I have checked all threads relating to 4wd, none have these symptoms,but my truck can t be unique!
My car is a 99 4wd auto with the 4 buttons on the dash and the 236 transfer case.
Recently the service 4wd light came on so i checked operation of the 4wd system, it works
perfectly,however, apart from 2HI, the lights on the buttons don t stop flashing as they should.
These faults must be related in some way but because my 4wd WORKS what could cause the lights to flash? I m afraid to ignore this, in case it turns into a bigger problem. Any ideas,
thanks, Steve.

 

Do not ignore it, get your TCCM scanned by a capable scanner and let us know what the codes are. It likely is an encoder fault when the encoder tries to return to 2HI.

In the mean time, go through and clean all of the electrical connections and make sure that the resistances output by the switch are proper (I have posted the resistances before - search for "+NV236+resistance" without the quotes and put swartlkk in as the author).

 

Thanks for the reply, i ll follow your advice asap. Can t get to the dealer for a while to get a scan done for codes.If it is an encoder fault as you think,would this be an easy fix or not.By the number of threads on 4wd problems with these trucks, it s probably not!

 

That all depends on what you definition of easy is. Work definition - there are harder repairs. Cost definition - it can be pricey.

 

Beats the hell out of no 4WD though....
Don't give up. You'll get through it. i'm entrenched in a knock-down drag out with my Encoder right now. Been rolling in the wife's 2WD Exploder and I feel dirty!
You'll get it eventually.
*worst pep talk ever*

 

Work definition,i built and run a 1975 strip only corvette with a 13.5:1 434 small block,with the nitrous it puts out 1100 hp,it runs mid nines at near 130. I ve owned this
car for 28 years and rebuilt everthing many times over.
Cost definition,the blazer is my daily driver used to earn a living and tow my racecar in season.Whatever the cost it has to run, but i don t always need 4wd, just reliabilty.

*worst pep talk ever* but i will get it eventually!!!!!!!!!!

 

do a search for "posi lock" 4wd. might be worth looking into if you understand the workings of it and only need the 4wd in specific circumstances. Either get the $200 'kit' and cut out the computer stuff (but not vacuum set up) or build your own for $25...

**EDIT** wait, you have a 4 button like me. as far as i understand, we are screwed as far as the posi set up goes... n/m

 

It seems the words reliable and blazer don t go together. The jeep cherokee that i traded for the blazer ran faultlessly for the 7 years i owned it. Just didn t feel right towing a chevy race car with a jeep!

 

Funny you should say that. My brother has a 92 Cherokee and follows a board kind of similar to this, when he has problems. The Cherokee seems to be just as problem riddled as the Blazer, but much MUCH more hated by the owners and fellow Jeepers with only the liberty drawing more scorn

 

Problem update, i found a loose vacuum pipe under the hood and flashing light problem is solved. The service 4wd light doesn t come on while driving,hopefully never again.
I LOVE MY BLAZER AGAIN!!!!!!!!!
If only all future problems would be as simple as this,dream on!