420A 2gNT Driving without a TCU

[Tequiza]

just had a question and wut you guys think on this. So i took off the tcu and drove without it just for a bit to see what would happ. well the odometer needle stayed at zero which before it was going to 80-100 in a 20-30 mph

it felt like it stayed in first gear and it drove amazing compared to when it had it on just no shifts :/ im guessing its the tcu that is giving me all this pain but what do you think? also i opened up the tcu and it covered in sum honey looking jello stuff like yellow see thru is that normal?

 

[SLIDER121]

With the tcu removed it should put it in limp-in mode. I wouldn't drive like that it is just to get you to a safe area or shop to get a problem fixed. If the whole board is covered in the jelly like stuff it is silicone to protect the circuts.

 

[Tequiza]

Thats so weird, with the TCU on it goes into limp mode without it it drives fine :? im so confused

 

[007jimmy]

With the tcu removed it should put it in limp-in mode. I wouldn't drive like that it is just to get you to a safe area or shop to get a problem fixed. If the whole board is covered in the jelly like stuff it is silicone to protect the circuts.

Isn't the TCU the reason it goes into limp mode?? Without the computer to send it into limp mode or shift for that matter that's why his car seemed to drive better although it stayed in first gear. Sure people have done it but I wouldn't recommend it. Tequiza, do you have access to a spare known working TCU?

 

[Tequiza]

007 jimmy what you say makes more sense, not at the moment ima get one on tuesday, im not driving the car at all only if i really have to, the tranny has been rebuilt but it would put me into limp mode still so im guessing its that. I even changed a relay ppl posted on sum other thread.
and thank you for giving me peace of mind, mechanics here dont know wut there doing >:0

 

[SupremeDsm]

007 jimmy what you say makes more sense, not at the moment ima get one on tuesday, im not driving the car at all only if i really have to, the tranny has been rebuilt but it would put me into limp mode still so im guessing its that. I even changed a relay ppl posted on sum other thread.
and thank you for giving me peace of mind, mechanics here dont know wut there doing >:0

I have a tcu for sale if you end up needing one. Let me know.

 

[ed1380]

With no ecu it defaults into 3rd gear. AKA limp mode.

With a no speed sensor it'll stay in 1st. My bet is that you have a bad speed sensor.

There might be a little light brown residue on the board from the flux for the solder. Take a good pic of the board for us to see.

 

[Tequiza]

I have a tcu for sale if you end up needing one. Let me know.

Yea thank you for sure but till tuesday afternoon ill let you know in case the one i get doesnt work

With no ecu it defaults into 3rd gear. AKA limp mode.

With a no speed sensor it'll stay in 1st. My bet is that you have a bad speed sensor.

There might be a little light brown residue on the board from the flux for the solder. Take a good pic of the board for us to see.

well im trying to figure out wut u mean but can you put in wording for a person that doesnt know mechanics terms srry i thought u were saying the flux capasitator im guessing the tcu take a pic of the inside?

 

[CrawlinZX14]

Yeah, take a pic of the inside of the TCU. Like the ECU's the TCU's can have leaks in their caps too. That could be the jelly like substance. But a lot of it is not right. I have never seen a gel covered board myself, but some pix would def help more. Sounds like you may have a bad TCU tho.

 

[007jimmy]

With no ecu it defaults into 3rd gear. AKA limp mode.

With a no speed sensor it'll stay in 1st. My bet is that you have a bad speed sensor.

There might be a little light brown residue on the board from the flux for the solder. Take a good pic of the board for us to see.

Makes sense. So a missing or a non working speed sensor would affect the OP's tach not reading right as stated in the first post??

 

[ed1380]

Just to make sure all the terminology is correct the tach is the rpm gauge. I'm assuming it works fine for the op.

The speedometer runs off the speed sensor which is in the tranny

 

[007jimmy]

yeah i would put money that is a bad speed sensor on the trans. i had a 99 firebird(i know dont a dsm) but one day i was crusing around lookin to take someones money and all the sudden it got stuck in 1st gear and the speedo tack was jumpy.if you shifted it though the gears like a slap shifter it would go through them but luckely being a mechanic i had my scanner with my that had real time data reading. i saw the glitches in the speedo output signal. it would work fine till 10 or so mph but then it would jump around from actual speed to zero to 120mph irratically. here it was just a loose pin on the one harness clips going to the speed sensor. once i fixed that i was able to do 4500k launches hanging the wheels 2-3off the ground for the first 500 ft of the track all day.. if it wasnt for the crazy money i got offered for the car i would probably still have it.

with the tcu hooked up its in "limp" mode so its only gonna give you third gear if its in the drive(overdrive) setting.. try hooking the tcu back up and going through the gears manually like start at first and run it to about 2500-3000 rpm and then put it in second gear.. it should shift but its will have a little kick to it.. then 3rd and then drive with the overdrive turned off if you have that option... also the TPS controls how much line pressure is being used.. you best bed its probably an obd2 reader that loggs rear time parameters..

 

[Tequiza]

Thanx for all the help guys... i got a new/used tcu and it works fine but still have a prob. :/ The new/used tcu fixed the speedometer from jumping to 80-100 mph when im driving like 20-30mph now its not doing that and also my door locks actually lock by pressing the button . so I still have the problem of going into limp mode >:O

1st gear to 2nd it sometimes jumps 2nd to 3rd jumps and then it stays in third (limp mode) i took it to a tranny place and it gave these codes
-36 Fault Immediate after shift
-53 Gear Ration error in third

They said its gonna need a complete overhall and rebuild the tranny :/ apparently my dumba** paid for a complete flush and other mumbojumbo ..what do you guys think? am i just better off going to the junkyard and getting a tranny for super cheap and doing it myself or i dunno any feedback would help