1999 Blazer: 4x4 wont engage, blinking 4x4 light - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 06-21-2010, 02:48 PM Thread Starter
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1999 Blazer: 4x4 wont engage, blinking 4x4 light

Ive got a 1999 s10 blazer and the 4x4 does not work. When I press the 4x4 buttons (low or high) the light blinks for a little wile and goes back to 2wd.

I read online that this issue is sometimes caused by the control box in the passenger kick panel. It can get corrosion in the connections or can have damaged wires. I removed the control box and checked the wires and cleaned the connectors and they where fine. When I conected the control box back up and tired to engage four wheel drive again the control box made a clicking sound wile the 4x4 light flashed. After about 4 or 5 clicks it stopped and the light went back to 2wd.

I tried it again and got nothing but the light flashing. I repeted the steps above a few time and everytime the control box was unhooked and conected back it would click on the 1st time only. 2nd time would be the flashing lights again .

So what should I check next? The T-case motor? Or start looking for a vacume leak? or what? Also if it is the T-case eletric motor, can it be rebuilt, or made to work in any way? I dont want to pay $250 for 4x4.

Thanks for your time!
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post #2 of (permalink) Old 06-21-2010, 08:00 PM
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These are notorious for this problem. The GM trucks use either a vacuum or thermal actuator for the front differential, I think the S-10 uses vacuum. So there is most likely some sort of vacuum problem, probably near the differential. The best way to fix it permanently is to ditch the factory set up and go with this: 4x4 Posi-Lok Positive Axle Engagement System for Chevy/GMC S-Series 4x4s
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post #3 of (permalink) Old 06-24-2010, 09:27 PM Thread Starter
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I don't care about fixing it long term. I just want to get it working so I can sell the blazer.

I was told that their is an vac actuator under the battary. I checked it out and it moves freely. I see nothing wrong with it. BUT I removed the vac line on it and blew into it and could hear air coming from behind the distrubtor.
Could this be my issue?
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post #4 of (permalink) Old 02-09-2011, 09:39 AM
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i have exact prob ??? lkn 4 fix also ! did u get one ????????
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post #5 of (permalink) Old 02-17-2011, 08:35 AM
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vac lines are notorious for getting a small crack and leaking. check all of your lines carefully. i had several to fix on the old chreokee
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