Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit/System Testing - T19 Multifunction Power Supply Converter Input/Output Circuit Test
Circuit/System Verification must be performed before proceeding with Circuit/System Testing.
- Ignition Off, disconnect the connector at the T19 Multifunction Power Supply Converter control.
- Verify a test lamp illuminates between ground circuit terminal 7 and B+.
- If the test lamp does not illuminate
Repair the open/high resistance on circuit 250 or the ground connection.
- Go to next step: If the test lamp illuminates
- If the test lamp does not illuminate
- Verify a test lamp illuminates between ground circuit terminal 12 and B+.
- If the test lamp does not illuminate
Repair the open/high resistance on circuit 250 or the ground connection.
- Go to next step: If the test lamp illuminates
- If the test lamp does not illuminate
- Verify a test lamp illuminates between B+ circuit terminal 8 and ground.
- If the test lamp does not illuminate and the circuit fuse is good
- Test circuit 8140 for an open/high resistance.
- if an open/high resistance is found, repair the fault on the circuit.
- Go to next step: If an open or high resistance is not found
- 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
- Test circuit 8140 for a short to ground
- If a short to ground is found, repair the fault on the circuit.
- Go to next step: If a short to ground is not found
- Test circuit 2173 for a short to ground
- If a short to ground is found, repair the fault on the circuit.
- Go to next step: If a short to ground is not found
- Replace the T19 Multifunction Power Supply Converter.
- Go to next step: If the test lamp illuminates
- Ignition On vehicle in Service mode.
- Verify a test lamp does not turn On between control circuit terminal 9 and ground.
- If the test lamp turns on
Repair the short to voltage on circuit 2173.
- Go to next step: if the test lamp does not turn on
- If the test lamp turns on
- Remove all appropriate fuses supplied by circuit 2173.
- Test for infinite resistance between control circuit terminal 9 at the T19 Multifunction Power Supply Converter and ground.
- If less than infinite resistance
Repair the short to ground on circuit 2173.
- Go to next step: If infinite resistance
- If less than infinite resistance
- Connect all connectors.
- Clear all DTCs.
- Road test the vehicle allowing a minimum of 5 engine auto stop/start events to occur.
- Verify DTC P0E38, P0E39, or P0E39 does not reset.
- If any of the DTCs reset
- Verify the Ignition circuit 439 at the K20 Engine Control Module is within 1 V of control circuit 2173 at the T19 Multifunction Power Supply Converter.
- if not within the specified value
Repair the open/high resistance in circuit 439.
- Go to next step: If within the specified value
- if not within the specified value
- Replace the T19 Multifunction Power Supply Converter.
- Go to next step: If any of the DTCs did not reset
- A fault is not currently present and may be an intermittent condition.
Do not replace the T19 Multifunction Power Supply Converter if you cannot reproduce the codes during a drive cycle.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.