Kenworth

Hello, I am new here, (kind of stumbled onto the site), and I'm hoping someone out there can help me.

I got a 99 s10 blazer with a messed up 4x4. Sometimes it will engage, other times it won't. If you push the auto 4x4 it will sometimes just flash and never engage and then when you push it back to 2Hi, it clicks to 4lo. Not really sure where to start with this one. The "dummy" light comes on occasionally, but if you turn off the truck it goes out and does not come back on.

I have done many things to this little SUV so I'm not afraid to get dirty. Can anyone point me in the right direction?

While I'm at it, I figured I would do a service to the 4x4 system,......I have the ambition, just lack the knowledge. Anyone up to pointing me in the right direction???

Thanks for any help you can pass on.

far2grumpy

Kenworth ... according to service manual there could be one of two transfer cases (TC) in 99 Blazer. I've attached a test procedure for TC with three buttons (2HI, 4HI and 4LO). Get in touch if your TC has more than three buttons. We'll need a different procedure.

The procedures have you count switch flashes ... I've pasted the codes below ... again ... get in touch if you need more information.

Diagnostic Trouble Code (DTC) List

<TABLE width="100%" border=1><TBODY><TR><TH vAlign=bottom align=middle>DTC
</TH><TH vAlign=bottom align=middle>Diagnostic Procedure
</TH><TH vAlign=bottom align=middle>Module(s)
</TH></TR><TR><TD vAlign=center align=middle>DTC 001
</TD><TD vAlign=center align=left>DTC 001
</TD><TD vAlign=center align=left>TCCM
</TD></TR><TR><TD vAlign=center align=middle>DTC 002
</TD><TD vAlign=center align=left>DTC 002
</TD><TD vAlign=center align=left>TCCM
</TD></TR><TR><TD vAlign=center align=middle>DTC 003
</TD><TD vAlign=center align=left>DTC 003
</TD><TD vAlign=center align=left>TCCM
</TD></TR><TR><TD vAlign=center align=middle>DTC 004
</TD><TD vAlign=center align=left>DTC 004
</TD><TD vAlign=center align=left>TCCM
</TD></TR></TBODY></TABLE>

Fluid changes are generally easy to do.

I recently changed Dexron III fluid in my transfer case ... (as well as 80W90 lube in front and rear differentials).

You need to verify which TC you have, as well as fluid type and quantity.

Following steps applied for my 2004 S-10 4WD pickup.

My transfer case holds 1.1 quart of Dexron III fluid.

Next step is remove the upper fill port plug using a 10MM hex tool (size needed for my 04).

Then remove the bottom drain plug and catch the mess.

Reinstall the lower plug (not too tight) ... service with ATF until fluid is just starts to leak from upper opening ... and put the top plug in (don't over-tighten).

Good luck!

Kenworth

I actually got the four button control. Auto 4W/2hi/4hi/4lo.

I am going to be checking the fluid levels and changing them later today as well as check the in dash control switches and the control box on the passengers side behind the kick plate for corrosion. If there is some bad connections, I will clean them up and re-post my findings. Hopefully this will take care of the problem if not, then will have to find something else to try and fix. will keep you updated and re-post what happens. Thanks again for your help.

Kenworth

Ok, I checked and changed the transfer case fluid,.....(over due I figured). I checked the module under the dash,....all good,......found that my actuator control was shot,....need to replace it,....did a test manually by depressing the actuator and then getting my father to engage the 4x4,.......it worked. vac lines work real well. 4Hi still does not light up nor will it engage. Did a temp fix to test the actuator,....it works, but controls are still funny. Have to play with it to get it back to 2wd.

I figure I need to replace the actuator control and the in dash switchs and then things should work out. keep you all posted.