B1138

B1138-CABIN HEATER 3 CONTROL CIRCUIT LOW





For a complete wiring diagram, refer to the Wiring Information. Electrical Diagrams

- When Monitored:
With the ignition on and the PTC No. 3 Relay command off.

- Set Condition:
The ECM detects a short to ground on the (K363) PTC No. 3 Relay Control circuit for 1.0 second.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Pre-Diagnostic Troubleshooting Procedure

1. DTC IS ACTIVE
1. Ignition on, engine not running.
2. With the scan tool, Clear DTCs in the Engine Control Module (ECM).
3. With the scan tool, actuate the PTC No. 3 Relay.
4. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Perform the CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking for an Intermittent DTC.

2. (F342) FUSED ASD RELAY OUTPUT 1 CIRCUIT OPEN OR HIGH RESISTANCE




1. Turn the ignition off.
2. Remove the PTC No. 3 Relay.
3. Turn the ignition on.
4. Using a 12 volt test light connected to ground, check the (F342) Fused ASD Relay Output 1 circuit in the PTC No. 3 Relay connector.

NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Is the test light illuminated and bright?

Yes

- Go To 3

No

- Repair the (F342) Fused ASD Relay Output 1 circuit for an open circuit or high resistance.
- Perform the ECM Verification Test. .

3. (K363) PTC NO. 3 RELAY CONTROL CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the Engine Control Module (ECM) harness connector.
3. Measure the resistance between ground and the (K363) PTC No. 3 Relay Control circuit in the PTC No. 3 Relay connector.

Is the resistance above 1000 Ohms?

Yes

- Go To 4

No

- Repair the (K363) PTC No. 3 Relay Control circuit for a short to ground.
- Perform the ECM Verification Test. .

4. (K363) PTC NO. 3 RELAY CONTROL CIRCUIT OPEN OR HIGH RESISTANCE




1. Measure the resistance of the (K363) PTC No. 3 Relay Control circuit between the PTC No. 3 Relay connector and the Engine Control Module (ECM) harness connector.

Is the resistance below 10.0 ohms?

Yes

- Go To 5

No

- Repair the (K363) PTC No. 3 Relay Control circuit for an open circuit or high resistance.
- Perform the ECM Verification Test. .

5. PTC NO. 3 RELAY
1. Install a substitute PTC No. 3 Relay in place of the vehicle's PTC No. 3 Relay.
2. Turn the ignition on.
3. With the scan tool, Clear DTCs.
4. With the scan tool, actuate the PTC No. 3 Relay.
5. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 6

No

- Replace the PTC No. 3 Relay.
- Perform the ECM Verification Test. .

6. ENGINE CONTROL MODULE (ECM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the PTC No. 3 Relay and the Engine Control Module (ECM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Search for any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the ECM Verification Test. .

No

- Replace the Engine Control Module (ECM).
- Perform the ECM Verification Test. .