*THIS IS A COPY PASTE FROM ANOTHER SUBSCRIBED THREAD*
Seen people talking about some 02 harness's and such here on the thread, so i copied and pasted what i wrote with pics.
Heres some pictures below on what to look for when looking at 02 harness's. I have gathered as much data as possible. I can confirm all these 02 harness' from their respectable cars from 87-93.
Lets look at the cannon plug first. Im going to label the 02 cannon plug from left to right from top to bottom. Holding the cannon plugs main clip portion at the 12 oclock position and the slots at the 4 and 9 oclock position. The top 4 pins are 1-4 and the bottom 4 pins are 5-8.
Notice the loop wire on the cannon plug on the below pictures. This loop is different than a 5 speed and AOD transmissions. The 02 harness's ARE different in those aspects. This is the culprit from the signal return trace being burned up. The loop wire we are focusing on are from a mass air 02 harness and or mass air engine harness from an 88-93 (87 is left out because there was not mass air then, and 88 only had california cars that were mass air with 8LD computers). Now sense 87 was left out ill also show a picture of the SPEED DENSITY 02 harness as well.
This is a picture of a speed density 02 harness. NOTICE There is NO loop wire.
This plug is from an AOD Transmission. From what i can tell. there is NO difference between an AOD mass air 02 harness from 88-93. They are all the same. Looking at the back of the cannon plug the wire is looped between pin number 5 and pin number 6
This is a plug from an 87-90 5 speed 02 harness. This pin is looped from pin 1 to pin 5.
And the last of the 02 harness loop wires are from 91-93 5 speed 02 harness's. Notice the loop wire from pin number 1 to pin number 6
so from a tuning standpoint for those with power adders. I have helped diagnosis problems at my local dyno shop for years of fox's. Wanted to mention people that run 87-88 cars that were naturally speed density cars that were still running original wiring and/or that have been either rewired to mass air or an engine harness swap. You will have to swap or repin your 02 harness as well along with the mass air harness as mention above. The software will have problems reading or talking to the 02's if you are going to chip the car on a custom tune. Its a nightmare for tuners and will run your dyno bill WAY up for the hours trying to figure it out.