Hi,

I have a 97 Blazer that is giving me a ton of problems. The latest is the 4 wheel drive is not engaging. I didn't realize this until I got stuck in my driveway this winter. I put it in 4 wheel drive and I hear a sound (like something is moving) and then the 4x4 light goes on. This however, is misleading because the car is not actually in 4 wheel drive. I tested it out and it is still stuck in 2 wheel drive. What Would make it go through the motions, and even trick the car into thinking it is actually in 4 wheel when it is not. It does the same thing for 4 low by the way.

I went to a garage and the guy says he suspects it is an actuator, but he also said it was over his head to fix it and I should go to a dealer or a transmission place. I just need to get an idea of what is wrong with it first so I don't get raped at either place. If anyone has an idea of where I should look, please give me some feedback.

Much appreciated

Mike

Check the vacuum hose going to the vacuum actuator.

Ok, I took out the battery and managed to get the metal plate out. The actuator is plain to see. I just tapped on the vacuum hose connected to the actuator and it fell off. I replaced it securly. I then inspected the vacuum actuator. I noticed a slight tear in the rubber flange surrounding the area where the shift cable connects to the actuator. I pushed on it and a bunch of oil or something came out of it. Is the rubber flange supposed to be sealed or do I need to replace it?

Thanks for the Help

Mike

Was this oil red like tranny fluid?

Ok, after further inspection, I would say it is Transmission fluid. I might be dripping down the shift cable.

What now?

http://www.automotiveforums.com/vbulletin/showthread.php?t=498812&highlight=vacuum+actuator

Ok, after doing a better search, I have found what my problem is. Apparently my transfer case vacuum swich is leaking as well, which explains why there is transmission fluid in the vacuum actuator.

Now, I need to get the part numbers for both the actuator and the switch.

I also need a bit of help with getting the cable disconnected from the vacuum actuator. I looked at the "how to", but my blazer is a 97 and if they are identical, then I'm just not getting it. there must be something I'm doing incorrectly, because the cable just will not come out of the vacuum actuator.

Finally, if someone could direct me to a "how to" or give me an idea on how to change the transfer case vacuum switch, I would appreciate it.

Thanks for the help so far.

Mike

Ok, I feel like I'm talking to myself. However, I will give it one last try. Can someone here give me some advice about what tool to use to take the Vacuum Switch off the transfer case. I was under there for like an hour trying to figure out how to get at it. There isn't much room in there at all. Maybe I need a lift so I can get at a better ange. Any help would be appreciated.

Mike

Its not gonna be easy replacing the Vacuum Switch with the TransferCase still in the truck. There is not a lot of space to move around the area where the switch is. If you can find out how to get the Tcase off and see if its not that hard, then you might wanna take the Tcase out first.

Hoping I don't have to take the transfer case off. It is tight under there, but I was able to fit a deep socket on it, but couldn't get the ratchet on there. My next step is to get a 7/8ths wrench and try to get a good angle on it.

try an offset wrench(ratcheting ones are really good but those get expensive though), maybe that'll work.
Do you have the switch already?

yes, I have the switch. I tried an offset ratchet 17 bucks, but I quickley realised that I need a ratchet that can move up and down. I think I have the answer, I first have to go to the store and buy one. I think I can get at it from the front side if I can just get the ratchet under the metal gas lines. If it works, I will post pictures. I am just hoping it is easier to get in than it is to get out. I did managet to get the ratchet on it, but I couldn't get enough torc to losen the nut. I will have to buy a ratchet with an extra long handle.

Getting at the transfer case switch is a little bit of a pain in the butt. Just take your time and have lots of patience when working with it. There isn't really that much room to work in, but it's possible. Definitely not worth all the trouble of taking the whole transfer case out.

When I did mine I had it up on jack stands. I layed with my head toward the front, and feet toward the rear and scooted up under the car, I could get a good clear view of what I was looking at that way. Taking it off wound up being the easy part. Getting it started back in was the hard part, I probably spent a full thirty minutes just trying to get it started back in the hole. Afterwards it's best to check and make sure you get the vacuum lines back on right as well. I didn't get mine back on right in the first place, and I had vacuum in 2wd, and nothing in 4wd, backwards of what it is suppose to be.

I had to replace the actuator and the switch both on mine as well. I really don't like that actuator being under the battery, so I'm trying to figure out another way to mount it somewhere more accesible.

Ok, I got the right tool for the job and managed to change the vacuum switch in about 10 minutes (including the time it took me to set up my jack stands). This, however did not fix my problem. I have:

Replaced the Vacuum switch under the T- case/
Replaced the Vacuum actuator under the battery.


It still doesn't go into 4 wheel hi or low. The light indicates that it is indeed in 4 Hi and 4 low, but it definately isn't in either gear. It remains in 2 wheel. When I press the button to engage it, I definately hear a thunk noise, which leads me to believe it is doing something.

I did notice Transmission fluid in my vacuum hose. Is that possibly screwing things up?


Is it hard to replace the vacuum hoses? Maybe I should do this next.

Also, do I have to prime the Actuator or something. Maybe I need to push it in manually the first time to get it set or maybe it should do it by itself. I'm really not sure what the next step should be.

Mike

Is the front axle coupler engaging - if not then no 4wd - that noise was the encoder motor in 4lo pulling the lower gear in - not used in 4hi but both require that axle coupler and the sender switch telling the TCCM the front is coulped. Try 4hi and see if the coupler moves - then pull the vac line under the hood and listen for the coupler to disengage (you will hear it if it works )

If the coupler isn't engaging, then what should I do next? Do I need a new TCCM? How do I test if the vacuum lines are all good? Is there any way I can manually engage the coupler? Anyway, I'm sure it has something to do with that because I do not hear the coupler coupling. But like I said, the Four wheel Hi light does light on, so the computer is being told that everything is working properly when it isn't.

Mike

Do you have a compressor and a blow gun? You might try disconnecting the vacuum lines and blowing them out to get the fluid out of them. Test for vacuum from the engine at the transfer case switch. Then connect them back up to the transfer case and see if you are getting vacuum at the front axle actuator when you put it in 4 wheel drive. I know it's hard to do with it under the battery. If you can get a vacuum pump you can activate the actuator with it to see if the front axle will engage with vacuum. You can also use the vacuum pump to see if the lines are good.

Make sure you got the vacuum lines back on the transfer case switch right too. It does make a difference on how they go on.

I somehow managed to put mine back on the switch the wrong way. I was getting vacuum to my actuator in 2-wheel drive, instead of 4-wheel. When I went to 4-wheel I lost my vacuum. I got back under it and turned the hoses to the right position, and it fixed that problem real quick.

I found out just by taking the vacuum hose loose from the actuator. It's a little bit of a pain taking the battery out and putting it back in, and I'm sure there are better ways. It's what worked for me though.

Ok, I will try all of your suggestions. When I attached the vacuum hose to the vacuum switch, I noticed a little notch in the hose and a small piece of plastic on the vacuum switch that was sticking out. I just assummed that was the guide to putting it in correctly. If this is not always true, then someone correct me. Anyhow, I guess I better double check and or try some other combinations. Also, I will take the battery out and connect it so I can see if my actuator is getting a vacuum. I will post results later. BTW, I'm going to get a OBD Sensor reading to see if there are any codes.

Mike

Ok, I have basically narrowed it down. I know know my vac lines are working. When I engage the 4 wheel drive, my vacuum actuator sucks in. The problem is, it doesn't take the wire with it. For the life of me, I can't get the actuator to clip on the the end of the wire it is supposed to pull. What am I doing wrong? It doesn't seem like the spring clip that came with the part is able to grasp on the the end of the wire. Should I go and get a cottor pin or something? Anyway, I have checked the "how to" and it basically said to just put it on. If someone could be very specific, maybe I will get this working. thanks for the help. BTW, I pulled on the wire with a pair fo vice grips and it does move, so it doesn't seem to be rusted or anything.

thanks for any suggestions.

Mike

Ok, seems all I needed to do was come up here and cool off, because when I went back, I realized that I needed to push:

1. Push the actuator in and place my finger on the vacuum hose connection so it will keep the plunger in.

2. remove the spring/latch

3. use a pair of vice grips and pull the wire toward the actuator.

4. release my finger from the vacuum hose connection.

5. make sure the grove in the wire was far enough up and then clasp the spring/latch on it.

Anyway, after replacing the actuator and the vacuum switch I finally got the 4 wheel drive to work. Thanks to everyone who had a hand in helping me along. Now, on to the air conditioner.


Mike

Ok, I got the right tool for the job and managed to change the vacuum switch in about 10 minutes (including the time it took me to set up my jack stands).

I may need to do the same job soon. Mind telling me what "the right tool for the job" is? Pictures are welcome :rofl:

You need a 7/8ths deep socket. And a socket wrench that has a hinge behind the head that moves up or down. (I bought the wrench for 12 bucks on sale at K-mart) Anyway, I jacked the car up and put it on jack stands. I layed with my head at the front and feet facing towrd the back of the blazer. You can fit the socket on the vac switch above the transfer case from the front (it takes a bit of time to find the best spot). then, you can put the socket on the wrench and you should get it off in no time. I suggest making sure the handle of your wrench is at least 10 inches long so you have enough leverage. Anyway, when you get it off, the other one should go on pretty easy, but I would hand tighten it first.

Good luck
Mike