So i put an 89 2.5t1 smec on my 88 2.2t1 harness in the Lancer Shelby and i've got no o2 signal.
JUST to be sure, did i cause a problem putting a computer expecting a 4-wire 02 on a 3-wire harness? I'm gonna go do some old-fashioned diagnosis but i figured if there's a chance it's an incompatibility issue i'd go ahead and ask!
Dont push the red button.You hear me?
I always thought the extra wire was for the heated sensor and it didn't matter
The 4th wire should be just a GND for the sensor heater. So, it shouldn't matter.
88 - the black wire is ground to the fuel rail bolt. the dark green/black wire is to the coil power. these are for the heater power. the black/dark green is the signal wire to the ECU. there is not a dedicated sensor signal ground. i think the sensor body is the ground for the signal. meter the sensor. see if the white heater wires are isolated from the body of the sensor. i dont remember. i always just swapped to the 4 wire sensor.
89 - black and dark green/black are still the same. heater power. the black/dark green is still the signal to the ecu. however, the 89 ecu also expects a black/light blue wire as a dedicated signal ground. this is the same wire as the black/lt blue signal ground on the TPS, the intake temp sensor, the map sensor etc. its the signal ground wire. now you dont really want to be connecting that signal ground to the power grounds (ie the o2 heater circuit) as it can dirty up the signal.
snag a 4 wire o2 and hook it to the 3 wires that are existing on the 88 harness, then run the signal ground over to the TPS and connect it.
Brian
Originally Posted by turbovanman
i really dont think it is given the wire color, the gauge of the older heater wiring, and what the wiring connects to. power ground (fuel rail bolt) vs sensor grounds ie TPS and MAP and stuff.
Brian
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older o2's just used the body of the sensor as ground. i think the 3 wire is like this.
on my old geo metro, i took a stainless hose clamp and clamped an extra wire around the body of the sensor to make sure the sensor had a good ground cause it was a 1 wire. i wanted it to get the max signal so it was lean as possible.
Brian
Awesome! I was worried the signal wire itself might have moved around on the 60-way but that's not the case. I have owned many 89s but never an 88 before so i just figured i'd ask.
Looks like there is not voltage coming off the sensor itself. Once i swap in a good sensor it should be good to go.
Dont push the red button.You hear me?
now the signal to the ECU on the 60 way i havent checked... chrysler usually made something keyed differently so the connectors wouldnt fit though if there was enough change from year to year.
www.oldschoolhotrodder.com has the pinouts of 88 vs 89 engine bay stuff so id do a quick double check but i think you are all set in swapping a 4 wire in there and connecting the signal ground to the TPS signal ground or whatever is close with a black/lt blue signal ground wire.
Brian
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