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What's going on CL,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
Sounds like it's losing line pressure when hot, which is usually a sign of a worn pump or accumulators in the valve body. I'm not an expert in the A340E, but I've had my hands on a few 4L60Es, and most automatics work more or less the same.
You might have a ecu that is starting to go bad, the ecu control the transmission and often times when they start to go bad it usually shows up when the ecu gets hot, as in running the car for a little while.
Usually it results in overfueling on the sc400's, but the ecu does control the automatic transmission so it is possible to be an ecu issue.
may be worth popping it open and having a look, since you say it drives fine until it warms up makes me think its not the transmission or solenoids cause they wouldn't shift right even half the time then.
Sounds like it's losing line pressure when hot, which is usually a sign of a worn pump or accumulators in the valve body. I'm not an expert in the A340E, but I've had my hands on a few 4L60Es, and most automatics work more or less the same.
That's what I am worried about, I am still looking to find what the exact line pressure should be, and I plan on installing a pressure gauge inline to see what the trans is seeing.
All the S400 ecu's controlled the transmission. I remember someone saying some obscure years on the LS400 that had them separate but don't quote me on that, in fact.. I kind of think that is a myth.
With a code 31 I would suspect ecu issues already, so figures its worth a look inside alot of members have been failing recently, the extreme heat, humidity and even cold can do weird stuff to electronics.
All the S400 ecu's controlled the transmission. I remember someone saying some obscure years on the LS400 that had them separate but don't quote me on that, in fact.. I kind of think that is a myth.
With a code 31 I would suspect ecu issues already, so figures its worth a look inside alot of members have been failing recently, the extreme heat, humidity and even cold can do weird stuff to electronics.
I will pull it tomorrow and crack it open and report my findings, hopefully there aren't any issues I can't fix
All the S400 ecu's controlled the transmission. I remember someone saying some obscure years on the LS400 that had them separate but don't quote me on that, in fact.. I kind of think that is a myth.
With a code 31 I would suspect ecu issues already, so figures its worth a look inside alot of members have been failing recently, the extreme heat, humidity and even cold can do weird stuff to electronics.
I opened the ECU, the label on the front said it was remanufactured already, plus there was a " JT's Parts & More" security tags on either side of the ECU. Cut those, popped it open and it looks perfect inside, zero signs of corrosion. Going to diagnose the trans itself once I get home from work today. 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
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. Time to find another harness to pull the correct colored wires from and splicing into this harness
I hope you have gone to removing too much of that - the fcty harness did use some shielded wiring in places and depending on the signal (if it needed protection) some wires not used were terminated with blue tape like that - when I went thru my harness, I found a number of them
That looks more or less factory, the shielded wire is for the knock sensors and they use the blue tape on some wires that are spliced together from factory.
not sure what you think is sliced and diced? sometimes re-manufactured ecu's have issues, they re-manufacture them but that doesn't mean they are perfect after that, I am usually suspect of them.
A340E weird issues
