dshobe

Hi there, first post... rebuilt the engine (347,000 miles!), got it all put back together and now the 4wd won't work... any ideas? thanks.

75k5toy

May sound like a dumb idea, but. any chances that you disconected the front drive shaft? I can't think of any other relation.

vital22re

iTrader: (2)

check the vacum lines for the add actuator.

dshobe

I don't think the front drive shaft was disconnected, but we did have trouble getting all of the vacuum lines reconnected to the right spots. So, maybe? The problem is the awful Haynes manual I have has really crappy diagrams and pictures. Any ideas on how or where i can figure out the proper spots for vacuum lines to go?

malteserunner

iTrader: (1)

Follow the vacuum diagram on the hood. Or, download an FSM off the net.

fireman1559

i have to agree on the vaccum lines. next question is is your 4x4 light coming on and do you hear a click under the dash. if so that knocks out electrical problems. if not id be checking under the dash and fuses to make sure they are not blown out. next go to your front diff you will have two vaccum lines one is a power line and the other is a return line both take 15 pounds of vaccum check the power line and if you hear the front diff click that is the fork engaging. and next take 15 pounds out and listen for the click that means the diff is good. then check the resivoir for leaks it will be in the passenger side fender well near the front of the vehcile if no leaks then follow the lines and check to make sure they are not cracked or broken. then check your VSVs to make sure they are working properly check the hanes manual on the proper way to check them.

tc

The problem is you have a Camry engine in a truck.

fireman1559

haha what does the motor have to do with the 4x4 system?

dshobe

oops, sorry. not an FE. Thanks fireman 1559, where are the fuses for the 4x4 system located behind the dash? Again, all I have at the moment (haynes manual) doesn't show anything like that.

fireman1559

its been awhile i had to sell my yota about a year ago so im gonna say check under the hood first if not there then on the driver side kick panel

tc

Is the 4WD light coming on or not?

If so, then the ADD is working, and the collar is moving within the diff. So, if the front wheels are not pulling, then something is seriously broke either inside the diff or the CV.

If not, then the collar is not moving. Most likely suspect is a vacuum line, next would be the electrical signal from the tcase to the solenoid.

Reedr125

Is the drive shaft turning when its in 4x4? I would check the front hubs. If you take them off, and jack up the rear end, you can put the truck in 4x4, put it in gear, and look in the end of the hub to see if the shafts are spinning!

TransAmBandit

I just lol'd at this.


Did you plug the ADD back in on the diff? I just did a 3VZ swap on a 4Runner and theres a plug that has to be disconnected when getting the engine harness out of the way.

KTM350SXF

I have a 1992 3.0 SR5. I can hear a click in the cab when I shift into 4wd but the light on the dash is not coming on and the front tires are not pulling.

The motor was rebuilt by an outfit that was supposed to be reputable but they kept my truck for over a year. When I got it back the 4wd wasn't working. I need to fix it but not really sure where to start. When I used a grounded test light to check for current at the socket on the actuator sensor it barely lights up on one side and lights up brighter on the other. Should I have current on both sides at the same time? It doesn't seem like this is right to me.

Can anybody help? Thanks.

RJR

The click you hear is the ADD relay clicking under the dash. That means the switch in your transfer case is working and the relay is likely good as well.

The relay controls two vacuum switches on the passenger side fender under the hood. Vacuum goes to them from a vacuum port on the engine, and then two vacuum hoses run to the front diff ADD actuator on the driver's side of the diff. So here's what I would do to trouble shoot.:
First, determine if it's a real 4wd problem or just a 4wd green light problem. Jack up both front wheels, start the engine, and pull the tcase into 4wd. Check if the wheels are locked in. One should spin backwards when you spin the other one forward. If that happens you are actually in 4wd but your light isn't working.

If no 4wd, then lower the front end and do the following:
- Start the engine with tcase in 2wd. Pull the vacuum hose from the engine to the vacuum switches on the fender and check for vacuum. If none, trace that hose back and figure out where the problem is. If you have vacuum, proceed to the next step.
- Pull the hoses off the vac switches that go to the front diff. Check for vacuum. There should be vacuum on one switch output and not on the other. Now move your tcase lever into 4wd. The vacuum should change to the output of the other switch. If this doesn't happen, you'll have to trouble shoot why the switches aren't working. Check for voltage on their terminals, and that it switches from one vac switch to the other when you move the transfer case lever.
- If things are good up on the fender, trace the vacuum hoses down to the actuator. Make sure you have vacuum on one hose and not on the other, and that it switches hoses when you move the tcase lever to from 2wd to 4wd.
- Try swapping the hoses on the diff ADD actuator. It could be that they got swapped, in which case things won't work.

Let us know what you find out and if you have further questions.

KTM350SXF

Thanks for the reply.

I'm positive the front tires are not pulling because I've been stuck 3 times on what might as well be wet grass this hunting season.

What triggers the light on the dash to come on? Does the signal come from the diff after the axles have engaged?

I confirmed that I have vacuum TO the switches on the fender FROM the motor, but NO VACUUM on either of the 2 lines running to the actuator.

I can't trust that all vacuum lines are hooked up correctly because the shop that worked on it did such a terrible job. I haven't found a reliable diagram for my 1992 4wd SR5. The Haynes manual barely mentions the front diff with actuator for auto locking hubs. It doesn't mention the actuator or the sensor at all.

RJR

The green light on the dash is triggered by the diff after the ADD has engaged. The sequence is
- move lever to 4wd, which applies spring pressure to gears to engage, and when they do
- a switch in tcase closes, sending a signal to
- the ADD relay under the dash, which closes (the clicking sound you hear) sending power to
- the ADD vacuum switches on the fender, right side, sending vacuum to
- the ADD mechanism in the differential, which moves into lock position and closes a switch which
- lights the green 4wd light. Ta Da, you are now in 4wd!!

Are you saying that you have no vacuum on the output of either vacuum switch, right at the switch itself? If that's the case, the likely problem is that there is no power going to those switches. Just because the ADD relay is clicking under the dash doesn't mean it is transferring power to the vac switches. One thing you can do is, with the engine off, hood up, and your head out the window, move the tcase lever. You should hear the relay click under the dash, but also a louder click from under the hood when the vacuum switches switch. It might help to have an assistant move the lever while you listen to the vac switches with your head under the hood.

I've attached a couple of docs from the FSM which may help you.

KTM350SXF

Thanks for the detailed explanation RJR!!!

Sorry I took so long to get back to you but I've been out playing in the Mississippi mud because with your help I was able to get ti working, Thank you!!!!

I had a click in the cab and had a click under the hood but no vacuum from switches under the hood going to the diff. Therefore no movement in the actuator to trip the switch to send the signal to light the green 4wd light on the dash (as I understood your explanation).

Here is what I decided to do-

I am the 2nd owner of the truck for the last 10 years. It blew the head gasket at 273k miles and it was already using a little oil so I decided to rebuild the motor. I let my trusted mechanic and friend pull the motor so I could take it to the, supposed reputable rebuild shop. It took almost 6 months to get the motor back. Finally!! My mechanic installed the rebuilt motor and it would show good oil pressure until it warmed up and then it would fall off of the gage. At that point the temp gage would run away toward overheating. My mechanic spent hours trouble shooting abd back tracking to make sure it wasn't something he did or didn't do to cause this before turning a warranty claim.

I reported the claim to the motor shop but they would not allow my mechanic to pull the motor. They wanted to have the truck whole so they could trouble shoot the problem. Of course this turned into a nightmare where I didn't get my truck back for more than a year. I finally had to threaten involving the courts after granting them a date, within reason where I could come pick my completely repaired truck. By this time I could have completed the job myself with a chisel and a ball peen hammer. Needless to say they met the week long deadline nut as I expected I got what I got... A really crappy job... The motor was leaking oil from both valve cover gaskets, the front seal, and the oil pan. At least I got it back right. Both of my parents were in two different hospitals in Memphis, TN at the same time and I needed my truck badly. I didn't think to check the 4wd when I picked it up. I myself pulled the motor down to repair the oil leaks but took care not to unhook any wires or lines without documenting them and taking pics. I put it back together and have been driving it for over a year without 4wd working.

I finally tracked down a vacuum line diagram on yotatech.com that helped me. It did not show the additional switch that mine has that is associated with the idle speed when the AC is on so I had to wing that part. Almost every line was hooked up incorrectly. Imagine that... I do have one concern about my work. There were 2 lines that had a one way inline valve ,(black and orange similar to a small engine inline fuel filter), The diagram I have only shows 1. Should the 2nd on be on one of the other lines associated with the idle speed while the AC is on? If so, which one? I'm sure it is for leak back or siphon prevention but right now it's in my jacket pocket because I can't figure out if it is supposed to be on the

RJR

Glad you got the 4wd working! Thanks for reporting back.
I can't really help you with the inline vacuum devices. They sprinkle those around, but I've never studied their function in detail. Some of them are what they call "vacuum delay" devices - they delay the application of vacuum downstream based on time or temperature.
I guess I'd leave the extra one on the shelf until you identify something else that isn't working properly that it might be related to.

KTM350SXF

10-4 Thanks again!

Time to research lift options and tire and wheel sizes to fit.