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Common 4X4 problems w/ 97 s10 blazer?


nendres
09-28-2005, 08:10 PM
Hey Guys-

I have a 97 blazer and the buttons for the 4X4 seem to work fine, and the front driveshaft turns but still no 4-wheel drive. I have hear that there is a common problem on these, but nobody sems to know what it is.
I know there is a vaccume pump under the battery(or something to that effect) that pulls a cable to the front dif, there is a vaccume switch in the dash and a couple wires that go to the differential where the cable goes in. Any advice on how to test these parts or ideas of what to try would be appreciated!

Thanks-

Nick

Jeremy Fitch
09-28-2005, 09:12 PM
Whats under the battery is a vacuum actuator, and its common for the boot on it to burst and thus it will not pull the cable any longer.

Mine went out, and when it did the lights on the dash showed it in 4 wheel but it never actually engaged. I had trouble finding this part at an auto store and got mine from a junk yard.

Just pull the battery and take it out and inspect it. There are 2 or 3 bolts holding it on that are accessible from the fender well.

Also another common problem with these trucks is the encoder motor.

nendres
09-28-2005, 09:26 PM
thanks for the reply- I will pull the battery and check the boot on the actuator. Where is the encoder motor? I am assuming the encoder motor is on the transfercase, so if that was bad would the front driveshaft still turn?

Nick

Jeremy Fitch
09-28-2005, 09:48 PM
thanks for the reply- I will pull the battery and check the boot on the actuator. Where is the encoder motor? I am assuming the encoder motor is on the transfercase, so if that was bad would the front driveshaft still turn?

Nick


Yes, its on the transfer case. The other components of the system are a vacuum switch, also on the transfer case, and a control module thats located under the dash that controls everything. There are many threads in the forums that relate to 4x4 issues, do so reading and I am sure you will find your problem with a little trouble shooting.


Also I have seen times where unhooking the battery for a few minutes to clear any trouble codes in the control module will get the 4x4 working again.

Jeremy Fitch
09-28-2005, 09:57 PM
Pay particular attention to riliths post in this thread:

4x4 Issues (http://www.automotiveforums.com/vbulletin/showthread.php?t=331547&highlight=encoder+motor)

nendres
09-28-2005, 10:05 PM
thanks again Jeremy- I will check this Thurs and post what I find.

Thanks-
Nick

nendres
09-29-2005, 07:59 PM
I didn't have enough time to dig too deep- but I took the battery out and it looks like the boot on the actuator is ok, but while the engine is running the boot always has vacumme pulling it in whether it is in 4 wheel drive or not. I am assuming that it should be out in 4 wheel drive and "sucked" in while in two wheel drive. If this is correct then I am thinking it must be something under the dash that controls the vacumme. Anybody have any idea where the controls are under the dash or if my theroy is correct? Thanks for any help.

Nick

jimk55
10-26-2005, 09:30 AM
Check on top of your transfer case, there is a vacuum switch with a vacuum hose going to the actuator under your battery. The vacuum switch on top of your transfer case sticks and will not let the actuator shift, thus not changing from 2-4 wheel drive or visa versa.

nendres
10-28-2005, 08:43 AM
thanks for the reply jimk55- I actually found that the vacumme line going to the canister under the hood was unhooked (fixed my vent problem too). Seemed to take care of the 4-wheel drive not engaging, but now when I put it in 4-wheel, it seems like it does not completely dissengage- the light goes off, but it still drives like it is in 4-wheel drive even if I put it in Neutral or Park, I have to turn the truck off to get it out. There also is a noise that shows up every once in a while now at hwy speeds when I start to slow down. Sounds a little like the tire is rubbing on something, only the noise sounds faster than the tire is spinning and the tire is not hitting anything that I can see. I've been too busy to look into this lately, but if anybody has any input it would be appreciated!

Thanks,
Nick

rlith
10-28-2005, 09:17 AM
thanks for the reply jimk55- I actually found that the vacumme line going to the canister under the hood was unhooked (fixed my vent problem too). Seemed to take care of the 4-wheel drive not engaging, but now when I put it in 4-wheel, it seems like it does not completely dissengage- the light goes off, but it still drives like it is in 4-wheel drive even if I put it in Neutral or Park, I have to turn the truck off to get it out. There also is a noise that shows up every once in a while now at hwy speeds when I start to slow down. Sounds a little like the tire is rubbing on something, only the noise sounds faster than the tire is spinning and the tire is not hitting anything that I can see. I've been too busy to look into this lately, but if anybody has any input it would be appreciated!


Thanks,
Nick


Check all your vac hoses for leaks and cracks as a matter of course... If it's not disengaging properly until you shut down the car, change the vac switch on the transfer case, it's probably sticky...

Paddle_Grl
10-28-2005, 09:41 PM
see this thread
http://www.automotiveforums.com/vbulletin/showthread.php?t=473777
the "tire rubbing" sound was addressed...I think it might help you out
Karin


There also is a noise that shows up every once in a while now at hwy speeds when I start to slow down. Sounds a little like the tire is rubbing on something, only the noise sounds faster than the tire is spinning and the tire is not hitting anything that I can see. I've been too busy to look into this lately, but if anybody has any input it would be appreciated!

Thanks,
Nick

nendres
10-29-2005, 09:40 AM
Thanks for the advice- I will check the vaccume switch on top of the transfercase and see what happens- the noise I hear is not too terrible of a grinding noise, so hopefully I can fix this before I ruin those gears. Right now I am out of town, so I won't be able to fix it until Tues or Wed, but I will let you know what I find out. Have a good one!

Thanks-
Nick

hootymo
10-30-2005, 05:00 AM
does this stuff also apply to the autotrac transfer case, or do i have a different setup?

rlith
10-31-2005, 07:16 AM
does this stuff also apply to the autotrac transfer case, or do i have a different setup?

Yours is a similar setup...But you don't have the vac actuator on the transfer case as it's all wheel drive... Though you have vac hoses that come into play for the awd...Again, check all vac hoses for dryrot and cracks.

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