P1629

Code P1626/1629, Pass-Key II (Theft Deterrent System) Fuel Enable Circuit:

Pass-KeyII Fuel Enable Circuit:

CIRCUIT DESCRIPTION
When the ignition is turned "ON," the theft deterrent module "reads" the key resistor pellet. If the proper resistance is recognized by the theft deterrent module, it sends a PWM fuel enable signal via CKT 229 to the PCM. The PCM looks for this signal during crank and allows fuel delivery by enabling the injectors when the signal is recognized.

DTC P1626 WILL SET WHEN:
^ The fuel enable signal is lost after the engine has started.


DTC P1629 WILL SET WHEN:
^ The fuel enable signal is not present during crank.


ACTION TAKEN (PCM will default to):
If the fuel enable signal is not seen during crank, the injectors will be disabled and the PCM will store DTC P1629, indicating a problem with the theft deterrent system or CKT 229. A current DTC P1629 will result in a "cranks but won't run" condition. DTC P1629 does not illuminate the MIL (Service Engine Soon). If the fuel enable signal is lost while the engine is running, the PCM will store DTC P1626 and the vehicle will run normally. As long as DTC P1626 is stored, the PCM will ignore any absence of the fuel enable signal and the vehicle will restart and run as long as the problem is isolated to the fuel enable circuit only. Refer to "Theft Deterrent System" for a complete description and diagnostic procedures. DTC P1626 does not illuminate the MIL (Service Engine Soon).

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. If vehicle will not crank with DTC P1626 or P1629 stored, the problem affects the entire theft deterrent system and is not isolated to the fuel enable circuit. Refer to "Theft Deterrent System" for diagnosis, when diagnosing DTC P1626 or P1629 accompanied by a no-crank.
2. The PCM supplies 5 volts to CKT 229 which the theft deterrent module pulses to ground when the correct key resistance is recognized. This test ensures that the PCM is supplying 5 volts and CKT 229 is not open or shorted to ground.
3. Checks the signal from the theft deterrent module. DC frequency on CKT 229 should measure around 50 hertz.
4. Checks for a faulty PCM or intermittent condition by clearing DTC P1626/P1629. Since the PCM ignores the absence of a fuel enable signal only when DTC P1626/P1629 is stored, the vehicle should not start if the problem is present and DTC P1626/P1629 has been cleared.


DIAGNOSTIC AIDS
An intermittent DTC P1626/P1629 and/or a possible no-start can be caused by the following:
^ Loss of power or ground to theft deterrent module - A loose ground or poor ignition or battery connection could cause an intermittent loss of the PASS-Key II fuel enable signal and DTC P1626/P1629 to be set.
^ Dirty, damaged, or loose connections or damaged harness - Check for any damage to the harness which could cause an intermittent open or short to ground, backed out terminals at the PCM and theft deterrent module connectors, broken locks, improperly formed or damaged terminals.