1990-1993 TT to 1995-1996 Engine Wiring Harness

[Augster]

After 24 years, the engine wiring harness of my 91 MT TT is brittle, cracking, split, and with broken connectors galore.

I've switched to the new-style 95+ fuel injectors courtesy of JWT's kit which now includes replacement pigtails.

Long ago I read that the 95+ wiring harness is a direct plug-n-play, except for the CAS and A/C clutch, but can't recall where I found that online article. Knowing someday I would do this upgrade, I bought a 95+ CAS and has been sitting in box for probably 10 years or more.

Can someone provide all the details for swapping in a 95+ engine wiring harness into a 90-94? Does the engine need to be pulled? That last question is probably moot for me since I will have to pull the motor to replace dead turbos anyways, but good-to-know for others.

TIA

[itsa300zx]

With what you are describing, you'll be good with the 95 harness. My suggestion would be to purchase from wiring specialties. They have included a quick disconnect near the ECU for easy of threading through the fire wall.

[evildky]

96 has no vtc, 90-93 has aiv's as well as vtc, so you'd need a harness for 90-93 unless you removed the iav's which basically do nothing. You can't use a 96 harness unless you run a 96 obd2 ecu and accessories and replace your cams.

[Augster]

I came across Z1 Motorsports engine wiring page and it states that a 95 wiring harness is usable in a 90-93 with the following notes:

http://www.z1motorsports.com/product_in ... ts_id=1551

This EFI Harness, although built for the '95 Twin Turbo Model, can also be used for any Twin Turbo model with upgraded (new style) injectors (equipped with a Manual Transmission) by changing only a few of the harness plugs. For the '94 model Twin Turbos with upgraded (new style) injectors this is a plug and play harness. For '90 - '93 Twin Turbo Models with upgraded (new style) injectors the connectors that need to be changed go to the AC Compressor Clutch and Crank Angle Sensor.

The '95 Twin Turbo models are equipped with a Boost Pressure Sensor that is not included on any of the earlier models. If you are using this harness on an earlier model you will have one 3 pin connector near the Mass Air Flow Meter that is not used.

Thus, it seems it will fit will only minimal modifications and with an unused connector hanging off.

[Augster]

96 has no vtc, 90-93 has aiv's as well as vtc, so you'd need a harness for 90-93 unless you removed the iav's which basically do nothing. You can't use a 96 harness unless you run a 96 obd2 ecu and accessories and replace your cams.

Will not be using a '96 harness; it will be a '95.

[Augster]

With what you are describing, you'll be good with the 95 harness. My suggestion would be to purchase from wiring specialties. They have included a quick disconnect near the ECU for easy of threading through the fire wall.

I just read up on this harness from Wiring Specialities and it seems perfect for what I need, and about $25 cheaper than the OEM harness from Z1. In addition, the Wiring Specialities harness includes disconnects at the components that may have different connectors depending upon model year; i.e. has connect tails for both styles of CAS, injectors, and AC compressor. I can sell off the CAS while keeping my old one and not worry about timing the new-style CAS.