Mr DNA

A couple of months ago I picked up a '94 4Runner with low miles at a good price, with the knowledge that the transmission was cracked and leaked ATF whenever it was running, although it was still fully functional. I got a used transmission with fewer miles on it, and wrestled that beast into the truck over a couple of weekends. During the installation there was nothing out of the ordinary that really gave me a hard time- linkages went back together, I had the torque converter fully installed, and all wiring connectors matched up. Since the old trans was known to work I did swap all four solenoids to the "new" trans, as with the tiny transfer case cooler (it was removed from the "new" unit). I also replaced the oil pump seal behind the torque converter and cleaned the filter in the pan. I filled with fresh ATF and drained and filled the chaincase portion of the transfer case.

Here's my issue- It is stuck in 4Lo. This is what I've tried:

1. Shifting the transfer while rolling slowly forward and backwards in all forward gears, N, and R.
2. Shifting the transfer while stationary in P and all gears.
3. Disconnecting the transfer shift linkage and manually putting the switch in the 2HI position
4. Unplugging the transfer switch on the transmission (when in 2HI all contacts in the switch are open)
5. Swapping the transfer switch with the one from the old trans.
6. Checking and adding 1/2 qt of ATF to the transfer chaincase.

I'm fairly confident that it is a wiring issue- while I understand that they are separate gear assemblies the transmission seems to shift fine and drives well (up to 25 mph).
One interesting detail is that even when the transfer switch is disconnected and I hear the ADD disengage (and verify by manually turning the front driveshaft) it will still engage after about 30 feet of driving, even with the "4WD" indicator light off.

I'd sure appreciate any reasonable suggestions (installing a manual trans is not reasonable- this is for the family, not just me). I just don't have enough experience with the internals of these transmissions and how they work to even know what to attempt next. Also, I'm not all that new to Toyota trucks- I've had an 85 4Runner and a 92 pickup in the past, but it has been about 8 years since I've had a truck at all.

scope103

The transfer case on the A340H is a little automatic transmission; planetary gears and one solenoid to engage them. So I would suspect a problem with installing Solenoid #4, so that it has pushed the O/D Direct Clutch closed. Is the front driveshaft "driven"? (so that four wheels would be driven, if the ADD was engaged) If not, the O/D Direct Clutch may be closed ("shifting" the transfer case into Lo), but the Direct Clutch has not engaged. Note that your transmission has an electronic diagnosis system; it can detect open/short in the solenoid circuits. Check that first.

Here's everything to know about the A340H: http://web.archive.org/web/201208020...autotrans.html

rustypigeon

Did you unplug the #4 solenoid wire? This is the green wire with a red stripe. It is to the rear of the Transfer Control Shaft Lever.

When the transfer is in L4, the #4 solenoid energizes, which then engages the O/D direct clutch. If you unplug the #4 solenoid wire, you can determine if there is a commanded signal to the solenoid, or there is a mechanical issue in the transfer case.

Mr DNA

Thanks, guys.
I got the code for the #4 solenoid failure, so tonight I'll be trying to not spill all that fresh ATF I just put in.
Also, I disconnected and re-connected the two wires systematically to see if that made a difference. The truck did stay in low range but the ADD and power to the front shaft did not engage.

One minor question- how consistent was Toyota with the wire colors throughout the years? The two wires coming from the transfer case are blue and red, but the blue one matched up with the green/red wire on the engine side of the 6-pin E3 plug. I assume that it also could be an aftermarket solenoid.

Thanks for your help!

rustypigeon

Here is the troubleshooting flow chart for code 65 (#4 Solenoid valve circuitry). Go to page AT-114...
http://htftp.offroadsz.com/marinhake...31diagnosi.pdf

...And page AT-130...
http://htftp.offroadsz.com/marinhake...34electron.pdf

...don't just automatically assume it is a bad solenoid like everybody else does. The links above will help you determine if you have a wiring problem or a solenoid problem.

I am looking at the wiring diagram for a '94 A340H right now. It tells me the the color of the wires and what pins on the connector they go to. It does not tell me what color the wire is after the connector to the solenoid. It does not make a difference either, as long as power from the green/red wire is going to the #4 solenoid.

In other words, the green/red wire connects the ECU to solenoid electrical connector. I am not sure what color the wire is from the connector to the solenoid, but it really does not matter as long as it is going to the #4 solenoid.

ECU---->G/R wire--->connector---?--->#4solenoid

Mr DNA

Rustypigeon, thanks for those links. Now an update:

1. Followed the electrical diagnosis procedure in those links and everything checked out- so there doesn't appear to be a wiring issue.
2. I dropped the rear pan this morning and found part of the manual valve lever sitting in the pan. The lever was in the 4Lo position.

So, when shifting the lever from outside the transmission it is only operating the electrical switch- the lever on the inside just slips. I can manually move it and it appears to stay in place, but without replacing that part there's no way it's going to work.
I did test the solenoid operation with the pan off and it seems to work as it should, activating when the transfer switch was placed in the 4Lo position.

Naturally, I have a few more questions-
1. Can that lever be replaced without doing more than pulling the valve body or does that require a full rebuild?
2. Can the lever be put in the position that corresponds to 2Hi and safely left there until I have more time to spend on the truck? We're not planning on anything that requires 4wd anytime soon.
3. What does the valve that is operated by that lever control? If my root issue is that the transfer will not come out of low range and the #4 solenoid controls Hi/Lo range, is this just a different issue?

I do still have the old transmission here and that lever appears to work properly. If it can be swapped over without a full rebuild I'd like to do that.

Thanks again for all your help.

954runner95

Hey Mr DNA, did you ever figure out the problem? My 4runner has the exact same problem yours does and I'm trying to figure out how to fix it.

dropzone

iTrader: (6)

best of luck

Mr DNA

Last Activity: 08-13-2016 11:32 AM

been over a year since he was around...