"Rebuilt" tranny installed - Now the O/D off light is flashing

[1989Sho30]

My father recently got a rebuilt transmission installed into his 1999 SHO. He said after about 3 miles on the interstate, the O/D Off light started flashing.

Wondering what possible issues this might be? He said if shifted fine, speedometer is working, and it cruised at 80mph (Freeway limit here) no problem. He said he feels a very very very light shudder shifting between 2 and 3rd going real slow.


I know this may not make a difference, But does the O/D off button make any different? The car it was originally going into had the button on the shifter - The one it went into is just the lever (P R N (D) D 1)

 

[rubydist]

he needs to get the codes read, if the o/d off light blinks, there will be a stored code.

it will be complaining of something wrong - a lack of tc lockup, excessive slip in one or more gears, a faulty shift solenoid, etc. etc. - you need to know what it is complaining about to know what to do to fix it.

 

[1989Sho30]

Would that be something Autozone could do, Or would we need access to a shop with a more detailed scanner?

 

[rubydist]

AZ should be able to do that. Just get the numeric codes, and we can decipher them for you.

 

[stephen newberg]

IIRC there is a change in the wiring that goes along with the change in the shifter in the '99 model year as they went hard at 'decontenting' the '99 to save on costs. I suspect this is the cause behind your light, and if a code is set, that could be associated also, but because the wiring is likely now wrong, it is not going to be easy to tell from the signal what is actually happening in the transmission

What RPM is the vehicle turning at 60 mph on the freeway after cruising for a couple of minutes? With that number we can tell if the electric overdrive and the TCL have kicked in.

pax, smn

 

[1989Sho30]

The only difference is the transmission the car was originally bought for had the O/D Off switch on the shifter, Where as this one doesn't have a switch at all.

The code he told me was P0743 TCC Solenoid voltage something.

 

[1989Sho30]

And I am not sure, I will have to ask. It might be a while though. First good snow on the ground, so it's parked for the time being.

 

[rubydist]

P0743 - Torque Converter Clutch Circuit Electrical

Possible causes
- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness is open or shorted
- Torque converter clutch solenoid valve circuit poor electrical connection
- Low transmission fluid level
- Dirty transmission fluid

Make sure fluid level is correct, and unplug and replug connectors to trans. Reset codes and drive again to see if code returns. If so, there is likely a failure of the tcc solenoid or it has an internal wiring issue.

I have seen cases where the solenoid wiring was pinched internally shorting it out. This type of thing may be solvable w/o removing the trans, but I would take it to the rebuilder and make him fix it.