|This is a re-post of a post i did back in 2012, with all the pictures restored. Link to original post.... La-Z-Link
I hope this helps somebody....
When using a 95 harness and ECU in a 96 coupe, there are a couple of wiring issues that need to be addressed in order for the AC and the Fuel Pump to run correctly. I ran into these issues while swapping a pre-96 non-obd2 TT engine, 95 ECU harness and pre-96 ECU into my 96 slicktop.
On the 96, the wiring to control the AC and the Fuel Pump Controller run via the interior body harness instead of the through the engine bay via the EFI harness like the 90-95s. So if you are using a pre-96 ecu and harness you need to add three wires between the ECU and the body harness connectors in the footwell. (easy to do, but was a PITA to figure out)
If you just plug in the standard 95 harness and ECU the car will run but the fuel pump will always be on high, and the AC will not work. (note that the AC system is fine - it just doesn't get the start signal electrically when you turn it on)
Here are the details for re-wiring the connection from the ECU to the fuel pump controller:
On the pre-96 cars the fuel pump controller is connected to the ECU through the EFI harness to the brown connector on the fender beside the fuse block (referred to as connector E12 in the pre 96 FSM). The wires are color coded purple and black with a pink stripe. Reference 95 FSM E&EC page 153 below:
On the 96 the FPC is connected to the ECU through the body harness via a brown connector in the footwell just above the ECU. This connector is referred to as F5 in the 96 FSM. As with the pre-96 the wires are color coded purple, black with a pink stripe. Refererence 96 FSM EF&EC page 317 below:
To resolve this issue you need to cut F5 off of the old 96 harness and splice the two wires into the new 95 ECU harness. The color coding is the same for both years so it is just a matter of finding the matching wires and splicing them together. For reference, the fuel pump wires connect to ECU pins 35 and 105, as shown in the first schematic (above).
Here are the details for re-wiring the connection from the ECU to the AC:
As with the FPC, on the pre-96 cars the AC is connected to the ECU through the EFI harness to the brown connector on the fender beside the fuse block (referred to as connector E12 in the pre 96 FSM). The wire is color coded sky blue. Reference 95 FSM HA page 89 below:
On the 96 the AC is connected to the ECU through the body harness via the white connector in the footwell just above the ECU. This connector is referred to as F2 in both the 96 and the pre-96 FSM's. As with the pre-96 the wire is color coded sky blue. Refererence 96 FSM HA page 98 below:
Note that the AC wire is connected to pin 2 on connector F2. Pin 2 is not used on connecter F2 on the 95 harness. So for this step you need to de-pin the sky blue wire and pin from connector F2 from the old 96 harness and insert it into slot 2 in the same connector on the 95 harness. Make sure to leave several of inches of working length on the salvaged wire.
The color coding for the AC is sky blue for all years, so it is just a matter of splicing the freshly salvaged wire from pin 2 in connector F2 to the matching wire from the 95 ECU harness. As shown in the third schematic (above) the AC wire connects to ECU pin 46 on the 95 harness. There are a couple of blue wires coming off of the ECU and it is tricky to isolate "sky blue" from "blue" while laying in the footwell so rely on the ECU pinout.
As a final step, I de-pinned and terminated all three of these wires from the connector E12 (brown on the fender) on the 95 harness.
Addendum: Location of connectors F2 and F5
The 96 ECU harness has a extra (relative to the pre-96s) brown connector on it that connects to the body harness just above the ECU in the footwell. This is referred to as connector F5 in the 96 FSM. Both harnesses have the white footwell connector referred to as F2.
96 ECU harness showing extra brown footwell connector - see F5 ....
95 ECU harness for comparision ....
ConVerTT - 93 Hi Compression TT Convertible (black)
XtraVerTT - 93 Hi Compression TT Convertible (glacier white)
SlickTTop - 96 OBD1 TT Slicktop (black)
Old Yeller - 90 Slicktop NA (PGY)
RedZed - 90 "factory" 2+0 TT
EmoZed - 89 RHD for parts - RIP
And their hot Asian Cousin - 01 Acura NSX NA