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Tocctsi

Probationary Member
8
0
Oct 7, 2002
Cherry_Hill_NJ
About 4 months ago, my auto transmission only had one gear in drive. It was only 3rd gear. This problem wasn't consistant though. Some days it would be fine and then other days no signs of 1st or 2nd gears. Then the problem just disappeared. Since then i Put in a JDM Engine, JDM Transmission, and a new 14 b turbo. Everything has been great, but lately I'm having the same "only 3rd gear" problem...I am aware that this is called fail-safe mode. Sometimes it will work but most times now it doesn't. I can't stand to drive like this. I have heard so many things on this and in the end i can only conclude that no body knows. I've heard things like it was TCU, but i took it to a transmission specialist that said that he checked it electronically. He thought it was the pulse generators, but it wasn't the pulse generoters. Now im hearing it's something mechanically with my Transmission. IM having a hard time believing this since it does still work sometimes. and the fact that it did it with my other tranny/motor. I'm pretty convinced in my mind that it has to be computer or electronic. It will cost me a lot to get mechanical work done to transmission, and logic tells me that it can't be mechanical. (what are the odds that both transmissions had the same problems, but in the same process I never changed any of the computers). Any suggestions?
 
I think that you are correct in your assumption that because it was doing the same thing with both units, it is most likely vehicle electronic related. What you need to do is try to get the trans codes out of the system and see what they are, as there are several things that can cause limp mode (mechanical and electrical). Also, what conditions does this happen under? It has also been my observation that Mitsu trans electronics are pretty reliable and being that it worked properly for a while after your engine swap, I would suspect a wiring problem of some sort. I'm happy to give you the details on how to check all of the electronics if you need that info.
 
It works when i first turn on the car when it's cold..then it will quickly go out anywhere from 10 feet down to the road to a mile or two.

I took it to a transmission specialist, and they are unsure. They checked the pulse generators and didn't see anything wrong with them. They believe that it's my solonoids in my transmission, since they told me they see they shut off. It would cost me over 300 to get them replaced, and I'm still not so sure that the solonoids are bad, since everything in the car is changed mechanically but left the same electronically. Unless it is true that both soloniods in the two transmissions i have.. have gone bad

Since I told these mechanics about the engine and transmission swap they still are unsure about the solonoids being bad or something making them bad
 
err... safety mode is usually 2nd gear... did you replace your tranny ECU?
 
I think that the thing to do is to check the electroincs before we start throwing computers in cars, in "hopes" of fixing the problem.
 
Zac83 Limp in mode is 3rd gear both solenoids are off for 3rd gear.

And I would not put a TCU in it until you find out what the codes are. It would be best to check the outputs of the pulse gens with a scan tool. I see alot of pulse gen problems because of the connectors. You can bend the male pins in the connector about 10 degrees for a better connection. Also I have seen the solenoid wires ground out on the valve body.

Let us know what codes are set in your TCU. I will try to help.

CraigB
 
It was scanned already, and my pulse generators were said to be fine. I will take your advise and check out the solonoid ground wires out of on valve box early this week. Thanks Craig B for this original suggestion
 
Originally posted by Tocctsi
It was scanned already, and my pulse generators were said to be fine. I will take your advise and check out the solonoid ground wires out of on valve box early this week. Thanks Craig B for this original suggestion

Are you saying that you have "limp" with no codes? If you have sol. wires shorted to ground you would indeed have codes. You may want to scan it again with a different scanner the next time that you experience the complaint, otherwise from a diagnostic standpoint we may be trying to "piss up a rope". Limp mode with no codes present is pretty uncommon, but a scanner not getting codes out of a Mitsubishi system is not. If, in fact there are no codes, I would suggest getting a d.v.o.m. and checking all of the trans related electronics right at the computer, that way you are checking the entire circuit, also check all wires for continuity to ground that are not supposed to have it. You may also want to visually inspect all wires going to the trans for damage. Sometimes even if you ohm all of the wires they can check out good but be bad when they rub or you go over a bump, etc. (This is why the nature of the problem is intermittent). I.E. if it's working good at the moment it will probably check out good electrically. It is also helpful to have an assistant wiggle wires and connectors around while you are testing them, as this may help you find a problem with a wire or a connection. If you need info on pin locations and electrical specifications I can probably help.
 
I didn't see mention of what year model it is. But I did see the JDM, 14B and am gonna assume it's at least a mitsu trans. I don't know if this is applicable for a mitsu trans like it is for the 2gnt auto but here goes.

On the 2gnt Auto, there are two speed sensors that detect input and output speeds. When one of them go out, it puts the transmission in to "Limp In". Neither of these will set ECU/PCM codes unless there is also a "No vehicle speed signal" code set. The Input and output speed sensors are primarily transmission monitored sensors. The output speed sensor determines vehicle speed as well. So when it goes out the speedo won't work.

My palm with scan software will not pick up any transmission codes and some Engine codes. So chances are your prefered tech may have the same problems. If you have a chrysler transmission let me know and I'll go in to more detail.
Doug
 
My transmission is mitsubishi since it came out of a galant from Japan. I will be sure to get this scanning done again by a technician and bring up everything that you guys have suggested. Another thing that i noticed is all of yesterday my car worked fine. I must have driven it 20 miles total and that wasn't all in one driving session. But today my car isn't working all the time. when I have noticed if my car isn't working, I'll stop it and shut it off in any random location on the the road..and about 1/4 of the times that i start it up again, it will have all its gears back but just for a limited time. Could this shed some light on this issue and help narrow it down
 
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