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Discussion Starter · #1 ·
having a real nightmare with my 4wd system on the r33 gtr v spec.
I have just done the headgasket and been mapped on dyno, 4wd worked perfectly prior to headgasket failure.

I can unplug the tps switch and the attessa doesn't even put up an error code ?
but if I unplug a wheel speed sensor fault code comes straight up.

we have been looking at the attessa pump at the back rear corner of the car and since unplugging the pump, checking for voltage and pluging back in we now have lost all 4wd, we didn't have much before but there was a little.


when I test for voltage there is 5v at the loom to the pump but when I plug the pump in the voltage is gone ?
gonna try running an earth incase its bad earth next.



just thought id stick this thread up incase anyone has any other ideas we can try. I want to 100% isolate the fault before we remove the gearbox and transfer box.
 

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If this fault has occurred after removing the cylinder head, I would look in this area and check that everything has been reconnected and you haven't left a ground connection off somewhere. The fact that the Atessa ECU isn't seeing the TPS switch being disconnected as a fault may mean that there is a short circuit or low resistance on this part of the circuit. If the TPS is closed at idle, and open when the throttle is applied then this could be the problem.
 

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Discussion Starter · #4 · (Edited)
just got to the attessa pump, if we give the pump 12v the 4wd locks up and does what it should. with regard to wiring id expect the ecu to still give up a fault code if it wasn't doing what its supposed to do.

looking at the attessa unit there is a pump, then a cylinder infront of it with a 2 wire switch next to it I have disconnected and bridged this switch as I think its a pressure switch but the pump still doesn't pump ?

all that's left is what appears to be the 2 distribution units a bit further forward 1 goes to the diff the other to the gearbox.
 

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Discussion Starter · #5 ·
If this fault has occurred after removing the cylinder head, I would look in this area and check that everything has been reconnected and you haven't left a ground connection off somewhere. The fact that the Atessa ECU isn't seeing the TPS switch being disconnected as a fault may mean that there is a short circuit or low resistance on this part of the circuit. If the TPS is closed at idle, and open when the throttle is applied then this could be the problem.



the tps voltage is as it should be, 5v across red and black, and white wire has 0.43v at idle increasing with revs.

wouldn't those figures be off if I had a wiring issue ?
 

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Discussion Starter · #6 ·
we have checked everywhere and cant find any connections we missed.

im getting to the point where I don't know what to do with it.
 

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Discussion Starter · #8 ·
PM Andy (R32 Combat) he has the wiring diagram and a lot of knowledge of the ATTESA system.

cheers I have pmd him.

the weird thing is if I unplug the pump the plug ecu side shows 4.7v, also if I test either side of the pressure switch wires ecu side with switch disconnected I also get 4.7v ?

as soon as I plug the pump in the voltage drops to 0 ?
 

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Skyline Section Manager
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Un-plug the TPS. Start the engine and see if the ATTESA throws up a fault code 75.

Its just a check to see if the ATTESA is detecting faults.
 

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Discussion Starter · #10 ·
Un-plug the TPS. Start the engine and see if the ATTESA throws up a fault code 75.

Its just a check to see if the ATTESA is detecting faults.
I did that andy it doesn't throw up a fault code ?

if I unplug wheel sensor or the attessa pump fault light comes straight on ?
 

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Skyline Section Manager
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I would suggest the ATTESA C/U might be faulty?
Is there any way you can try another?
 

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Discussion Starter · #12 ·
I would suggest the ATTESA C/U might be faulty?
Is there any way you can try another?

I could try and find one and buy it I guess, its a v spec though so a pain to find.
I did have a little bit of 4wd, but once I unplugged the attessa pump and checked the voltage, plugged it back in it hasn't worked at all since unless I 12v feed the pump myself.

once I pressured the pump with 12v I had the car off the ground in gear and coundnt stop front wheels on brakes it was going to stall the engine.

im rubbish with wiring, but can the wires not be tested to see that there doing what they should and reading correct voltage ?


I guess I could test engine or fcon ecu outputs and makesure they are getting to the attessa ecu, I need an idoits guide to do it though lol
 

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My angle is that if the c/u doesn't know the TPS signal is missing, and that nothings seems to work but there is no warning light or functioning 4WD, something very odd is afoot.
 

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Discussion Starter · #14 ·
My angle is that if the c/u doesn't know the TPS signal is missing, and that nothings seems to work but there is no warning light or functioning 4WD, something very odd is afoot.

indeed mate very odd, its seems such a coincidence that its stopped working after we did the headgasket and went to the dyno I still wonder if a wire is at fault, but then why no error code.


does ur control unit use all the original equipment ?
 

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Discussion Starter · #15 ·
I guess I do really need to trace the tps wire somehow and confirm the signal is getting to the attessa ecu, I know its getting to the fcon as its just been mapped and the fuelling is doing what it should.
 

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Good work Matt. Lol.

Carl, I have posted a link at the top of this section with all of the wiring diagrams.
 

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Lol Andy, as you know I now have a 'couple' of spare ATTESA parts I'm not using after the run around before TOTB buying up what seemed like a complete new system lol :/

Thanks again for all your help mate! :bowdown:
 
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