Trailer Tow Module (TTM)

Domestic market vehicles equipped with an optional trailer tow package include a trailer tow wire harness connected between the body wire harness and the left rear lamp unit. The trailer tow harness includes a molded four-way trailer tow connector and an integral cover that are snapped into a bracket on the trailer hitch receiver platform.

Fused B(+) for the plug receptacle is provided by the Power Distribution Center (PDC). The BCM determines if the trailer tow configuration is going to be used. The BCM is triggered to apply the vehicle configuration once the receptacle is in use. The TTM is then actively receiving commands from the BCM for lighting activations. The BCM outputs the requests to the TTM on the CAN-IHS. The TTM then controls the following trailer lighting output:

• Stop Lamps
• Turn Signal Lamps
• Park Lamps
• Reverse Lamps
• Hazard Lamps

There are relays in the PDC that the BCM manages in order to provide voltage feeds to the receptacle. They are backup lamp relay control, left rear turn signal relay control, right turn signal relay control, and tail lamp relay control. The BCM activates the proper lighting driver whenever the a trailer lamps status signal is active. This in turn causes the PDC relay to actuate and provide a trailer tow relay output feed to the receptacle. With combined rear lighting, the BCM uses the same circuit and relay to request stop lamp activation. The trailer tow receptacle receives this feed through both the right and left rear stop/turn signal feeds.

If there is a fault detected in the system by the BCM or TTM, the BCM will signal the IPC to display the appropriate message. If the TTM detects a fault in the circuits between it and the lighting outputs, the TTM will store a Diagnostic Trouble Code (DTC).