Service Procedure

1. Remove the passenger's side kick panel.

2. Remove the ECM.

3. Following the instructions packed with the new PROM, remove the old PROM from the ECM and install the new PROM in is place. See "Parts Information" section of this Campaign Bulletin for the PROM part number.

4. Reinstall and connect the ECM and kick pancl.

IMPORTANT

5. Start engine and idle until it reaches operating temperature. Turn ignition switch to "OFF" position.



6. Connect the Tech 1 scan tool to the ALDL connector.

7. Start the engine and check idle speed. Record idle speed on the Repair Order for later reference.

8. Turn ignition switch to "OFF" position.





9. Disconnect the tachometer filter connector (Figure 1). This will force the duty signal to 10% (full rich condition).

10. Start the engine and measure oxygen sensor output voltage on the Tech 1. Depending on the idle speed recorded in Step 7 above, perform the appropriate procedure described below:

a. If the idle speed in Step 7 was equal to or less than 950 rpm (M/T models) or 1200 rpm (A/T models):

^ And if oxygen sensor output voltage is equal to or greater than 550 mV (M/T models) or 650 mV (A/T models), go to Step 12.

^ Or if oxygen sensor output voltage is less than 550 mV (M/T models) or 650 mV (A/T models), go to Step 11.



b. If the idle speed in Step 7 was greater than 950 rpm (M/T models) or 1200 rpm (A/T models):

^ And if oxygen sensor output voltage is equal to or greater than 600 mV (M/T models) or 700 mV (A/T models), go to Step 12.

^ Or if oxygen sensor output voltage is less ban 600 mV (M/T models) or 700 mV (A/T models), go to Step 11.

c. Turn ignition switch to "OFF" position.

11. a. Inspect wiring between oxygen sensor and ECM for opens or shorts. Repair as required. If a wiring repair is made, repeat Step 10.

b. If wiring has no opens or shorts, replace the oxygen sensor as follows:

^ Run engine until it reaches normal operating temperature.

^ Apply a small amount of penetration oil to the oxygen sensor threads and allow on to absorb.

^ Disconnect oxygen sensor connector.

^ Remove the heat tube and heat shield.

^ Loosen the sensor by using a punch or chisel to tap the hex area of the sensor with a hammer. DO NOT USE AN IMPACT WRENCH.

^ Unscrew the oxygen sensor, using care not to strip the threads.



NOTE
If the oxygen sensor threads are stripped, or if the exhaust manlfold becomes damaged during this procedure, replace the exhaust manifold as described in the appropriate Workshop Manual.

^ Install new oxygen sensor (see "Parts Information" section of this Campaign Bulletin) to exhaust manifold.

^ Reinstall heat shield and heat tube.

^ Connect oxygen sensor connector.

^ Go to Step 12.

12. Reconnect the tachometcr filter connector.

13. Disconncct the Tech 1.

14. Affix a campaign label to the inside of the driver's door. Using a ball-point pen, fill in label with Campaign Number 91E253 and dealer code.

DEALER RESPONSIBILITY

Isuzu dealers are responsible for repairing any affected vehicle at no charge to owners, regardless of date of purchase, mileage or selling dealer.

Whenever a vehicle subjcct to this campaign is in a dealer's vehicle inventory, or arrives at a dealership for service, the dealer must take the necessary steps to ensure this campaign correction has been made before selling or releasing the vehicle.






FLAT RATE MANUAL UPDATE INFORMATION