hey all new to the site have a question ive owned 2 blazers now and 4 different s10 trucks and ive never had one do what this blazer is doing it was fine one day driving down the road at 70 mph then all the sudden it jerked real hard and the tach jumped all the way up and never worked again, if anyone can help me let me know something im kinda lost at this point. also after all that when i shut it off the dash lights and headlights will flash for a few seconds then they go dark??? is it electrical problem or what IDK HELP!!!!!

 

I have the same problem please help

 

Welcome to the Blazer Forum AT.

We really need more info on your Blazer such as; year model, 8th VIN character, miles, previous issues and/or work performed, and exact current problem or problems, (tach issue, cutting out, and/or just the headlights flashing, etc).

Meanwhile, many (if not all) 2nd Gen. Blazers have the headlight relay located behind a small cover within the glove box (the owner's manual may, or may not, explain this). This H.L. relay is often situated next to at least 1 identical relay (fuel pump, etc). If this the case, then you might try temporarily swapping the fuel pump relay into the headlight relay socket to see if it cures the flashing headlight issue. Note: these (like all) relays do go bad from time to time (I pulled, and then tested, a couple from my local wrecking yard just to keep as spares that are stored in the glove box).

Otherwise, I'd suspect the hi-low beam selector switch/lever.

 

Sorry but that is a 2001 with a 4.3 Vortec V6 a 4L60E transmission should just been replaced it is a 2 wheel drive 2 door with a hundred sixty thousand miles tach work until transmission replacement any help would be appreciated thank you

 

Did a shop replace the transmission? If so, did you explain to them that the tach was working before they did the work?

That said, I'd first check the fuses. It's not uncommon for wiring to be pinched between the eng. block and transmission housing after such work. This issue can, of course, result in one or more blown fuses.

Another thing to check would the ground wire terminal located on the driver's side frame rail just below the drivers seat. However, not all Blazers have such a ground. The good thing is that this ground is pretty easy see and get at.

There should also be a group of ground wires that terminate on a stud located at or near the rear of the passenger side cylinder head that you'll want to carefully check. I can't say for sure, but there may actually be 2 separate ground wire groups crimped to separate ring terminals that attach to this single stud. These ground wires are known to crack and fail due to heat and age. They may also have been left unconnected. The nut to this stud can be somewhat difficult to get at.

 

I has the same symptoms a few years ago with my 2000. Turned out to be a bad distributor assembly.

 

Thanks for answering so quick checked grounds there ok no signal to white wire on cluster my son and I replaced tran's i have worked in body shop for twenty plush years never had this much problem before

 

Ya, some auto transmission changes go easy and some don't. I could tell you a couple of AT replacement/rebuild trouble stories that might help you feel better, but I don't want to waste your time and/or go off topic. Anyway, I'll look into the tach problem and get back to you.

 

Tajohns34 makes a very good point.

 

Thanks for all the help you're not wasting my time I just appreciate everything you're doing thanks a lot