My 2004 chev suburban keeps blowing the 50 amp MBEC fuse and I can't figure out what is causing it.

Have the HAVC System diagnosed to find a problem

Odds are it has a leak & needs to be tested & repaired

did u replace the relay just a curious question, sometimes they have rust and water in the inside of the relay but my guess would be that you have a bare wire rubbing somewhere, causing the fuse to blow, anything significant has happened before that issue?

I had this same problem with a 1997 Z71 K1500. That fuse was receiving power from the ignition switch in my truck. After putting 4 ignitions in it in 6 months, I finally figured out that every time I put the transfer case in 4Low, the service engine light would come on & the ignition switch would go bad soon after. The electric motor that engaged transfer case was bad. Every time I engaged 4 Low, It would throw power surge to ignition & blow it up.

Ok I don't know who these people are giving advice but I hope they are not gm mechanics. There is a fuse under the hood marked MBEC 1 50amp. If it blows it knocks out both power seats seat heaters and power windows passenger side front and back. I can't believe all this wiring ****!

If the fuse blows on different trailers then it's all down to the vehicle. You either have incorrect wiring on the vehicle, a short OR the fuse is not of a high enough value to cope with the additional brake lights? You could try removing all the trailer bulbs EXCEPT the brake lights - e.g. if it's trying to power up the indicators too? That would stop the fuse blowing...... OR remove the brake bulbs from the vehicle & see if it operates the trailer without blowing...... Check the total wattage of ALL the brake lamps & see if the fuse is actually of a high enough rating? Be aware though that increasing the value of the fuse could cause damage elsewhere! As a rough guide a 25 watt bulb will pull around 2 amps at 12 volts - so 4 bulbs may pull up to 8 amps & clearly blow a 5 amp fuse! If in doubt take it to an auto electrician...... The wiring needs to be correctly protected!

i have a 95 gmc suburban that keeps blowing the fuse when break is aplied i even disconected the back lights and it does the same what could it be

IF it is blowing when you adjust seat then a wire is shorting in the seat harness

There is a fase under the hood marked trailer tail lights,it is a 15amp fuse and if continues to blow ther is a problem in the trailer wireing or the plug on the trailer.

You might have a short in your wiring some where from the actuator back to where the wires go through the cab .could have been rubbing on something to cause this . just a thought

I have the same exact problem so i would be very thankful if any know the reason