Circuit/System Verification

1. Ignition ON.
2. Verify no DTCs set.
   • If any DTCs are set 

     Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

   • Go to next step: If no DTCs are set 
3. Ignition ON.
4. Test for greater than 12 V between the battery positive terminal and negative terminal.
   • If 12 V or less 

     Refer to Battery Inspection/Test .

   • Go to next step: If greater than 12 V 
5. Verify no DTCs set.
   • If any DTCs are set 

     Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

   • Go to next step: If no DTCs are set 
6. Verify the scan tool parameter:
   • Battery Sensor Module Battery State Information parameter reads Available.
   • Battery Sensor Module Reset Occurred - Using Estimated State of Charge reads No.
   • If not the specified value 
   1. Refer to Battery Sensor Module Learn 
   2. Test drive the vehicle. Verify the Stop/Start System is functioning correctly.
      • if a condition exists

        Refer to Stop/Start Disable, Inhibit, and Restart Reasons 

      • Go to next step: If No Conditions exists
   3. All OK.
   • Go to next step: If the Specified Value 
7. Test drive the vehicle.

   Verify the Stop/Start System is functioning correctly.

   • If a condition exists 

     Refer to Stop/Start Disable, Inhibit, and Restart Reasons 

   • Go to next step: If No condition exists 
8. Verify the infotainment system remains active during a start/stop event.
   • If the infotainment system turns off or restarts during a start/stop event. 

     Refer to Circuit/System Testing - Power Supply Transformer Circuit Malfunction

   • Go to next step: If the infotainment system remains active during a start/stop event 
9. All OK.

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 
NOTE:

If equipped with S38 Ignition Mode Switch (RPO BTM), the vehicle will not power up after the T19 Power Supply Transformer is disconnected. Unplug the connector with the ignition on/vehicle in service mode. Verify the malfunction indicator lamp is illuminated on the driver information center after disconnecting the connector to verify the vehicle is still powered up.

3. Ignition ON/Vehicle In Service Mode, verify the vehicle is not equipped with S38 Ignition Mode Switch (RPO BTM).
   • If the vehicle is equipped with S38 Ignition Mode Switch 
   1. Reconnect the harness connector at T19 Power Supply Transformer.
   2. Ignition ON/Vehicle In Service Mode.
   3. Disconnect the harness connector at T19 Power Supply Transformer with the ignition still on.
   4. Proceed to step 4.
   • Go to next step: If the vehicle is not equipped with S38 Ignition Mode Switch 
4. Verify a test lamp illuminates between each B+ circuit terminal 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 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.
   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.