Identifying Engine and the right Engine Harness

[Jivaldinho]

Hi all, desperately looking for some help.

I have recently purchased an NSX here in the UK. It is a 99 3.0 auto, it was an ex show car that used to belong to Knights Racer after which it went through various owners and cowboy mechanics before it reached me.

The car's speedometer wasn't working and currently the car is running in limp mode (won't go above 4000 rpm). After what seems like an eternity investigating we found what looked like a piece of the harness missing. This was located near the ECU and it seems to be the harness coming in from the engine bay connecting to the harness in the main compartment. the mechanics patched one of the cables from the small block in the pic below to the part of the missing block and now the speedometer works but the car is still in limp mode.





So i went to a Breakers to find the relevant loom but it became even more confusing.

there were 3 NSX's at the breakers yard. 2 Autos and 2 manuals. 1 auto which was not being stripped had the configuration shown in the picture including the missing piece of the loom. That was a 96 NSX. The other 96 Auto didn't have the larger grey block connector, it only had the smaller grey Block connector. The 2 manuals also only had the 1 small grey block connector and not the larger one. My car is currently at a garage and they tell me the interior loom hasn't been taken out or changed but it does look like the loom coming in from the engine bay has been disturbed / changed. This could be a possibility as going from pictures of my car that are readily available on the internet, My NSX at one point had a red top engine but currently has a black top engine. If an engine swap was done then it looks like the loom was changed as well. As far as i can tell I have the 3.0 engine so is it a case of finding an engine harness to match my engine and interior loom or find an interior loom / ecu to match the current engine loom?

If i do go for an engine harness, how do i identify the engine age / model to select the right loom as I assume over the years there were changes that resulted in different looms.

PS one thing did stick out on 4 NSX's at the breakers yard. the one with the 2 grey blocks and and missing loom was a Japanese import. I don't know if this is significant or not.

Guys I am tearing my hair out with this one. Any help would be appreciated!

 

[OLDMNSX]

Greetings,
Since you have had the car did it ever run right?

From the pictures it looks like there is one wire that has been cut. Can you find the other end of that wire? What were the Grey connectors in the picture connected to? They look like ECU connectors. Do you have a OEM maintenance manual with the wiring diagram? I don't think that you need to replace the harness, just track down the missing / broken wire. Some people get very intimidated by wiring diagrams, but they are really just road maps of the wiring in your car. Familiarize yourself with the diagram and then just start looking for components and wire colors. Take your time.

What is the serial number (its actually a part number) on the current engine? If the car had a "Red Top Engine" i.e. NA2, then the ECU had to be changed and other wires, connectors, sensors etc due to the OBD II of the NA2 engine. I kind of wonder if it was really converted to OBD II, and not just the valve covers and intake cover? I don't know for sure since I have not done a NA1 to NA2 swap but I would think it would be a lot of wiring changes.

Keep us updated.
Brad

 

[Jivaldinho]

so it turns out I am running 99 NA1-DBW-4 O2 sensor-AT spec ECU + 94 AT engine (replaced TH body with DBW version) + non-DBW engine loom (information courtesy of Kaz) now the fun starts getting everything to work with what is already there