Circuit/System Testing

Power Supply Transformer Circuit Malfunction

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the T19 Power Supply Transformer. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 Ω between each ground circuit terminal 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.
   • Go to next step: If less than 10 Ω 
3. Ignition ON.
4. Verify a test lamp illuminates between each B+ circuit terminal and ground.
   • If the test amp does not illuminate and the circuit fuse is good 
   1. Ignition OFF.
   2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
   • If the test lamp does not illuminate and the circuit fuse is open 
   1. Ignition OFF.
   2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, test or replace the T19 Power Supply Transformer.
      • Go to next step: If the test lamp illuminates 
5. Verify a test lamp illuminates between each ignition circuit and ground.
   • If the test lamp does not illuminate and the circuit fuse is good 
   1. Ignition OFF.
   2. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than If 2 Ω, verify, Refer to Power Mode Mismatch .
   • If the test lamp does not illuminate and the circuit fuse is open 
   1. Ignition OFF.
   2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, test or replace the T19 Power Supply Transformer.
   • Go to next step: If the test lamp illuminates 
6. Install a test lamp between the control circuit terminal 5 and ground.
7. Verify the test lamp illuminates while cranking the engine.
   • If the test lamp does not illuminate 
   1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K20 Engine Control Module and disconnect the KR27 Starter Relay.
   2. Test for infinite resistance between the control circuit 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 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 K20 Engine Control Module.
   • Go to next step: If the test lamp illuminates 
8. Test or replace the T19 Power Supply Transformer.