P1641
CIRCUIT DESCRIPTIONA dash light is illuminated by the Powertrain Control Module (PCM) when the ignition is ON with the engine OFF, or if the diagnostics have detected certain errors related to the engine performance or the engine sensor status. When the PCM is commanding the Malfunction Indicator Lamp (MIL) ON, the voltage potential of the circuit will be low, near 0 volts. When the PCM is commanding the MIL OFF, the voltage potential of the circuit will be high, near the battery voltage. The primary function of the PCM in this circuit is to supply the ground for the MIL circuit.
CONDITIONS FOR RUNNING THE DTC
The ignition is in the ON position.
CONDITIONS FOR SETTING THE DTC
^ The MIL is requested ON.
^ The voltage on the MIL control circuit is high (near the battery voltage).
or
^ The MIL is requested OFF.
^ The voltage on the MIL control circuit is low, near 0 volts.
ACTION TAKEN WHEN THE DTC SETS
^ The control module stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
^ The driver information center, if equipped, may display a message.
CONDITIONS FOR CLEARING THE DTC
^ A current DTC Last Test Failed clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ Use a scan tool in order to clear the DTC.
DIAGNOSTIC AIDS
A malfunctioning bulb, the control circuit shorted to ground or battery voltage, will cause a DTC P1641 to set.
An intermittent may be caused by the following conditions:
^ Poor connections
^ Rubbed through wire insulation
^ Broken wire inside the insulation
TEST DESCRIPTION
Steps 1-11:
The number below refers to the step number on the diagnostic table.
2. This test ensures that both the ON and the OFF states are commanded.