Circuit Description
A dash light is illuminated by the 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 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 stores in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL off after three consecutive trips without a fault condition. |
| • | A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle). |
| • | Use of a Scan Tool will clear the DTC codes. |
Diagnostic Aids
A malfunctioning bulb or the control circuit is shorted to ground will cause a P1654 to set.
Test Description
The number(s) below refer to the Step number(s) on the Diagnostic Table.
-
Be sure that both the ON and the OFF states are commanded. Repeat the commands as many times as necessary.
-
If no trouble is found in the control circuit or the connections at the PCM, the PCM maybe malfunctioning, however, this is an extremely unlikely failure.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 |
Important: Before clearing any DTCs, use the Scan Tool Capture Info to save freeze frame and failure records for reference, as the Scan Tool loses data when using the Clear Info function. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||
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 any additional DTCs were stored, refer to those table(s). 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 |
Was a repair performed? | -- | ||||||||
7 | The Service Throttle Soon lamp control circuit is shorted to ground. Repair as necessary. Is the action complete? | -- | -- | |||||||
8 |
Is the repair complete? | -- | -- | |||||||
|
Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. 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 |
