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Discussion Starter #1
I was backing out of my drive way and when I put the car in first it died and my engine light came on. I couldn't get the car to start for a minute or so and couldn't get it out of first to roll it out of the road. Does anybody know what the error codes P1646 and P1647 mean. I know it has something to do with the SMT electronics,but don't know what to do to fix it. Also is there a way to get the car into nuetral if it happens again. Any help would be awesome. Thanks.
 

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1646/1647 are general duty "I'm Pissed" Codes from the SMT AND the Engine Electronics..

SOMEHOW the SMT was trying to find a gear, and could not.. The Engine Electronics asked the SMT for some Information, and the SMT ignored the Engine Requests.. So the Engine Turned off..

A General "SMT Tune Up" might get things back in Order..

This is one of 'Those things' that depending upon the Quality of the Person working on the car NEXT, will either have a Fine or Fatal outcome. I'm not kidding.

It could be something as simple as you need to Change the SMT Fluid ( It's like DOT4 Brake Fluid ) or you might need a Sensor Relearn.. Or you could have a 'Bad GSU Coupling Pin ' ..

But finding the problem and solution can be a problem..

any history on the car?..

and as for finding Neutral.. Once the Shifter inside, and the Trans Outside do not agree on where things should be.. usually Manual Intervention is necessary.. It involves pulling the Air Box, and getting to the Trans and Shifting it by Hand..

Cap
 

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Discussion Starter #3
Thanks for the response. Sounds scary. I took it to transmission shop today and on the way the engine light went out and I had no problems. I hope they don’t make it worse.

As far as some history I have had the car less than a year. When I bought it I had the SMT fluid changed at a Toyota dealership. I haven’t had any problems with the SMT until now. I did think something was wrong once but it turned out to be a heat sheild rattling, but it sure sounded like gears grinding. The only other problem I had was the accelerator position sensor but I was able to replace that myself. It’s been running great until now.

I must be honest I got the car with the SMT so my wife could drive it too, and she doesn’t want me to get rid of it, but I feel the SMT is a ticking time bomb so I’m probably going to sell it.

Thanks again for the response.
 

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I had almost the exact same situation a bit more than 2 years ago with those codes, literally while backing out of the driveway. Has not happened since.
I only remember it because I was on my way to get re-inspected for something stupid (IIRC they failed me the first time for my wiper blades), and I cleared the codes.... only to get failed for emissions "not ready." Why they felt the need to plug into the OBDII port to reinspect my wiper blades, I'll never know.

I think of the SMT as an attractive lady. If you can overlook the occasional mood swing you should get on well. If you fight it..... well, good luck to ya.

Moral of the story: clear the codes, drive normally, see what happens.
 

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Discussion Starter #5
Well took the care to a transmission place and they ran a diagnostic on it only to find out it is not the wires connecting the ECU to the transmission. They seem to think it is the ECU because it won’t even allow the codes to be cleared and the check engine light is back on. Does anyone know if the ECU can be done at home or is it to complicated and need to be done at the dealership?
 

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They ALWAYS want to Replace the ECU.. It's NEVER the ECU or the TCU..

Need to get the Transmission and the Shifter into neutral..

Then things MIGHT start working again..

EDIT:.. how good are you at Fixing Things..

Cap
 

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Discussion Starter #7
The car is driving fine but the engine light is back on....so it will go in neutral. I'm ok at fixing things but not a mechanic by any means. Would it be called a ecm instead of an ecu.
 

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Normally the Car Hiccups, and the Garage says it needs a new Computer..

So you drop a Grand on the Trans Computer, and it does it again..

So you drop another Grand on the Engine Computer..

It Does it again..

So now it's 2 Grand on the Gear Shift Unit ( GSU ).. and it may or may not do it again..

The Problem needs to be diagnosed, by someone that knows SMT's.. Not just a Guy that can work on cars for a living..

There is a BIG Difference..

IS THERE THE POSSIBILITY THE BATTERY IS AT ALL WEAK?..

One of the things that has been Identified, is the SMT's are REALLY funny about Flaky Electrical problems.. and SOMETIMES the Erratic Problems go away with a New Battery..


The ECU ( Engine Computer ) has Ignition Key Information Stored in it.. A new ( Replacement ) Computer needs to be Zaped to recieve new key Information.. ( Dealer Usually.. )

The Trans Computer has Learned Information that must be taught to the Trans Computer.. it's a Learn by Doing thing Requires Software to do it..

It's available.. but requires knowledge to run it.. Most Shops can't do it.. ( Dealer Can )

I'm not saying the Dealer is any Smarter that the Other BoZos that work on Cars.. but they have the right tools.. For the Bozos to use..

Cap
 

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DO NOT LET THEM REPLACE THE ECU OR THE TCU..

If yours is a 5 Speed, I have Spares..

The ECU I'll have to Zap to accept new keys, so the dealer will not charge you 150$ to do it..

The TCU.. Well .. it's a Process to do a sensor relearn on them.. and it must be done in THAT car.. With Techstream Software.. so a dealer is Likely.. they CAN charge about 150 to do that..

But that is just to get you out of a Bind..

It's something simple.. Bad Battery.. Frozen SMT Fluid.. Something..

Cap
 

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Never go reverse to to S, take the time to stop in neutral for a half of a second. You have to let the reverse to neutral sequence end before starting the neutral to 1st sequence. It's probably not broke, just freaked out. I would take it to Mr. T. to clear the codes and do a sensor relearn just in case you had a bad number stored from the freak out... and you can more tan likely talk them down to the same price for a relearn as a computer diagnostic (half hour billed, 50 bucks here)
 

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codes

My car always throws these, but the software is so vague, it could be a number of things, but not the computers, they just did not have all the info from how advanced the car was for its time, with everyone's help and your patients, u will get it. Nicholas
 

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Discussion Starter #13
You guys are great. Thanks for all the help. Cap it is a 5 speed so I'll see what mr.T has to say then I might have to take you up on the offer.
 
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