4wheel drive problem

Asked by Feb 09, 2014 at 11:01 AM about the 1994 GMC Sierra 2500

Question type: Maintenance & Repair

I have a problem with my 4wheeldrive not
engaging at the front axil. The transfercase is
working. I know there is an actuator but im
wondering if there is a problem caused by the
previous owner modification to the heater
system. There is a manual shutoff valve
installed in the hotwater hose. Also there is a
30amp fuse in the 4x4 fuse socket. The lable on
the fuse box says 25amp. Anyway, any thougt
as to what I should search for

1 Answer

11,595

The '94 has the thermal actuator in the front end. They are slow and they do fail. It probably kept poping the fuse while it was on it's last leg. The last one I bough was about $180 bucks. They are very easy to change and thats were I would start. I think a 15" cresent wrench fits on it. Just un-plug and thread out. If your on level ground the front diff fluid should not leak out. You can pull and test the old one to see if its the problem before you buy a new one. You never know if there is wiring damage. I use a fuse holder. I strip both ends, twist and tin them (cover them with solder so they are like a probe) do it to a scrap wire also. The plug should only have 2 pins. Cannot remember the colors. Would assume the black is ground. Use a 20/5 amp fuse and probe the + and - from your battery. It will S......L.....O......W.....L....Y extend if it's good. Takes 8 to 20 seconds usually. If it doesn't move replace. Dielectric grease in the elec connectors on re assembly helps keep the moisture out.

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