I bought my 99 Blazer in January, and the 4WD system had intermittent problems at the time - occasionally, if it was in 4WD, the switch would blink at me, it'd change to 2WD, and the "Service 4WD" light would come on. Since then, the problem has increased in frequency. Usually, the problem would go away if I restared the car. It is now at the point where the 4WD system does not work at all.

I happened upon a thread in the DIY forum...
https://blazerforum.com/m_152088/tm.htm
... and used my multimeter to test the switch, in the hopes that it'd be something that simple and cheap to fix. But my results have me unsure.

According to step 4, resistance should be as follows:
Normal - 9.09K ohms
2 Hi - 1.82K ohms
Auto 4WD - 64.9 ohms
4 Hi - 715 ohms
4 Lo - 3.16K ohms

My switch tested as follows:
normal - 9.09k ohms
2 Hi - 1.516K ohms
Auto 4WD - 64.9 ohms
4 Hi - 662 ohms
4 Lo - 2.33k ohms

So the only two selections that gave acceptable reading are normal and Auto 4WD. Normally, I'd figure the switch is the source of my problems, but I'm left with a question. If Auto 4WD is giving the correct reading, why isn't it working? It gives me the same problems that 4 Hi gives (I have yet to use 4 Lo) - it blinks at me, activates the light on the dash, and switches back to 2 Hi.

Can anyone provide insight? I'll probably replace the switch regardless (since the other readings were out of spec), but I don't want to be surprised if replacing the switch doesn't solve all my 4WD problems. By the way, the Blazer only has about 51K miles on it (and I got it from my friend's grandparents), so I will be truly surprised and disappointed if the 4WD system is shot.

 

I had pretty well the exact same problem, don't know where the thread is at though... either way I took it to the dealership and they replaced the Transfer Case Control Module, haven't had a problem with it since

 

That's what I kept coming across when I searched for problems, but I was optimistic and hoping it'd be the switch. How much did it cost you?

 

... the switch didn't solve the problem. I'm gonna take it to be scanned, but I fear it's the TCCM. Anyone know where I can get the best price on this part?

 

From the dealership it was about $900 parts and labour, but thats here in Calgary and everything seems to be more expensive here so.

Good Luck

 

$900 USD or CND? And how much for just the parts, if you know? I don't pay people for any service I can do myself... that even includes cutting my hair.

 

junkyard or auto recyclerwould be your best bet....should be dirt cheap there.....Are you sure that the t-case motor is working properly?

 

I'm going to have it professionally diagnosed (I have a friend who works at a shop and is willing to check the codes), so at this moment I am just speculating completely.

 

haha dude man, I don't think I want to see what your haircut looks like, unless you just buzz cut it.> no offense by the way. It was 900 cdn, just the module was $700

Good luck!

 

It's all clippers... 1/2" on top, 3/8" on the sides.

And thanks for the response.