The electronic throttle control body controls the idle speed by allowing a controlled
amount of air to enter the intake manifold. Actual idle speed is continuously compared
to the ECM commanded idle speed. DTC P0506 will set if the actual idle speed is less
than a calibrated value from the ECM commanded idle speed.
DTC PARAMETERS
DTC P0506 will set if the actual idle speed is less than 100 rpm from the ECM
commanded idle speed when:
| • | IAT is greater than 34°C (93°F) |
| • | ECT is greater than 80°C (176°) |
| • | EVAP diagnostic not running |
| • | No ECT, EVAP, IAT, TP, or VSS DTC has been set |
DTC P0506 diagnostic runs continuously once the above conditions have been met.
DTC P0506 is a (type B) DTC.
Diagnostic Aids
Verify the ECM's ability to control engine rpm by using ENGINE SPEED CONTROL
in the SPECIAL FUNCTIONS section of the Scan tool., which will give the user the ability
to increase or decrease rpm in increments of 25, 100, and 500 rpm. Comparing the ACUTAL
RPM with the DESIRED RPM, both should be within 100 rpm of each other.
Possible causes of low idle:
| • | Accessory drive component loading engine |
| • | Damaged air induction tubing |
