OBDII TCU ECU question

[Huskymaniac]

Is there any way to get the transmission temperature reported through the live data on the OBD2 port? Is the TCU wired directly to the transmission temperature warning light or does the ECU control the light? If the ECU does then the ECU must know the temperature, right? Maybe the TCU can be modified to send the temperature to the ECU if it doesn't already do so?

[b3lha]

The TCU reads the sensor and controls the light.

I don't yet have a copy of the OBD2 control units to study. As far as I know, the OBD2 SVX has an OBD1 TCU. So I don't think it's possible to get any transmission info via OBD2. It is possible to read transmission temperature using OBD1.

You could confirm whether the TCU supports OBD2 by looking at the wiring diagram. Is the OBD2 "K-Line" diagnostics wire (pin 7 or 10 of the diag connector) connected to the TCU? Or is it only connected to the ECU?

The 97 TCU is different hardware and software to the earlier cars and we don't know how to mod it. Even if we could mod it, the mod you are suggesting would be difficult.

[Huskymaniac]

Originally Posted by b3lha

The TCU reads the sensor and controls the light.

I don't yet have a copy of the OBD2 control units to study. As far as I know, the OBD2 SVX has an OBD1 TCU. So I don't think it's possible to get any transmission info via OBD2. It is possible to read transmission temperature using OBD1.

You could confirm whether the TCU supports OBD2 by looking at the wiring diagram. Is the OBD2 "K-Line" diagnostics wire (pin 7 or 10 of the diag connector) connected to the TCU? Or is it only connected to the ECU?

The 97 TCU is different hardware and software to the earlier cars and we don't know how to mod it. Even if we could mod it, the mod you are suggesting would be difficult.

Where would I be able to get the wiring diagram?

Also, any idea if the TCU error codes get reported through the OBDII port or if we need to do the manual button dance?

[b3lha]

Originally Posted by Huskymaniac

Where would I be able to get the wiring diagram?

Somebody on this forum may have it, or access to it.

Originally Posted by Huskymaniac

Also, any idea if the TCU error codes get reported through the OBDII port or if we need to do the manual button dance?

If the TCU is OBD1 like I think it is then the select monitor will read them using OBD1 through the SSM pins of the OBD2 port.
I think a standard OBD2 reader will probably only give you engine codes and data.

[Huskymaniac]

Originally Posted by b3lha

Somebody on this forum may have it, or access to it.

If the TCU is OBD1 like I think it is then the select monitor will read them using OBD1 through the SSM pins of the OBD2 port.
I think a standard OBD2 reader will probably only give you engine codes and data.

That would suck. I have a pretty good OBDII reader. However, I don't know if I can read the TCU codes because I may not have one to read yet and, if I did, I may not know there is one to read if it can't read it. I guess I can only know for sure if I was reading one which would require having one to read. Maybe I am better off not knowing.....

Do all TCU codes cause a light to flash somewhere?

[1986nate]

The ATF temperature light will blink 16 times on startup if there is a code instead of pre-95 models flashing the power light. So more than likely, code retrieval is going to be the same.