Hey All. I kind of hijacked someone else's thread here with my question (shout out to @Bad Luck for the immediate replies):

https://www.toyota-4runner.org/3354022-post23.html

I have had the truck for about 2 months. The CDL has never worked.

As mentioned further in that thread, I managed to track down a wiring diagram for the 2002 that was advertised as usable on the 2001. It doesn't match the pin numbering or the wire colors on the connector to the switch.
There are 4 contacts wired in the 10 pin connector. One at the top of the connector is a ground, the one diagonal from that has 12VDC when lights are on. These aren't on the 4WD schematic (briefly looked at interior lighting. Not there either). The other 2, also diagonal from each other at the bottom of the connector, one shoots to about 40 ohms to ground, but it moves around at first, then settles in as if I'm shooting through a component. I assume this goes to the 4WD ECU as the diagram states (just not the correct pin number or color). The other shoots open to ground and never has voltage in any 2 or 4WD position (2WD, 4WD H, 4WD L). UPDATE: with the lights on I get various voltage between all of the pins. I shot the contacts on the back of the CDL switch depressed and released. I never got continuity. I was apprehensive about jumpering the contacts on the connector as I couldn't really trust the diagram I had, but I did it anyway. It had no effect in any 2 or 4WD configuration. I can post the voltages I got, but it seems nonsensical without a schematic I'm confident in. Today, I tried to engage CDL with the lights on for giggles. It still didn't work.

Things I found odd:
The switch never makes continuity. Is it a relay type switch? It doesn't read as such in the diagram.
One of the contacts that go to the CDL switch should be a spliced ground according to the diagram. I'm not sure if it is always a ground, but it appears to be if I am reading the diagram correctly.

The CDL switch was very easy to get out. It appears that someone was already troubleshooting this before I bought it. I didn't test it before I bought it. I was on pavement and 4WD worked fine. Dude said it worked.

The diagram doesn't list what type of signal is on the wires to and from the 4WD ECU. That would be helpful.

Any assistance troubleshooting is appreciated. I'll pony up and buy the TIS manuals if I have to, but I've put a bunch of $$ in this thing already. Kid in college... all that stuff.

Thanks!

@VGKBlackhawks I had a hell of a time troubleshooting my 2000 Limited so I'm always willing to help anyone else in the same boat if I can. Do you have a link to the electrical wiring diagrams you're using? Have you tried ohming the circuit between the switch and the 4wd computer? Without access to the wiring diagram I'm pretty much just guessing at how the system works. I'm guessing it changes ground paths when on/off. Have you thought about trying another switch?

@Bad Luck
As long as the switch is as advertised in the schematic, I eliminated the switch by placing a jumper wire in the connector. I just can't trust the drawings (check PM).
I have not ohms checked the wiring at the computer, again because of the diagram. Unless there are other suggestions here I'll buy another. Hopefully this isn't something crazy, like a rewire that someone has done.

Does everyone else with an 01 SR5 have a light in their switch? I was reading on another forum that they had a switch with a spot for a bulb, but no wiring or bulb installed. I can't remember if that was an 01 though. I've been reading threads for days.

I have an 01 and my switch does NOT light up. just the yellow bulb inside the 4 green tires on the instrument cluster.
When I bought my runner years ago I found that a lot of my dash bulbs did not work and the PO had removed several more. Gave me fits until I finally removed the dash pod and found the missing bulbs.
did I mention that I HATE electrical problems........good luck
Dave

I looked at the wiring diagram you sent me. The 4wd ecu is looking for ground to see if the switch is engaged. It might take a while but I would try to check the resistance between the switch and ecu and switch and ground. I'm hoping it's just a bad switch but it's hard to eliminate that without an accurately color coded wiring diagram. What colors are the wires at the switch?

I'm not going to be too much help, but I did just want to confirm that the switch itself doesn't light up (on my 02 at least). Also, the switch is just a momentary type switch...it doesn't stay in when pressed or really give you any indication that it's done anything. It returns to the same position when you release it and doesn't really "click" or anything. When I first tried my CDL, it didn't seem to do anything at first, but I found it worked if I held it for a second or two.

Finally, with both the 4WD switch and CDL switch, how you drive matters somewhat. My "secret" for getting both the 4WD and CDL to engage quickly is to cruise at a steady speed above 10 MPH, hit the switch, then press the gas pedal slightly then release it. Both the 4WD and CDL engage as soon as I release the gas pedal and the drivetrain gets a bit of engine braking reverse force on it.

Good luck with your diagnostics!

I'm right here with @rightyouareken , probably not much help, but I can also confirm my 2001 SR5 does NOT light up, and is the same style that returns to the same position after being pressed.

However, my CDL has also NEVER works since I've owned the truck. I've never needed it, so I've never tried to fix it. 4wd engages perfectly fine and always has, but my center diff has never been locked.

If you keep working on yours and figure it out, i'll definitely be interested in seeing what the fix was. Unfortunately, I'm not going to put any effort into fixing mine...which is no help to you.

Hey guys. No real update. I haven't been able to troubleshoot much. My daughter has my car, so I have to drive this every day. I'll keep you posted after I can tear into it.

*SOLVED* (Not by me)

So I gave up and paid someone to look at the 4Runner.

There was a stowed connector behind the dash that was wired to the 4WD ECU, but it wasn't wired for the CDL switch back light. They rewired the connector for back light, stowed the other connector and all is well!

Slightly embarrassing that I couldn't find the stowed connector, but I'm glad to have a truck that I can take of road. I'd love to know how or why someone did that... the joys of 3rd ownership!

@quicksilvr - check behind your dash for a stowed connector... it makes no sense, but maybe yours was stowed as well?