Questions About My 4x4 System

[MDTrailrider]

I have a 1998 SR5 V6 4Runner with a 5 speed manual transmission. I believe that it is a relatively early 1998 model because it was manufactured in November 1997. The vehicle does not have the rear locking differential.

Last year I discovered that my four wheel drive had stopped working. I’m worried that I may need it and want to see if I can fix it. I read what I could find on your website and the internet. I’ve also looked at what I could find in the Factory Service Manual to try and figure some things out. As a minimum I want to be sure it isn’t something simple before I bring it in and I want to be knowledgeable if I do have to talk to a service rep.

I’m unable to determine exactly what four wheel drive system my vehicle has.

First, the owner’s manual distinguishes between systems with “Lever Type with Manual Transmission” and vehicles with A.D.D. including those with manual transmissions. I can’t find any reference to A.D.D. on my window sticker, on the vehicle or in the 1998 sales brochure that would indicate my vehicle has it. There also is no fuse for A.D.D. I don’t know if there should be one. What confuses me is the owner’s manual shows a hand drawn illustration of what the A.D.D. hubs look like with either aluminum or steel wheels. There is no illustration of what non A.D.D. hubs look like. The illustration looks like the hubs on my vehicle. What is disconcerting is that the instructions for vehicles with A.D.D. recommend that the vehicle be driven for 10 miles a month in four wheel drive to “assure that the front drive components are lubricated”. There is no such requirement for vehicles without A.D.D. I was always under the impression that my vehicle did not have A.D.D. I have only engaged four wheel drive occasionally in the winter or summer and probably gone a couple of years without engaging it once or twice. I have not used it much.

How can I determine if I have A.D.D.?

How can the system be unstuck if lack of lubricating it every month is the cause of the problem?


Second, 4H can be engaged while driving 50 mph with A.D.D but only 25 mph without it. I’ve tried engaging 4H at 20-25 mph. I want to try it at 45-50 mph.

What will happen if I try to engage 4H at 45-50 mph and I don’t have A.D.D.?


Third, my window sticker says the vehicle has “2-Speed Transfer Case/4WDemand” as standard equipment. I thought that 4WDemand is the push button system automatic transmissions come with. There is no push button system with my vehicle. Mine has the “Lever Type with Manual Transmission”.

Is there anything I’m missing about 4WDemand?

Fourth, when I set the manual transfer case lever in 4H, N or 4L the 4x4 light on the dashboard does not illuminate. Also when I set the lever to 4L the vehicle is in low gear.

Is that just 2L since I am not getting power to the front wheels?

 

[JohnsD90]

Ok well im pretty sure i dont have ADD (on the truck) and i got a 5 speed, and i engage 4wd at 50 and it just engages. And i hope you realize that you have to roll a little before the dash acknowledged you are in 4H.

 

[TheDurk]

The ADD system is largely internal to the front diff, not the hubs (the hubs are different; they just don't look wildly different). It's mainly a vacuum system so no separate fuse. You can look for the actuator sticking out of the front diff or the twin VSV's which are on the wheel well. I forget exactly where and it's too cold to go look. There are vacuum hoses going from the VSV's to the diff. They are worth finding, because they are frequently the cause of the problem. Based on your symptoms, I'd say (WAG here): 1) You have ADD, and 2) It's not working. Climb underneath and see if the front propeller shaft turns by hand in 2WD and does not in 4WD. Here is an article to give you a start:

Linky

Periodic engagement is a must with any auxiliary transmission, ADD or not. Use it or lose it. Gears and bearings like oil, and they get it by turning through it and slinging it around. Good luck.

EDIT: I looked around and here is a decent diagram of the pieces. GIYF. It's a '94 pickup, but it's close.

 

[Martinjmpr]

Don't all 3rd gen 4runners have the ADD? I know some of the earlier Tacos did not (the ones with manual hubs) but I thought the 4runners all got the ADD system?

Also, to the OP: Other than the light not coming on (which could be a malfunctioning light) what leads you to believe your 4wd isn't working? Have you tried it on a low-traction surface to see if the front wheels are spinning?

I'm not a mechanic, but it sounds like your t-case is working the way it should (Since you don't have the pushbutton T-case, there's not a lot to go wrong with it)which would lead me to believe a vacuum problem with the ADD is the likely culprit.

 

[JohnsD90]

The ADD system is largely internal to the front diff, not the hubs (the hubs are different; they just don't look wildly different). It's mainly a vacuum system so no separate fuse. You can look for the actuator sticking out of the front diff or the twin VSV's which are on the wheel well. I forget exactly where and it's too cold to go look. There are vacuum hoses going from the VSV's to the diff. They are worth finding, because they are frequently the cause of the problem. Based on your symptoms, I'd say (WAG here): 1) You have ADD, and 2) It's not working. Climb underneath and see if the front propeller shaft turns by hand in 2WD and does not in 4WD. Here is an article to give you a start:

Linky

Periodic engagement is a must with any auxiliary transmission, ADD or not. Use it or lose it. Gears and bearings like oil, and they get it by turning through it and slinging it around. Good luck.

EDIT: I looked around and here is a decent diagram of the pieces. GIYF. It's a '94 pickup, but it's close.

Hey, why dont you bring your surf up from brazil? I'd love to see it and how the diesel rides cause im still contemplating the swap.

 

[TheDurk]

Hey, why dont you bring your surf up from brazil? I'd love to see it and how the diesel rides cause im still contemplating the swap.

My HiLux SW4 is gas (not called a Surf in Brazil) and it's worth twice there (new or used) than it is here before you even think about shipping it (cost $50k new). Plus it would never meet US safety and emissions regs. Lastly, my ex- has it and would never give it up--although I do get to use it when I'm there. (see my post in the diesel thread).

Actually, I thought that generation of diesels could not be made to meet US standards and that was why they never imported them. I don't have a source for that; I just sorta remember reading it.

As to martinjmpr: My '99 FSM and my Owner's manual both talk about the non-ADD version (and the FSM has the detailed diagrams and breakdown instructions). Whether any were actually sold, I do not know. Mine is a 5sp with ADD.

Hey MDTrailRider: my two sons live in Ellicott City. I am there frequently. Maybe we can meet at the Judge's Bench and you can tell me about off-road down there? I'll buy.

 

[JohnsD90]

Actually, I thought that generation of diesels could not be made to meet US standards and that was why they never imported them. I don't have a source for that; I just sorta remember reading it.

There are a number of them here so they can pass emissions. Emissions isnt why they didnt bring them, they didnt bring them because the american public does not like diesels, and the government was fine with this because the less fuel efficent the car the more tax money they get.

 

[MDTrailrider]

I’ve had the vehicle for 12 years and a week. I’ve use 4H numerous times, 4L once and never had a problem before. I’ve tried getting it into 4H or 4L at a stop, rolling forward, rolling backwards, from N and into 4H on the fly at 25 mph. Nothing works. I got stuck on wet roots on a canted and steep fire road. I had to back down before I slid off the side of the mountain. Last weekend I got stuck on a thin patch of snow. Someone had to push me to get going. How embarrassing.

I did not exercise the system for ten miles every month as the owner’s manual says. I didn’t believe the truck had A.D.D. I still don’t know if it does.

I’m going to get under the truck tomorrow. The temperature is supposed to be in the 40’s in the afternoon. That will be the first time in over a month. Also the rest of the snow melted off the driveway in front of the garage today.

I’m going to see if I can determine if the truck has A.D.D. Then I’m going to check vacuum hoses if there are any. Then I’m going to look for damage and see if I can somehow free the system if it’s just stuck. I’m also going to see if I can turn the front propeller shaft by hand in 2H but not when the system is set to 4H.

Does anyone know what I can do to free the system if it is stuck? Should I try a rubber hammer as I’ve read in other threads? If I do, should I just pound on the differential tube and the actuator? Is there anything else I should pound on? Where else could it be sticking? I assume the system engages inside the differential tube and not at the hubs. I’m looking at the FSM diagrams but I don’t know enough about trucks to know what a lot of the parts do.

 

[MDTrailrider]

Hey MDTrailRider: my two sons live in Ellicott City. I am there frequently. Maybe we can meet at the Judge's Bench and you can tell me about off-road down there? I'll buy.

That sounds good. When will you be coming down from NJ? I’ve never been to the Judge's Bench. Is it a couple of blocks west of La Palapa and Ellicott Mills Brew House on Main Street?

My schedule has finally gotten quiet now that it’s too cold to dirt ride, camp or backpack, football season is all but over and deer season is over.

 

[TheDurk]

There are a number of them here so they can pass emissions. Emissions isnt why they didnt bring them, they didnt bring them because the american public does not like diesels, and the government was fine with this because the less fuel efficent the car the more tax money they get.

This is the thing I remember reading. It sort of puts it into the "You're both right!" category. Interesting reading if you haven't seen it:

Linky

Of course, this has nothing to do with ADD. Feel free to answer in the diesel thread, I'll see it.

 

[brian2sun]

These are the options that you could have from the factory on a 4runner:
A.D.D.
Manual hubs
Auto hubs ('84-89 4runners only)

If your hubs have a dial on them that you turn to lock then you have manual hubs. If there is no dial then you have A.D.D. Simple as that. The true auto hubs were not offered after '89 (and thank God because they were awful and you had to put it in reverse and go 1/4 turn to engage).

 

[TheDurk]

That sounds good. When will you be coming down from NJ? I’ve never been to the Judge's Bench. Is it a couple of blocks west of La Palapa and Ellicott Mills Brew House on Main Street?

My schedule has finally gotten quiet now that it’s too cold to dirt ride, camp or backpack, football season is all but over and deer season is over.

Yeah, but maybe only half a block or max one block up from those two. A golf shot... I'll be down at the end of the month when son #2 comes back from Brazil to go back to school.

 

[Martinjmpr]

These are the options that you could have from the factory on a 4runner:
A.D.D.
Manual hubs
Auto hubs ('84-89 4runners only)

That makes sense. If there are no manual hubs, there has to be some way to disengage the front differential from the wheels - hence the ADD. I know I've seen Tacomas with manual hubs but I don't think I've ever seen a 3rd gen 4runner with hubs. I'll start looking, though, since there are 80 brazillian 3rd gen 4runners in Colorado.

If your hubs have a dial on them that you turn to lock then you have manual hubs. If there is no dial then you have A.D.D. Simple as that. The true auto hubs were not offered after '89 (and thank God because they were awful and you had to put it in reverse and go 1/4 turn to engage).

I don't know, My 1990 Montero had the auto hubs and they weren't that bad. You didn't actually have to put them in reverse, you just had to have the vehicle go in the opposite direction from the one it is going when you disengage 4wd. So, if you back up and disengage the 4wd while backing up, you could then drive forward and the hubs would disengage.

Did the Toyotas have a separate light for the hubs? My Montero did. There were two green lights on the dashboard, one of them had the typical "4x4" graphic (the two axles displayed) that was for the T-case. Then right above it was another green light that read "wheel lock." If that light was green your hubs were locked. When in 4wd normally both lights would be green. If you shifted out of 4wd without reversing direction to unlock the hubs, the "wheel lock" light would stay green while the other one went out.

 

[brian2sun]

I don't know, My 1990 Montero had the auto hubs and they weren't that bad. You didn't actually have to put them in reverse, you just had to have the vehicle go in the opposite direction from the one it is going when you disengage 4wd. So, if you back up and disengage the 4wd while backing up, you could then drive forward and the hubs would disengage.

To clarify, the auto hubs for Toyotas in the 80s sucked, other car brands had some better designs.

 

[MDTrailrider]

I got under the 4Runner and this is what I have found so far.

The 4Runner does have A.D.D.

There does not appear to be any damage.

There is fresh oil on the bottom of the front differential. I believe that is from changing the oil filter every 3,000 miles or so. I did it in December. Some oil always runs down the side of the engine when I remove the filter and the differential is directly in the oil path.

When I place the transfer case in 4H the front propeller shaft does not turn by hand.

There does not appear to be anything wrong with the vacuum hoses at the actuator, the VSV’s or vacuum reservoir. I can’t find the vacuum system components in the FSM and it is not as described in the A.D.D. article at off-road.com. There is a vacuum hose running from the front of the intake manifold with a blue filter to a small 4 way plastic vacuum manifold. I assume the intake manifold is the vacuum source. Two of the hoses run to the A.D.D. VSV’s. One is marked with blue. The other has no apparent color code. I assume it is supposed to be the brown line. The last hose runs into the fender and down to a vacuum canister suspended in the front driver side wheel well in front of the tire. Everything appears to be in good condition and undisturbed as it came from the factory.

Pounding on the differential tube, actuator and front differential with a rubber hammer did not free the system if it is stuck from lack of use.

I’m going to try driving the truck with the transfer case set to 4H for several miles to see if spinning the front differential can lubricate the system enough to unstick it if that is actually the problem.

I probably need to start checking electrical circuits next if driving with the front propeller shaft engaged doesn’t fix it. I have virtually no experience with that. I have an electronic Craftsman Multimeter with about 31 dial settings. Can I use that? I ask because I blew one circuit on it years ago testing something. I don’t remember what circuit it is or what I was testing.

 

[Pure 98]

I'm having some trouble with my 4WD Too, here are some pic that i have posted. hope it helps

http://www.toyota-4runner.org/3rd-gen-t4rs/59161-please-help-my-98-4wd.html

 

[brian2sun]

Although I haven't has problems w/ my ADD, I have heard that 90% of the time it is the actuator, a relatively cheap part to replace. If you're not sure what to do or look for, I would take it to a shop and ask them to just test it for you.

 

[TheDurk]

I have never worked on an ADD because mine has never broken. But I'll help as much as I can until somebody shows up who knows more.

In the '99 FSM, the ADD stuff starts on page SA-48. Yours can't be too different.

On the multimeter, odds are you blew the fuse. That would usually affect only the current circuits. What you need are the resistance and voltage circuits. If on resistance you get zero when the leads are touching, and infinity when they are apart, that circuit is fine. Then see if you get 1.5V DC on a flashlight battery or 12 volts DC from your car battery. Then see if you get 110 V AC on an AC outlet. If you can, voltage is fine. If you are uncomfortable doing all that, you need some help. If you want to change the fuse, open the case and look for a small glass cylinder. Sometimes it is next to the battery and sometimes you have to open the whole back. Sears usually puts a spare or two in there--I have had a few Sears VOM's.

I would start at the VSV's if I were doing it. One should have vacuum in 4WD and the other should have it in 2wd. So pull off the hoses (one at a time so you don't swap them) and check where the vacuum is (engine running, of course), change the transfer lever and check again. If vacuum switches from one VSV to the other, it's time to pull the actuator and see why the sleeve is not engaging. If it does not, then the problem is on the electrical side or at one of the VSV's. The FSM tells you how to proceed in either case. Good luck.

If anybody has actually done this, please chime in.

 

[steezemcqueen]

I would start at the VSV's if I were doing it. One should have vacuum in 4WD and the other should have it in 2wd. So pull off the hoses (one at a time so you don't swap them) and check where the vacuum is (engine running, of course), change the transfer lever and check again. If vacuum switches from one VSV to the other, it's time to pull the actuator and see why the sleeve is not engaging. If it does not, then the problem is on the electrical side or at one of the VSV's. The FSM tells you how to proceed in either case. Good luck.

If anybody has actually done this, please chime in.

exactly. mine had the same problem with 4wd. sometimes it would shift into 4wd but not out or not into 4wd at all or just take a really long time to do anything etc...i started by removing the add actuator to see it it moved freely. once i checked that it moved with no issues, i checked the vacuum tubes and found that there was hardly any change between 2wd and 4wd. i swapped the VSV's and it works perfectly now.

 

[Pure 98]

exactly. mine had the same problem with 4wd. sometimes it would shift into 4wd but not out or not into 4wd at all or just take a really long time to do anything etc...i started by removing the add actuator to see it it moved freely. once i checked that it moved with no issues, i checked the vacuum tubes and found that there was hardly any change between 2wd and 4wd. i swapped the VSV's and it works perfectly now.

How much were the VSV's?