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/A 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.
- Go to next step: 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/B and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - Go to next step: If infinite resistance.
3. 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
- Go to next step: If colder than -39°C (-38°F)
Install a 3 A fused jumper wire between the signal circuit terminal 1/B and the low reference circuit terminal 2/A.
Verify the scan tool ECT sensor parameter is warmer than 149°C (300°F).
- If warmer than 149°C (300°F)
1. Ignition OFF, remove the jumper wire, 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.
  - Go to next step: If less than 1 V
Test or replace the B34 engine coolant temperature sensor.