Tiletony

Thx runner. I just assumed it wasn't ADD because of the manual hubs! But come to think about it, it is an SR5 94 truck. I believe those came with the ADD. Ok so I haven't dealt with those. So I will look over your diagram. I am sure I will have questions

Tiletony

I looked over the post but I am not understanding. The truck 94 now has a sas with the 3.4. So I don't need all the vaccum lines or do I? In order to get the dash light to work. Or is it just a wiring deal. As I said earlier I thought all I needed was to hook up the connectors on the transfer case but that didn't work

SacRunner

Let me start by walking you through my 3.0 4WD wiring with ADD and I'll point out where the vacuum lines are needed. Lets start with the simplified wiring diagram from that other thread:



The "4WD (I6)" switch at the bottom of the diagram is a physical switch in the transfer case that's open (not connected) when in 2HI and closed in 4HI and 4LO (connected). When that switch is closed, it provides a path to ground for current to flow from the top of the diagram (+12V) through the ADD relay which causes the "4WD" terminal of the relay to be energized and the "2WD" terminal to be turned off (mechanically, there's a spring that holds the switch to the 2WD terminal, but when current flows through the coil in the relay it generates a magnetic field that overcomes the spring tension and pulls the switch against the 4WD terminal).

That "4WD" terminal connects to the VSV for 4WD and activates that VSV (while deactivating the VSV for 2WD). When the VSV is activated, it allows vacuum to pass through it to the ADD actuator on the front of the front differential (see below, that big wort looking thing on the axle tube next to the diff). When the 4WD port on the ADD receives vacuum it pulls a splined gear over that connects the differential to the driver side axle shaft.

When that gear is in proper position, it closes another switch, "ADD (A5)" which provides a path to ground for the 4WD light in the dash, and the 4WD light becomes illuminated.

If your truck was originally equipped with ADD, all you would need to do is ensure that that "ADD (A5)" switch is bypassed (the 2 wires leading to the plug should be soldered together) and you should have a functioning 3.0 ADD 4WD system that will work for a SAS truck.

Here's a picture of my ADD front diff, taking note of the two vacuum lines, and the white electrical connector (near the front diff mount):


Something that would be easy to find, look on the passenger fender for the VSVs. Mine were in a group of 3 VSVs but only the brown (looks red) and blue are used (brown for 2WD and blue for 4WD); I don't remember what the green one was for, but I didn't need it with my swap.


For the 3.4 swap, the ADD switch can and should still be bypassed as described above (by soldering both sides of the ADD switch connector's wires together).

I know that was probably more detail than you needed, but hopefully it helps to paint a picture of what could be going on.

Tiletony

That is ALOT of help! Runner, thank you for the detail info! Answers all my questions and a great education! I LOVE this forum. You guys are great! I will attack this problem later today and update you. Thx you for ALL your help. Greatly appreciated.

Tiletony

I don't have power the blue vav but I have power to the brown?? I check when engaged and not engaged

SacRunner

Now that I think about it, it shouldn't matter what voltages you get at those VSVs as you shift between 2wd and 4wd; in fact you could removed the ADD relay entirely and replace it with a jumper (short piece of wire) between pins 1 and 2 of the connector (this would replace the coil in the relay with a piece of wire and bypass the wires going to those relays entirely; then you could remove those VSVs from the truck, you'd still have some orphaned wires, but its not a big deal since there'd be nothing connected on either end).

If I were you, I'd start looking for the "ADD Indicator Switch" (what I called "ADD (A5)" in my drawing) connectors or wires. There will be 2 wires run together, typically as part of the engine harness out the front and down along the water pump to where the front diff would be; on my 91 they were G-W (green with a white stripe) and either G-R (green with a red stripe) or G-Y (green with a yellow stripe) and my 97 4Runner donor's were G-R and G-B (green with a black stripe). If you can find them, temporarily short the wires together (if the connector is still installed, use a short length of wire, otherwise strip 1/2" of insulation from them and twist the wires together then apply a little electrical tape for temporary insulation so they don't short) then try shifting between 2wd and 4wd; I would think the dash light should turn on.

Tiletony

K. I traced the pink wire from the new ecu into the motor but couldn't follow it to end. But now that you green and red wires I believe that is the wires I hooked up the switch in the transfer case. So I can undo it and start over. But can't I just find and trace the wires from the dash and hook them up to the pink ecu and the transfer switch?? The gage cluster is the original 94. Before I disconnected the transfer switch wires that I believe I hooked up wrong I ran a small wire from both VSV and it shorted the gage cluster out. So some where it has to be connected right?

SacRunner

I'm confused, why are you chasing a pink wire?

The 97 4Runner EWDs I'm looking at only have a pink wire from the ECU to the Crank Position Sensor and a separate pink wire from the ECU to one of the 2 O2 sensors; neither of which have anything to do with the 4WD circuits.

What's the year and model of your swap's donor electronics (ECU and harness; they're not necessarily from the same vehicle)? Do you have the EWDs (Electronic Wiring Diagrams) from https://techinfo.toyota.com/ ?

Tiletony

I read threw the wiring diagram post from The Monch and he showed from the 3.4 ecu wire 20 I think to be a pink wire that was the 4x4 indicator. But the truck is an 94 3.0 5 speed. Now has a 3.4 in it with the soild axel so all the wires for the original from diff are not there which is good I guess but that switch in the front diff is not present. So I need to fin it to tie them together. On top of I THOUGhT I had the trans case switch hooked up, but I don't think I had the right wires to it as nothing worked and there wasn't power and power.going threw the wires I hooked up. All the ecu are for the 3.4 but there is still a lot of 3.0 wiring and I think it confused me. I was thinking just make my own circuit from the trans case to the ecu to the dash light ??? I figured that should work and be easier as I have no need for the ADD and no switch in the front diff any more