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2003 MR2 with the SMT. Front: 205/45/16, Rear 215/40/17. Sport Tuning T9-2 Black Mach Lip Wheels
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Discussion Starter · #1 ·
Today while driving my 2003 MR2 the SMT light (Sprocket with Exclamation in the middle) came on, so I pulled and turned the car off for a few minutes. Restarted the car and continued driving and the light came back on the jerk and spudder to a stop. Damn it! I was stuck in morning rush hour traffic and didn't want to get stranded in the middle of the road. Turned it off again and waited for about 20 minutes. I was able to race over to my local guy who worked for Toyota and knew the MR2 models very well. Turns out the ECU has failed. I will find out tomorrow if he can find one. Fingers crossed. I really want to get the car back on the road, but I have to watch my finances since I'm on medical leave and living on my savings.
 

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I hope your local guy is correct. However I’d say it is very unlikely that the ECU is the fault. The Transmission Control Unit (TCU) is more likely to generate the SMT system warning light, however that is quite rare also. Recently 2 people have reported a TCU that is truly failed. Position sensors are much more likely to be the cause of a system failure. However accurate diagnosis requires the specific error codes, and a copy of techstream software to retrieve those codes. To help yourself, I would verify that your guy used techstream software to make his determination, and relay the specific error codes to us.
 

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I hope your local guy is correct. However I’d say it is very unlikely that the ECU is the fault. The Transmission Control Unit (TCU) is more likely to generate the SMT system warning light, however that is quite rare also. Recently 2 people have reported a TCU that is truly failed. Position sensors are much more likely to be the cause of a system failure. However accurate diagnosis requires the specific error codes, and a copy of techstream software to retrieve those codes. To help yourself, I would verify that your guy used techstream software to make his determination, and relay the specific error codes to us.
^^^this^^^
 

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2003 MR2 with the SMT. Front: 205/45/16, Rear 215/40/17. Sport Tuning T9-2 Black Mach Lip Wheels
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Discussion Starter · #4 ·
Here are the codes that were persent:
P0442 Evap Emission
P0860 Gear shift module no comm to/from transmission
P1646 Transmission Control Unit Fault
P0942 Hydraulic Pressure Unit
 

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The P0442 only affects evaporative reclamation system. It may be a leaky o-ring on the gas filler cap, or torn seal at the gas tank vent, or a bad charcoal canister.
P0860 and P1646 are both generic TCU errors. They typically appear any time the TCU is not communicating, for any number of reasons. Absolutely no reason to replace the ECU or TCU until you do some more checking. (This is likely where the Toyota dealer makes all their money - first step, replace the computers!)
P0942 - THIS code actually means something. BGB says possible errors are faulty: HPU relay, pressure sensor, HPU fuse, 12v pump motor or TCU.

I'll wager you money (or some good used parts) that replacing the ECU and TCU will not fix the problem. If I had to pick a component to replace, I'd choose the HPU. If the shop will do more than replace expensive components, I'd ask them to investigate the HPU. Open the door and verify the HPU runs. Remove the HPU relay and verify it is clicking reliably. Remove the HPU from the car and do some checks on the bench. Run the motor with 12V and see how many amps it's pulling. Check the pressure sensor to see if it's tracking pressure properly (apply 5V power, and monitor output voltage as pressure rises). Check both position sensors the same way (apply 5V to two pins, monitor output voltage on the third pin to verify it increases as the position arm is moved).

Motors are difficult to repair, best find a used part.
Pressure sensors are available - but I'm the only one in the world with new ones for sale.
Position sensors are not available new - but we have a repair that fixes them.

I'm happy to discuss this with your guy if he want to call me.
 

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Cycle times of the pump will identify which part is faulty, most of the time.
 

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2003 MR2 with the SMT. Front: 205/45/16, Rear 215/40/17. Sport Tuning T9-2 Black Mach Lip Wheels
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Discussion Starter · #7 · (Edited)
The HPU is right at 25 second every time. He said the TCU is bad not the ECU. A new TCU will need reprogramming correct? He is not using techstream.
 

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TCU is a possibility. I’m not convinced the HPU has been ruled out, but at least it’s running. Techstream is mandatory to program a new TCU, or reset the system after replacing many of the components. I can send you the procedure to download a (free) copy. You’ll need a J2534 cable from eBay or Amazon.
 

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2003 MR2 with the SMT. Front: 205/45/16, Rear 215/40/17. Sport Tuning T9-2 Black Mach Lip Wheels
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Discussion Starter · #9 ·
TCU is a possibility. I’m not convinced the HPU has been ruled out, but at least it’s running. Techstream is mandatory to program a new TCU, or reset the system after replacing many of the components. I can send you the procedure to download a (free) copy. You’ll need a J2534 cable from eBay or Amazon.
I ordered a cable today. Plan B is to send to car to MonkeyWrench to redo the SMT or switch to manual.
 

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2003 Toyota MR2 Spyder 2.0L Stroker
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I ordered a cable today. Plan B is to send to car to MonkeyWrench to redo the SMT or switch to manual.
Get techstream first. That's going to tell you what is going on. I agree with Cyclehead that the ECU is likely not the culprit and neither is the TCU. Unless they been sitting in water from a clogged top drain.

The HPU could be the issue.

You also have DDPR Racing right in Sealy. MR2 experts or send it here to Florida and I'll sort it. Guarantee to be less expensive that MWR.
 

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2003 MR2 with the SMT. Front: 205/45/16, Rear 215/40/17. Sport Tuning T9-2 Black Mach Lip Wheels
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Discussion Starter · #13 ·
My car is back home. No error codes. The original TCU is back in the car. Some guy from Toyota was telling my guy the TCU does not need to program. Triz thanks for the info on DDP Racing. I drove out there, talked to Dave (cool guy) and got a tour of the shop. I hope to get the car to him next week. Leaning towards tranny swap. I guess the is my forever car. The hardtop and BC Racing coilovers will have to wait.
 

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The P0442 only affects evaporative reclamation system. It may be a leaky o-ring on the gas filler cap, or torn seal at the gas tank vent, or a bad charcoal canister.
P0860 and P1646 are both generic TCU errors. They typically appear any time the TCU is not communicating, for any number of reasons. Absolutely no reason to replace the ECU or TCU until you do some more checking. (This is likely where the Toyota dealer makes all their money - first step, replace the computers!)
P0942 - THIS code actually means something. BGB says possible errors are faulty: HPU relay, pressure sensor, HPU fuse, 12v pump motor or TCU.

I'll wager you money (or some good used parts) that replacing the ECU and TCU will not fix the problem. If I had to pick a component to replace, I'd choose the HPU. If the shop will do more than replace expensive components, I'd ask them to investigate the HPU. Open the door and verify the HPU runs. Remove the HPU relay and verify it is clicking reliably. Remove the HPU from the car and do some checks on the bench. Run the motor with 12V and see how many amps it's pulling. Check the pressure sensor to see if it's tracking pressure properly (apply 5V power, and monitor output voltage as pressure rises). Check both position sensors the same way (apply 5V to two pins, monitor output voltage on the third pin to verify it increases as the position arm is moved).

Motors are difficult to repair, best find a used part.
Pressure sensors are available - but I'm the only one in the world with new ones for sale.
Position sensors are not available new - but we have a repair that fixes them.

I'm happy to discuss this with your guy if he want to call me.
You sir, Rock...
 

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My car is back home. No error codes. The original TCU is back in the car.
The previous codes pretty much indicate the HPU. Other things can affect it’s operation, like battery condition, relay, TCU, and low fluid level. Repairing the HPU or replacing with a known good used one will be a lot cheaper than a conversion.

Edit: If you do choose the route of converting to a conventional manual, would you mind pulling the accumulator and inspecting it to see if it has failed? It unscrews, then you stick something in the end of it to see how far in it goes.
 

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2003 Toyota MR2 Spyder 2.0L Stroker
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My car is back home. No error codes. The original TCU is back in the car. Some guy from Toyota was telling my guy the TCU does not need to program. Triz thanks for the info on DDP Racing. I drove out there, talked to Dave (cool guy) and got a tour of the shop. I hope to get the car to him next week. Leaning towards tranny swap. I guess the is my forever car. The hardtop and BC Racing coilovers will have to wait.
Dave's a great guy.

It's a shame your not closer although I've had several members ship there car here to me. You can't go wrong with Dave.
 
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