Circuit Description
A dash light is illuminated by the powertrain control module (PCM) if the diagnostic has detected certain errors related to the accelerator pedal position (APP) sensor. When the PCM is commanding the Service Throttle Soon lamp ON, the voltage potential of the circuit will be low (near 0 volts). When the PCM is commanding the Service Throttle Soon lamp OFF, the voltage potential of the circuit will be high (near the battery volts). The primary function of the PCM in this circuit is to supply the ground for the service throttle soon lamp.
Conditions for Running the DTC
The ignition is in the ON position.
Conditions for Setting the DTC
| • | The Service Throttle Soon lamp is requested ON. |
| • | The voltage on the service throttle soon control circuit is high (near the battery volts). |
or
| • | The Service Throttle Soon lamp is requested OFF. |
| • | The voltage on the Service Throttle Soon control circuit is low (near 0 volts). |
Action Taken When the DTC Sets
| • | The PCM will not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | A history DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures. |
| • | The scan tool Clear Info function was used. |
Diagnostic Aids
A malfunctioning bulb or the control circuit is shorted to ground will cause a P1654 to set.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
Tests the ON and the OFF states.
-
Ensures that the replacement PCM, which utilizes an electrically erasable programmable read only memory (EEPROM), is programmed when installed. If no trouble is found in the control circuit or the connections at the PCM, the PCM may be malfunctioning, however, this is an extremely unlikely failure.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool Capture Info to save the Freeze Frame and Failure Records for reference. The data in the control module is deleted once the Clear Info function is used. Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
Important: Be sure that both the ON and the OFF states are commanded. Repeat the commands as many times as necessary. Does the lamp turn ON and OFF with each command? | -- | |||||||||
3 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs are stored, refer to those tables. Are there any additional DTCs stored? | -- | Go to the applicable DTC table | Go to Diagnostic Aids | ||||||
4 |
Is the lamp OFF? | -- | ||||||||
5 | With a fused jumper wire connected to ground, probe the lamp control circuit in the PCM harness connector. Is the lamp ON? | -- | ||||||||
6 |
Did you perform a repair? | -- | ||||||||
7 | The service throttle soon lamp control circuit is shorted to ground. Repair as necessary. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||
8 |
Did you perform a repair? | -- | -- | |||||||
|
Important: The new PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||||||||
10 |
Does the scan tool indicate the diagnostic Passed? | -- | ||||||||
11 | Does the scan tool display any additional undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK |
