Powertrain Controls - ECM/PCM

DTC 61 Chart:

Cruise Control System Circuit:

CIRCUIT DESCRIPTION
The cruise switch within the turn signal lever receives ignition voltage from a 10 amp fuse through CKT 439 to the turn signal lever-cruise switches. The cruise "ON/OFF," "SET/COAST," and "RESUME/ACCEL" switches are inputs to the cruise control portion of the PCM.
The cruise servo vent and vacuum solenoids output is controlled by high side drivers in the PCM. When the ignition is "ON" the PCM looks at these output lines and will set DTC(s) if an incorrect status is seen on any line.
The vent solenoid is a normally open (de-energized) solenoid valve that allows any vacuum in the cruise servo to be depleted. When the solenoid is energized ("ON"), the cruise servo holds vacuum allowing the servo to stay retracted and hold open the throttle.

DTC 61 WILL SET WHEN
- CKT 403 is shorted to voltage when the vent solenoid is commanded "OFF."
- CKT 403 is open.
- CKT 403 is shorted to ground when the PCM is commanding the vent solenoid "ON."
- One of the above conditions are met for more than a half of a second.

ACTION TAKEN (PCM WILL DEFAULT TO)
The PCM will not allow cruise control operation with a current DTC 61 set. DTC 61 does not illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).

DTC 61 WILL CLEAR WHEN
The fault no longer exists and the ignition switch is cycled "OFF" and "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Checks for a short to voltage or a faulty PCM.
2. Checks for a short to ground or a faulty PCM.
3. Checks CKT 403 for an open.
4. Checks CKT 403 for an open or short to ground or a faulty PCM.
5. Checks for an open in the ground path or a faulty cruise control servo.

DIAGNOSTIC AIDS
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.
Check for:

Poor connection or damaged harness
Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.