Circuit/System Testing

Ignition OFF and all vehicle systems OFF, disconnect the X2 harness connector at the X50A Fuse Block-Underhood. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 10 Ω between the ground circuit terminal C5 and ground.
- If 10 Ω or greater
1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, repair the open/high resistance in the ground connection.
- If less than 10 Ω
Connect the X2 harness connector at the X50A Fuse Block-Underhood. Disconnect the X2 harness connector at the K33 HVAC Control Module, ignition ON.
Verify the E18 Rear Defogger Grid is not activated.
- If the E18 Rear Defogger Grid is activated
1. Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block-Underhood.
2. Test for less than 1 V between the K33 HVAC Control Module control circuit terminal 19 and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V, replace the X50A Fuse Block-Underhood.
- If the E18 Rear Defogger Grid is not activated
Connect a 3 A fused jumper wire between the control circuit terminal 19 and B+.
Verify the E18 Rear Defogger Grid activates.
- If the E18 Rear Defogger Grid does not activate
1. Ignition OFF, remove the jumper wire, disconnect the X2 harness connector at the X50A Fuse Block-Underhood, ignition ON.
2. Test for infinite resistance between the K33 HVAC Control Module control circuit terminal 19 and ground.
  - If less than Infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance
3. Test for less than 2 Ω in the control circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the X50A Fuse Block-Underhood.
- If the E18 Rear Defogger Grid activates
Replace the K33 HVAC Control Module.