Circuit/System Testing

Ignition OFF and all vehicle systems OFF, disconnect the B34 engine coolant temperature sensor harness connector at the sensor. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 5 Ω between the low reference circuit terminal 2 and ground.
- If 5 Ω or greater
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for less than 2 Ω in the low reference circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the K20 engine control module.
- If less than 5 Ω
Ignition ON.
Verify the scan tool ECT Sensor parameter is colder than -39°C (-38°F).
- If warmer than -39°C (-38°F)
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for infinite resistance between the signal circuit terminal 1 and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the K20 engine control module.
- If colder than -39°C (-38°F)
Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.
Verify the scan tool ECT sensor parameter is warmer than 149°C (300°F).
- If colder than the 149°C (300°F)
1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V
3. Ignition OFF
4. Test for less than 2 Ω in the signal circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the K20 engine control module.
- If warmer than 149°C (300°F)
Test or replace the B34 engine coolant temperature sensor.