Diagnostic Aids

Check for any of the following conditions:

• The CMP sensor output may be affected by temperature. Inspect the sensors operation and internal resistance at various temperatures. The CMP sensor resistance when cold should be between 835-1,400 ohms at -10 to +50°C (+14 to +122°F). The CMP sensor resistance when hot should be between 1,060-1,645 ohms at 50-100°C (122-212°F).
• The CMP sensor performance can be checked with a DMM and a scan tool. The AC voltage output of the CMP sensor, as measured with a DMM across the sensor electrical terminals, is approximately the same as engine speed. Run the engine at several different engine speeds and compare the numerical value on the scan tool with the numerical voltage reading on the DMM. If the reading of the DMM and the scan tool are not nearly equal, inspect for a faulty sensor or signal rotor.
• A DTC P0340 that sets while driving and checks OK may be caused by inadequate CMP sensor circuit shielding. Check that the CMP sensor circuit is properly shielded and that the drain wire is fastened securely to ground.

An intermittent malfunction may be caused by a fault in the CMP sensor electrical circuit. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions .

Repair any electrical circuit faults that were found. Refer to Wiring Repairs .

The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.