P1641

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
A dash light is illuminated by the Powertrain Control Module (PCM) if diagnostics have detected certain errors related to the engine performance or engine sensor status. When the PCM is commanding the 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 battery volts). The primary function of the PCM is to supply the ground for the MIL circuit. This is a type D DTC

CONDITIONS FOR SETTING THE DTC
- MIL requested ON.
- Voltage on MIL control circuit high (near battery volts).
or
- MIL requested OFF.
- Voltage on MIL control circuit low (near 0 volts).

ACTION TAKEN WHEN THE DTC SETS
Will not turn ON the MIL.

CONDITIONS FOR CLEARING THE MIL/DTC
- A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.

DIAGNOSTIC AIDS
A faulty bulb or the control circuit shorted to ground will cause a P1641 to set.

TEST DESCRIPTION
Number(s) below refer to the Step number(s) on the Diagnostic Table.

2. Be sure that both the ON and the OFF states are commanded. Repeat the commands as many times as necessary.
9. If no trouble is found in the control circuit or the connection at the PCM, the PCM maybe faulty, however, this is an extremely unlikely failure.