Wiring diagrams for 96/OBD2

[Huskymaniac]

Can someone point me to known accurate wiring diagrams for my 1996 OBD2 car? I found some supposed 1997 service manuals that came from what appears to be a Russian source but some stuff in there about torque values and wheel bearing parts was not accurate so I don't feel I can trust the wiring diagrams either. I am working on some interesting projects involving the TCU and ECU for us poor OBD2 folks.

[TomsSVX]

What do u need to know?

Tom

[Huskymaniac]

What do u need to know?

Tom

I want to know all of the wires going to and from both the TCU and ECU and their color codes.

[TomsSVX]

I can try and look that up on my old mitchel disc. Do you mind if i ask the goal of this?

Tom

[Huskymaniac]

I can try and look that up on my old mitchel disc. Do you mind if i ask the goal of this?

Tom

A couple of things.

1. I have built a little electronic module that can be clamped onto the ATF temp sensor line to read that sensor directly. It converts the voltage to a temperature and displays it on an LED readout. I want to make sure I tap into the correct lines for the sensor, ground and power.
2. I would like to start thinking about how one would program a standalone EMS to interface to my TCU.
3. I would like to see if there is a way to fool the TCU into doing things a little differently like lock up the Torque Converter in third gear when the stick is in "3".

[icingdeath88]

http://www.phantomotaku.com/SVX/

Has some service manuals, with some wiring diagrams.

I have also attached some things that may be useful.

http://www.subaru-svx.net/photos/files/deadeye95/12431.PDF

[Huskymaniac]

http://www.phantomotaku.com/SVX/

Has some service manuals, with some wiring diagrams.

I have also attached some things that may be useful.

http://www.subaru-svx.net/photos/files/deadeye95/12431.PDF

Thanks for posting that but I think they are all OBD1, right?

[icingdeath88]

Ah, sry. First link I think still has some 97 stuff.

[TomsSVX]

Obdii tcus are the same as obdi except for barometer in an obdii is external to the ecm. I had a hydra running on an obdii auto. The tcu coded for something that i cannot remember bit it had no effect on performance

Tom

[Huskymaniac]

Obdii tcus are the same as obdi except for barometer in an obdii is external to the ecm. I had a hydra running on an obdii auto. The tcu coded for something that i cannot remember bit it had no effect on performance

Tom

When you say they are the same, are you talking about the connector and wire colors or the guts too? I recall Mike saying something about obd2 tcus not being programmable the same way obd1 tcus are.

[TomsSVX]

Im not 100% sure but i remember they take all the same inputs save for can connection to the engine ecu

Tom

[Huskymaniac]

Tom,

Did you ever find the 1996/1997 TCU wiring diagrams? I want to make sure the one I have been using is accurate. If it is, the OBD1 and OBD2 TCUs should be interchangeable, aside from size and fit. It looks like the connectors are the same and the pinouts are the same. I am coming back around to an idea of using a modified OBD1 TCU in an OBD2 car, after figuring out how to shoehorn it in there.

[TomsSVX]

Tom,

Did you ever find the 1996/1997 TCU wiring diagrams? I want to make sure the one I have been using is accurate. If it is, the OBD1 and OBD2 TCUs should be interchangeable, aside from size and fit. It looks like the connectors are the same and the pinouts are the same. I am coming back around to an idea of using a modified OBD1 TCU in an OBD2 car, after figuring out how to shoehorn it in there.

Never found them but what you are suggesting will not work. The obdii tcu talks within the can... obdi does not. You willhave a check engine light on

Tom

[Huskymaniac]

Never found them but what you are suggesting will not work. The obdii tcu talks within the can... obdi does not. You willhave a check engine light on

Tom

I have been able to talk to the TCU using SSMI over the SSM pins. Do you know of someone that tried it and had it not work?

[TomsSVX]

Closed area network was mandatory for all obdii vehicles. This way all modules associated with powertrain can talk to eachother... take one out and the engine ecu will cry about it

Tom

[Huskymaniac]

Closed area network was mandatory for all obdii vehicles. This way all modules associated with powertrain can talk to eachother... take one out and the engine ecu will cry about it

Tom

Are yousure that was true back to 1996? See this link:
http://www.evoscan.com/technical-vehicle-manuals/153-can-bus-controller-area-networking

I have uncovered one difference in the wiring. I had to look at the wiring of a 1997 legacy tcu to find it. The tcu pin that used to run to the power mode light for obd1 models runs to the atf temp light on obd2 models and the pin that used to run to the atf temp light now runs to pin 80 on the obd2 ecu. The tcu sends some sort of diagnostic signal on that line to the ecu but I have no clue what. Could it just be the blinks that used to be sent to the atf temp light on obd1 models? Maybe there is a way to drive that pin on the ecu to make it happy.

As far as I can tell, those are the only lines that may prevent an obd1 tcu from plugging into an obd2 car. Obd2 tcus also monitor the supply voltage on the tps but the obd1 tcu does not and that pin on the obd1 tcus is a NC so it shouldn't matter.

[Huskymaniac]

I really want to test the above theory about driving pin 80 in the ECU with a diagnostic waveform equivalent to the "Power Light" flashes one gets in an OBD1 car when you start the engine:

"If a malfunction occurs in any self-diagnosis components, POWER light will flash when engine is started and running for 8 seconds. Power indicator light will come on for 2 seconds and will either signal a self-diagnosis malfunction (blinking for 8 seconds) or okay signal (light will go out). If light does not flash after initial 2 seconds, system is okay. In case of malfunction, trouble code is output as light flashes."

I would like to get a copy of the wiring diagram for a 96 or 97 SVX. All I am working of off now is the wiring diagram of a 97 Legacy and the pinouts of the ECU and TCU for both OBD1 and OBD2 SVXs. Really, I just need to know which of the diagnostic wires from the TCU (B56 pins 11 and 12) go to the ATF Temp warning light and which goes to pin 80 in the ECU.

The waveform probably isn't quite as simple as that power up sequence quoted above but it may not be very different. Maybe the 2 second pulse is the same but the code number is sent after that if there is a problem so that the ECU know what the problem is instead of that there just IS a problem.

[icingdeath88]

I would like to get a copy of the wiring diagram for a 96 or 97 SVX. All I am working of off now is the wiring diagram of a 97 Legacy and the pinouts of the ECU and TCU for both OBD1 and OBD2 SVXs. Really, I just need to know which of the diagnostic wires from the TCU (B56 pins 11 and 12) go to the ATF Temp warning light and which goes to pin 80 in the ECU.

If you really want to find some wiring diagrams, this batch of files is a good place to start looking: http://www.subaru-svx.net/forum/showthread.php?t=60472

[Huskymaniac]

If you really want to find some wiring diagrams, this batch of files is a good place to start looking: http://www.subaru-svx.net/forum/showthread.php?t=60472

Those files are for a 1994 (OBD1) car, correct? I need OBD2 wiring diagrams. There are the files from that Russian source. It appears as though MOST of those files are accurate. The ONE exception I have found is the wiring diagram for the TCU. Figures.:rolleyes:

But, based on the other diagrams, primarily the ECU ones, I am 99% confident that I was right on my original assumption of the "diagnostic" pins. Connector 55 pin 12 of the OBD2 TCU goes to the ATF temp light and connector 55 pin 11 of the OBD2 TCU goes to pin 80 on the ECU connector. That means that, if an OBD1 TCU were to be used in an OBD2 car, connector 68 (same as 55) pin 11 would have to be swapped with pin 12 as this was the ATF temp light pin for the OBD1 TCU. Also, connector 68 pin 12 would have be non-connected (or connected to a lamp installed elsewhere for power mode indication) and the appropriate diagnostic waveform would need to be sent to ECU pin 80 through TCU connector 55 pin 11.

For people with a 5MT swap in OBD2 cars, if that correct waveform can be determined and sent to pin 80 on the ECU, the CEL would probably not come on for them either.

[icingdeath88]

Those files are for a 1994 (OBD1) car, correct? I need OBD2 wiring diagrams. There are the files from that Russian source. It appears as though MOST of those files are accurate. The ONE exception I have found is the wiring diagram for the TCU. Figures.:rolleyes:

Most of the files are for OBD1 cars, but there is also some information for a 97. Worth having a look at least.