DTC 99

DTC 99 Chart:

Cruise Control System Circuit:

CIRCUIT DESCRIPTION
The Powertrain Control Module (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.
A current DTC 99 may cause the vehicle to operate in "Power Management." While in "Power Management," the PCM will shut "OFF" fuel to individual cylinders to avoid overrevving the engine in case the throttle is being held open by a sticking cruise control throttle cable, brake vacuum release valve, or cruise control servo. "Power Management" may be perceived as a severe engine miss or lack of power.

DTC 99 WILL SET WHEN
- Engine running.
- Cruise Control (C/C) disengaged for a least 2 seconds.
- C/C servo position greater than 160 counts (DTC 99 not previously set) or greater than 96 counts (DTC 99 previously set).
- If Throttle Position (TP) sensor is not failed, throttle angle greater than 20 degrees or greater than 16 degrees (DTC 99 previously set).
- If TP sensor is failed, Manifold Absolute Pressure (MAP) greater than 70 kPa (DTC 99 not previously set) or greater than 55 kPa (DTC 99 previously set).

ACTION TAKEN (PCM WILL DEFAULT TO)
The PCM will not allow cruise control operation with a current DTC 99 set. The condition that causes the DTC 99 may also cause the vehicle to operate in "Power Management." DTC 99 does not illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).

DTC 99 WILL CLEAR WHEN
The fault no longer exists.

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 99 to set. DTC 99 can also be set by manually compressing the cruise servo to raise engine speed.