'93 A4LD not locking up at high Elev. Any Ideas?

[Trucknbear]

It seems the torque converter isn't locking up in my 93 Ranger when I get above about 6000+ft Elevation. It works fine at lower elevations.. This problem just showed up when I got out in New Mexico in the High Desert area around Santa Fe. Being from TN.. Ive never had the truck this high up before.. Any Ideas on what this problem could be? The Trany is overheating now on long drives.. and I dont want to burn it up while IM out here working. Any Help with this would be greatly appreciated.
Jack

 

[rhauf]

It seems the torque converter isn't locking up in my 93 Ranger when I get above about 6000+ft Elevation. It works fine at lower elevations.. This problem just showed up when I got out in New Mexico in the High Desert area around Santa Fe. Being from TN.. Ive never had the truck this high up before.. Any Ideas on what this problem could be? The Trany is overheating now on long drives.. and I dont want to burn it up while IM out here working. Any Help with this would be greatly appreciated.
Jack

I would make sure that you have it locked in (drive) not overdrive, when this happens, to prevent it from overheating. do you have a trans temp gauge?

it may not be locking because you're having to push the throttle down further to go the same speed (do to less air density) and the TPS is telling the transmission you're on the gas, and to unlock. (it normally unlocks under heavier-than-cruise throttle level) this is the only thing i can think of.

you may want to change the fluid if it's been running hot. broken down transmission fluid = broken transmission it's always a good idea to change the fluid these anyway, the clutch for the lock up converter puts dust into the fluid which clogs up the valve body and causes other problems (this could be a contributing factor perhaps?)

 

[MrShorty]

The first thing I would do would be to determine if the fault is electrical or mechanical. Put a voltmeter across the solenoid and watch it while you drive. If the PCM commands lockup and the transmission doesn't respond, then the problem is mechanical. If the PCM doesn't command lockup, then there's a sensor out of range or an electrical fault.

 

[Trucknbear]

Hello there..
I appreciate your comments and input on my problem... As you suggest. I do put it in Drive now when this occures... I dont want anything to happen to my truck.
I'm still unsure if the lower air density is the issue really... Even so if that were the case.. it seems when I let up off the throttle.. it would then lockup... but its not doing that either... I know during normal driving.. when I remove pressure from the gas pedal.. the converter seems to release so the truck will coast.. or it seems that way to me... And then when slight pressure is applied.. it will lock back up again and continue to pull normaly unless.. I reach a grade in the road and have to apply added pressure... Which is normal as well.. I assume...
But in this case... When at a very high Elevation.. It doesnt even seem to go into the "coast" mode when I release all pressure on the gas. So It deffinately seems the high Elevation has a deffinate relation to the problem.
Im just curious.. if their is a differant modulator valve for higher altitude applications?
Ive checked.. and I dont believe my truck has a MAP sensor. Which would detect elevation changes.. So I guess the TPS and the MAF sensor have to do the job. Along with the Modulator valve.
I've even disconnected then battery to allow the EEC to reset. Perhaps I didnt wait long enough on that.. ITs got me stumped.
Once again.. I do appreciate your input and ideas. Thank you
Jack

 

[MrShorty]

I don't think the lower air density would explain it either. To those of us who live in this part of the country, 6k ft really doesn't seem that high.

Im just curious.. if their is a differant modulator valve for higher altitude applications?

To my knowledge, there isn't a different modulator. Modulator only effects 1-2 and 2-3 shifts and doesn't have anything to do with TCC lockup, so, where you aren't complaining of problems with those shifts, modulator doesn't seem like a likely candidate anyway.

Did you ever ascertain for certain whether the PCM is commanding lockup or not?

Grasping at straws on this one: any chance you are "underestimating" the load on the engine? I'm not familiar with the area immediately around Santa Fe, but I know that a lot of times, what looks flat is really enough of an up-grade to maybe convince the PCM to unlock the TCC.

But in this case... When at a very high Elevation.. It doesnt even seem to go into the "coast" mode when I release all pressure on the gas. So It deffinately seems the high Elevation has a deffinate relation to the problem.

I'm not quite sure what to make of this. Does it feel like it is dragging? Same in D or OD? (BTW, TCC can lockup in 3rd or 4th, so driving it in D wouldn't necessarily effect the problem you describe. Only prevent it from upshifting into 4th gear)

 

[Trucknbear]

TCC lockup.

Hello Mr. Shorty.
Im not sure if their is a lockup command being sent to the TCC. Honestly.. I don't know where to attatch a volt meter to on the Trany. to check for voltage. I dont have a book on this truck here with me. So visual referances really aren't available.. Im mostly goin on the Trial and Error method of trouble shooting. This has just totaly got me thrown though. I purchased a Temp. guage for the trany. and then realized their really wasnt anyplace to install it in the transmission.. I dont need a fluid leak now as well.. So.. Ive put off installing it.
I understand the theory about possible being in a pull and not really realizing it.. and that keeping the TCC from locking up.. But it doesnt seem to lock up in the Drive position as well.. and I dont believe theirs that much of a pull on it.. Especially when I know IM going down hill... Gaining speed without any pressure on the gas pedal.. and it still doesnt engage the TCC. But once I get below the 6K Elev. range.. It all seems to just start working fine.. Absolutely no issues at all.. IM just baffled... and I know better then to try to take it to a FOMOCO garage.. With the milage on my truck.. they would declair it DOA.. and that would about be the end of it with them.. LOL. It really doesnt seem to be dragging or pulling hard in any way... Running pretty goood really... Although.. The do fly out here on the interstates. and it can have a hard time maintianing those speeds on some of the hills out here... But heck... 388K miles... IM really not complaining... I really do appreciate all your input with my problem here.. IM willing to try about anything to preserve my truck. Im just out of ideas here. Thanks.
Jack

 

[lifeguard379]

To my knowledge, there isn't a different modulator.

there actually is a height altitude modulator. i will try call my buddy and get the part number for every one

 

[MrShorty]

I don't know where to attatch a volt meter to on the Trany. to check for voltage. I dont have a book on this truck here with me.

Autozone used to have an electronic version of Chiltons available on their website. I've found the wiring diagram there adequate for this circuit. I'd be real surprised if the Santa Fe library system doesn't have a manual with a reasonable wiring diagram in it either.

When I've done it, I've usually carefully backprobed the PCM 60 pin connector at the pins indicated by the wiring diagram so that the positive lead is on the red wire (positive side of the solenoid) and the negative lead is on the TCC solenoid pin.

 

[ESherman]

I was searching the forums and ran across this thread. I have the exact same problem at high altitude With my 92 Explorer. I'm at lower elevation now so it locks up fine. Anyone come up with a solution yet?

 

[Trucknbear]

93 Ranger TCC lockup problem at high altitude

Hello again everyone. Im still out here in the Santa Fe area of NM. The problem with my TC not locking up at high altitudes still persists. Ive even tried the "Forced Lockup" switch addition to try to cure the problem.. Not sure if I attached to the wrong wire from the PCM, or if its just a mechanical problem Im dealing with. But.. even with the switch turned on to ground the lead to the TCC it still doesnt lock up.. And even when at lower altitudes... when the thing is working perfectly. when I switch on the ground to the TCC, it doesnt stay locked up.. so.. Im feeling that I may have attached to the wrong wire out of the PCM. ITs getting warmer weather again and Ive already had the tranny. overheat once on me... dumping fluid out all over the exhaust system and creating a mess while going down the road.. Any new input or ideas would be greatly appreciated. Even though its a little gas hog.. I still love this little truck.. Who wouldn't after 397K miles on it. Ya just gotta admire that. Thanks.

 

[MrShorty]

Check how you wired in your switch. If you ground TCC solenoid and it doesn't engage the TCC (in 3rd or 4th gear -- TCC won't engagen in 1 or 2), then there's some problem with the wiring or a mechanical/hydraulic fault inside the transmission.

 

[Trucknbear]

Hello Mr. Shorty. Thank you.. Indeed.. I will be looking into that.. Their seems to be some confusion on exactly which pin number wire I should connect the ground switch to.. Ive read a couple articles on the matter.. and one says to connect to pin #53 and one says #54. Would you by any chance happen to know the correct pin or wire that I should be connected to.. At this time.. I believe I have it connected to the Orange wire at pin #53. Its nice to hear from you again.. I hope it was a good winter for you.
Jack♦

 

[MrShorty]

and one says to connect to pin #53 and one says #54.

The wiring diagram from autozone's website (same as in Chiltons) for my '92 shows that pin 52 is for the 3-4 shift, 53 is for TCC lockup, and pin 54 is for the AC WOT cutout relay. Check with a wiring diagram to see if your '93 uses the same pin assignments as my '92.

 

[Turdle]

there actually is a height altitude modulator. i will try call my buddy and get the part number for every one

Yes. I googled this and found there is indeed a "high elevation" modulator valve which increases fluid pressure a tad to hold the higher gear at elevation. This should also firm up shifts at a lower elevation

I see 3 "reference" part numbers,

TM54 and TM74. According to rockauto, the TM74 is for "non altitude"

http://www.explorerforum.com/forums/showthread.php?p=1817971

This shows "altitude" modulator to be TM78

 

[Trucknbear]

Hello Mr. Shorty. Just wanted to drop you a line to let you know.. After checking my connection for the Manual Lockup switch.. Indeed I had connected it to the wrong wire.. Not sure if I'm on the right pin but at least Im on the right wire. (Purple With Yellow stripe). Now when I ground the wire.. the TCC does lock up firmly. Im happy to say.. SO.. I suppose the problem still lies somewhere in the PCM side of things. No idea where to take that issue.. but at least now.. I can keep from overheating the transmission till a better solution is found.. I really do appreciate all your help..