Trailer control module issue
 

Test the pins with a load like a light bulb. DMM has Too high of impedance to show the correct v when loaded (that will help determine bad ground or connector)

Yeah, have you connected an actual trailer to the car yet? I wonder if the problem would go away when you have actual wires and loads.

No actual trailer yet.

I've also used a test light which lights up and beeps with power.

I'll check resistance for the earth and check continuity on the Canbus to the LCM.

Ok I've done some real time Data logging with a scan tool. For some reason there is no "Turn Indicator, Trailer, Right" showing in the trailer light module.

It does sound like it thinks the trailer is connected.

So I have traced all the wiring and it seems ok. A strange thing though is when I use my scan tool to activate the trailer lights the only one that seems to activate during the 15 sec test are the reverse lights.

However when I check functionality of the trailer lights manually using the indicators, brake pedal and lights using the scan tool they all show that they activate only while operating the car controls.

Again, no messages from the car on the dash until I operate something, then I get the check trailer lights message.

I'll upload the wiring diagrams for those interested.

I think Pin 10 is mislabeled at left when the description says right in the first schematic.

Appreciate your help.

For a moment I thought maybe you were on to something with checking the canbus line (maybe getting pulled down with module plugged in) but then (one would think) you shouldn't be able to access the module through the bus. You get an "A" for effort though! ;) I would be checking the vehicle lights even though they "seem" to be fine there could be a bad connection, poor ground, bad (maybe shorted)/wrong bulb that only comes into play with the module plugged in.

I've checked the ground for the AHM module and get continuity and 0.2 ohms resistance which seems pretty normal.

Pic of the offending 15 pin AHM and the trailer 12 pin connector.

The original unit that caught fire in the boot when it flooded. I might add that when the damage occurred the rear light indicators were doing weird things like staying on for a while then going off even though the car was turned off.

Is there any of the burnt wiring left that you haven't pulled apart and checked ?? I'm assuming the connectors have all been checked, cleaned and plugged in and out a few times ?