Green93

Hey guys, I am trying to cross another thing off the list of problems before I can start getting the fun stuff. I just finished my engine rebuild and she is running great (so far).

The other day on a test drive I pulled over to the side of the road on some dirt and tried to shift it into 4hi. I got nothing. No dash light. No 4WD. She has been sitting for about 3 years and I'm not sure how long before that the 4WD had been used. So we're looking at a long time for a truck that should be clicked in every month or so to keep things loose.

My truck is a 1993 3VZ-E auto tranny with A.D.D. hubs. What are the first things that I should be checking on a vehicle that hasn't been into 4WD in so long? Is there anything in the A.D.D. hubs that need to be taken apart and lubed up? Any other places that I could check if it has been siezed? I'm reading the FSM right now so I can go test the vacuum solenoids and things.

Thanks for any input you can give me.

Jason

93Toyota PU

Sounds like vacum solenoid or vacum problem to me.

CoedNaked

Might as well do a 3.4 swap while you're in there.

RobD

Read this link http://toyota.off-road.com/toyota/ar....jsp?id=399612 and see what you can glean. It might also be the switch on the transer case.

And a 3.4 swap is a great idea. You'd love one.

Green93

Funny.

Green93

Thanks for the link. I read through it and it sounds like they basically outline the procedure in the FSM, but with a little more info. I'll look into it a little more tomorrow. There was a cluster of three vacuum hoses going under the plenum that I'm not 100% sure I got right after putting the engine back in. I'll check those too.

Thanks

RobD

Sounds like it, then. If it turns out to be a vacuum switch, I think I still have mine left over from my 3.4 swap.

You might want to just pull one line at a time from the actuator and see if there's any vacuum on them.

If that doesn't work, pick up a set of Aisin or Warn hubs, swap them for the ADD hubs, then run a constant vacuum to the actuator and bypass the whole ADD system.

Green93

Well I didn't feel like troubleshooting my 4WD on Sunday so ended up removing my interior and installing 4 new speakers instead. Today I figured I'd dive in and started down the FSM procedure.

First I removed the ADD solenoids (VSV1,VSV2). They tested out at 41.5 and 41.0 ohms which is within spec. Next I applied battery voltage to check the air flow....nothing. No air flow on either. Just a click of the solenoid when I apply the battery.

Am I missing something? With the VSV's sitting on the bench, attached to nothing else, I should get air flow....correct? So these are tiny air pumps? I know these are likely to fail but I find it hard to believe this will be that easy. If anyone sees fault in my testing let me know. I'm not going to go any farther testing right now until I hear some responses.

Thanks,

Jason

toybota

I am not positive on this one here but knowing about solenoids i would say no. They do/are not supposed to put out air on their own. They are connected to the engine which runs 15lb-in vacuum at idle. When power is applied they click(open to allow the motors vacuum to pull on the diff. They are simple a valve controlled by a solenoid. My 4wd works and the light doesn't in low but does in 4hi. I broke mine once and it was the cv joint. It made noise though to make it a suspect.

CoedNaked

Hey Jay, I was in Langley this past Saturday and Sunday picking up a few things from Steveston Marine (boat paint mainly). Both times I did a quick driveby to see if you had the garage open as I was gonna pop some caps in your ass but I had no gun and no caps, so I figured if your garage was open then I'd just check out your truck. Anyways, if you need my truck to do any diagnostic work for a few hours let me know. Plus I'd like you to compare mine versus yours driving wise, etc. How many K do you have on it now? (rebuild I mean). When are you gonna change the oil again?

Green93

Well the FSM shows the VSV's disconnected during the tests. I didn't think they were supposed to pump air but wasn't sure. I guess I'm supposed to pump air in and see which way it is directed by the solenoid. That makes more sense. Guess I was eager to find the problem. I'll go check them again.

Jason

Green93

You should have stopped by and banged on the garage door. I was out about half the day Sat but had the truck all torn apart on Sun. You have my cell number don't you? Usually have it with me when I'm in the garage.

Oil will be changed pretty soon. I am around 450kms now. Not sure If I should do it at 500 or 1000.

Jason

RobD

What Toybota said. All they do is switch open or closed to allow vacuum.

I would trace your vacuum lines. Probably have one or more split.

Green93

Well just tested the VSV's and they pass. Used a spare piece of vacuum hose to blow into it as I touched the terminals with a battery. All is well with them, which means my search goes on. There was a wire that went to the ADD indicator switch that was loose. When the truck is in 2WD I can spin the front drive shaft. I just put it into 4WD and now I can't spin the drive shaft. There is still no 4WD light on the dash so I'll check the bulb tomorrow. If the front drive shaft locks up I still might not have power to the front wheels though, correct? I'm still a little hazy on how the system works.

Thanks for the help so far. I'll hopefully get time to look into it further tomorrow.

Jason.

RobD

What you've done is engaged your transfer case. Hence, the no turning of the front drive shaft. The question now becomes "with the transfer case engaged, are the VSVs activating your ADD actuator?"

https://www.yotatech.com/forums/f116...stions-124409/

Post #12 has a pdf file of the ADD circuit for a 91 4Runner. Now, how it operates and the colours used might differ from your 93, but here goes. The transfer case switch on the diagram is I6. You'll notice that when you close it, it completes the circuit to ground. If you trace the B-O wires from I11 through I9, you'll notice it goes through the relay and triggers it (closing across pins 4 and 6 on the ADD relay), sending power to V2 and engaging the vacuum to your actuator. When that slides into place, the switch for your ADD (A5) engages, turning your light on. When you disengage 4WD, the relay opens (closing contacts 3 and 6 on the ADD relay), V1 now engages, and the vacuum pulls the actuator off the front axle. The switch on your actuator (A5) opens and the light goes out.

Green93

Thanks Rob. I saved that PDF file to check with later. I will have to wait till the weekend to do further testing. I can get a vacuum tool then to test the actuator.

I have a game plan. Let me know if this makes sense.

I already tested the VSV's and know they function properly. I know that the transfer case engages since it locks up the drive shaft. If I were to pull the 2 vacuum lines off of the actuator I should be able to feel a vacuum on one, and either pressure or neutral on the other. If I have someone shift it into 4WD then I should feel the vacuum switch to the other hose, correct? And as long as those hoses hold vacuum then I should be able to eliminate a vacuum leak as well. I am also going to pull the plug going to the actuator position switch and jumper the 2 terminals together to test if the dash light works...so I don't have to rip the gauge cluster out.

Hopefully it turns out that the actuator is just gummed up or something. If not then there are a couple more components left to test. All this will have to wait till the weekend though. I miss having the 4WD but I won't need it before then anyways.

Thanks for all the help,

Jason

RobD

Sounds good. Might be worthwhile to borrow or rent a vacuum gauge, to see how much vacuum you're pulling.

Green93

So today after my first oil change I decided to check into the 4WD again.

First I jumpered the plug going to the actuator. When I did I could hear the solenoid behind the dash clicking and the 4WD light came on when I shifted into 4HI. Next we pulled extra vacuum on the lines going to the actuator thinking that it was just stuck. Still nothing. Put a vacuum gauge on the line to the solenoids...nothing. We had vacuum from the plenum so started looking at the lines. One line into the vacuum canister(in the wheel well)looked a little worn so I tried to pull it off. The whole nipple broke off the canister. Looked to be about 75% rusted off. So we just bypassed the canister and I now have 4WD. My father in law is going to braise new nipples onto the canister and she'll be as good as new.

Anyways...I'm happy. Something fixed that wont cost me a dime......for once.

Jason

Jay351

Sweet! Another thing off the list.