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OBD 1 Diag port reader

Old 03-24-2014, 05:46 PM
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I doubted there was an rewrite capability. In the older Mitsubishi ECU's we had to remove the PROM and solder in a socket allowing us to use a EPROM.

If you're at all interested: http://www.realhomemadeturbo.com/for...p?topic=9612.0

Thank you again for sharing your work!
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Old 03-24-2014, 05:57 PM
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Sadly no rewrite possible through the port and Propriatary ROM.
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Old 04-11-2014, 01:29 PM
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Originally Posted by jbtvt View Post
Awesome project! Unfortunately I know that at least my '90 doesn't have TE2, only TE1. Not sure about the '85 and '88 but probably not. No way to get around that, that you know of?

Anyone that's used this, are you modifying the connections using small spade connectors to the male pins, chopping off the wire at the back of a separate female connector and tying in there, or...?

Also, would this be a compatible 9 pin serial port? Cheap if it is - Amazon.com: TRENDnet USB 2.0 to RS-232 DB9 Serial Converter, TU-S9: Electronics
So, after I purchased the hardware for this project, and luckily beofre I spent the time to solder it all together, I checked my diag port and I do not have TE2 either... what a burn!!! I was looking forward to this, even made time for it today....

Guess I have to diagnose it the old fashioned way.. what the plugs look like. lol
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Old 04-15-2014, 10:46 AM
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RJR, and all, without the TE2 option, are there other ways to see the various sensor inputs that the ECU is seeing? Similar to the O2 sensor....
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Old 04-15-2014, 10:53 AM
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Not that I know of. You could look at the detailed wiring diagram of the ECU and make some measurements on the ECU terminals to pick off the various sensor inputs there. You'd still have to make the conversion from raw volts to useful units such as ECT, etc.

It's also possible that the TE2 terminal exists on your ECU but just isn't brought out to the diag port. You might want to check that out.
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Old 04-15-2014, 10:54 AM
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Thanks, I will look to see if the TE2 connector is at the ECU.
Thanks!
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Old 05-29-2014, 06:55 AM
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Hello RJR!

So, i finally got around to checking to see if I have a TE2 output on the ECU. So, I DO have a pin at the location that the FSM says is TE2, but no wire on the connector to the harness. How can I check to see if this TE2 connector on the ECU is active and not just a place holder? I was looking for some voltage measurement in the FSM..... I'd like to confirm this before doing all the other work with your diag port program.

Thanks!
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Old 05-29-2014, 07:19 PM
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The TE2 pin (if such there is on your ECU) is an input which, when shorted to ground, tells the ECU to enter a specific diagnostic mode. So, to safely check it out on your ECU, here's what I would suggest you do.
1) Turn the ignition switch to "ON" (not accessory, but don't start the truck.) Measure the pin with your DVM. If it is a true TE2 pin, it should measure 12V or so.
2) If TE2 measures 12V, then check if it is configured as in input (meaning it won't blow something up if you short it to ground). To do this safely, get a 12V bulb with leads attached, and connect it from TE2 to ground. If the bulb lights, your pin is not an input, and you should proceed no further. Your ECU does not support the data output diagnostic mode.
3) If the bulb doesn't light, then it is safe to short TE2 to ground.
4) Turn the key to OFF, short TE2 to ground, and turn the key back to ON. Watch the check engine light. It should be blinking at a rapid rate, about twice as fast as it does for "reading codes."
5) If the check engine light is flashing properly, next measure the voltage at pin VF1 of the diag port. It should read about 2.5 volts. This means that VF1 is outputting a digital data stream that switches between 0 and 5 volts, and averages about 2.5 volts. If the voltage on pin VF1 is stuck at either 0V or 5V, it means no data is being clocked out of the port and you can't use my program.

If everything checks out, you're ready to connect to your serial port and run my program. Read the instructions again and good luck!
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Old 05-30-2014, 09:52 AM
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Excellent! Thanks RJR,

I'll return with the outcome as soon as I get a chance to test it out.
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Old 06-22-2014, 04:37 PM
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I finally got around to this. Checked TE2 pin on ecu for 12 volts. Nothing. I plugged the connector and pushed a hard wire through to hit the pin, again nothing. TE1 of course tested fine as my baseline.
So. Sucks. FYI future forumers, my 4runner is manufactured Aug 1991.
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Old 06-30-2014, 09:39 PM
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This is awesome! A year or so ago I started an arduino project to parse the same data and output it to a serial port. I'll find the code and get it uploaded somewhere so people can use it in the next few days. This could be the start of a really cool project.

See: https://www.yotatech.com/forums/f116...eading-265312/
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Old 06-30-2014, 10:59 PM
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Awesome work, guys!
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Old 12-29-2018, 06:49 PM
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Bit of a thread bump. I've constructed the cable but not having any luck getting it to communicate with the program. I'm using a serial to usb adapter and windows 10. Will either of these effect the ability to read the data? I'm getting a signal at the vf1 plug on the diagnostic post
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Old 12-29-2018, 07:53 PM
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I need more information. Have you run the program in test mode and done the checks I outlined in the user guide? Can you provide some screen shots? It should work with Windows 10 as long as you have the Microsoft .NET 4.0 environment loaded. The program or OS would tell you if that wasn't the case.

I've just been trading PM's with another user who had to remove the 13K pull-up resistor to make things work. Different serial adapters may require some experimenting in that area.

What year/model of 4runner or truck do you have? The pre-1992 models didn't provide a data stream, as far as I've been able to tell.

Another possibility is that the program is looking at the wrong COM port. The program defaults to automatically finding the lowest numbered COM port. If you have a built-in serial port that is at a lower number than your USB-serial adapter, the program will grab the wrong port and won't communicate with your adapter. To fix that, figure out (using Device Manager in Control Panel) which COM port your USB-serial adapter is using, and set that in the .ini file. Instructions for doing that are in the user guide.

Last edited by RJR; 12-29-2018 at 07:57 PM.
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Old 01-01-2019, 02:48 AM
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Cheers for the reply. I manually configured the com port and still no luck. I've also tried a couple of different adapters and also desoldering the resistor. The engine and loom are from a 1992 and I've tried a ecu from this vehicle and a 1995. There is fluctuating voltage on the vf pin and the check engine light is flashing fast with the key on and then goes out with the engine running. The data doesnt seem to change when I put the jumper on the cable in the test mode. Here is a screen shot of what comes up when I hit the read button


Last edited by crum; 01-01-2019 at 02:52 AM.
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Old 01-01-2019, 08:34 AM
  #36  
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OK, you say the screen doesn't change when you short pin 8 to pin 4 on the DB9 connector while running in test mode. Let's start with that. There's no use in connecting to your 4runner until you can pass this test. You should see the screens change as shown in the user manual. (with some slight variations because you are using metric units)
Two things to check.
(1) Make sure you are running "ToyotaDiagTestMode.exe" for test purposes, not "ToyotaDiag.exe".
(2) If you are running the TestMode program, then it seems likely you have miswired the DB9 connector. The wiring diagram in the user manual shows the back of the female DB9 connector (the side you solder to). It's easy to get confused with connectors and wind up with a mirror image of the proper connections.
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Old 01-01-2019, 09:21 AM
  #37  
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Also, measure the voltage on pin 8 when the program is running in test mode. It should be above 5 volts, probably more like 10-12 volts. If it is close to zero or negative your serial port is not being programmed correctly.

Edit: Sorry, I should have said measure the voltage on pin 4 with respect to pin 5. That voltage should be as stated above.

Last edited by RJR; 01-01-2019 at 02:31 PM.
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Old 01-01-2019, 03:26 PM
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Hi not having any luck with the jumper still. I also hooked the resistor back up and it made no difference. I'm getting about 8.98v between pins 4 and 5 with and without the program running, there is no change in voltage when I hit read data either.
I'm using a serial data cable between the adapter harness and the usb converter if that makes any difference.
Here is a couple of pics of the harness pins which I'm 99% sure are correct

*edit* now getting 2.3v between pins 4 and 5 but still not changing when program is enabled. Voltage suddenly dropped from close to the previous 9v when I had the multimeter hooked up




Last edited by crum; 01-01-2019 at 03:41 PM. Reason: extra information
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Old 01-01-2019, 03:53 PM
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I still suspect you have a wiring problem. You say you have a serial data cable going between the output of your USB adapter (presumably a male DB9 output) to your wired connector (another male DB9). Note that the user manual calls for a female DB9 connected directly to the male output of the USB-serial adapter. What do you know about that serial data cable in between? Is it a standard cable or a "null modem" cable? I think you need to ohm out that cable and make sure that there aren't some pin crossover functions going on inside of it. It's common for pin 6 to swap with 4, 7 with 8 and 2 with 3. If that's going on in your cable things won't work.

If you have a female DB9 handy, I would suggest wiring it up exactly as shown in the user manual, and then plugging it directly on to the male DB9 of the USB-serial adapter. Get that working and then go from there.
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Old 01-02-2019, 01:37 PM
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After going over the serial cable it appears the pins are crossed over as you suggested might be the case. I swapped pins on my soldered plug to match and got the laptop to read some data from my ecu but the figures are incorrect. I'm going to purchase a female solder on plug and make a new harness so I can bypass the serial cable. I'll report back once I've tried the new loom
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