B166F

B166F-RIGHT TRAILER TOW LAMP CONTROL CIRCUIT LOW





For a complete wiring diagram refer to Diagrams/Electrical.

- When Monitored:

Continuously

- Set Condition:

When the Front Control Module does not detect voltage on the Trailer Tow Relay Control circuit.





Diagnostic Test

1.INTERMITTENT CONDITION

Turn the ignition on.

With the scan tool, clear all FCM DTC's

Actuate the Trailer Tow Lamps.

With the scan tool, read DTC's.

Does the scan tool read: B166F-RIGHT TRAILER TOW LAMP CONTROL CIRCUIT LOW?

Yes

- Go To 2

No

- The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

2.PDM FUSE 21

Using a 12-volt test light connected to ground, check the PDM Fuse 21.

Does the test light illuminate and was the fuse OK?

No

- Replace the PDM Fuse 21 if open and check for a short to ground on the Relay Output circuit or correct the open B(+) circuit to the fuse.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

Yes

- Go To 3

3.OPEN FUSED B(+) TO RELAY

Remove the Trailer Tow Relay from the PDC.

Using a 12-volt test light connected to ground, check the Fused B(+) circuit at the relay connector.

Does the test light illuminate?

No

- Replace the Power Distribution Center.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

Yes

- Go To 4

4.RIGHT TRAILER TOW RELAY

Install a known good relay in place of the Trailer Tow Relay.

With the scan tool erase DTC's

Cycle the ignition from on to off 3 times and leave on.

With the scan tool, read DTC's.

Does the scan tool display the same DTC?

No

- Replace the original Trailer Tow Relay.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

Yes

- Go To 5

5.(L656) TRAILER TOW RELAY CONTROL SHORTED





Remove the Right Trailer Tow Relay.

Disconnect the Front Control Module from the PDC 49 - way connector.

Measure the resistance between ground and the (L656) Trailer Tow Relay Control circuit at the relay.

Is the resistance below 1000.0 ohms?

Yes

- Replace the Power Distribution Center.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 6

6.(L656) TRAILER TOW RELAY CONTROL OPEN





Measure the resistance of the (L656) Trailer Tow Relay Control circuit from the relay connector to FCM connector.

Is the resistance below 3.0 ohms?

Yes

- Replace the Front Control Module.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Replace the Power Distribution Center.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test