94 SC400 weird trans issues

[Michael Fodor]

What's going on Lextreme,long time reader/lurker, I have been in the process of restoring my '94 SC400, first road test of the car was awesome, till the car acted like it shifted to neutral, pulled over, shut it down, started it like 5 mins later car drove fine to the house. Did it a few more times, so I swapped all 4 of the solenoids out for some known good ones from my buddies wrecked '94 LS400 trans (car was t-boned). And while I was in there I added a transgo shift kit, put it all back together, and the shifts are much firmer, car runs and drives fine, till it gets to temp, and then goes to neutral, shut it off turn it back on, and it drives fine again. And did a full flush of the transmission with Toyota T-IV fluid.

The only code its throwing is "31" for mass airflow, but mass airflow tests good, I am lost, idk if I should buy all new solenoids, it's not throwing codes for anything else so idk where to begin, and I really don't want to have to take it to the dealer. Also I have been trying to hunt down a original FSM set for the car as well, not some repop copy

Kindest regards,
-Mike

 

[gloverman]

Have you done any other testing? Like to confirm if its mechanical or electrical? You can unplug the solenoids and go for a drive with three gears. If it faults its most likely a mechanical issue. If not its likely an electrical issue. I'd be looking to resolve that afm code too. The trans fault light only shows no faults ie constant on off flashing? Not the Cel, the trans fault light.

 

[Michael Fodor]

No I haven't done any further testing yet, Are you talking about unplugging the solenoids inside the trans or just unplugging the connector on the back left corner external ? And if your referring to the OD light blinking at me, no, the only thing that is on is the check engine light sir.

 

[Spinnetti]

Have you done any other testing? Like to confirm if its mechanical or electrical? You can unplug the solenoids and go for a drive with three gears. If it faults its most likely a mechanical issue. If not its likely an electrical issue. I'd be looking to resolve that afm code too. The trans fault light only shows no faults ie constant on off flashing? Not the Cel, the trans fault light.

Does a MAF fault change how the trans operates? My car is running rich, and sometimes will hit the rev limit without shifting. I don't see any codes tho

 

[Michael Fodor]

Does a MAF fault change how the trans operates? My car is running rich, and sometimes will hit the rev limit without shifting. I don't see any codes tho

Hey man, how about you search or make your own post about your issue instead of thread jacking mine

 

[Spinnetti]

Hey man, how about you search or make your own post about your issue instead of thread jacking mine

Because its related - you got a MAF code, so its relevant what happens to the trans if the MAF fails. No need to be hostile.

 

[Michael Fodor]

Not being hostile, just telling you to make your own post bro

 

[gloverman]

Yes , overdrive light is the check light for the trans. I would be wiring that up, while wiring up a diagnostic port which is normally under the dash to get live data and manually driving without solenoid connector connected. This is just basic diagnostic. Also checking ecu commands to trans. Good luck

 

[Michael Fodor]

Yes , overdrive light is the check light for the trans. I would be wiring that up, while wiring up a diagnostic port which is normally under the dash to get live data and manually driving without solenoid connector connected. This is just basic diagnostic. Also checking ecu commands to trans. Good luck

How would you go about wiring those up ? So with the shift solenoid harness disconnected the trans will still shift off line pressure alone like a "old school" non electronically controlled trans?

 

[gloverman]

To wire the od light you get the correct diagrams for your ecu then connect the correct wires. Its an electronic trans, removing the solenoid plug means it wont shift unless you move the shifter. This is basic transmission diagnostic. Cheers

 

[Michael Fodor]

I pulled the ecu apart, didn't see any signs of corrosion around any of the capacitors, I did notice a a black discoloration on a few of the pins that go into the harness, cleaned them up bright and shiny. Going to take a look at the harness side and clean it as necessary. And it will be a good start for trouble shooting the trans to rule out internal issues. Thank you for the help again

-Mike

 

[Michael Fodor]

Well the female pins in the harness connectors are very corroded that match the corroded pins in the ecu. Also the wiring harness is sliced and diced trash from what I can see are those pins as well. I will try and resize and upload those photo's