EGR Valve: Testing and Inspection

- DISCONNECT CABLE FROM NEGATIVE TERMINAL OF BATTERY

CAUTION: Work must be started after approx. 20 seconds or longer from the time the ignition switch is turned to the "LOCK" position and the negative (-) terminal cable is disconnected from the battery.


- DISCONNECT EGR VALVE CONNECTOR

EGR Connector Identification:

- INSPECT EGR VALVE RESISTANCE

Using an ohmmeter, measure the resistance between terminal B1 (or B2) and other terminals (S1, S2, S3 and S4).

Resistance (Cold): 19.9 - 23.4 ohms

Removing Stepper Motor:

- Inspect EGR valve operation

(a) Remove the three bolts and stepping motor from the housing.

Checking Operation:

(b) Apply battery voltage to terminal B1 (or B2), and while repeatedly grounding (*S4) - (S4 and *S3) - (S3 and *S2) - (S2 and *S1) - (S1 and *S4) in sequence, check that the valve moves toward the open position.

HINT: Keep the terminal marked with an asterisk (*) grounded while proceeding to the next grounding.

Checking Operation:

(c) Apply battery voltage to terminal B1 (or B2), and while repeatedly grounding (*S1) - (S1 and *S2) - (S2 and *S3) - (S3 and *S4) - (S4 and *S1) in sequence, check that the valve moves toward the closed position.

HINT:

^ Keep the terminal marked with an asterisk (*) grounded while proceeding to the next grounding.

^ Perform this operation after opening the valve by performing step (b) above.

If operation is not as specified, replace the EGR valve assembly.

(d) Reinstall the stepping motor to the housing with the three bolts.