Circuit/System Testing

Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B55 Hood Ajar Switch. It may take up to 2 min for all vehicle systems to power down.
Test for less than 10 Ω between the low reference circuit terminal C and ground.
- If 10 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 10 Ω
Ignition ON.
Verify DTC P257F is set as current
- If DTC P257F is not set as current
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the K20 Engine Control Module.
- Go to next step: If DTC P257F is set as current
Install a 5 A fused jumper wire between the signal circuit terminal A and ground, ignition ON
Verify DTC P257E is set as current.
- If DTC P257E is not set as current
1. Ignition OFF, 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. 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 DTC P257E is set as current
Test or replace the B55 Hood Ajar Switch.