Attesa code 18 / pump malfunctioning

[weikleenget]

Hi all, trying to get my AWD system working properly after a soup to nuts rebuild. The computer is throwing codes 8, 9 (ABS was deleted) and also code 18 which seems to be the issue. Today we tried the bleed procedure and still doesn’t work.
 

Here’s the description from the builder: on ignition the pump pumps oil, when the pressure reaches the desired value, the pump turns off and the oil is stored in the tank by closing the check valve, in our case it seems to me that it does not work and when the pump pumps up the pressure to the operating level , the sensor turns it off and the liquid is squeezed back through the pump into the tank, you can even hear the pump spinning in the opposite direction, the pressure decreases and the sensor turns on the pump again, and this all repeats endlessly.

The AWD system worked after I bought the car but not since the rebuild. I changed the G sensor to the Do-Luck unit, maybe that could also be the issue? It’s a pain to change so we haven’t tried it yet

 

Hopeful to get this worked out, I really wanted an AWD skyline. Thanks 🙏 

[Duncan]

Probably worth starting with the 32 GTR workshop manual (you didn't say which car and don't have it on your profile).

https://www.hgeconsulting.com.au/gtr_32_service_manual_indexed.pdf section c3 stars page CH-57

[weikleenget]

My mistake yes it’s a 32 GTR, I’ll check it out but we did find the code 18 troubleshooting and all the referenced points have continuity, so the flow chart says the computer is faulty. Just seeing if anyone had a similar issue before shotgunning parts. Thanks

[Duncan]

Yeah that does suck considering how hard these computers might be to find, wherever you are.

80s Electronics were mind blowing to the 80s, but not so much these days. Might be worth opening the computer and looking for any burned tracks or components or other obvious issues rather than replacing it straight up

[weikleenget]

I think it’s possible a defective part on the hydraulic pump like the pressure switch is causing the fault, I checked the troubleshooting flow chart again and it actually says hydraulic unit failure, so I guess that’s the pump, but my pump is cycling constantly so my thinking is either a valve was installed wrong or a part is not working properly

Or the do-luck G sensor is defective?

[Duncan]

Issue inside the hydraulic unit was my thought after looking at the guide too, but I haven't really heard of that before. Potentially it is just the pressure switch has failed, original is not available but there are aftermarket equivalents like this from Frenchys https://frenchysperformancegarage.com/products/fpg-nissan-gt-r-attessa-pressure-switch-replacement

I can't see how the g sensor would cause the issue but it is easy to check, just unplug it. The hydraulic unit should pressure up regardless of what the ECU thinks is happening in the car

 

[joshuaho96]

On 11/25/2023 at 3:12 PM, weikleenget said:

I think it’s possible a defective part on the hydraulic pump like the pressure switch is causing the fault, I checked the troubleshooting flow chart again and it actually says hydraulic unit failure, so I guess that’s the pump, but my pump is cycling constantly so my thinking is either a valve was installed wrong or a part is not working properly

Or the do-luck G sensor is defective?

G sensors do not affect the pump. Entirely separate issues. Most likely your hydraulic unit has some fault. Is your nitrogen accumulator reasonably new? If it’s original you probably need to replace it along with whatever else is broken. 

[weikleenget]

8 hours ago, joshuaho96 said:

G sensors do not affect the pump. Entirely separate issues. Most likely your hydraulic unit has some fault. Is your nitrogen accumulator reasonably new? If it’s original you probably need to replace it along with whatever else is broken. 

Yes the accumulator was changed new, I’ll try change the pressure switch and see if it clears the fault

[joshuaho96]

6 hours ago, weikleenget said:

Yes the accumulator was changed new, I’ll try change the pressure switch and see if it clears the fault

yep, both can fail: https://www.gtrusablog.com/2013/06/attesa-ecu-fault-code-18-and-19.html