Originally Posted by GOUSC
My vehicle has a 30 amp trailer brake fuse. It is not the standard 2 blade fuse I am used to. It is rectangle shaped, see the pink fuse in the center of the attached picture.
That is likely not a fuse. It is probably a circuit breaker. Your truck should have the built in trailer brake controller, a trailer brake power control module, and there may be more than one involved.
Only replace it with the proper type!
If you cannot get to an auto parts store, and you say it looks like a MaxiFuse, see if it matches a Bussmann CB1921-30 Type II MAXI style breaker, or it may be the smaller Bussmann CB222-30 Silver-Colored Type II ATC style breaker.
The key is which circuit breaker type
GM uses in that position, given the brake controller circuits.
Type 1 - Automatic Reset: This type of breaker will recycle on-off continuously when overcurrent does occur.
Type 2 - Modified Reset: the breaker will remain in the tripped position as long as there is power to the circuit. Once you remove power, the circuit breaker resets.
Type 3 - Manual Reset: the breaker stays tripped until you reset it, usually with a button or lever.
Within our Airstream, there is a type II breaker in the breakaway switch circuit.