Codes P1626/1629, Pass-Key II Fuel Enable Circuit: Notes

When ignition is on, theft deterrent module reads the key resistor pellet. If proper resistance is recognized by theft deterrent module, it sends a PWM fuel enable signal to PCM. PCM looks for this signal during crank and allows fuel delivery by enabling the injectors when signal is recognized.

Code P1626 will set when the following condition is present.

• Fuel enable signal is lost after engine has started.

Code P1629 will set when the following condition is present.

• Fuel enable signal is not present during crank.

If fuel enable signal is not seen during crank, injectors will be disabled and PCM will store Code P1629, indicating a problem with theft deterrent system or fuel enable input circuit. Code P1629 will result in a cranks but will not run condition. P1629 does not illuminate the Malfunction Indicator Light (MIL).

If fuel enable signal is lost while engine is running, PCM will store Code P1626 and vehicle will run normally. As long as Code P1626 is stored, PCM will ignore any absence of fuel enable signal and vehicle will restart and run as long as problem is isolated to fuel enable circuit only. P1626 does not illuminate the Malfunction Indicator Light (MIL).

1. If vehicle does not crank with Code P1626 or P1629 stored, problem affects the entire theft deterrent system and is not isolated to fuel enable circuit.
2. PCM supplies 5 volts to fuel enable input circuit which theft deterrent module pulses to ground when correct key resistance is recognized. This test ensures PCM is supplying 5 volts and circuit is not open or shorted to ground.
3. Checks signal from theft deterrent module. DC frequency on circuit should measure approximately 50 hertz.
4. Checks for a faulty PCM or intermittent condition by clearing Code P1626 or P1629. Since PCM ignores the absence of a fuel enable signal only when Code P1626 or P1629 is stored, vehicle should not start if problem is present and Code P1626 or P1629 has been cleared.