4WD Light and SelectTrac issues

[67GMC]

On an '84 with Select Trac, what makes the 4WD light on the gauge cluster come on? Is it a vacuum switch under the hood or is the switch on the transfer case? Is the switch on the transfer case only showing the "emergency" or part-time 4WD light? Mine doesn't seem to have any harness to the Transfer Case and there's what looks like a vacuum switch mounted on the fire wall with a plug vacuum line and no wiring to the inside. Puzzling. Also, does the vacuum disco get it's vacuum from the ball or from the black can?

[Tatsadasayago]

On the NP 228/229 there is a switch mounted on the front half of the case (Engine side) near the junction of the input housing and chain case housing. When the linkage is moved into 4HI or 4LO the shift fork moves and allows the tip of the switch to drop into a notch in the shaft. That closes the circuit and sends power to the dash indicator.
I honestly don't remember seeing a indicator switch on the front axle disconnect.
Note that there should be another switch on the backside of the chain case which is a oil level warning indicator. Many confuse those with the shift indicator, which is on the other side of the chain case.
The wiring for both switches comes off the firewall harness near the transmission hump if memory serves.
I recall the vacuum ball being the source for the front axle diaphragm. The coffee-can is for the cruise control diaphragm.

Hope this helps you.

[67GMC]

Thank for the reply. Since there's only manifold vacuum connected to the coffee can, maybe that's why my cruise doesn't work. Found out today that there's two little light bulbs on the 2WD-4WD switch under the dash too. Mine were both burned out so fixed those while my noggin was in that area. I'm thinking there should be some stray wires running around that used to control the 4WD light but I don't see anything extra underneath near the Transfer Case or in the engine bay other than the firewall mounted vacuum switch. I'm going to check that harness coming up near the transhump in the morning.

[Tatsadasayago]

If the wiring for the switches doesn't drop from the firewall, they may pass from the inside through the floor.
It's been way too many years since I worked on the late FSJs and I've forgotten most of it.

If the wiring is gone, as in cut out, you can make your own harness easily enough.

[67GMC]

Figured out why my cruise control doesn't work-no actuator under the hood! The module and controls are inside but no device to hook it too. Probably explains the lack of hose to the coffee can vacuum reservoir! I've got some chopped wires coming out of the firewall by the brake booster. I'm thinking that these fed the actuator.

Would be nice if anyone has a picture of the setup for the cruise control under the hood.
Thanks

[67GMC]

Just resurrecting my old post. Still not sure how the 4WD light gets its signal. There is a vacuum switch mounted on the firewall that looks promising but can't find a wire to go to it. If there's a wire on the transfer case, where does it go to the harness. It's a minor thing as my 4x4 works fine but annoying if the light is there but no way for it to turn on.
Thanks

[SJTD]

I happen to be going through the wiring diagram for the '84 to clean up the harness in the dash on mine so I can maybe answer.

RED wire from the IGN LPS fuse goes to the 4WD light then an ORN wire from the light to the EZ terminal in the big C100 connector on the firewall. Far left column,second from the top as viewed from the engine compartment.

From there an ORN wire goes down to the switch on the transfer case.

Idunno where on the transfer case the switch is, mine is long gone and replaced with a 300.

The switch closes in 4WD.

I don't know what you have in the way of tools or skill but what I would do is disconnect the wire from the switch and ground it and the light should be on. Then with it in 4WD measure the resistance between the switch and ground and it should be zero. One condition won't be met.

If the switch is good and you don't have 12V there I'd move up to the C100 connector and look for voltage there.

Slip a probe through the goo that's all over the C100 connector to the EZ terminal and ground it. Should light the light. Or check the voltage there and make sure it's 12V.

[67GMC]

Perfect! thanks for the detailed response. There is no wire to the T/C so now I know there should be and can work backwards.

I spent many hours trying to fixe an issue with the parking lights blowing the fuse when I put the headlights on. I ended up taking all of my harnesses apart wire by wire. Turned out to be the resistor wire from the alternator shorting out inside the harness that goes along the firewall. It got hot enough to melting some wires and those crimps inside didn't help. While I was at it, I fixed up wires all around the area, new grounds for the turn signals etc. Signals are much brighter now.

The 4WD light never came on since I've had it. I wasn't sure it was really hooked to the T/C or if it was just a light that came on with the vacuum from the dash switch.

[weeegoneeer]

I don't think there is a 4WD indicator switch on the 229s that came with the '84 - mine doesn't have one. Read somewhere that the switch was added for '85 up.

[SJTD]

Idunno.

The wiring in the dash was all there for mine. The light for 4WD was plugged into the cluster.

The harness from the dash to the TC is in a box so I can't say if that wiring's there. Don't recall if the TC had a switch.

There's an E-Drive window but no light was installed in that hole.

[kansasboy001]

I don't think there is a 4WD indicator switch on the 229s that came with the '84 - mine doesn't have one. Read somewhere that the switch was added for '85 up.

That is true. The 83 and 84 229s don't have the electric 4wd switch on the transfer case

[SJTD]

I'm going to agree with Weeegon and Kansas. The wiring diagram shows the stuff that's there for the 208 but there's no note about it not being used for the 229 so I didn't know/remember. Been 25 years or so since I drove it with the original TC.

Looked in the manual and there's no mention of an indicator light for the 229 but it does address it for the 208.

Sorry for the misinformation.

[kansasboy001]

I'm going to agree with Weeegon and Kansas. The wiring diagram shows the stuff that's there for the 208 but there's no note about it not being used for the 229 so I didn't know/remember. Been 25 years or so since I drove it with the original TC.

Looked in the manual and there's no mention of an indicator light for the 229 but it does address it for the 208.

Sorry for the misinformation.

If you ever swap in a newer 229 or 228 with the electrical plug it is very easy to wire in. The plug for the tcase is a 2 pin male weatherpac connector but with male terminals inside rather than female like normal. The plug just needs power from the light on the dash which should run to the upper plug on the transmission harness, and a path the ground. The light grounds through the switch.

[67GMC]

Thanks for the replies. It's odd they would put a bulb there if no light was to come on. The "Emergency Drive" socket has no bulb.

Maybe a 1984 issue.

[weeegoneeer]

I'm thinking the same cluster was used in other configurations that did support the switch. I was thinking about putting some sort of vacuum switch in-line to control the indicator, but there is a pretty big indicator by looking at the 4WD selector switch itself. Also, by just using a vacuum switch it wouldn't let me know if it was actually in 4wd, just that I want it to be in 4wd.

[candymancan]

Tbh i didnt even trust my 4wd light. I had to drive in snow or do a full figure 8 to see if the front end would bind slightly.. ( viscous coupler causes binding a little bit)