Which TV Trailer Brake Fuse – 2018 GMC 2500 TV

[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. I have read that some GM products have this fuse to blow and then your trailer brakes can’t activate. I wanted to be proactive and carry a spare.

The owner’s manual does not give a part # for this. I went on Amazon and there are various options to choose from. There are low profile, standard / tall profile. They can be;

ATR – single circuit protection
ATL – dual circuit protection
FMM – newest and smallest fusible link

I saw a Bussman FMM-30 Maxi Fuse (slow blow Micro Female) that looked promising and reviews said if worked the Chevy Silverado. However, a message popped up for this item that said it wouldn’t fit my vehicle.

Which one do you purchase?

[wulfraat]

I believe that fuse is for 12v hot power to charge your travel trailer batteries.

I have lithium, and due to the voltage requirements that differ from the GM alternator I actually pulled that fuse so as not to mix voltages. Brakes work fine and are powered by a different lead. I have a 2017 2500 HD, same truck.

[GOUSC]

Originally Posted by wulfraat

I believe that fuse is for 12v hot power to charge your travel trailer batteries.

I have lithium, and due to the voltage requirements that differ from the GM alternator I actually pulled that fuse so as not to mix voltages. Brakes work fine and are powered by a different lead. I have a 2017 2500 HD, same truck.

I've attached a copy of the fuse diagram from my owners manual. If I'm reading it right, (and it's possible I'm not), It appears to me the 30amp fuse I'm referring to is fuse #1 for the trailer brake. Fuse #2 is for the trailer batteries and is a little further away. It is not in my original picture but would be below fuse #63, the trailer parking lamps fuse.

[wulfraat]

Looks like you are correct (sorry was going from memory). The battery fuse looks to be the same format (30A). That could certainly act as your spare in a pinch (remove battery fuse and use for trailer brakes).

[gklott]

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.

73/gus

[2dabeach]

GOUSE....Just stop at any GMC or Chevrolet dealer and they can match you up with the proper part.

[GOUSC]

All good advice. I had read on a boat forum I follow where people have had issues finding these fuses at dealerships and auto parts stores when on the road.

I'll start with my local dealer / also ask them the suggested questions and go from there. Thanks to everyone for the suggestions.

[GOUSC]

Just for closure on this item. The dealership did not have this fuse in stock, nor could they supply a correct part # for it. They suggested NAPA. NAPA did not have it in stock and they could not provide a part #. Auto Zone had it in stock. Attached is a picture of the fuse packaging in case anyone needs this in the future.