Circuit/System Verification
- Ignition ON. Measure and record the voltage at the battery terminals. Verify that the battery voltage is 11-15 volts. Repeat with the engine running.
- If the battery voltage is not within the specified range, go to Charging System Test .
- Engine running. Observe the scan tool Ignition 1 Signal parameter in the ECM data list. Verify that the scan tool displays a value that is within 2 volts of the battery voltage recorded in step 1.
- If the scan tool parameter is not within the specified range, replace the ECM.
- Go to Diagnostic Aids .