TCU or ECU

[slvrbllt]

My 92 laser appears to be stuck in third gear. From what I have read it is in Limp mode. I have been reading on Limp mode and have seen that you can check the diagnostic connector to throw out the codes. I am confused though because some places it says this is for the ecu and others it is for the tcu. Can someone please clear this up for me> I really want to see why my car is stuck in Limp mode.

 

[slvrbllt]

any help would be greatly appreciated

 

[DashLaflash]

Check out this thread this guy had the same problem http://www.dsmtuners.com/forums/newbie-forum/318150-tranny-wont-shift-stuck-high-gear.html. They suggest checking the fuse that powers the TCU and for any loose wires. The TCU is located near the ECU so pull off one of the kick panels near the center console to see if you can get to it. It definately seems to be stuck in limp mode. You most likely need to replace the TCU if nothing else works. Have you tried disconnecting the battery for like 10-15 minutes and then reconnecting it. This might clear out any codes you have.

 

[wondersb]

That happend to me and it was the fuse I think it was a 10amp fuse in the fuse box under the dash.

 

[slvrbllt]

Check out this thread this guy had the same problem http://www.dsmtuners.com/forums/newbie-forum/318150-tranny-wont-shift-stuck-high-gear.html. They suggest checking the fuse that powers the TCU and for any loose wires. The TCU is located near the ECU so pull off one of the kick panels near the center console to see if you can get to it. It definately seems to be stuck in limp mode. You most likely need to replace the TCU if nothing else works. Have you tried disconnecting the battery for like 10-15 minutes and then reconnecting it. This might clear out any codes you have.

when i first started reading about limp mode. I read that the ecu could have been the problem so I went and bought it off another laser. I shoud have done some more reading to see that 90 laser ecu are not compatible with 92 laser ecu. The 90 laser ecu will start the car but will stay on for about 3-4 seconds so I think that ecu is shot. I went to check out another junkyard and ran another ecu and that one threw my CHECK ENGINE light on but still appeared to be in limp mode but not as bad. I continued reading up on this and found the diagnosis connection by the fuse box inside the car. This is where my confusion comes in... According to my LED I got no codes and all seems well...
I left my negative terminal disconnected so im going to check it out... any other suggestions of possible causes????

 

[slvrbllt]

That happend to me and it was the fuse I think it was a 10amp fuse in the fuse box under the dash.

you took it out of limp mode with just a fuse!!
Im gonna check my fuse box. Which fuse should I be looking for

 

[jimmythesaint]

Check out post #13 here. http://www.dsmtuners.com/forums/new...elp-here-just-bought-my-1g.html#post151966653

Complete with pics, good luck.

 

[DashLaflash]

when i first started reading about limp mode. I read that the ecu could have been the problem so I went and bought it off another laser.

Well the ECU is the engine control unit and the TCU is the transmission control unit. The TCU controlls your transmission and is the thing you will have to replace if your current one is no good. The two are separate from each other and you should only have to change the TCU if you find out the fuse is not the problem, which hopefully it is. Read the thread that jimmythesaint posted, you should be able to find everything you need.

 

[slvrbllt]

I have diconnected the terminal for 24+ hours and it still didnt kick it out of limp mode. My next step is going to be check the tcu! I have also seen that the solenoid can also be the problem. Should I continue with the tcu or look into the solenoid??

 

[jimmythesaint]

It wont take 20 minutes to pull the TCU out and check it, so go ahead and check it. Usually when these computers go bad one of the caps leak acid on the board and you can see it (and smell it ).

 

[slvrbllt]

here is my tcu opened up
it seems like it did leak where I made the blue circle

now begins the hunt for a new tcu

 

[GooeyGus]

Before you buy a new one, try soldering a new capacitor in there. Make sure that you clean everything up really well after you get the old one out but before the new one is in. It will cost about $1 for the cap so you might as well!

 

[CopeCowboy]

My AWD 1g is also stuck in limp mode, I pulled my TCU today and it looks fine. I checked the 10amp fuse as well, but it's still in good working condition. Can TCU's go bad without looking as if they are bad? Are there other factors that can cause limp mode?

 

[slvrbllt]

Before you buy a new one, try soldering a new capacitor in there. Make sure that you clean everything up really well after you get the old one out but before the new one is in. It will cost about $1 for the cap so you might as well!

I want to try to solder but without really knowing how to mess with it NO THANKS!! I might try to do it after I buy my other tcu. That way I have my car running with a good tcu and can play around with the leaked one