Dorman 600-490 4WD Actuator Compatible with Select Chevrolet/GMC Models

I bought this to replace the old style thermo-actuator on my 1995 GMC Suburban. Works great, no issues so far.

Bought this Electronic version to replace the failed 4WD actuator in my 1996 Chev Silverado. The original has some sort of "heated wax" internals that is prone to failure, and very slow to actuate. This replacement is fully electronic and responds immediately when the 4WD button is pressed. It comes with the actuator, a small spacer, and the replacement wiring. The body of this actuator is slightly shorter than the original so a spacer (included) is needed inside the axle mounting tube to make up the difference. The dimension of this spacer is shown in my photos. The wiring comes with a detailed diagram and description of connections required. One end of the included wire loom plugs into the new actuator, the other end plugs into the 2 connector end from the original actuator on the truck, and then there's a third wire that must be connected to an ignition-on power wire somewhere in the truck. The required wire is a brown wire which is powered only when ignition is on. The suggested connection is to the brown wire going to the transfer case, but I found another brown wire next to my under-hood fuse box that was easier to access and worked just as well. Once installed, I discovered my 4WD switch was also problematic and needed to be removed and the connections cleaned. Once this was done the 4WD is engaging and disengaging reliably again and much faster than with the old "wax" actuator. My 4WD indicator lights are also now lighting up reliably again after not having worked for many years. Very happy with this replacement/ upgrade kit from Dorman. Hope this electronic version lasts longer than the old version.

Very well written instructions that include wiring diagrams to show exactly where the one wire needs to be spliced. Very easy to follow the instructions and install the kit. Worked exactly as expected and fixed my 4WD issue.

Fits and works great in my 1989 k1500. 20 minute install been working great for months now. Thanks, Dorman for putting this kit together and helping us keep these trucks going.

Wish the unit was metal rather than plastic. I used Teflon tape on the threads. Just snug it tight, don't overtorque it. I followed other reviewers suggestions and ran the wire to the "keyed hot" lug on the convenience center inside the cab. Works very well.