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Old 01-15-2012, 12:21 AM
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Default 4x4 front axle wont engage

I have a 1996 4 door blazer just got it, When driving in 2hi shifting in too 4hi i can hear it click over and it shows I'm in 4hi Same as when i stop to put it in 4lo. but it won't engage I have no traction but pretty good tires. I live in a very hilly area and need 4x4 to get around....

ok I did some more looking today, It will switch into 4hi/low but i have no power going to the front axle

Last edited by bobmclay; 01-15-2012 at 12:43 AM.
Old 01-15-2012, 10:00 AM
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These trucks seem to have quite a few issues with the 4wd systems, and although this site hosts the most information that I've found, sometimes responses are, well- some leave a lot to be desired, IF you get a reply at all. With that being said, there are many knowledgeable individuals on here that certainly know their stuff!

I'll try my best to help you out, I have a 99- and I'm not too sure how similar they are in the respect to the 4wd systems.

Based on what you've described I would start by tracing out all of the vaccum lines that run your 4wd. If you're not too sure on where to start, if I were you, I'd start by looking under my battery tray and inspect the rubber diaphram on the 4wd actuator. You'll have to remove your battery and tray to get at it. (Or atleast I had to, not sure about the 96's). Have a look at it and look for tears, rips, ect. You'll also find a vaccum line that operates it, check that out as well. It is possible that if fell off. If the diaphram is good, follow the vaccum line, inspecting it for holes or rot. I would think that if you're axle isn't engaging, that it is probably vaccum related, unless your axle cable is kinked or broken.

Good luck!! Maybe someone that is a bit more familliar with these trucks will help ya out. It took a bit for someone to reply to my 4wd issues, but there is quite a few smart members on here that are more than willing to help someone out!
Old 01-16-2012, 02:06 AM
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thanks coolen I'm getting to it tomorrow I ordered a axle actuator its coming in tomorrow i hope i can fix it by tomorrow cause we have a snow fall warring...lol its for about 6" ya ya not much snow but there call for snow all week here. Im in BC 40 miles east of van... im fine with out it but its very hilly here. I was able to get around in 2hi in 6" of snow with fish tailing but i didnt hit anything it was 3am and had to come home in a snow storm about 40 mile and the plow system sucks here and i live up a big hill.
Old 01-16-2012, 02:08 PM
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coolen is exactly right on where to start with your leaking vacuum search. Another way to tell if you have a leak is to switch your heater controls and back and forth and see if the air flow will move from the floor to the dash and back and forth. The 4x4 and heater controls run on the same vacuum supply and often when one doesn't work neither does the other. This does not always work but it is an easy place to start diagnosing the problem. The vacuum system on these can be very faulty especially when the temp is cold. The rubber lines wear out after time and are often hard to trace and find the leak. Most autoparts stores sell rolls of the vacuum tubing to replace the lines as you follow them thru the engine compartment. I would do a search on here and find the vacuum diagram that has been posted on here many times and use that to work with. I had the same issue and I took the extra steps to eliminate the vacuum system from my 4x4. If you look at my build thread I have a small right up and pics on the first page. I will try to answer any questions you may have as well. I'm certainly not an expert on these things and there are many very knowledgable people on here that I'm sure will help out as well. Hope this helps!!
Old 01-16-2012, 06:05 PM
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Yep, look at the diaphram and the cable. When we had our 95 the corrosion/acid from the battery ate thru the sheath and cable.
Old 01-16-2012, 08:01 PM
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As stated, #1 - check for vacuum to the front axle actuator when in 4HI or 4LO. If you have vacuum and it pulls down pretty good, then the problem is either with the actuator itself or with the cable. The actuator should be able to pull the actuator 1/2" to 3/4" to properly engage the front axle.
Old 01-17-2012, 01:41 AM
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Hi rexmburns.
My heat wroks awsome no comeplants with that. I got the 4wd actuator to day and will start with that. while I was under the blazer I found out it has a reloaction kit for the oil filter on the front cross member facing the rad
Old 01-21-2012, 09:51 PM
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ok got it fixed it was a $3 vacuum t Click the image to open in full size.
Old 01-23-2012, 12:41 PM
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Ive replaced the 4x4 actuator which was really oily, and that didnt fix mine. Also replaced the vacuum switch since the ball thingy was stuck and still didnt fix it.

(mines a 92 blazer tahoe lt)

Didnt check for vacuum yet, too cold, and it rained yesterday...(freezing rain)

I hear clicking in glove box and can hear encoder motor working...but buttons only work when I have in nuetral. (why is this?)
Old 01-23-2012, 01:18 PM
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Default 4x4 hubs

I'm having a similar issue with my '97 blazer 4wd. I have good vacuum and can see it pulling in and holding the actuator under the battery cover. I can hear the cable moving at the front differential. I removed the nut that holds the cable into the differential to make sure it didn't pull out easily, thinking maybe it was broke inside. It did not come out.

I am sure it is not in the transfer case. I can put the truck in 4hi and 4lo and the driveshaft to the front differential will rotate and in 2hi it does not. The lights stay full on with whatever type drive I select and stays in that selection as well. On occasion I have some trouble getting back into 2hi, but not always.

I am sure it is in the hub locking mechanism somewhere, but am at a loss where. I'm half debating to just change out the cable to the differential because I can't think of anything else it could be. Maybe it isn't pulling it far enough? Can it be anything else?

Does anyone know too what the device on the differential right where the cable comes into it is? It has two electrical wires to it; looks like a sensor maybe?
Old 01-23-2012, 01:18 PM
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01, 1996, 2000, 4wd, 4x4, 97, actuator, axle, axles, blaer, blazer, chevy, engage, front, vacuum, wont

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