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.
Description And Operation: Operation
The Trailer Tow Module (TTM) controls and monitors the lighting for the trailers that are properly connected to the vehicle. The TTM on this vehicle controls the lights of a trailer only. It does not control the trailer brakes.
The TTM outputs:
- Instrument Panel Cluster (IPC) display requests
- Trailer connection status and information signal
- Chime requests
The TTM monitors the Controller Area Network - Interior High Speed (CAN-IHS) bus network for lighting requests from the Body Control Module (BCM) and other inputs. The TTM is responsible for its own logic, actuation and sensing.
The hardwired outputs by the TTM include the following:
- Backup lights
- Stop lights
- Parking lights
- Position lights
- Turn and hazard lights
- Trailer fog light, if equipped
The TTM makes certain that these lighting functions are maintained synchronous with the vehicles lighting requests as read on the CAN-IHS bus. The TTM then sends the appropriate ON or OFF output signal to the respective trailer lights. The TTM also sends an output signal failure to the IPC indicating if the trailer light operation has failed. The IPC will then display the appropriate indiction.
The TTM has three power feeds:
- Two 25 Amp fused B(+) power supply circuits from the rear Power Distribution Center (PDC)
- One 10 Amp fused RUN/START relay output from the interior PDC
The TTM is provided ground at all times by a circuit connected to a ground terminal on the lower right D-pillar gusset.
Brake Module Provision
The brake module provision provides the electric brake power and signal feed in a connector, located behind the Electric Parking Brake (EPB) switch, for an aftermarket trailer brake controller to the 7-way trailer tow connector. The brake signal comes from the Antilock Brake System (ABS) module. It is supplied fused B(+) from a 30 amp fuse in the interior PDC and has a continuous ground at a grounding stud near the left side of the instrument panel carrier.
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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.