Powertrain Controls - ECM/PCM

DTC 74 Chart:

CIRCUIT DESCRIPTION
This diagnostic test monitors Intake Air Temperature (IAT) sensor voltage. If the PCM detects a large change in sensor output voltage in a 0.25 second period of time, DTC 74 will set.

DTC 74 WILL SET WHEN
- MAP sensor voltage has changed 0.3 volt (11°C) in 250 milliseconds.
- Two seconds have passed since ignition switch has been turned to the run position.

ACTION TAKEN (PCM WILL DEFAULT TO)
DTC 74 does not illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).

DTC 74 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. Checking DTC 74 snapshot value to determine if an intermittent high resistance or an intermittent low resistance caused the DTC to set. An intermittent high resistance can be caused by an open in CKT 452 or CKT 472. An intermittent low resistance can be caused by a short to ground on CKT 472.