Speed wiring
 

Hey all. Looking for a bit of wiring tech. Here's the scenario:

Recently installed a fresh 22re into a 1993 pickup. I did not have the original ecu or harness for the truck, so I used a late 80s ecu and harness. The exact year of these parts is unknown. There is no sticker on the computer. Anyways, the 1993 truck has the 3 wire speed sensor and applicable instrument cluster. The harness is missing this connector, most likely because it came on a vehicle with a cable driven speedometer.

So, everything is running and driving great. I manually wired the speedo, and it works fine. However, the ecu has a speed input (spd) which is not connected. This is causing the truck to continue adding fuel on deceleration. I'm running a wideband and can see this clearly. It also seems to be causing high idle when coming to a stop, until it's throttled down (could be unrelated).

Anyway. What is the correct way to hook the ecu spd port. This is just one wire.

3wire Speed sensor
Black/pink stripe - 12v in
Green/blue stripe - chassis ground
Green red stripe - speed signal out

Gauge cluster:
Green/red stripe: speed signal in (cluster has its own speed ground)

Ecu
Green/blue stripe (spd in) - ??? What wire goes here ???
Attachment 131143

You can find the harness part number just above the steering column, underneath the speedometer cluster. Then type it into google or Toyotapartseast.com and it should tell you what year the harness is from and then I would wire it to that year.

I don't know wiring but could the electric speedometer be a source of information for the computer as well? 92 and above is electric speedometer and 91 and older is mechanical.

Also some newer models and California models have a down stream O2 sensor so am wondering if that couldn't be an issue.

I am more comfortable in the 89 and older models and not the best on wiring, just offering some suggestions.

thanks for the suggestion. while that is great to know for the future, the harness/ecu in use come from an unknown vehicle, therefore impossible to look for the part number. Downstream o2 sensor... Although thinking out of the box is great that is not the issue. I'm getting great reading from the primary o2, which is all that is necessary. The problem is the truck is not cutting fuel on decel, which all fuel injected cars are supposed to do. The high idle i mentioned previously seems to be a sticky throttle body (unrelated).

I believe it to be one of two wires that goes to the ecu. either the green/red stripe (speed signal) or the green with blue stripe (speed sensor ground). The colours point to the ground wire but I'm not sure that makes sense.

here is a schematic for the 80s ecu. Not great at reading these. calling wiring gurus.
Attachment 131119