[Q]OBD2 SC300 5 Speed TT swap w/working OBD2 Port
01-07-13, 02:20 PM
#16
yeah, the wiring can be a challenge but its really not that bad if you don't mess with the twins.
you will be doing the exact same wiring as if you had a odb2 na-t that is not vvti, except you have to wire up the cam and crank sensors to the wires in the stock distributor plug, and the TPS on a GTE throttle body is reversed so you will have to reverse all 4 wires in the TPS connector.
for the 2 cam sensor wires, do not cut and extend them, from the distributor plug unwrap the harness and pull the 2 cam wires back they will reach the GTE cam sensor spots. Crank sensor wire will need to be extended and run to crank sensor on crank. the last wire is the ground wire you have 2 options.
option #1 you splice that 1 ground wire into 3 and run 1 to each sensor, and jump the pins at the ecu like in my TT ecu mod thread.
option #2 is you use that 1 ground wire for one of the sensor grounds, and run 2 new wires from the ecu to the other 2 sensors, thus making 3 individual grounds which is how TT's are normally setup.
Both ways should work but the one which is more correct is #2.
Best advice I can give anyone doing one of these jobs, is figure out how many "new wires" you will need to run from the ecu to the bay and their lengths (ignitor wires, cam/crank grounds if option 2, other stuff you want to add on, etc..). Wrap all of these together and pop it through the firewall at once.
obviously the most professional looking is to dewrap the entire harness, run everything where its supossed to go and re-wrap it but that 1 step can take longer than the rest combined.
you will be doing the exact same wiring as if you had a odb2 na-t that is not vvti, except you have to wire up the cam and crank sensors to the wires in the stock distributor plug, and the TPS on a GTE throttle body is reversed so you will have to reverse all 4 wires in the TPS connector.
for the 2 cam sensor wires, do not cut and extend them, from the distributor plug unwrap the harness and pull the 2 cam wires back they will reach the GTE cam sensor spots. Crank sensor wire will need to be extended and run to crank sensor on crank. the last wire is the ground wire you have 2 options.
option #1 you splice that 1 ground wire into 3 and run 1 to each sensor, and jump the pins at the ecu like in my TT ecu mod thread.
option #2 is you use that 1 ground wire for one of the sensor grounds, and run 2 new wires from the ecu to the other 2 sensors, thus making 3 individual grounds which is how TT's are normally setup.
Both ways should work but the one which is more correct is #2.
Best advice I can give anyone doing one of these jobs, is figure out how many "new wires" you will need to run from the ecu to the bay and their lengths (ignitor wires, cam/crank grounds if option 2, other stuff you want to add on, etc..). Wrap all of these together and pop it through the firewall at once.
obviously the most professional looking is to dewrap the entire harness, run everything where its supossed to go and re-wrap it but that 1 step can take longer than the rest combined.
01-07-13, 05:55 PM
#17
Rookie
Thread Starter
yeah, the wiring can be a challenge but its really not that bad if you don't mess with the twins.
you will be doing the exact same wiring as if you had a odb2 na-t that is not vvti, except you have to wire up the cam and crank sensors to the wires in the stock distributor plug, and the TPS on a GTE throttle body is reversed so you will have to reverse all 4 wires in the TPS connector.
for the 2 cam sensor wires, do not cut and extend them, from the distributor plug unwrap the harness and pull the 2 cam wires back they will reach the GTE cam sensor spots. Crank sensor wire will need to be extended and run to crank sensor on crank. the last wire is the ground wire you have 2 options.
option #1 you splice that 1 ground wire into 3 and run 1 to each sensor, and jump the pins at the ecu like in my TT ecu mod thread.
option #2 is you use that 1 ground wire for one of the sensor grounds, and run 2 new wires from the ecu to the other 2 sensors, thus making 3 individual grounds which is how TT's are normally setup.
Both ways should work but the one which is more correct is #2.
Best advice I can give anyone doing one of these jobs, is figure out how many "new wires" you will need to run from the ecu to the bay and their lengths (ignitor wires, cam/crank grounds if option 2, other stuff you want to add on, etc..). Wrap all of these together and pop it through the firewall at once.
obviously the most professional looking is to dewrap the entire harness, run everything where its supossed to go and re-wrap it but that 1 step can take longer than the rest combined.
you will be doing the exact same wiring as if you had a odb2 na-t that is not vvti, except you have to wire up the cam and crank sensors to the wires in the stock distributor plug, and the TPS on a GTE throttle body is reversed so you will have to reverse all 4 wires in the TPS connector.
for the 2 cam sensor wires, do not cut and extend them, from the distributor plug unwrap the harness and pull the 2 cam wires back they will reach the GTE cam sensor spots. Crank sensor wire will need to be extended and run to crank sensor on crank. the last wire is the ground wire you have 2 options.
option #1 you splice that 1 ground wire into 3 and run 1 to each sensor, and jump the pins at the ecu like in my TT ecu mod thread.
option #2 is you use that 1 ground wire for one of the sensor grounds, and run 2 new wires from the ecu to the other 2 sensors, thus making 3 individual grounds which is how TT's are normally setup.
Both ways should work but the one which is more correct is #2.
Best advice I can give anyone doing one of these jobs, is figure out how many "new wires" you will need to run from the ecu to the bay and their lengths (ignitor wires, cam/crank grounds if option 2, other stuff you want to add on, etc..). Wrap all of these together and pop it through the firewall at once.
obviously the most professional looking is to dewrap the entire harness, run everything where its supossed to go and re-wrap it but that 1 step can take longer than the rest combined.
One thing I noticed is, I cant find a good pinout for the obd2 sc300...I got a great one for the obd2 TT though with JDM and USDM wire colors too
@ http://www.97supraturbo.com/Tech.html
Last edited by Lowlexus; 01-07-13 at 05:59 PM.
01-08-13, 11:42 AM
#21
Rookie
Thread Starter
Most of the ones I found on the net so far are not really complete the obd2 SC should have 2 o2 sensors and I'm only showing one which that's obd1...buy I'll keep the search....let me know if you find one
01-08-13, 02:16 PM
#22
sounds good, also take a look at your oil pump on your 96 and see if it has a crank sensor on it w/ crank sensor wiring. I had heard that odb2 non vvti also have a crank sensor on the oil pump in addition to the distributor sensors. The oil pump crank sensor is like a secondary one, the ecu still uses the distributor sensors to run but what I am getting at is the wiring and plug should be there already which is one less thing you will need to rewire when doing a gte swap which uses the same type of oil pump crank sensor.
you would probably have to find that pin at the ecu (from oil pump sensor) and move it to the primary crank signal spot (thus removing the pin coming from the distributor for crank). then you just wire up the 2 cam sensors off the distributor plug cam wires and split the ground to 2 grounds for the cam sensors. so you would Ignore the old distributor crank sensor wire in this scenario (you could re purpose it as a second cam ground if its on its own circuit but that might be difficult to tell ). hope that made sense.
why they have the additional crank sensor on non vvti odb2 is still a bit of a mystery, apparently it just lights up the CEL if you disconnect it, car still runs. must have had something to do with odb2 requirements is my guess.
you would probably have to find that pin at the ecu (from oil pump sensor) and move it to the primary crank signal spot (thus removing the pin coming from the distributor for crank). then you just wire up the 2 cam sensors off the distributor plug cam wires and split the ground to 2 grounds for the cam sensors. so you would Ignore the old distributor crank sensor wire in this scenario (you could re purpose it as a second cam ground if its on its own circuit but that might be difficult to tell ). hope that made sense.
why they have the additional crank sensor on non vvti odb2 is still a bit of a mystery, apparently it just lights up the CEL if you disconnect it, car still runs. must have had something to do with odb2 requirements is my guess.
Last edited by Ali SC3; 01-08-13 at 02:20 PM.
01-08-13, 02:55 PM
#23
Rookie
Thread Starter
sounds good, also take a look at your oil pump on your 96 and see if it has a crank sensor on it w/ crank sensor wiring. I had heard that odb2 non vvti also have a crank sensor on the oil pump in addition to the distributor sensors. The oil pump crank sensor is like a secondary one, the ecu still uses the distributor sensors to run but what I am getting at is the wiring and plug should be there already which is one less thing you will need to rewire when doing a gte swap which uses the same type of oil pump crank sensor.
you would probably have to find that pin at the ecu (from oil pump sensor) and move it to the primary crank signal spot (thus removing the pin coming from the distributor for crank). then you just wire up the 2 cam sensors off the distributor plug cam wires and split the ground to 2 grounds for the cam sensors. so you would Ignore the old distributor crank sensor wire in this scenario (you could re purpose it as a second cam ground if its on its own circuit but that might be difficult to tell ). hope that made sense.
why they have the additional crank sensor on non vvti odb2 is still a bit of a mystery, apparently it just lights up the CEL if you disconnect it, car still runs. must have had something to do with odb2 requirements is my guess.
you would probably have to find that pin at the ecu (from oil pump sensor) and move it to the primary crank signal spot (thus removing the pin coming from the distributor for crank). then you just wire up the 2 cam sensors off the distributor plug cam wires and split the ground to 2 grounds for the cam sensors. so you would Ignore the old distributor crank sensor wire in this scenario (you could re purpose it as a second cam ground if its on its own circuit but that might be difficult to tell ). hope that made sense.
why they have the additional crank sensor on non vvti odb2 is still a bit of a mystery, apparently it just lights up the CEL if you disconnect it, car still runs. must have had something to do with odb2 requirements is my guess.
01-10-13, 09:53 AM
#24
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It's SO much easier to convert a GTE harness to USDM spec, than it is to convert an GE harness to GTE spec. I've built an OBD-II compliant GTE harness from an JDM GTE harness that went into a 99 Tacoma 4x4 for a customer in Washington state. He needed to be able to pass state inspection as well. He passed with flying colors.
Also, OP, I feel your pain with the state inspection. I'm originally from NEPA. South Carolina where I currently live has no state inspection at all! Anything goes! :-)
-Cam
Also, OP, I feel your pain with the state inspection. I'm originally from NEPA. South Carolina where I currently live has no state inspection at all! Anything goes! :-)
-Cam
01-10-13, 10:33 AM
#25
I didn't think it would be that much easier but I haven't done it so I can't say. I assume its something like extend the whole harness and do all the body plug wiring plus whatever wiring changes the odb2 requires from the JDM standard. Definitely another option though that would make it easier to keep the sequential twins if you wanted to go that route.
I could get a single turbo odb1 GTE running on a ge harness pretty quick, which is why I always ask if gte owners are keeping the stock twins. the ignition wiring and map sensor doesn't take much time to wire up.
I fonud this article for keeping the odb2 codes from coming up for the vsv's for the twins which could help the OP.
http://mkiv.com/techarticles/obd2_co...svs/index.html
I could get a single turbo odb1 GTE running on a ge harness pretty quick, which is why I always ask if gte owners are keeping the stock twins. the ignition wiring and map sensor doesn't take much time to wire up.
I fonud this article for keeping the odb2 codes from coming up for the vsv's for the twins which could help the OP.
http://mkiv.com/techarticles/obd2_co...svs/index.html
01-10-13, 11:48 AM
#26
Rookie
Thread Starter
I didn't think it would be that much easier but I haven't done it so I can't say. I assume its something like extend the whole harness and do all the body plug wiring plus whatever wiring changes the odb2 requires from the JDM standard. Definitely another option though that would make it easier to keep the sequential twins if you wanted to go that route.
I could get a single turbo odb1 GTE running on a ge harness pretty quick, which is why I always ask if gte owners are keeping the stock twins. the ignition wiring and map sensor doesn't take much time to wire up.
I fonud this article for keeping the odb2 codes from coming up for the vsv's for the twins which could help the OP.
http://mkiv.com/techarticles/obd2_co...svs/index.html
I could get a single turbo odb1 GTE running on a ge harness pretty quick, which is why I always ask if gte owners are keeping the stock twins. the ignition wiring and map sensor doesn't take much time to wire up.
I fonud this article for keeping the odb2 codes from coming up for the vsv's for the twins which could help the OP.
http://mkiv.com/techarticles/obd2_co...svs/index.html
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