Circuit/System Testing

Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B34B Engine Coolant Temperature Sensor. It may take up to 2 min 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 Radiator Coolant Temperature 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 Radiator Coolant Temperature sensor parameter is warmer than 137°C (280°F).
- If colder than 137°C (280°F)
1. Ignition OFF, remove the jumper wire, disconnect the harness connector at the K20 Engine Control Module.
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 137°C (280°F)
Test or replace the B34B Engine Coolant Temperature Sensor.