i have done a obd2 to obd1 conversion using a p72 ecu on my 97 gsr and a conversion harness from blown90hatch.
with the obd2 p72 the iab's work fine. but when i put in the obd1 ecu and the harness the iab's stay open all the time because there is no vacuum to close them. i have read that the obd1 controls the iab's by giving a constant 12v power at 5800 rpms while the obd2 gives a constant ground to the iab's at 5800 to make them open up (or vice versa, i cant remember right now). is this why i am not getting vacuum with the obd1 ecu? can i just switch the wires around at the iab's plug or do i need to switch wires on the harness ? any help would be greatly appreciated.
thanks