Gave this some thought, your screwed...J/K, work this problem backwards. Disconnect the battery negative. Repeat- disconnect- you don’t want to trigger air bags or damage one of the electronic modules. Use the following- this is for a 98 so may have some differences depending on your year and options. Use a voltmeter and do some checks from the connector to ground and such. Probe inside the module too, from the power to ground and such like pins B to C should not be shorted. Then try say a alligator clip to tie a pin on connector to one lead and take other lead to fuse box and check to that. Best I can recommend is process of elimination- by working backwards should be able to pin short down. I doubt ignition switch itself but the multifunction arm, could be a pinched wire. Can drop the cover underwheel (2 screws on mine) and peek around and follow it down shaft towards the brake pedal area. To see that lower part will have to drop knee cover. Overall guess, short either in wiring coming down steering column or in module under hood. Hope these diagrams can help.


https://cimg0.ibsrv.net/gimg/blazerf...3281bb8adc.png
Layout under hood (this for 1998 Blazer)
https://cimg8.ibsrv.net/gimg/blazerf...7e5f09de9e.png
1998 blazer. Check with voltmeter- continuity for shorts

https://cimg7.ibsrv.net/gimg/blazerf...e9a8db4403.png

Wow, should have asked them what area they moved wires around at. Odds are same general area is source for brakes lights shorting to blower. Best guess under the lower panels on drivers side above brake pedal. Good luck.

I keep wanting to write up a detailed explanation of how to do the diagnostic for this but without knowing your skill level with tools like a digital multimeter or if you even own one alone how detailed I have to be that I get 3 to 4 paragraphs in and delete all. (Done that 3 times already).

WIll make a simple guess, the issue is in one of two spots. EIther its in the harness area in the first diagram I posted toward passenger side or in the connector near the brake switch at base of steering wheel column. To test any of this I would do just this. Unplug the wipers (Number 1 in first diagram), replace fuse, turn on key..did fuse blow? Yes/no? If yes, power wire c in that connector is shorted somewhere. No, assume issue is with motor itself. Seeing you said it worked for a while after shop jiggled some wires I think we can say its a short.

That harness from wiper run toward passenger side to several connectors as you can see in diagram 1. Look at that whole thing going over there. Mine was rubbing but not shorted where it crossed over the box for the heat/air in Blazer. Next follow it the other way to firewall. Make sure it all looks okay. You could take a digital meter that beeps, using two alligator clips and put one to pin c and other to ground. (Fuse out please!) Move that wiring around till you hear beep come and go. That’s your shorted area. There should be no short (beep) between that pin and the fuse. Best I can do to simplify this. Any deeper would take a lengthy handsfree phone call or facetime to try to walk you thru it.

Yep, short. Most likely under hood near that Air Condition unit 13/14/15 area in diagram 1. LIke I said above, fuse out, multimeter and alligator clip leads do continuity checks for short. Black lead to ground, other probes the connector. Wiggle wires, see if you can locate where it starts/stops. Best is a meter that beeps so you do not need to see it just hear it and you move wires around. Best I can do remotely like this. We both know its shorted, and run in that harness. Need to roughly find area its happening at and then fix. So you just keep moving around, can check under dash area near feet too, when you hear that thing beep and then not then beep you found your trouble area. Pin C is the line to fuse. If C (should be yellow) meets ground fuse blows. Crossing fingers for you.