resistance between the APP Sensor 5-volt Supply circuit and all Sensor Ground circuits in the PCM C4 harness connector.

Is the resistance above 100 kohms for all measurements?

Yes

- Replace and program the Powertrain Control Module.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

No

- Repair the APP Sensor 5-volt Supply circuit for a short to the Sensor Ground circuit that measured below 100 kohms.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

11. 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 DTCs.

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. 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.