Questions and Answers

Pontiac Bonneville DTC 63 SPS Q. Greetings, I have a 1993 Pontiac Bonneville SE 3.8 liter 6 cylinder VIN 'L'. I recently ran a check on the computer and it gave me code: '63' Cruise control problem (SPS indicated low). What does this mean? I could not find anything in my Chilton's manual on it. Any help would be greatly appreciated. Thanks a million, James

A. Did you check under Service Manuals on this site? I don't have a manual for that model and doubt anything but a Bonneville manual would help you here. You could call a dealer.

Circuit Description - Solenoid Circuits:
The cruise servo vent and vac solenoids are output lines and are controlled by high side drivers in the PCM (in this case, the circuit is grounded on one side and the "high side drivers" in the PCM provide power.) When the ignition is "ON", the PCM looks at these output lines and will set codes depending on the status of each line.

Circuit Description - Servo Position Sensor (SPS):
The PCM supplies a 5 volt reference signal to the servo position sensor through circuit 398, and then monitors the signal return through circuit 399. Depending on the actual servo position, the signal on CKT 399 will vary, indicating the actual servo position. The PCM uses this information to control the servo position when cruise is engaged.

The PCM controlled cruise control system is designed to monitor itself to be sure that the desired cruise servo position and actual cruise servo position are equal to each other. If the actual servo position is too low when maximum servo position is commanded, the PCM will set Code 63.

Code 63 will set if the following conditions are present.

• Throttle position sensor signal indicates throttle opening sell than 50%.
• Desired servo position is 90%.
• Actual servo position is less than 2%
• Above conditions are met for 3 seconds.

NOTE: Code 63 does not turn on the MIL light.

Diagnostic Aids

1. A cruise throttle cable that is sticking or binding can cause a code 63 to set.
2. Outside interference such as CB antenna lead near the PCM wiring harness may cause a false SPS reading and set a false code 63.
3. An intermittent may be caused by a poor connection, worn through wire insulation, or a wire broken inside the insulation. Check for:
   • Poor connections or damaged harness. Inspect harness connectors for backed out terminals, improper mating, broken locks, bad terminals, poor terminal to wire connections, and damaged harness.