Civic with B20 and Integra Auto,ECU,TCM OBD1...need help!

civicjason · Post by **civicjason** » Tue Mar 05, 2013 5:11 pm

Car is complete except the car does not shift properly. Car shifts the same with or without the TCM connected. I have an obd2a to obd1 jumper harness from rywire and their tech support is no help at all. I am on my 2nd auto the first was obd2 and this one is obd1. Could this just be a bad tcm, wiring harness or sensor? Something else? If anyone has the pinouts for the Integra P75-A51 ecu, TCM P78-A01, and the Civic OBD2a ecu I would love to have them. Thanks, Jason

JaredKaragen · Post by **JaredKaragen** » Thu Mar 07, 2013 6:32 am

OBD1 ECU's dont have the hardware to control the OBD2 tranny. You will need to wire up an obd2 ECU in parallel, so that it can get all sensor data, but not throw a CEL for anything major so the tranny doesnt go into any type of safe mode. The OBD1 will actually control the ICM, injectors, etc. I am assuming your shifts are hard as a rock; no slip in them. and improperly timed. Telltale sign of an auto trans part that is necessary but not present on OBD1 ECU's.

civicjason · Post by **civicjason** » Thu Mar 07, 2013 4:05 pm

The transmission is an obd1 but there is a chance we have the obd2 sensors in it because the obd2a harness connectors would not plug into them. Would it be as simple as swapping the obd2 connectors from the obd2 automatic to the obd1 automatic?

JKOBD · Post by **JKOBD** » Fri Mar 08, 2013 2:36 pm

civicjason wrote:Car is complete except the car does not shift properly. Car shifts the same with or without the TCM connected. I have an obd2a to obd1 jumper harness from rywire and their tech support is no help at all. I am on my 2nd auto the first was obd2 and this one is obd1. Could this just be a bad tcm, wiring harness or sensor? Something else? If anyone has the pinouts for the Integra P75-A51 ecu, TCM P78-A01, and the Civic OBD2a ecu I would love to have them.

Jason, I am the tech support for this harness and I have offered to inspect the harness and return ship for free. You have yet to take me up on the offer. You have taken the car to two different mechanics and multiple things have been changed around and many parts swapped and many unknown parts added. We can only do so much when you have people performing the swap that appear to not know what they are doing with it 100%.

JaredKaragen wrote:OBD1 ECU's dont have the hardware to control the OBD2 tranny. You will need to wire up an obd2 ECU in parallel, so that it can get all sensor data, but not throw a CEL for anything major so the tranny doesnt go into any type of safe mode. The OBD1 will actually control the ICM, injectors, etc. I am assuming your shifts are hard as a rock; no slip in them. and improperly timed. Telltale sign of an auto trans part that is necessary but not present on OBD1 ECU's.

That is incorrect. The most OBD1 Integra ECUs and some OBD2a ECUs communicate with the OBD1 Integra TCU (Transmission Control Unit; sometimes referred to as TCM; Module). I have built over 2000 harnesses and 300 AUTO harnesses that use both the ECU/TCU combo as well as the JDM OBD1 GSR auto ecus that control the auto functions and do NOT need a TCU. He does not need an OBD2a ECU wired in parellel with his setp. The OBD2a Civic engine harness is ok to use on this new setup, but he needs to confirm that he has the correct sensor connectors plugged in since the OBD2a trans has more than the OBD1 ECU/TCU requires. In addition, he needs to verify that the TCU is correct.

civicjason · Post by **civicjason** » Fri Mar 08, 2013 5:01 pm

JKOBD wrote: Jason, I am the tech support for this harness and I have offered to inspect the harness and return ship for free. You have yet to take me up on the offer. You have taken the car to two different mechanics and multiple things have been changed around and many parts swapped and many unknown parts added. We can only do so much when you have people performing the swap that appear to not know what they are doing with it 100%.

My mechanic doubts the harness is wrong but I plan to take you up on your offer if I must but we are going to try a different TCM and ECU but same models (P75-A51 and P78-A01) and test some wiring before I send it back to you. I don't know what different parts you are referring to because the swap has the same parts that I started with just a different automatic because the first one went bad. My current mechanic is good but his specialty may not be automatics but he's good so I'm sure he can make it right.

JKOBD wrote: That is incorrect. The most OBD1 Integra ECUs and some OBD2a ECUs communicate with the OBD1 Integra TCU (Transmission Control Unit; sometimes referred to as TCM; Module). I have built over 2000 harnesses and 300 AUTO harnesses that use both the ECU/TCU combo as well as the JDM OBD1 GSR auto ecus that control the auto functions and do NOT need a TCU. He does not need an OBD2a ECU wired in parellel with his setp. The OBD2a Civic engine harness is ok to use on this new setup, but he needs to confirm that he has the correct sensor connectors plugged in since the OBD2a trans has more than the OBD1 ECU/TCU requires. In addition, he needs to verify that the TCU is correct.

TCU and ECM are correct but potentially bad so I'm trying different ones once they are delivered. My new automatic from hmotorsonline is a JDM 94 Integra obd1 automatic and the connectors do not plug into my Civic harness connectors because they do not match for some reason so the harness from the obd2 auto was used but I'm having problems like was mentioned above. So I think you are saying the harness is just plugged into the wrong sensors correct?

JKOBD · Post by **JKOBD** » Sat Mar 09, 2013 10:05 am

I designed this harness so that you can use existing connector sensors (even if the plugs are different from OBD2 to OBD1....you can still swap them and plug it into the trans) so that you aren't stringing wires all through the engine bay. The location of the sensors are close enough to be able to reuse the stock wires. If he is a Honda mechanic, he should have all the service manuals to be able to chase things down.