420A in limp mode. HELP

[tballer25]

I have a 98 GS which goes in and out of limp mode. When the engine is cold the car will shift through gears for a few minutes of driving, however, Once it gets into 3rd or 4th gear it stays in what I believe is 3rd. If I shut off the car and turn it back on it stays stuck in 3rd. If I wait several hours it will shift fine for a few minutes again. Vicious circle. I have done a lot of searching on here and other sites and everything points to the TCU. So I went ahead and ordered one online and tried to replace it today. It is cramped in the absolute smallest place ever. I am a big guy and getting down there by the firewall seems impossible so before I kill myself I wanted to me sure that my problem is the TCU. I am not the most car savvy person but I can follow instructions. I would really appreciate any help. I do not want to have to pay $$$ to a transmission shop that is probably going to lie to me. Thanks for ANY and ALL input.

Please if you have any input as to anything else that I could check before swapping the TCU let me know! Also, what is the easiest way to get the TCU out and swap it with another one? I have searched for hours and haven't found any written out instructions. ANY help is appreciated..

thanks

 

[tballer25]

Okay, so I am going to just assume that I am a total n00b right now. I spent all day taking things apart and trying to get to what I was 100% sure was the TCU. I swapped it out with what I think is a working TCU and my car is still in limp mode. It's pretty frustrating. I was very sure that my TCU was the problem. Just to make sure I want to attach a photo of what I replaced. Please confirm that this is the TCU.

From searching for this problem I keep reading that there is a simple fuse that can be problematic, also there is some sort of relay. All the information I find about the fuse/relay seem to pertain to the 1g. I have a 2g n/t. Is there anywhere that I can look for the fuse/relay? I am really at a loss here, and I sure don't want to take the car to a mechanic because I seriously doubt it is a real problem with the transmission since it works fine for a couple minutes on a cold start.

 

[Bud92gsx]

Check for a blown fuse.

Usually a simple blown fuse or tcu is the problem.

You could always make one of these http://www.dsmtuners.com/forums/articles-drivetrain/320324-homemade-shifter-automatic.html That will rule out a wiring problem.And confirm that there is a problem with your tcu's. Has been done alot of times, so It should work to rule things out.

 

[tballer25]

Check for a blown fuse.

Usually a simple blown fuse or tcu is the problem.

You could always make one of these http://www.dsmtuners.com/forums/articles-drivetrain/320324-homemade-shifter-automatic.html That will rule out a wiring problem.And confirm that there is a problem with your tcu's. Has been done alot of times, so It should work to rule things out.

I appreciate the help. I am going to have to check the fuses on the drivers side panel. Ever since I had this problem I have been researching the homemade auto shifters. If I decide to go that route Ill definitely be in touch with you. Thanks!


Anyone have any other suggestions? Possibly about replacing a relay or something else?

 

[xtotek]

What does your transmission fluid look like? Once you've swapped out a TCU, don't you have to disconnect the battery for awhile so everything resets?

 

[Bud92gsx]

Easy stuff first man.Relays, fuses. Boom.That don't work, your looking at tcu next.and after that wiring could be bad.

I've seen it a few times.And 9 times out of ten, people get bad tcu's, or forget to check simple stuff like fuses or relays.

It's not rocket science.I'm not sure Why your kinda shutting me down. I can check fuses,relays, swap in tcu's, and build that shifter in no time. Simple.I may be a tad butt hurt, but I'm sure other people will tell you the same thing i'm saying.

 

[tballer25]

What does your transmission fluid look like? Once you've swapped out a TCU, don't you have to disconnect the battery for awhile so everything resets?

I had it disconnected for a few minutes then test drove. No limp for about 1 min then stuck in limp, just like the other tcu.

Easy stuff first man.Relays, fuses. Boom.That don't work, your looking at tcu next.and after that wiring could be bad.

I've seen it a few times.And 9 times out of ten, people get bad tcu's, or forget to check simple stuff like fuses or relays.

It's not rocket science.I'm not sure Why your kinda shutting me down. I can check fuses,relays, swap in tcu's, and build that shifter in no time. Simple.I may be a tad butt hurt, but I'm sure other people will tell you the same thing i'm saying.

Sorry if i came off like that. I am just frustrated with the car, thats all. I appreciate the insight and help. I have to assume its a fuse now or something simple, I'm really hoping that its not bad wiring, even though I guess thats plausible since it goes in/out of limp. I got the replacement tcu off of ebay for $30...so its possible that it doesn't work.

Seriously, if i make one of those shifters and run into any trouble Ill ask you any questions if you are willing to help.

 

[Bud92gsx]

Yep if you run into any trouble.Just pm me.I usually pop into tuners a couple times a day.And I wrote the article, so I should probably help if someone runs into trouble right..

But again.I have seen people get tcu's from shops that were bad.So your not the first to be frusterated with a tcu.