2001 Tacoma, not engaging fwd gears

[Pitch]

(I also posted this in the Mud Tacoma forum, but as it had not seen much action, I will try here too).

I am looking for some knowledge about my daughter's 2001 Tacoma (3.4, auto, DBL cab, rear locker, 4x4, 169k, no engine or transmission mods).

Backing up from initial start up is fine, but it does not readily engage the fwrd gears. It actually creeps fwrd slowly, but no change in rolling speed with increased engine rpm. I can run the shifter through Drive, 2nd, low, neutral, and no change in the end result. It will eventually catch with an audible, palpable, bang. Then fwrd progress is normal for a while.

No change when vehicle is hot vs cold. No change when it is garaged vs out in the cold (low teens *F)

Tranny fluid is older, but at the appropriate level.

No check engine or transmission lights on the dash.

If I jack up the rear end, both tires off the ground, and the TC and transmission are both in neutral, I can spin either rear tire fwrd or reverse x2-3 revolutions before the drive line binds up.

I am thinking this is a transmission issue; perhaps a valve body is stuck? Besides looking for disconnected plugs, what should the next diagnostic step be? Is a transmission flush worthwhile? Maybe freeing up debris in the mysterious inner workings?

Other thought (less likely) is transfer case. Again, 2wd-4hi-N-4lo: shifting is no issue.

Input appreciated!

 

[Dimples]

I'd say this one needs a professional trans mechanic. There are so many things like line pressures, servos, valves, clutches. Well the list goes on. An auto trans is something that is best handled in a shop.

 

[medtro]

Not sure if there is anything you haven't read here.

Automatic Transmission May Not Shift Correctly at High Mileages : Toyota Tacoma Drive Train

 

[Pitch]

@Dimples, the plan is to take it to a reputable, local, Toyota mechanic just after the New Year. 2.5 week wait to get in (wish CBT was closer). Just trying to figure it out, as as I don't wanna wait!. I have no intentions of breaking into an auto trans. Yep, over my head!

@medtro , thanks for the link. Nothing definitive there, but the cable linkage idea is a possibility.

 

[peacesells63]

Sounds like either a pump or valve body issue. I had a similar issue with a Ford Aod trans, reverse was normal. Forward would move slowly, but would barely catch enough to make it up my driveway. Turned out to be a damaged pump.

 

[Funner]

Is the OD light blinking? That would indicate a tranny code to be pulled by diagnostic equipment. Any indication of strawberry milkshake appearance to the tranny fluid? That would indicate a tranny cooler failure. The tranny cooler failure as I recall was a somewhat common failure, that was bad news for the tranny.

 

[Pitch]

Negative on both points, Funner. No codes, no blinking lights. Fluid levels are good. Browning up a little, maybe. Definitely not a strawberry milkshake.

 

[Living in the Past]

Glad you got it figured out but not what I thought the problem would be. Having this power train in a 3rd gen. 4Runner happy to hear it wasn't in the transmission or the transfer case.

 

[Pitch]

Thanks Living in the past. I should post the follow up here too:

To follow up. Trans and TC were fine. The rear brake drum mechanism was getting bound up, compounded by oil contamination from a leaking axle seal and a bound up e-brake cable/mechanism. The wheels would turn fine in reverse, but bind up when moving forward after several revolutions. New axle seal, new brake shoes, and a freed up brake cable took care of the problem. Way cheaper than a trans-fix too.