mizombie

Hey guys, i'm hoping someone can steer me in the right direction on this. I purchased a non-running truck with a bad 3.0. I have done a 3.4 swap and I need a little insight. I used a harness set up from ORS.

The truck in question has an ADD system, I'm not familiar with it. The front differential has a position switch that the pigtail has been cut. Where do i tie that into the electrical system. I looked at the original harness and I havent found where it actually connects at to the main harness. Help would be greatly appreciated.

wyoming9

iTrader: (1)

It would be nice to know just what vintage your trying to make work.

Do you know if all the parts are even there ??.

Trying to find something that has been removed is very frustrating .

mizombie

It's a 91 sr5 xcab. Original 3.0 threw 2 rods.

As far as I can tell it's all there for the ADD system. All my others have been manual hubs which I plan to go back to when the parts an time is there. The switch is still in the diff, just the wire pigtail is there. All the VSV stuff is there too.

SacRunner

Tell us about your truck:

• Truck or 4Runner?
• Year?
• Originally 22RE or 3VZ (3.0L)?
• Auto or Manual?

Tell us about the donor (the ECU is the most important part):

• Tacoma, 4Runner, T100, Tundra?
• Year?
• Auto or Manual
• 2wd or 4wd?

If ADD equipped, the 3.4 engine harness should have a connector with a Green-Black and a Green-Red wire that connects to the front differential, and then it should have a couple of connectors that plug-in to the transfer case, one for 2wd/4wd, the other for High/Low range indication. All three of those are brought across to the 3.4's body/dash harness where the actual ADD logic lives. You'll need to tie those lines into your 3.0's body harness to maintain that functionality.

If ORS didn't build all of that into your swap harness, there's a good chance that your donor was from a 2WD vehicle and simply doesn't have that extra wiring.

SacRunner

Also, follow the link below, register for the 48 hour option (it has been $15, no idea what it is now), then download all of the EWDs (Electrical Wiring Diagrams) and FSMs (Factory Service Manuals) for both your current truck and your donor truck, then spend some time reading through the EWDs, that will show you the wiring diagrams/schematics for both trucks and you can determine how to theoretically wire it all up. From there you'll need to dig around the truck to see where and how to physically wire it all up.

https://techinfo.toyota.com/

RJR

The ADD position switch simply lights the green 4wd light. The ADD itself is actuated by vacuum from a couple of vacuum valves on the right front inside fender. You don't need the green light for 4wd to work, but without it you have no indication if the ADD has actually switched into gear.

Also, if you don't have a connection for the indicator light, there's a good chance the ADD actuation switches that control the vacuum solenoids are also not connected, in which case 4wd won't work.

The techinfo.toyota.com link is a great source of info, and last time I checked, about a month ago, it's still $15 for 48 hours. If you set aside some time, you can download and save all the info you need easily during that time.

mizombie

91 truck
4wd, manual
3.0

donor is:
96 4runner
4wd, manual
3.4


RJR, thanks for that excellent reply. That was some of the best info i was looking for.

The 91 was bought in non running condition, so i do not even know if the 4wd worked previously. I picked it up as a replacement for my 94 that died of frame rot and 472k.

The ORS harness splices into the 4wd position switch at the transfer case. I know there is wiring done for the ADD, its marked in the new harness where it plugs into the ECM.

SacRunner

The 96 4runner 3.4 engine harness should have the two wires (green-black and green-red) for the ADD position switch (on the front diff) coming off the front, driver's side of the engine, then down the front by the water pump, with a clip actually holding these 2 wires to the top bolt of the thermostat housing, then from there it should extend down to the diff.

On my swap, the guy that pulled the motor forgot about that connector, left it attached and hoisted the motor out anyways, tearing the wires about 6" away from the diff. Aside from the trouble of ID-ing what they were, this wasn't a problem since I had to splice the connector from my 3.0's harness onto the 3.4's in place of it's connector anyway (the connectors are different, the plug on the 3.4 harness won't connect to the 91 ADD module).

mizombie

On my 3.4 there is a y-g wire for the oil pressure switch. A large black-red wire containing a red and a green wire for the crank position sensor. That is all I have in that location.

I double checked the original 3.0 harness and did find the wires for the diff position switch. they were broken and hiding in the loom.

SacRunner

Did the 3.4 engine harness come from the same 96 4Runner donor? Does that engine harness have the extra plugs back on the transmission end for the transfer case (2wd vs 4wd and HI range vs LO)?

From your description, it almost sounds like the engine harness may be from a 2WD donor, but I'm just guessing.

mizombie

I don't know if they were from the same vehicle or not. I bought the motor from a shop in Louisville that were supposed to do the swap for a customer. The guy dropped off the motor and never returned for it or had the swap done. So the shop owner put it up for sale after a year. The ecm is for a 4wd and manual transmission.

Toyota is pretty good about making the wiring universal or at least they used to be on the older stuff .

There are a couple extra plugs on the 3.4 harness that aren't going to used. Without looking at the ewd I'm not for certain what they are for yet. My main concern is if I can't get this wired up right away if it will keep the truck from running properly. I am planning on swapping out to the manual hub set up as soon as time allows. I just want to get the truck on the road before weather gets bad. My little celica doesn't like deep snow.

RJR

It won't affect how the engine runs at all, if that's what you are asking. See my previous post 5 posts up or so about what needs to be connected to have 4wd, vs. what you need to detect 4wd engagement.

You can easily figure out if the 4wd is actually working by blocking the rear wheels and jacking up one front wheel. Start the engine with the transmission in neutral and move the transfer case lever from 2wd to 4wd. In 2wd you should be able to easily turn the lifted front wheel, and the front drive shaft should not turn. In 4wd it should be impossible to turn the front wheel.