Trailer lights

[clark2!]

Just had DEF software update. Now my trailer lights including brake lights and turn signals do not work when the lights selector is set to AUTO. They work when set to manual selections. Anyone else have this? Any suggestions?

 

[2004LB7]

the trailer lights, or all lights are controlled by the BCM so it's unlikely to be from the update. unless they updated the BCM too.

what does the dealership say about it?

 

[clark2!]

the trailer lights, or all lights are controlled by the BCM so it's unlikely to be from the update. unless they updated the BCM too.

what does the dealership say about it?

We called the dealer yesterday and they have never heard of this before. If a fuse it would be one under the hood, not in the cab. Called a different mechanic, not the dealership yesterday also. He said it is common for program updates to mess up systems other than the stated update.

 

[2004LB7]

unlikely to be a fuse. otherwise they wouldn't work at all

yes, on occasion updates can make other items act weird but it's usually related to the module being programmed. even more rare to effect another module not being programmed. I'd make the dealership fix it since it seems to have been caused by something they did

have you tried disconnecting the batteries to see if a hard reset will fix it?

 

[TheBac]

Moved to Electronics section.