Test Description

WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers in the diagnostic procedures.

3

This step determines if proper sensor activity is present. When in Closed Loop fuel control, the HO2S voltage should rapidly vary between more than and less than the bias voltage.

7

This step determines if the PCM and the high and low circuits between the control module and the HO2S connector are operating properly.

10

This step determines if the HO2S heater circuit operates correctly up to the HO2S connector.

11

This step determines if the proper circuit resistance exists between the HO2S Low circuit and control module ground.

16

This step determines if the proper circuit resistance exists between the HO2S low circuit and control module ground with a COLD sensor. A loose HO2S or faulty thread to exhaust electrical contact causes higher resistance when the HO2S is cold. Although 500 ohms is allowed, the typical resistance should be less than 50 ohms.