Code P1550, Cruise Stepper Motor: Notes

The stepper motor cruise system differs from the up integrated (PCM-controlled) cruise system previously used in that it is a stand-alone system. PCM still retains the ability to disable cruise if conditions are detected which would make cruise control operation undesirable. PCM may inhibit cruise control if the following conditions are present.

• Engine not running long enough for cruise control operation.
• Codes P0705 or P1630 set.
• Engine speed too high or too low.
• Vehicle speed too high or too low.
• Transmission range input indicates Park, Neutral, Low or Reverse gear selected.

If PCM detects any of these conditions, it will interrupt the cruise inhibit signal circuit to request that cruise control disengage.

• Cruise status signal circuit indicates an open or a short to voltage while cruise is engaged and vehicle speed is less than 7 MPH.

Code P1550 will set when the following condition is present.

• Cruise status signal circuit indicates that cruise is still engaged while PCM is commanding cruise to be disabled. P1550 does not illuminate the Malfunction Indicator Light (MIL).
  NOTE: Test numbers refer to numbers on diagnostic chart.

1. Ensures PCM is detecting a current fault.
2. On 3.8L, this ensures circuit is not open or grounded and proper voltage is being supplied by SMCC Module.