Four wheel drive won't engage

[fastcat800]

Pulling my boat out last nignt I had no 4 wheel drive. I had to load a half dozen people in the back of the truck to get it out. The indicator lights on the floor have never worked. I put it in 4wd when I am backing up as it takes a while to engage on the '94's. Any ideas on where to start looking would be helpful.

[20050627|3|008327|000043|65.183.99.20]

http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=008789#000001
http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=008752#000001


Pretty standard problem on the GM trucks. Stupid design initially but the replacement from GM works well (although I need to do mine).

[BobND]

If you have the original actuator on your IFS axle (and it sounds as if you do, based on your mention of a time delay in lockup), it is a thermally-activated unit, and has likely gone to actuator heaven. The replacement is a gearmotor actuator that offers instant engagement.

A wiring harness kit is required to switch to the newer actuator, in addition to the actuator.

[rjschoolcraft]

Do make the switch to the new actuator, but check the connector at the transfer case as well. This can have an intermittent contact issue and prevent 4wd engagement.

[MTTwister]

A wiring harness kit is required to switch to the newer actuator, in addition to the actuator.

Evidently there are a few different actuator connector types available. This connector is next to the acutator, slung over the right axle tube.
When I got mine for the Dealer, "this is what you need". Well, it wasn't. I cut and soldered the old connector's plug onto the new harness so they would mate up. Mine needed a flat pin style, and they gave me a round-pin style. Not insurmountable, just another PITA .

GMParts Direct wanted to know the Axle number to supply a harness. Now I know why...

[fastcat800]

Thanks for the help guys. I found another Posi-lock that NAPA sells. It's $179 and the one made in Las Vegas is $199. Anyone have any exp. with the NAPA one as it's in stock. The instructions say it has a button to push and cable engagement but does not tell you what the button does. Here is the web site http://www.4x4posi-lok.com/ Can you screw up your 4WD if you do things out of sequence with these?

[20050627|3|008327|000043|65.183.99.20]

The only problem with the Posi-Lok is you have to do two things to get 4wd. Either push the dash button or pull the t/c lever AND pull the cable.

The big advantage I see is that you can get 2wd-lo easily.

I know from a 4x4 site that lots of serious 4 wheelers go to the posi-lok over either a straight replacement or an upgrade. I'm still thinking about what to do on mine as mine is going south.

And if you buy from the dealer, you have to buy both an actuator and a new wiring harness to make the swap just a plug in.

[fastcat800]

I bought the GM unit so I only will have to pull the lever to get it in 4WD. I got it wholesale so it was $193 with sales tax. I do see the connector issue you are talking about MTTwister. Pay $70 for a harness and then have to splice your old connector on to it!

[fastcat800]

I was wrong about the connectors, they are the same so it plugs into the harness and the actuator just fine. There is a brown wire about 5 feet long with no conector on the new harness. Where does it go? Is it a power wire?

[BobND]

The brown wire sources fused "4X4 power" from a wire on a switch at the top LH side of the transfer case.

[MTTwister]

It's also a hot in run wire, fuse 24 off the fuse block under the hood I believe, although I tapped mine into the transfer case connection. a 4 wire connector on top of the transmission, "socket "D" ", so it's on one end or the other - ( pretty dirty and dark under there.. smile.gif )

[fastcat800]

So I look for the switch on the top LH side of the transfer case and connect it to the wire that has power to it when I put the truck in 4WD? Or does it need power to it when the ignition is on? Sorry guys I am a bit confused.

[fastcat800]

I found the switch after I installed the new actuator and spacer. It has a brown, blue and green wire going to the connector. Anyone know which wire it is I need to connect to?