Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the B34 ECT sensor.
- Ignition OFF for 90 s, test for less than 5 Ω between the low reference circuit terminal A and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
- Ignition ON, verify the scan tool ECT parameter is colder than -39°C (-38°F).
- If greater than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the K20 ECM.
- Install a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT parameter is greater than 149°C (300°F).
- If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
- If all circuits test normal, test or replace the B34 ECT sensor.
- Inspect for the proper operation of the OEM block heater cord by verifying that the thermostat has turned OFF the heater at temperatures warmer than -10° (+14°F).