Circuit/System Testing
WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
If an engine mechanical noise can be heard, repair the condition before proceeding with this diagnostic. Refer to Symptoms - Engine Mechanical
.
- Test for an intermittent and a poor connection at the affected KS.
- With the ignition OFF, disconnect the affected KS.
- With the ignition OFF, measure the resistance for infinite ohms from the sensor signal terminal on the KS to a good ground and the low reference terminal on the KS to a good ground with a DMM.
- If resistance does not measure infinite ohms at both terminals, replace the affected KS.
- Connect the DMM between the terminals of the affected KS. Set the DMM to the 400 Hz scale, let stabilize at 0 Hz. Tap on engine block with a non-metallic object near the affected KS while observing the signal indicated on the DMM.
- If the DMM does not display a fluctuating frequency while tapping on the engine block, replace the affected KS.
- Turn the ignition ON, engine OFF. Set the DMM to the DC voltage scale. Measure for 4.2 volts from the KS signal circuit to a good ground and the KS low reference circuit to a good ground with the DMM.
- If over 4.2 volts with the ignition OFF, disconnect the PCM and test the KS signal circuit or the KS low reference circuit for a short to voltage.
- If under 4.2 volts with the ignition OFF, disconnect the PCM test the KS signal circuit or the KS low reference circuit for an open, a short to ground or high resistance.
- Test for intermittent or poor connections at the PCM.
- If all circuits test normal, replace the PCM.
IMPORTANT:
Do not tap on plastic engine components.