DTC 30

DTC 30 Chart (1 Of 2):

DTC 30 Chart (2 Of 2):

CIRCUIT DESCRIPTION
The PCM controls idle RPM by increasing or decreasing the throttle angle by commanding the Idle Speed Control (ISC) motor to extend (increase throttle angle) or retract (decrease throttle angle). Anytime the ISC motor plunger is resting on the throttle stop and the Throttle Position (TP) switch is closed, the PCM will command the ISC motor to extend or retract until the desired engine RPM is achieved. If the desired RPM cannot be achieved, DTC 30 will set.

DTC 30 WILL SET WHEN
- DTC(s) 21, 22, 24, 26 or 27 are not set.
- Vehicle speed is less than 1 mph.
- TP switch is closed.
- The difference between actual and desired RPM is 288 RPM or more.
- Engine is not receiving a power steering load.
- ISC motor is in extend mode for more than 29 seconds and TP sensor indicates a throttle angle less than 9.2 percent.
OR
- ISC motor is in retract mode for more than 29 seconds and TP sensor indicates a throttle angle greater than 1.2 percent.

ACTION TAKEN (PCM WILL DEFAULT TO)
With a current DTC 30 set, the PCM will illuminate MIL (Service Engine Soon).

DTC 30 WILL CLEAR WHEN
The fault no longer exists and ignition switch is cycled "OFF" and "ON."

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

1. Checking for ISC motor codes that can cause other problems.
2. Checking if cruise control is engaged causing idle problems.
3. Checking for proper ISC motor operation.
4. Many engine fuel and emissions system faults may cause unstable idle. If the base engine idle is not steady, the ISC may not be able to control idle to within the range of commanded idle speed.

DIAGNOSTIC AIDS
Many engine fuel and emissions system faults may cause unstable idle. If the base engine idle is not steady, the ISC may not be able to control idle to within the range of commanded idle speed.
- Check for cracked spark plugs, secondary ignition arcing, vacuum leaks (hoses/manifold) ISC valve operation.
OR
- Check for throttle and cruise cable binding.
- Check for proper TP sensor to throttle body installation.