B17F6-12

B17F6-12-TRAILER TAILLAMP CONTROL - CIRCUIT SHORT TO BATTERY





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

Theory of Operation

Three relays are used to provide voltage to the Trailer Tow connector. The trailer tow relays are used to switch fused battery voltage directly to the Trailer Tow connector when requested. The trailer tow relays are activated through a ground path provided by the Body Control Module (BCM).

- When Monitored:
With the ignition on.

With the park lamps active.

- Set Condition:
If the Body Control Module (BCM) detects greater than expected current flow on the (L657) Trailer Tow Park Lamps Relay Control circuit.





1. VERIFY THE DTC IS ACTIVE
1. Turn the ignition on.
2. With the scan tool, clear all DTCs.
3. Turn the Park Lamps on.
4. With the scan tool, read DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

2. ATTEMPT TO SET THE OPPOSITE DTC
1. Turn the Park Lamps off.
2. Turn the ignition off.
3. Remove the Park Lamp Trailer Tow Relay.
4. Turn the ignition on and wait 10 seconds.
5. With the scan tool, read DTCs.

Does the scan tool display DTC: B17F6-14-TRAILER TAILLAMP CONTROL - CIRCUIT SHORT TO GROUND OR OPEN?

Yes

- Replace the Park Lamp Trailer Tow Relay.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 3

3. CHECK THE (L657) TRAILER TOW PARK LAMPS RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS
1. Turn the ignition off.
2. Disconnect the BCM E harness connector.
3. Turn the ignition on.
4. Measure the voltage between ground and the (L657) Trailer Tow Park Lamps Relay Control circuit at the Park Lamp Trailer Tow Relay harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the (L657) Trailer Tow Park Lamps Relay Control circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 4

4. INSPECT RELATED WIRING AND CHECK FOR TSBS
1. Turn the ignition off.
2. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Park Lamp Trailer Tow Relay and the BCM.
3. Look for any chafed, pierced, pinched, or partially broken wires.
4. Look for broken, bent, pushed out or corroded terminals.
5. Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Replace the BCM. Body Control Module - Removal.
- Perform the BODY VERIFICATION TEST. Body Verification Test.