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1988 4runner 3.0/auto t-case issue

Old 08-08-2007, 10:21 AM
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1988 4runner 3.0/auto t-case issue

I've found a 88 runner that is local and at a DAMN good price but it has an issue that has me baffled.

The damn thing will only drive in 4lo. 4hi does nothing 2wd does nothing. The rear drive shaft doesn't engage at all.

This is the in monstrosity that is the one piece trannsmission/t-case so my options are limited. (3.0/A340H auto)

My question is. Is there anything small (electrical maybe) that would cause a chain driven t-case to work in 4lo but not any other gear? It doesn't make sense to me that low would work but nothing else does.
Old 08-08-2007, 10:21 AM
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http://www.autoshop101.com/forms/AT09.pdf

If I'm reading this right. "There is a "low speed brake" that locks the ring gear to thet-case"
And there is solenoid that keeps the "low speed brake" from being applied when in 4lo. If this solenoid is shot would that knock out 2wd and 4hi or am I reading to much into waht that "brake" actually does?

I guess what I can't get my head around is if 2wd and 4hi are both a direct drive thru the t-case and the t-case is chain driven. How the hell is it that they don't work but Low gear does?
Old 08-08-2007, 10:45 AM
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There are two forks in the transfer case. One that controls the front driveshaft (2wd/4wd) and one that controls high/low. Neutral is between 4hi and 4lo. Somehow, the 4hi/4lo fork can engage the planetary gear that gives you 4lo, but it does not go from neutral to 4hi where it engages the input shaft and rear output shaft directly. Don't know why this happens though, you probably have to take it apart to figure it out.
Old 08-08-2007, 10:55 AM
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Originally Posted by runethechamp
Don't know why this happens though, you probably have to take it apart to figure it out.

Is it a common problem or something that would lead me to believe this thing has been beat on? The truck is pristine! Everything is stock and clean as a whistle. He's only asking 800.00 for it because he thinks the "transmission is broke"


Thanks for the reply
Old 08-08-2007, 11:22 AM
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Originally Posted by gp_frk
Is it a common problem or something that would lead me to believe this thing has been beat on? The truck is pristine! Everything is stock and clean as a whistle. He's only asking 800.00 for it because he thinks the "transmission is broke"


Thanks for the reply
Never heard about it before. Sounds like a small problem though. Do you have a stick to shift into 4wd or not?
Old 08-08-2007, 11:49 AM
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Yes there is a "stick" to shift the t-case.
Old 08-08-2007, 12:10 PM
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Just making sure we have the right info here. According to this page (http://www.4x4wire.com/toyota/faq/parts/) you have the A340H transmission/tcase combo, with electronically controlled tcase shifting.

But that isn't right if you actually have the stick to do the shifting? I'm just not that familiar with the AT options the 4runner had. Maybe somebody else can clarify...
Old 08-08-2007, 12:21 PM
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I have completely torn down and reassembled that type transmission. Very complex with the integrated transfer case.
There are two primary solenoids on the transmission side that select your gears. There is a solenoid in the transfer case side. Two pans on the bottom. Small pan is difficult to remove because its between transfer case and X-member but doable. Lastly, wiring and computer which is under your shifter plastic console. I suspect a bad solenoid. Pull the big pan an check resistance/continuity of both solenoids. I think they run about 5 ohms. One screw and they pull out. Simple process. Unless the transmission has 300K or has been abused, its likely electrical. All your transmission connectors with main harness are on pass side near starter. I would pull them and clean as well. If its not electrical, I would consider a 5-speed conversion. It would likely cost you $3000 to rebuild that A340H.

My $0.02
Old 08-08-2007, 12:38 PM
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I don't actually have possession of the truck yet. I'm weighing my options as to whether it is worth my time or if I should just keep looking for another 4runner.

I was thinking electrical as well since it drives fine in 4lo. Forward/Reverse all worked great. Thanks for the advice.
Old 08-08-2007, 01:45 PM
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I would look further just because it's a V6/auto - nothing wrong with the components per se, plenty reliable, but it's just not a good combo in the real world.

But, since it's only $800, you could pull the motor, tranny, and tcase and swap in a 3.4L or a 2.7L Tacoma/4Runner drivetrain and still be in the normal range for what a PRISTINE (as you put it) 1st gen 4Runner will probably run ya...
Old 08-08-2007, 01:57 PM
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You can pick up a good used tranny for $300- $1200 . Mt. goat has one on here for sale in the " for sale " section. I sold one last month for $350 in good working order. $ 800 for the rig in " pristne condition" is a great deal .
Old 08-08-2007, 04:53 PM
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I have a manuel transmission that I just got it done swapping and I also having this issue. It will only move on 4Lo and is only spinning the front wheel, not 4 wheel as it suppose too. There is a wire that is coming out from the t-case that I haven't got it connected to anything and do not know if I need to connect that to get the 4wd working?
Old 08-10-2007, 04:35 AM
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Thanks for all the help guys I guess I have two more simple questions.

If its an electrical problem would the computer throw a code? And is there a way I can get up under the truck and shift it manually to make sure the t-case is in fact not the problem?
Old 08-10-2007, 04:43 AM
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Originally Posted by gp_frk
Thanks for all the help guys I guess I have two more simple questions.

If its an electrical problem would the computer throw a code? And is there a way I can get up under the truck and shift it manually to make sure the t-case is in fact not the problem?
Yes go to back back of the x-case and you'll see a big horseshoe shaped linkage. YOu can shift taht maually and that controlls the x-case.
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