Jump to content
SAU Community

Recommended Posts

Hi everyone, might be in the wrong section but it is climate control related, I really need help here, searched and searched but turned up nothing, seems this is a new problem.

Car in question is a 95 V-spec BCNR33. The climate control recently developed a strange problem; when it is turned on, it will sometimes only blow air to the footwell regardless of changing through the modes/temp/AC on or off. But just let it run and it will eventually blow air to the correct channel selected and switching between modes then becomes normal.

Here's the weird thing, as soon as it directs air correctly, it triggers the 4WD/A-LSD lights (same thing if AC on/off).

I don't think it's the plastic gears cos there's no abnormal noise, crunching or anything, just the inability to change air direction when required, I suspect an electrical issue, is the climate control system connected to the Attesa somehow? Would sticky air control gears coming free cause a sudden/heavy electrical load to affect the Attesa?

Please help, guys, this problem has me stumped! Cheers in advance, guys!

Darrel.

Link to comment
https://www.sau.com.au/forums/topic/484473-climate-control-triggers-4wd-light/
Share on other sites

1 hour ago, Darrel said:

is the climate control system connected to the Attesa somehow

No.

1 hour ago, Darrel said:

I suspect an electrical issue

Yes, sounds like a wiring fault, like insulation damaged on 2 adjacent wires (one from AC, the other from ATTESA CU to dash, for example).

1 hour ago, Darrel said:

Would sticky air control gears coming free cause a sudden/heavy electrical load to affect the Attesa?

No. But it does sound like you have at least a version of the usual mode door actuator failure.

46 minutes ago, GTSBoy said:

No.

Yes, sounds like a wiring fault, like insulation damaged on 2 adjacent wires (one from AC, the other from ATTESA CU to dash, for example).

No. But it does sound like you have at least a version of the usual mode door actuator failure.

Hi @GTSBoy, cheers for that, I'm leaning towards an electrical fault in the climate control then cos when I got the car the control panel had been relocated into the glove compartment by the previous owner in Japan, I had it moved back and it's been problem-free for 3 years now, will take a look at it and check the door gears too and update. Cheers mate!

18 minutes ago, Duncan said:

I don't suppose you have any way to monitor the car's voltage when the issue occurs....it might be dropping and ATTESSA is the first thing to complain

Hi @Duncan, did think of it too and was contemplating a daisy-chain ground cable from the trunk to the engine bay but I didn't notice any lights dimming or engine stuttering etc. I think my turbo timer might have a voltmeter feature though, I'll check and if not I'll install one, thanks for your input!

24 minutes ago, GTSBoy said:

Why would you do that? The body is one big piece of steel wire.

Thought it might help given the aging/deteriorating cables & connections. Not necessary then? @DuncanI've set my turbo timer to display real time voltage, will monitor and update. 

Just now, Darrel said:

I've set my turbo timer to display real time voltage, will monitor and update.

That monitors the voltage where the turbo timer is connected. Will not tell you if you have a problem where the ATTESA CU is powered. You need a multimeter, manually probe the power connections while you wait for the AC to cause the light to come on.

Agreed....but if it is what he has....

I was wondering if there was a voltage drop with the AC on, the ATTESSA is pretty voltage sensitive, particularly if the subframe earths are missing/broken etc

7 hours ago, GTSBoy said:

That monitors the voltage where the turbo timer is connected. Will not tell you if you have a problem where the ATTESA CU is powered. You need a multimeter, manually probe the power connections while you wait for the AC to cause the light to come on.

I will try that, might you have a pin out for the Attesa CU? 

7 hours ago, Duncan said:

Agreed....but if it is what he has....

I was wondering if there was a voltage drop with the AC on, the ATTESSA is pretty voltage sensitive, particularly if the subframe earths are missing/broken etc

I was thinking that too, which got me thinking if they shared a common earth or supply (of course that doesn't make sense 😅 )

5 hours ago, Darrel said:

I will try that, might you have a pin out for the Attesa CU? 

Not for an R33. The R32 GTR wiring diagrams are posted on here, by me, sometime in the last couple of years. The ATTESA CU's are not the same, but the power and earth terminals might be.

  • 2 weeks later...

Hi guys,

A bit of an update, gremlin is still at large, checked voltage when the AC triggers the 4WD light, stable at 13.x, no voltage drop or surge. However, I took off the control panel and found some likely culprits causing the AC problems; an IC & a few caps, although I still don't know how it links to the Attesa. I've sent the control panel to a capable electrician, he said it looks promising. Any opinions, guys? Thanks in advance and have a pleasant weekend.

Regards,

Darrel.

IMG_20230310_121206.jpg

IMG-20230311-WA0023.jpg

IMG-20230311-WA0024.jpg

IMG_20230310_120622.jpg

Well, there's probably nothing wrong with those caps, but they're easy to test for ESR and swap if needed, so go right ahead. That chip looks bad. Are the black contacts burnt? From heat?

Anyway, if they are damaged thus, then my original point remains valid. Wiring problem somewhere else (ie, outside the respective modules). Cause a short somewhere and the high current runs to places it will do damage.

@GTSBoy will likely swap those 28 year old caps just to be safe. Not sure what the black stuff on the chip is, could be burnt as you said and likely damaged so will replace it too. Will get this fixed and get the AC harness checked, maybe something went wrong when they removed harness extension. Will update then, cheers!

  • 1 month later...

Hi guys!

Just wanna update everyone, I've found the issue.

Climate control system was faulty but totally unrelated to the Attesa fault. The PCB was corroded from the leaking capacitors and caused the erratic function, tried to fix it but no avail so I got a pre-loved unit and that fixed it but Attesa fault still came on.

Now the main issue. I noticed that throttle input would prevent the Attesa fault from coming on for example when you hold the gas constant at around 1500 rpm it wouldn't come on. Made me think if it had anything to do with TPS so I checked the TPS voltage at the throttle body. A long while ago when I checked it was about 0.4 almost 0.5 v, I thought it might have gone out of spec but it was exactly where I left it. So I checked the TPS signal at the Attesa CU and I was getting about 0.02, practically nothing. I proceeded to adjust the TPS till I got about 0.8v and checked the signal at the Attesa CU, I got 0.4v. I went for a drive and viola, no fault since then. I consulted Google and apparently it is quite common for the TPS signal to drop out in power FC. I'm not sure why causes this but I suppose the easy fix to this is to install a unity amplifier to repeat the TPS signal to the Attesa CU.

Anyway, I hope this helps our mates here facing the same Attesa fault gremlin, I don't know for sure but if it can happen to PFC I think it could happen to stock ECU's too. Hope this helps and cheers for all your input, thank you very much, guys!

Good update :)

In that case, you should check the continuity of the TPS wire from the ECU to the ATTESSA unit. If it has high resistance, it is unlikely to be the only wire in that loom with a problem

3 hours ago, Duncan said:

Good update :)

In that case, you should check the continuity of the TPS wire from the ECU to the ATTESSA unit. If it has high resistance, it is unlikely to be the only wire in that loom with a problem

Hi Duncan, yeah you're right, I wouldn't be surprised if I find a few signals out of spec, I'll get to it when time permits. Cheers for that!

Yes, a dirty pin or a strained connection where all but a few strands of wire have pulled out of the back of a crimped pin sound like a reasonable cause.

Mind you....it's not as if there's supposed to be any current flowing in these wires. There shouldn't be any voltage drop. They literally are just voltage signals. Put 1V in at one end and fully expect 1V visible at the other.

I might suspect earth connections. If you have poor earths somewhere, then you get different CUs around he car thinking that 0V is in a different place, leading to the sort of thing you've observed.

And....for the love of Mike, do not just randomly install some sort of amplifier into a signal line meant to control a CU's decisions. That can only lead to worse things.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
    • Hi,  Just joined the forum so I could share my "fix" of this problem. Might be of use to someone. Had the same hunting at idle issue on my V36 with VQ35HR engine after swapping the engine because the original one got overheated.  While changing the engine I made the mistake of cleaning the throttle bodies and tried all the tricks i could find to do a throttle relearn with no luck. Gave in and took it to a shop and they couldn't sort it. Then took it to my local Nissan dealership and they couldn't get it to idle properly. They said I'd need to replace the throttle bodies and the ecu probably costing more than the car is worth. So I had the idea of replacing the carbon I cleaned out with a thin layer of super glue and it's back to normal idle now. Bit rough but saved the car from the wreckers 🤣
    • After my last update, I went ahead with cleaning and restoring the entire fuel system. This included removing the tank and cleaning it with the Beyond Balistics solution, power washing it multiple times, drying it thoroughly, rinsing with IPA, drying again with heat gun and compressed air. Also, cleaning out the lines, fuel rail, and replacing the fuel pump with an OEM-style one. During the cleaning process, I replaced several hoses - including the breather hose on the fuel tank, which turned out to be the cause of the earlier fuel leak. This is what the old fuel filter looked like: Fuel tank before cleaning: Dirty Fuel Tank.mp4   Fuel tank after cleaning (some staining remains): Clean Fuel Tank.mp4 Both the OEM 270cc and new DeatschWerks 550cc injectors were cleaned professionally by a shop. Before reassembling everything, I tested the fuel flow by running the pump output into a container at the fuel filter location - flow looked good. I then fitted the new fuel filter and reassembled the rest of the system. Fuel Flow Test.mp4 Test 1 - 550cc injectors Ran the new fuel pump with its supplied diagonal strainer (different from OEM’s flat strainer) and my 550cc injectors using the same resized-injector map I had successfully used before. At first, it idled roughly and stalled when I applied throttle. Checked the spark plugs and found that they were fouled with carbon (likely from the earlier overly rich running when the injectors were clogged). After cleaning the plugs, the car started fine. However, it would only idle for 30–60 seconds before stalling, and while driving it would feel like a “fuel cut” after a few seconds - though it wouldn’t fully stall. Test 2 – Strainer swap Suspecting the diagonal strainer might not be reaching the tank bottom, I swapped it for the original flat strainer and filled the tank with ~45L of fuel. The issue persisted exactly the same. Test 3 – OEM injectors To eliminate tuning variables, I reinstalled the OEM 270cc injectors and reverted to the original map. Cleaned the spark plugs again just in-case. The stalling and “fuel cut” still remained.   At this stage, I suspect an intermittent power or connection fault at the fuel pump hanger, caused during the cleaning process. This has led me to look into getting Frenchy’s fuel hanger and replacing the unit entirely. TL;DR: Cleaned and restored the fuel system (tank, lines, rail, pump). Tested 550cc injectors with the same resized-injector map as before, but the car stalls at idle and experiences what feels like “fuel cut” after a few seconds of driving. Swapped back to OEM injectors with original map to rule out tuning, but the issue persists. Now suspecting an intermittent power or connection fault at the fuel pump hanger, possibly cause by the cleaning process.  
×
×
  • Create New...