DTC 68

DTC 68 Chart:

Cruise Control Circuit:

CIRCUIT DESCRIPTION
The PCM controlled cruise control system is designed to monitor itself to be sure that the desired cruise position and actual cruise position are equal to each other. DTC 68 will set and disengage the cruise control when the Servo Position Sensor (SPS) feedback reading to the PCM is significantly higher or lower than the commanded value.

DTC 68 WILL SET WHEN

Case 1: Throttle angle 20 degrees or greater
SPS indicating stroke at least 7% greater than commanded value for 2 seconds.

Case 2: C/C servo commanded to 46% or less of maximum stroke
GSPS indicating stroke at least 19% less than the commanded value for 2 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
The PCM will disengage cruise control if a current DTC 68 is set and C/C set speed exceeds vehicle speed by more than 8 km/h (5 mph). DTC 68 does not illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).

DTC 68 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 cruise control servo operation, servo throttle linkage, and vacuum.
2. Checks cruise vacuum release valve, vacuum lines for restrictions, and servo throttle linkage for binding.
3. Checks vent valve in cruise control servo.

DIAGNOSTIC AIDS
A cruise control throttle cable which binds or intermittently sticks can cause DTC 68 to set. Outside interference such as a CB antenna lead near the PCM wiring harness may induce a false SPS signal and set DTC 68.

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.