DTC 40

DTC 40 Chart:

Power Steering Pressure (PSP) Switch Circuit:

CIRCUIT DESCRIPTION
The Power Steering Pressure (PSP) switch is a normally closed switch which opens when PSP exceeds 450 to 650 psi. The PSP switch closes again when pressure drops below 100 to 450 psi. The PCM uses the PSP to determine if high PSP loads are present to control idle quality.

DTC 40 WILL SET WHEN
- Engine running.
- Vehicle speed is 45 mph or greater.
- PSP switch opens for 60 seconds or more.

ACTION TAKEN (PCM WILL DEFAULT TO)
With a current DTC 40 set, the PCM will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).


DTC 40 WILL CLEAR WHEN
he fault no longer exists.

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

1. Tech 1 should cycle from "NORMAL" to "HI PRESS." to "NORMAL." If Tech 1 displays "NORMAL," there is an open or short to ground in the circuitry. If Tech 1 displays "HI PRESS.", there is a short to voltage in the circuitry.
2. Checking if CKT 495 is shorted to voltage or if the power steering pressure is faulty.
3. Checking if CKT 441 or 15 amp ERLS fuse is open.
4. Checking if the power steering pressure switch is open.
5. Checking if CKT 495 is open or if PCM is faulty.

DIAGNOSTIC AIDS
This diagnostic test monitors the power steering pressure switch. When a load is placed on the power steering such as full lock, the switch opens. DTC 40 sets when the vehicle is above 45 mph and the power steering pressure switch is open.