wontonrunner

Hey guys,

I am new here however not new to 4x4ing. I spend time on Pirate and many of the Canadian forums and have come across this one on many occaisions while trying to troubleshoot or improve my ride.

I have spent several months searching diligently all over the net to try and solve my auto tranny problems. It started out back in september last year. I was out wheeling and dipped the truck in a mud hole. Not a first for me and not the deepest hole. It was only 2-3 feet deep. Barely covered the top of my wheels. I am use to mud and water up to my headlight.

4 low stopped working and i got stuck and i had to start shifting manually afterwards. I was able to get it working intermittently for a day or so and then nothing.

Total history is as follows. OD quit working about 2 years ago. I never used it after going from the 33's to 38's because didnt want to damage the tranny. But when i went back to my 33's i tried it out and nothing. Then at that time 4 low quit working. THen after that the tranny quit shifting properly. It now starts out in i assume 3rd gear when i am in drive. If i manually shift to 1st it starts out there and then when into 2nd gear manually i assume it hits third and there is no difference between 2nd and drive. I unplugged the battery for a day to clear codes and it still wont shift right and then codes get kicked out again. I have followed most of the fsm proceedures. Unplugged the solenoids and it shifts properly manually thru the gears. I have put 12 volts to all 4 solenoids and can hear them all click properly. I can jump the 4 low solenoid with 12 volts and drive in 4 low.

I am baffled. It seems to have gone into limp mode and i cant get it out. I tried a different computer before 4 low quit to see if the od issue was computer related and no difference. It also wont kick down.

THe most recent code i got was 62 if my memory serves me correct. it corresponds to solenoid 1 i think. I had also had at one time an electrical short or bad solenoid 4 get kicked out as well. Wiring is good from the computer to the solenoids when i read the resistance values.

What could it be?

I am thinking of just changing out all the solenoids with a set from another tranny. I know the OD solenoid is not the culprit because i have put it onto a switch and can manually turn it on and off and can feel the diference.

Any ideas?

toowacky

The TPS is also an input for the ECT to determine shift points. When I first bought my 89, it shifted erratically, and most of the time I had to manually shift otherwise it would start in 3rd. Using a multi-meter to measure resistance on a couple of the connectors (can't remember which right now), the resistance readings were all over the board as I moved the TPS through its travel. The wipers that ran on the resistor tracks were really worn out. I ended up buying a new one, adjusting it to spec, and problem solved.

So, I would look there if you haven't for the shifting issues, I'm not sure about the others. Try a spare if you have one. Good luck.

wontonrunner

I forgot to mention. That was one of the checks i did from the FSM. I adjusted it off of the truck when i tried a different throttle body off on a standard to see if that was the problem. Aside from the standard throttlebody not having a location for a kickdown cable, everything else ran flawlessly so i assumed it was not the tps. However i might just swap the tps out anyways when it warms up.

Targetnut

I don't have specific diagnostic info right in front of me but I'll tell you what I'm thinking.

Shift solenoid codes can indicate a electrical problem or a mechanical problem. the code for a mechanical problem tells you that when the ECM commands the solenoid to operate, nothing happens. This can be caused by a faulty solenoid or something wrong in the valve body or even a problem with a servo in the tranmission that is not applying because of a bad seal.

If this happened after swamping it, you may have sucked in some dirt (a hot tranny dipped into cool water cools off causing the fluid to contract lowering the pressure inside the case) that now has created a problem within the transmission.

I'd say to do what you can to follow the diagnostics for the codes you have and if you are getting nowhere then it would probably be best to seek professional help.

wontonrunner

YOU ARE THE MAN!!!!:bigclap:

The only reason why i swapped out tps's was because you had mentioned that when yours went you had to manually shift and kept starting out in third. I thaught the only reason why it would start in third was because of a bad shift solenoid. Also i really couldn't understand why 4x4 low would drop out from a failed tps however i had read before that the throttle has to be in a certain position for the 4low to engage so figured rather then pull solenoids out of another tranny i would try this last easy thing.

I had checked the tps months ago and set it up and it measured out right at that time but it actually must have crapped out after that. Last night i probed all the solenoids from the cab again and once again they all clicked and they all measured 14 ohms so I was still baffled. Then i pulled off my throttle body and swapped out the tps for my spare one. Set it up according to a link that i think i printed off of this website a year or so ago. Right off the bat i new it was starting out in 1st gear.

Down the road i noticed it was shifting again and that it was downshifting as well. Got on the highway and it kicked down once but then it wouldn't. Switched on the od light and it was kicking out a code. AWWWW CRAP, too good to be true. Then a couple miles down the road i punched it, revs went up to 6000 and the backend kicked out!!!!! (It was icy and i didnt know). Flashing code was gone and everything is perfect!!!!

I still dont think that the OD works properly, but it hasnt for a few years now. However since i have it on a switch i can engage it at will so.

I am as happy as a pig in ?…?…?…?…!!! (sorry about the vulgarity, im just really happy. You guys can edit this if you like)

So here is what i recomend to any other 340H owners as far as proceedures for diagnosing tranny shift issues.

1. If your tranny is shifting goofy, 4 low stops working, or your tranny is starting out in a higher gear when you are in drive, first jump your diagnostics terminal as per the FSM to see if you are getting any codes.

2. Unplug the GREY plug that is in the back corner of the passenger side front fenderwell. Test drive the truck and shift manually. Start out with the shifter in 1st gear. You will know if it is starting out in first. Shift to second when you are at around 2500-3000 and at a constant speed. You should feel the tranny drop go into second gear. When you are at around 2500-3000 rpm's and constant speed shift into drive. You will feel the tranny go into OD. If you feel the tranny shift every time. THen your solenoids are likely good.

3. While the solenoids are unplugged, take a multi-meter and check the resistance of each solenoid. They should measure around 11-15ohms. If they are good you can probe each solenoid with 12 volts. If you hear all 4 solenoids click then they are likely good.

4. If the solenoids are good and you can shift manually thru the gears when the solenoids are unplugged then its likely an electrical issue somewhere else or TPS issue . From my experience with my tranny, I would now just swap out the TPS and see if that makes the difference. Mine tested good but it was still bad. Don't forget to plug the grey plug back in after you have finished probing the solenoids. Also disconnect your positive terminal on you battery while you replace your TPS. This will ensure that your previous codes are wiped from the computer.

5. Consult the FSM for further diagnostics and tests or take it to someone who has the proper diagnostics equipment.

rezrunner92

Just a quick thought. Even though a solenoid Ohms out correctly, and even though a solenoid clicks when you apply 12 Volts, it can still be clogged or leaky, and be bad. If this happens, it usually won't give a solenoid code because as far as the computer knows, it commanded the solenoid to change state and it did. The computer won't know if it is clogged. Wipe the end of the solenoid off and blow into it as you apply the 12 Volts.

Babypig

Have you adjusted the kickdown cable? Another possible problem is the trans temp sensor. If they get to crudded up they send a false signal that the trans is too cold and no overdrive. So when you start driving the od will work but if its cold out (and you live in Winnipeg) the coolant can get just cool enough that combined with the crudded up sensor causes a no overdrive. Just a thought.

wontonrunner

True

I don't know about this one though, because the speed sensor on the tranny would be saying one thing and the TPS would be saying another and I would think that the conflicting data would trigger some kind of code. The reason why i say this is because I have over-ridden my overdrive by installing a switch on the solenoid. When there is 12 volts to the solenoid it does not go into OD. When the circut is interrupted it goes into OD. If you hammer on the throttle with it manually over-ridden it remains in OD but the kickdown cable drops gears and the revs go to 6000+ RPM's. Within seconds of doing that the computer started throwing a code. I cant remember what it was. It happend quite a while ago, but i do recal it throwing a code and the only way i can explain it is that it was from the conflicting data.

I have never checked the tranny temp sensor or the water temp sensor. I think both do affect the tranny though. I will look into that one of these days. Are they easy to get too? OD doesnt work in the summer time either but maybe since changing the TPS things will change.

I haven't adjusted the kickdown cable either but i believe the steps involved are in the FSM. I adjusted the throttle cable. It should be snug but not tight right?

And i was going to adjust the kickdown cable but the info i had seemed a little confusing. It sounded like the cable is suppose to be adjusted so that at full throttle the little indicator on the cable is 1mm past the boot? But which end of the indicator do you take the measurement too.

Oh I'm in regina not winnipeg but ether way it still gets cold.

reggie 00

How and where did you go to by pass the OD solenoid?
Mine act similar to yours in some of the things but i never get a OD light, and it sporadically will go into OD on the Freeway, so sensors and TPs are on the docket, but i wouldn't mind having direct control of the OD either.
Thanks

rezrunner92

True you would probably get SOME sort of code but not a solenoid failure code. You would get something along the lines of ?gear incorrect ratio error, or maybe a speed signal code or something.

Mostly my point was you can't just say, "Well I don't have a solenoid code so I know my solenoids are good." You also can't say, "Well I have a solenoid code so my solenoid has to be bad." Neither one of those statements can be true. The only thing the codes do is give you a place to begin the diagnostic procedure. They are not some magic thing that tells you exactly what is wrong with your car.

wontonrunner

If you are getting some of the same issues that i was getting, then i would at least check your TPS out.

The way the OD solenoid works (as far as i can tell) is that when there is 12 volts to the solenoid OD is OFF. If you interrupt the 12 volt supply to the solenoid, it engages the OD. The switch i installed simply interrups the 12 volts going to the solenoid when you throw the switch.

What i did to bypass the OD solenoid was I pulled the computer out of the truck. Its located behind the kickpannel on the passenger side.
I unplugged the 3 harnesses from the computer. Then I located the wire that controlled the OD solenoid, snipped the wire and soldered in 2 longer wires so that i could locate the switch in a convenient place. i am going to locate the switch probably on the console. I just used a cheap toggle switch that i could get a cover for. That way when the cover is open i can throw the switch and the OD solenoid is off (OD is engaged) and when i want to turn it off i just close the cover and it turns on the switch (OD is disengaged).

The only problem i have encountered is that when you are using cruise control and you have over ridden the OD, if you slow down to the point where the computer wants to drop down gears to hold the speed or if you go to accelerate and the kickdown cable kicks in. It revs over 6000rpm because it is stuck in OD. I cant imagine it being good for the motor or the tranny. You will have to remember to close the switch when you go to pass or come to a hill.

I want to do the same with the lockup solenoid once i find the time and figure out the wiring.

wontonrunner

I see what you were saying. But i used the term "likely" because it is a very good indicator that the solenoid is good. The resistance test confirms the electical function of the solenoid is good. ie wireing is good and ground is good.

If you can hear the clicking of the solenoid that means that mechanically the solenoid is likely good because the clicking sound you hear is the solenoid moving in and out like it is suppose to but a partially plugged or leaking solenoid will not be detected.

I believe that if you did have a plugged or leaking solenoid that this would be caught during the test drive in step 2 of my guide. (but not 100% sure)

The guide that I provided above is meant to simply be an easy route to follow to try and fix ones tranny issues without having to get real dirty and start opening up and tearing apart the tranny to check the solenoids. The more involved troubleshooting is in step 5 after the simple external things have been looked at first.

I personally have never had one of these trannys apart and i went thru every step i could to troubleshoot and avoid opening the tranny up. I would think that this would be the preferred route that most people would also like to take.

reggie 00

Got some pics?
And what wire is for the OD?
Color code?