P0698

P0698-SENSOR REFERENCE VOLTAGE 3 CIRCUIT LOW

For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation


The throttle pedal produces two voltage signals proportional to the pedal movement. The voltages are created by electronic circuitry within the pedal assembly. The primary signal varies between 0 and 5 volts and the secondary signal varies between 0 and 2.5 volts. The Engine Control Module uses the two signals to validate throttle pedal position to control engine fueling. The ECM illuminates the MIL lamp immediately after the diagnostic runs and fails. The ETC lamp will also flash. During this time the customer will be in a limp home mode. The ECM will turn off the MIL lamp after the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
With engine running.

- Set Condition:
Low voltage detected at the APPS supply circuit or low voltage detected at the APPS 1 5-volt supply.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview


1. (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO BATTERY NEGATIVE




Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the APPS harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance of the APPS 1 (F855) 5-volt supply circuit between the sensor harness connector and battery negative
Is the resistance greater than 100 k ohms?

Yes


- Go To 2


No


- Repair the (F855) 5-volt supply circuit shorted to battery negative.
- Perform POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test



2. (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO OTHER CIRCUITS
Measure the resistance between the (F855) APPS 1 5-volt supply circuit at the ECM harness connector and all other circuits in the ECM connector.
Is the resistance greater than 100k ohms?

Yes


- Go To 3


No


- Repair the APPS #1 (F855) 5-volt supply circuit shorted to other circuits.
- Perform POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test



3. INTERNAL ECM




Reconnect the ECM harness connectors.
Turn ignition on, engine off.
While monitoring with the scan tool, connect a jumper wire between the (K23) APPS 1 signal circuit at the sensor harness connector and the (F855) APPS 1 supply circuit at the sensor harness connector.

NOTE: With the APPS disconnected it is normal to have a APPS 1 and APPS 2 low voltage DTC set.

Did a APPS 1 voltage too high DTC set?

Yes


- Go To 4


No


- Replace and program the ECM.
- Perform POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test



4. APPS
Reconnect the APPS harness connector.
Ignition on, engine not running.
Monitor the APPS 1 and APPS 2 voltage with the scan tool while depressing the throttle pedal.
Is the voltage transition shown on the scan tool smooth while depressing the throttle and is the volt swing smooth?

Yes


- Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). Intermittent Condition


No


- Replace the APPS.
- Perform POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test