BNR32 AC pin 9

[BourneToLive]

Hello, 

I recently purchased an AC kit from Frenchy’s Performance Garage (FPG) that I am trying to wire up. Somebody at FPG was kind enough to send me a diagram of what it’s supposed to look like. I will attach it. Everything is pretty easy to understand, except for where I’m supposed to find the ECU pin 9 feed. I figured, from the diagram, that the wire was connected to the OEM drier pressure switch (which I removed) and that I could get a feed from there, but there are two wires and I am not entirely sure anymore. Pin 9 on the ECU is the AC Relay. This is a new kit released by FPG intended to be installed by professionals, but that’s not an option for me. 

Edited September 29, 2022 by BourneToLive

[joshuaho96]

6 hours ago, BourneToLive said:

Hello, 

I recently purchased an AC kit from Frenchy’s Performance Garage (FPG) that I am trying to wire up. Somebody at FPG was kind enough to send me a diagram of what it’s supposed to look like. I will attach it. Everything is pretty easy to understand, except for where I’m supposed to find the ECU pin 9 feed. I figured, from the diagram, that the wire was connected to the OEM drier pressure switch (which I removed) and that I could get a feed from there, but there are two wires and I am not entirely sure anymore. Pin 9 on the ECU is the AC Relay. This is a new kit released by FPG intended to be installed by professionals, but that’s not an option for me. 

One pin is 12V, the other pin is ground. Pin 9 on the ECU is going to be the ground side. When you turn the car on even if the engine isn't running it will send voltage to the pressure switch. Use a multimeter to measure the voltage of the pins to determine which side is positive and which side is negative if you don't know the wire colors. The negative side is pin 9 if that diagram is correct. I would have to check the factory service manual to be 100% sure.

[BourneToLive]

The two wires that ran to OEM drier pressure switch are Aqua/White and Green/Yellow. I’m not sure about the aqua one. I’ll attach a picture of the wires. 

[joshuaho96]

11 minutes ago, BourneToLive said:

The two wires that ran to OEM drier pressure switch are Aqua/White and Green/Yellow. I’m not sure about the aqua one. I’ll attach a picture of the wires. 

Did you try measuring the voltage on the pins to try and figure out the polarity? It's either that or you can measure the voltage of each pin relative to chassis ground. Once you know where the voltage drop occurs that will narrow things down significantly.

[BourneToLive]

I should be able to determine with a test light as well, right? 12v IGN wire should light up the test light. I don’t have a multimeter on hand at the moment. 

[BourneToLive]

1 hour ago, joshuaho96 said:

Did you try measuring the voltage on the pins to try and figure out the polarity? It's either that or you can measure the voltage of each pin relative to chassis ground. Once you know where the voltage drop occurs that will narrow things down significantly.

I just tried with a test light. Clamped to a good grounding point and start poking around in the connector. Nothing happened with the Aqua/White wire, and with the Green/Yellow wire, I heard a click around the relay box. 

[joshuaho96]

20 minutes ago, BourneToLive said:

I just tried with a test light. Clamped to a good grounding point and start poking around in the connector. Nothing happened with the Aqua/White wire, and with the Green/Yellow wire, I heard a click around the relay box. 

Reasoning about it if the switch were actually closing you would have the AC relay click on in both instances, so presumably the green/yellow wire is the +12V side of the pressure switch while the aqua/white wire is the ground side. From your diagram the ground side is switched by the ECU pin 9 so my guess is the aqua/white wire is what you're looking for as a mediocre electrical engineer.

I would recommend going to harbor freight to get a cheap multimeter to verify what I'm saying still but if you can't be bothered maybe someone else will check my work.

[GTSBoy]

The test light is to automotive electrical diagnosis as tapping on the chest is to working out what is going on in the lungs of a patient. It was fine, 100 years ago, when that was all they had. Now, we have actual tools for this job.

Using a test light in this context requires actual thought.

I think I concur with Josh's opinion above. The wire that lead to the relay clicking on is the hot one. That's why the relay clicked on when you earthed it through the test light. You made enough current flow through it to pull it in. Therefore, obviously enough, the other side of the pressure switch will go to the ECU and provide the two steps required to make the AC come on. Those being sufficient charge pressure, and the ECU asking for it.

[BourneToLive]

Alright. That’s good enough for me. I appreciate the help guys. 

[BourneToLive]

I have a follow-up question. Based on the picture I added of the wires, which ones would you say is which? Would you say the solid blue w/stripped wires are for the pressure switch 12v IGN/Pin9 wires and the solid red w/ white and solid black w/white are for the relay and ground? If it seems obvious to you, I’m sorry; I just want to be sure.

Edited October 6, 2022 by BourneToLive

[Duncan]

They really have not given you enough information to install this kit. Are there any tiny tiny numbers on the pressure switch to determine which is 1,2,3,4 that way?

Diagram shows pin 1-2 are a circuit and 3-4 are a circuit, so assuming the switch is normally closed (I think it is because the switch turns off when target pressure is reached) you can use your multimeter to identify which 2 pairs have continuity.

If it was factory wiring you would guess the red wires are 12v and white wires are earth but this is aftermarket so all assumptions are off.

[BourneToLive]

18 hours ago, Duncan said:

They really have not given you enough information to install this kit. Are there any tiny tiny numbers on the pressure switch to determine which is 1,2,3,4 that way?

Diagram shows pin 1-2 are a circuit and 3-4 are a circuit, so assuming the switch is normally closed (I think it is because the switch turns off when target pressure is reached) you can use your multimeter to identify which 2 pairs have continuity.

If it was factory wiring you would guess the red wires are 12v and white wires are earth but this is aftermarket so all assumptions are off.

Yeah, there was not much information provided because the kit was intended to be installed by a professional. I don’t have that option in my area, so I’m on my own. 
 

The connector does have numbers on it. I labeled them appropriately based on the diagram I was given, but it didn’t make sense to me because of the colors of the wires that matched the numbers. I watched FPG’s install video on YouTube (didn’t cover wiring the kit) and noticed that their wires are terminated in a different order on the connector side, which is why I asked the question. I just want to be sure. 

[joshuaho96]

14 hours ago, BourneToLive said:

Yeah, there was not much information provided because the kit was intended to be installed by a professional. I don’t have that option in my area, so I’m on my own. 
 

The connector does have numbers on it. I labeled them appropriately based on the diagram I was given, but it didn’t make sense to me because of the colors of the wires that matched the numbers. I watched FPG’s install video on YouTube (didn’t cover wiring the kit) and noticed that their wires are terminated in a different order on the connector side, which is why I asked the question. I just want to be sure. 

Do you have the spec sheet for the switch they provided? Looks like there's some writing on the switch so you should be able to look up the part.

[BourneToLive]

I got myself a multimeter. There was no continuity in either of the pins. I’m just gonna wing it and see what happens. 

[BourneToLive]

This is what I managed to come up with, so far. Worst case scenario, I have to depin and move around some pins at the pressure switch. I know everything else is right. I’m think about splicing both the pressure switch ground and fan ground together. That shouldn’t be an issue right?  Excuse the amateur wiring. 

[Duncan]

honestly mate, have you given frenchy's a call? They have not provided you enough information and you risk blowing something expensive up if you get it wrong. No mechanic would have got this far without giving the supplier a rocket about wasted time and poor instructions

[BourneToLive]

On 10/10/2022 at 6:12 PM, Duncan said:

honestly mate, have you given frenchy's a call? They have not provided you enough information and you risk blowing something expensive up if you get it wrong. No mechanic would have got this far without giving the supplier a rocket about wasted time and poor instructions

I have reached out by email for clarification, but they stopped responding the fourth email. I found this picture diagram on the trinity pressure switch and found it helpful. 

This is what I got so far: 

Black/white= 12v IGN AC feed

Blue/red= Ground

Red/white= ECU AC pin 9

Blue/white= Relay