1999 Limited 4WD issues (multi-mode transfer case)

[willhaman21]

Foreward: Since I know some people on this site love to rip on newbies for not searching before asking. I have searched all over the internet for the past year, and still haven't found anyone with the same issue as myself...

So, all you 4WD gurus, I need your help. I have a 99 Limited, with the multi-mode transfer case, and elocker. Ever since I bought it, there have been a few gremlins in the 4wd system that I have yet to work out, and I really want that to change!

Here's the synopsis: On occasion, when going to shift into 4WD, or AWD, I get instant flashing 4WD indicator lights, and no change from 2WD. I can shut of the rig, restart it, and it is now clearly in 4WD, but lights are still flashing, and so unable to take it out of 4WD. I can swap the vacuum lines in the engine bay to disconnect the front axle so I can still drive on dry roads, but the front propellor shaft is still engaged and spinning. I cannot figure out how to get it to stop either, just let it sit for a few days. I can test to see if it is "fixed" by hitting the AWD switch, and if the flashing stops for a few seconds, but then resumes, I can swap the vacuum lines back, and voila, back into 2WD.

Keep in mind, this issue is INTERMITTENT! Half the time it works, half the time it doesn't. It seems to happen a lot more when switching from 2WD to 4WD than it does when switching from 2WD to AWD, but it has happened both ways.

I have replaced:
- front axle sensor
- one of the rear transfer case sensors, which had intermittent continuity when I initially tested all the sensors
- 4WD computer (Note: On the old computer, I could disconnect the wiring harness when the 4WD light was flashing, and upon plugging it back in, everything would go back to as it should be. This lead me to believe it was the computer, so I replaced it with one out of an 00 Limited. The part numbers were NOT the same, I believe. With the new computer, unplugging and replugging does not solve the issue.)

And still no dice. So any advice? I'm honestly thinking it has to be the wiring harness, which I don't know how to go about fixing. Thanks in advance.

 

[jgue467]

So when this happens have you performed the steps in the manual (or under driver visor)? PM 'The Durk', he's an expert in this gen of 4wd systems. Luck! :cowboy:

 

[willhaman21]

So when this happens have you performed the steps in the manual (or under driver visor)? PM 'The Durk', he's an expert in this gen of 4wd systems. Luck! :cowboy:

Yep! I tried all that stuff the first day, and no help I've seen him post on a lot of related threads that I've read about the subject, I should do that haha

 

[Ol'Blue]

Hope it helps.

Ok I will throw this in and it's my .02.

I had a customer with almost the same issue. He was told by the ever knowing local "They know everything" it was the T-Case. So I was like "ok" He wanted to replace it because I did the home work to find his a Multi Mode T-case because I know 4Runner. Same year as your also.

So this part came in. Well we finally got the truck back. He told him flat out were going to test some things before we waste out time on this crazy issue. He has the same flashing light not wanting to turn green with all 4 wheels.

Well after many hours of testing everything it came down to the 4 Moudels that look like a oil pressure switch. Durke I'm having a brain fart. What are they called again?

Anyhow- I got a quote for all 4 of them from Toyota. It was around 400 in parts. Best part is this- They are special order and once you buy them they are yours.

Now the fun part. You have to test the Omes in each one to find which one if any are not working correctly.

This is my .02 on it. Now lets see what Durk has to say and see if we are on the same page.

I'm not looking forward to this on my 99 if it happens. I'll just replace all of them at be done with it.

Blue

 

[adkins]

I had 5 bad sensors on my 99. All three on top of the transfer case were bad along with the front diff sensor and rear sensor on the case actuator. Check those ones as well. Change your fluid too.

 

[adkins]

Part numbers for those are 35080, 35090 and 35110. I don't have the prefix in front of me but it's the same as the front diff sensor.

 

[TheDurk]

Hi--. It pretty much has to be an issue with the T-case actuator, or possibly with the T-case itself. You've told me enough to rule everything else out. I'm afraid that's as much as I can help you, as I have a J-shift, and I really know nothing about those electrically actuated T-cases. Apparently it's a little tricky--some people have not been able to put them back together.

There is a test routine in the FSM for these things, and that's where I'd go next. Just the actuator is serious bucks to replace, so if that is the fault, a working used T-case may be the economical choice.

A wiring fault is always possible, but I wouldn't go there unless I was sure the T-case actuator is working correctly, unless there is evident damage. If it is, then you would want to check if the correct signals are arriving at the 4wd ECU in each mode position. It is the lack of said signal that causes the light to flash.

I've posted the '99 EWD before. I'll see if I can find it. I've used up my attachment limit on this site, so I can't just post it again.

EDIT: I found it. This is from my paper '99 EWD. http://www.toyota-4runner.org/3rd-gen-t4rs/155303-possible-5-speed-swap-input-appreciated-3.html#post1701338

Basically, you would want to verify continuity on all five wires between the 4wd ECU and the 2-4 select motor shown on the to page in the linked post. Plus confirm good ground. No other fault would match your symptom set.

 

[willhaman21]

Sorry guys, I've been super busy with finals week and school in general at the moment, so I haven't been on in a few days. I really appreciate all the input, and I will definitely have a shot once I get home next week with a multimeter on all the switches under the rig. I replaced the rear one on the actuator last winter, and that got my AWD back, but still have intermittent issues with it not wanting to engage. Also, whoever mentioned changing my fluid, that's been on my to do list for a while, so I think that'll be my next plan of action. Thanks again guys!