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If you use a consult cable and the free software OBD scan tech, you should be able to access the auto section of the ECU. It will display the status of all the relevant sensors and solenoids. This works on a s1, I know there are some differences with the later ECUs. That would be a good start to see what is going on. You can log the sensors as well to capture what is happening when the gears flare.

Ok, despite my inability to read japanese symbols, I think I have found the correct wiring diagram for a 96 Stagea RS4V, and it clears up a lot of problems. Turns out a 7.5 amp fuse in the drivers side knee fusebox supplies the AC relay coil, AAC, boost solenoid, VVT and o2 sensor signal. It didn't look blown, but it was and has happened more than once. Since I don't use the boost solenoid, I will disconnect it to reduce the power draw and see if it causes an error. Perhaps a resistor will be needed in to bridge the plug so the ECU still thinks its connected.

Is the bleeder open?

Marko Paulo?

Lol thanks. Ive got the ATTESA working again, had to feed it a new tacho signal. Ill check out Trojan, it would be good to chat with them anyhow.

Are there any recommendations for regassing A/C systems on skylines/stageas in Canberra? Is the receiver dryer a pricey unit on an RB25?

Ok after a bit of testing on the dryer unit, Im only more confused. This is all I could determine: Pink wire - 12v, when earthed it activates the A/C thermo fan Yellow/black wire - 12v, when earthed it activates the FICD relay Black - earth? When you bridge the above to this pin they activate Blue wire - ???. Hard to get a voltage reading. 1v max. Earthing doesnt seem to do anything.

Pin 46 should be the signal from the climate control/ AC control to tell the ECU when the climate control "thinks" the AC should be running. The ECU can disable the AC, for example on wide open throttle, among other situations. It also bumps up the idle to account for the load on the engine. If the ECU allows the compressor to run, then it grounds pin 9. I would do a lot of research before bypassing factory safety features. For one, does an AC compressor have a rev limit? Does the ECU cut the compressor after a certain RPM?

Thanks, I have a suspicion that the problem is in that plug. The day when the air con worked, I fiddled with that plug. Maybe the connection isn't very good. There is pressure in the system, I just don't know how much. I did test the schrader valve on the air con pipes for an instant. If it was genuinely tripping a low pressure switch, it shouldn't be intermittent?

BTW Ive tested the relay too and its fine.

Firstly I used extension wires to simultaneously plug the relay in while using the multimeter. Voltage was measured between the +ve pin on the relay coil and battery ground, without the relay coil forming a circuit. It measured 6.8 volts, where I understand it should read battery voltage. I then completed the relay coil circuit by grounding it to the battery. It did not activate the relay and the voltage dropped to zero. So the one fuse can't directly be connected to both the coil and the switch, there must be something in between the fuse and the relay coil responsible for the voltage drop. Where are the pressure sensors? I can only find the 4 pin plug on the dryer unit. Is that both a high and low pressure cutoff and how can I test it?

After tons of searching I still cant find a straightforward answer. My understanding that activating the clutch compressor goes thusly: (Battery +ve) ------> (low pressure switch) ------> (A/C relay coil) ------> (ECU pin 14) ------> (Battery ground) Keep in mind this is a stagea s1, so pin number will be different. Its mainly the components that Im interested in. The problem I am having is that the air con compressor will not turn on. The ECU side seems to be fine. I notice that when I probe the A/C relay terminals, the power terminals read battery voltage (normal), however the relay coil terminals only reads about 6.8 volts, whereas what I read in the R33 manual states it should be battery voltage. If I try to manually ground the relay coil, there isnt enough power to make the relay click, and the voltage drops to zero. So, is my diagram above correct? If so then am I right in thinking that the low pressure switch is causing this? Is it an on/off state switch or some kind of resistor? Where is the switch? Its odd that the air con did come as normal once a week or two ago, however I have not been able to replicate that.

Pretty hard to believe the kms are genuine, unless its a garage queen. Its like 4000 kms a year. While I find the handling and steering of the stagea to be better than new cars Ive tried, it comes at the expense of refinement, noise and ride quality. Still, you love the car for its flaws. Plus with the money you sink into it, it would be silly to sell.

I figure that will be the case, but I think my ECU is still faulty too. I dont think the piggyback ECU is going anywhere, maybe its time for a mad 1990's "futuristic" digital dash? Im not sure why they didn't catch on.

Woohoo, well a long story short, the ATTESA requires an RPM signal (along with a TPS signal, but that was functioning) It seems both the tacho pin on the stock ECU is non-functional, and also appears as though the tacho itself is faulty. Its hard to tell exactly where and how the wires to the tacho and ATTESA are joined, but I fixed the 4WD by splicing a new wire from the tacho pin on the ATTESA harness to one of the aux outputs on the adaptronic which I configured as a tacho signal in WARI. The warning lights cleared straight after starting the car, and I could hear the pump priming. Such a beautiful sight. Tach is still dead, ironically it will probably be more of a problem then the 4wd...

Well, theres definitely no lights coming from the attesa computer in the back. I can't even see the "port" where the light would be that people have referred to (mainly on r32s though) Tried manually bridging the 4WD relay in the engine bay to hear if anything worked. Strangely the synchro light went out! Also, I did an ECU scan through OBD scan tech. It can only detect 3 computers: engine, auto trans and airbag. I now have NFI how to read any codes from the attesa.

Id keep looking! Its worth trying some other gentle solvents which have no effect on the car paint, like an orange solvent. Once you start taking off material, only a respray puts it back.

Negative on that as well.

The synchro button? It has been off, though I tried turning it on and off. Had no effect.

double post

Just bumping this. I have put my head in through the passenger side flap in the boot to try and see any flashes of light. I tried this with the ignition in the on position, and straight after starting, but could not see any lights. I have read that the car needs to be driven over 30kmh for a minute to bring up error codes, even though the warning lights are on the dash as soon as the car is started. Can anyone confirm this? Where exactly is the flashing LED? I poked around with a mirror looking for a light on the computer, but all I could find was a small hole in the computer approximately on the bottom right of the unit, if you are looking at it from inside the boot.

In the boot behind the carpeted interior panel, just rear of the strut tower, passenger side. You can see it through the flip down panel. Out of interest what program were you using to read the attessa codes? I have 4WD, synchro and ABS lights always on the dash and neither ECUtalk nor OBD scan tech give me any codes for it!

For my awd s1, strangely stagea specific shocks were too long, and GTR shocks fit just right.

It is like having the synchro button on, with the light and the low speed clunking. However the position of the synchro button doesnt make a difference. The auto gearbox seems to be functioning normally as far as I can tell. Does the attessa system have its own computer and such? I remember something behind the carpet at the rear of the wagon on the passenger side. Opposite side to the reservoir tank.

* Make that ignition signal. Theres no coils attached to the stock ECU.