annoyingrob

I've been having a problem with my truck for probably 8 months now, and it's really starting to annoy me. It's missing 3rd gear. The transmission shifts 1, to 2, to OD, back down to 2, etc. It never goes into 3rd.

If the OD-OFF switch is pressed, it makes no difference. It will unlock the torque converter for a second, then lock it back down when I press it, which I would assume means that the tranny is getting a signal, but isn't switching into 3rd.

Since I'm only missing one gear, I would assume that both shift solenoids are working fine. If one solenoid was bad, I would me missing two gears. I'm leaning towards maybe something wrong with the valve body? I have an extra A340 out of a Toyota Aristo V, which should be somewhat similar, so I do have some spare parts.

anyone have any ideas?

annoyingrob

Seriously? Nobody has had an issue with their auto, or has experience with transmissions?

Sure, make me pull out my FSM........

Junkers88

Although this does not relate to Toyotas I had the same problem on a Ford years ago and after dropping the tranny and taking it to a bad @$$ tranny man (ol' Greg Kurns was a GOD with these things) it turns out there are some sort of bands that engage the gears and the one on my third gear was busted. This may not be the same for Toyotas.

I'm sorry I don't know more than that.


edit: this was on a 1976 model truck and I don't know if there were any sensors involved......

annoyingrob

Did some more troubleshooting last week. With the computer unplugged, I can manually shift into 1-3-OD with the shifter like I should, so I'm leaning more to a faulty transmission computer now.

I hooked up a volt meter to the transmission diagnostic port, and took it for a drive. It ran through 1-7 volts just like it should, but obviously, when the computer was telling me it thought it was in 3rd, it wasn't. TPS signals from the main ECU were also fine. The next step (Hopefully this week if I get some time) will be to take a look at the signals right off the solenoids, to make sure the ECU is giving them what it thinks it's giving them.

There's an R151F 3 hours away from my house for a decent price, it's SO tempting to just go get it.

annoyingrob

Hooked some leds to all 4 solenoid dignals coming out of the transmission ECU (go go A340H ), and they're perfectly fine. I'm starting to think that MAYBE the #2 solenoid IS bad, and the transmission is shifting into 2nd by itself (without a solenoid signal) as a failsafe. Next step is to test the solenoids themselves.

It may also be some debris inside one of the fluid cavities.

archerybuff

This sounds exactly like what my 88 is doing. Please give us an update or a cure if you have found it.

annoyingrob

The update is that the transmission downshifted from OD into 2nd while going 100km/h, thereby over-revving my motor, and spinning a bearing in the bottom end.

I'm finished with troubleshooting this auto. I'm going to the junkyard, getting a new motor, and a 5 speed.

annoyingrob

New motor in, and I sort of gave up on this problem. What I ended up doing was cutting the "2" signal going to the ECU so that when I shift it into 2, it still thinks it's in drive. Because the 2 position mechanically limits the transmission into 3rd as a fail safe, the truck will shift 1-2-3 in "2", and if I need OD, I can shift back up into "D". It's not perfect, but it works pretty well.

samwell121

Never resolved this? I am going through the same thing...

spddm0n

Interesting...I have the same problem. I also don't have any response from the system when I press the overdrive button. "In" or "Out", there is no change in the transmission gears and there is no light in the dash or anything. Is there a light in the dash for overdrive?

samwell121

I am currently troubleshooting this issue, My OD Light functions as it should, and when I switch OD On or Off( doesn't matter which), it drops briefly to 3rd before going back into OD. I got an new TCC and problem is exactly the same. I noticed due to the slack in the shift linkage, I can "find" 3rd in between 2 and OD. I am about to get a W56 and do a manual swap for other reasons as well, but Plan on rebuilding my A340H and will pursue this issue til I find the cause.

space-junk

iTrader: (1)

check the shift solenoids. those are the most common issues with these transmissions.

dropzone

iTrader: (6)

this--you can get the 3 solenoids for about $65

samwell121

I replaced Solenoids and tested old ones. Will put old ones back in next time im in there, they are obviously superior quality and actuate much harder than the aftermarket ones. Just noticed on a 2nd test of my tps that I have some dead zones in the range. Replacing this 31 year old TPS and see what, if anything I get. I have codes 5 (O2 Sensor) and 7 (TPS) on the KOEOff tests...

spddm0n

Ok, so I found something interesting...
Without barking too loud about NOT being able to locate the FSM for the 88 Pickup with V6 (EVERY link I tried is broken), I landed on the idea of looking for the O/D relay. I found an old wiring diagram that I "thought" was wrong, but turned out to be correct, it's just calling certain electrical devices by different names.

Ok, here it goes....
On the 22RE models (which I have the 3VZE), there is something called the O/D Relay (4 CYL ONLY) and the O/D IND (assuming this means "INDICATOR" and is the small light illuminating the O/D symbol) (4 CYL ONLY). The wiring diagram I found is from the 1988 TOYOTA Pickup & 4 Runner book of diagrams. On page 5-610, these two devices are listed in the area of B27 and C27. There is also a device called O/D IND (V6 ONLY). There is NOT a device called the O/D RELAY (V6 ONLY).

So, I managed to find the physical device under the dash, printed with the name O/D and looks like a relay (Toyota Part Number: 89530-35090). This shows up in Toyota references (online) as a COMPUTER ASSY, TRANSMISSION CONTROL. This is NOT on the wiring diagram, but I did find something called the A/T OIL WARN COMPUTER on page 5-611 of the book of wiring diagrams in the are of C31. I matched the colors of the wires on the connector with those on the wiring diagram.

1 - RED/YEL
2 - BLK/YEL
3 - LT GRN/RED
4 - LT GRN
5 - WHT/BLK

It is a five wire black plastic box that looks like a replay, but once you open the little box up, there is clearly more to it than a relay. It has some old school 1988 logic in it (circuit board).

I'm wondering if this box is bad and could be contributing to the reason that I don't have the proper transmission function. I also found a burnt bulb in the O/D INDICATOR. There is a second bulb in the light, for general illumination, and it was good, so I swapped it into the slot where the burnt bulb is (actual indicator), but this did not cause the indicator to work. My guess is the little black O/D box burnt out and caused the bulb to burn out.

Does anyone have the FSM for the 88 with V6 they can send me? Or, is there a section in the book that describes how to test this little black box? These aren't plentiful these days and I hate to just starting buy random electrical boxes on ebay without first knowing if it's bad. I can probably do some basic continuity tests and see if it's getting the right signals when power is expected to be be present under the right conditions.

Let me know if anyone has a good link to the 88 FSM with V6. I do have the one with the 22RE and the 89 and newer vehicles don't seem to be equipped the same. Toyodiy.com shows that only the Trucks and 4Runners manufactured from 08/1985-02/1989 had these little black boxes.

samwell121

A/T has a temp warning light on the dash, and a sensor somewhere in the tranny just fyi.. I'll look around for your FSM

samwell121

Found it for you! 1988 4runner & Pickup Service manual- https://www.ulozto.net/!qziYtX6q/toy...4runner-88-pdf

Do the "slow download". Makes you wait 5 min but all 1046 pages are there. Hope this helps!

spddm0n

Holy Crap! How did you find that link!!!!

Wow, I didn't think to look at sites like that. Just looked for good links within the forum communities.

Sweet! It's downloading!!!

Thanks!!!

samwell121

thats exactly where I found it

http://www.toyota-4runner.org/classi...wnloads-2.html

spddm0n

Bummer. That PDF is also just the 22RE engine. Can you take a second look? Maybe the 3VZE truck FSM is out there too.