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1998 Toyota 4Runner, 1981 Toyota Puckup
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Discussion Starter #1 (Edited)
Hey all, looking for some advice with my 98 4runner auto transmission! Drove normally until I fired it up one day and it was stuck in reverse, but hardly moved. The shifter however would move through all of the positions just fine. Checked the shifter linkages - all good, tight and adjusted correctly. Shut her down for another day. Next time i tried it was stuck in drive (even when in park position) but would only jerk forward briefly with a good amount of throttle given. No check engine lights, and I checked codes and nothing came up. Drained and pulled oil pan, oil was very dark, but didn't see and shavings. Checked the solenoids with an ohm meter and all seemed okay, tested them with 12v as well, heard 2 of them click and one didn't so I pulled that one off and bench tested it to find it too worked fine. Shift lock control and key interlock solenoid both are fine, as is the shift lock solenoid. Reassembled with new filter and replaced oil from the sump with fresh stuff. Fired it up again to find nothing had changed. Tempted to bight the bullet and bring it to a shop but thought I'd check here first.
Appreciate any input!
Cheers
 

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01 Avalon XL, 03 Avalon XL
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992 Posts
I am many miles from being a transmission expert, so take this with a ton of salt.

There are 3 key things in getting your transmission into a gear and having it move the vehicle... (1) mechanical linkage, (2) oil pressure, and (3) a functioning torque converter.

(1)
This one seems to be the most likely -- problems with the mechanical side of things, inside the transmission. (And now that I look at it, there are various pipes that are just press-fitted into the overall, electrical valve body -- check to see if any of these have come out.

There are elements of the mechanical linkage that you may not have checked. There is an axle on the external lever on the case. This axle feeds to the interior and connects internal things. One of these is a quarter- or half-circle with bumps on the periphery and a pin sticking out of its side. The bumps are part of the design that gives you a positive feel when moving the selector in the car through the gears -- detents.

The pin engages a multi-channel valve shaft and moves the shaft. The shaft itself back and forth in a small, cylindrical, mechanical valve body to enable oil to flow to various solenoids & clutches and/or just feed oil back to the innards (neutral, park) involving no clutches.

If the axle is broken, or the pin is broken or somehow disengaged from the mechanical valve, or the circular dingus is no longer turning with the axle, then the valve won't select a gear. (HOWEVER, if the circular dingus isn't turning, you won't have any definite feel at the cabin gear selector of going through the gears because the bumps won't create the detent.)


(2)
The oil pressure side (from the transmission oil pump) is the next element. If the pump is no longer putting out enough pressure, clutches won't engage correctly and it's possible that gear selection goes wonky.

Only easy way to check this that I can think of is to remove one of the transmission cooling lines to the radiator and seeing if there is a healthy flow. But that won't tell you if the internal pressures are up to spec.

Usually (I'm told) the pump gets whiny before it fails completely.

(3)
As for the torque converter, it sounds as though yours is working.


Of course, there may be problems with the clutches themselves, but you should have had slippage and a lot of heat prior to the sudden loss of gear selection.
 

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1998 Toyota 4Runner, 1981 Toyota Puckup
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Discussion Starter #3
Thanks for the reply! Nothing as far as those press fitted pipes jumped out at me as being out of place, although all I did in there was take out the filter. The half circle rotates fine when moving the shifter in the cab, but maybe the link between that and the valve piston could be broken. Maybe I’ll pop the cover back off and double check that. No wining or apparent slippage prior to this which does kind of point to some kind of broken linkage.
 
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