600-490 4WD Actuator | Fits Select Chevrolet / GMC Models

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.

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

Fits perfect on my 88 k 1500. Relatively easy to install. Instructions were very helpful. Brought my non-functioning four-wheel drive back to life. In the long term is a great investment knowing that the newer style actuator is less expensive than the older style and quicker to activate. Perfect fit.

Works, but had the wrong wiring plug to hookup to my trucks wiring. I had to cut the plug off my old actuator and put it on the new harness. The blue wire on the new harness is the hot wire. I used my 12 volt test light to find the hot wire on my trucks wiring harness plug (the plug that goes to the actuator), and then hooked the old actuator plug to the new actuator harness. The brown wire just needs to go to switched power, so I hooked it to an old vacuum sensor on top of the engine that I don't use anymore. 1996 Chevy K3500 6.5 diesel

The only way to go unless you like changing out thermal actuators works way faster and is easy to install just need to run one of the extra wires to a keyed ignition source. Tested it out before I even installed it to make sure it worked and it only takes about 3 seconds for it to engage and disengage

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.

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.

Receiving connector on truck side to the old thermal actuator is different and won’t work with this harness in the kit. I had to take the old one out and connect it to the new wiring harness. I wish kit came with teflon tape and three zip ties. Besides that Great product. Fast engagement of 4x4 when done and done. Took some wiring work since I had to reuse old connector and I don’t know what is blue wire and black one. On Old thermal both are the same color. Truck side I had to figure out which to blue and which to black since I had to reuse old connector.

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.