I did the brake light switch and it was inexpensive...$9.??, but tricky to install. It didn't solve the no brake lights problem.
RE: the plastic cover: I took a good look at it in the daylight and found an embossed label of Batt+ on it. So I then looked at the underhood fuse/relay box. It was the protective cover for the terminal on the left side of that fuse/relay box, if you are facing the fuse/relay box from the driver's side fender. It just slides over the terminal and must have fallen down under the air box. I am sure the guy said: 'Well, next time I remove the air box , I will retrieve it.'. How many still have that protective cover on their Blazer?

 

I am right in the middle of removing the old Multifunction switch and need a Torx /Star socket in E 5, which the 1AAuto guy on the posted vid says is a rare socket. It seems I read on this forum , someone mentioned you could --in a pinch ---substitute a standard 4 mm socket! Does anyone know exactly what regular socket subs. for a E 5 Torx socket. There is one on the bottom of the ignition switch area that must come out to replace this old MF switch. Please let me know so I can put this project back together and get on the road. Thanks, Jim

 

I think a deep 4mm may be better than the standard 4mm. I borrowed and used a standard depth 4mm and it worked with some finagling. It must be a high quality socket. I had a cheap 4mm from one of those 19.99 sets and it just spun. There is only one of these E 5 bolts on the top of the steering wheel cover.

 

If you watched the 1AAuto vid, you get to a point in the project where you can test the MF switch before you button everything up. I did that and 'everything worked except the brake lights' and the 3rd light=CHMSL. So I am back to where I started. To recap, I have put in a new brake light switch on the brake pedal, cleaned the two hidden grounds near the radiator on the driver's side and finally a new BWD M.F. switch. I have looked at the trailer connector and it looks intact. I haven't done any elec. testing on it. It did work last time I hooked up a trailer. This SUV is a former police vehicle and had radios, sirens, and other police gear installed. This wiring and/or the removal of the equipment for the sale to the public may have caused this problem. Where do I look next?

 

After putting in a Brake light switch and a M.F. switch on the Blazer and still no brake lights, I found the problem. I checked the fuses again. This time I found a 20 amp fuse in the under hood fuse/relay panel that was blown. It is the fuse on the right hand all the way down to the bottom. Thanks for all the responses and help.

 

How did you remove the bolt from the junction block where it plugs in at? I've turned and turned and mine won't come out. That's all I have left to do to take mine out. I don't know what else to do.

 

Mav, I just saw your post. I didn't have that problem on the bolt. It came out easily, so yours may be stripped. Actually, it is probably the plastic housing probably stripped when some one overtightened the bolt. I would try putting Vise grips on the bolt and pulling it out as you twist it. This is a aggravating job without having to deal with difficult bolts, also. Good luck, Jim aka OP