a negative signal for the IAB's. i know that the USDM does. the reason why i am skeptical is that i know on USDM OBD1 gsr harnsess, the IAB wires are pink/blue and black/yellow. but my JDM harnsess is just solid black instead of black/yellow and i know that USDM OBD2 ecu sends a positive signal and there wire is solid black.

 

bump

anyone?

 

There are two ways to check this.

1. Look at the JDM wiring harness and if it has a red/blu and black wire and the black wire is continuous to ground then the JDM GS-R ECU uses a positive trigger. With the JDM engine harness off of the motor do a continuity test between the black wire and the thermostat ground terminal on the engine harness.

2. Put a USDM OBD1 GS-R ECU in your properly wired car. Make sure that the dashpot arm moves on startup. Put the JDM ECU in your car and start it. If the dashpot arm does not move something is different (i.e. polarity of IAB trigger).

Good luck.

-kenji

 

encase anyone cares, the OBD1 JDM P72 does send a positive signal (same as USDM OBD2 P72).

 

I was going through a similar trial not too long ago (all OBD1). I did the A17 and A20 swap trick and the IAB still did NOT work with my JDM P72. Swapped in a borrowed USDM P72 and it worked perfectly.

I sent the JDM ECU to a friend of mine to have it checked out. It uses a positive trigger, just like Kenji said.


[Modified by DaiJekBok, 10:32 PM 9/11/2002]

 

so is the jdm p72 ecu a good choice for the usdm gsr 98 spec? let me know guys. I dont wanna spend 220 for an ecu if it wont do what i need it to do.

 

so is the jdm p72 ecu a good choice for the usdm gsr 98 spec? let me know guys. I dont wanna spend 220 for an ecu if it wont do what i need it to do. by the way...you can fix this positive/negative signal problem with the use of a relay to switch from negative to positive and vice versa...Hope this helps..

 

ya, that ecu will work fine for you. no need to mess with a relay and ****, just make sure the "ground" wire coming off the IAB is connected to the type that it is meant to be connected to. meaning either a regular ground or a "hot ground"