Vspec A-lsd Info

[rb4door]

Hey guys,

i've performed a search and found some topics covering the A-LSD,

however my question is a little different to the information provided so far, so i'm

hoping one you resident GT-R experts can help me out.

I recently imported a series 3 BCNR33 V-spec.

The car has an Impul ECU that came with it from Japan,

and a Nismo 320 cluster I installed.

Normally when I turn the ignition on, the A-LSD light

will illuminate for the standard cluster warning light fault check.... as soon

as you start the engine, the A-LSD light goes off.

The scenario:

Since i've had the car on the road, I have not seen the A-LSD light

come on once whilst driving.

The other day (my first time in the wet with the car) - I did a wide open

throttle launch from first gear and into second on a very wet road.

The front torque meter pretty much went maximum on the launch and all

through first gear.

After backing off midway through second gear and slowing down, I noticed

(for the first time ever) the A-LSD light was on - and it wasnt going off.

I drove for about 4 minutes more back home, then turned the car off.

Started it again about 20 minutes later and went for another drive, the A-LSD light

was now off.

I havnt seen the light come on since, except for when you start the car.

Now my questions:

1) is the A-LSD light a "fault" light or is it supposed to illuminate when the specific computer

controlling it has commanded it to come on?

2) do I have some form of error (with the Active LSD itself) since the light came on solid and remained on even with sedate driving afterwoods?

3) Is it just something to do with the fact its running the Impul ECU and its getting that error

mentioned in Paulr33's A-LSD DIY guide (http://www.skylinesaustralia.com/forums/in...howtopic=107656

any advice or help much appreciated

[MANWHORE]

A-LSD light is a fault light. The Slip light is the one that comes on when you slip the wheels.

The stock cluster on r33 has a slip light. Did you buy that cluster from the for sale section? It only ahs an A-lsd light.

[govich]

Maybe it went into the ALSD fail (self-protection?) mode as discussed in the thread you linked. He did note that it wouldn't lock until he restarted the car.

[rb4door]

thanks govich - now i've re-read his thread and

you guys rekon the A-LSD light coming on means its

failed or turned off - makes a bit more sense.

I've had some confusion with this as other GT-R owners

have told me that when the light comes on it means its working!

The "clean" dashboard normally means everything is working, its

only when a light comes on something is wrong.

Kind of like stories some people tell that when the Hicas light comes

on it means its working

The reset obviously did the trick.

I'm still left wondering if I have a problem with the Active LSD

itself or its this aftermarket ECU issue.

I'm tending to think there is something up with the ECU as the rest

of the car is flawless.

Edited July 31, 2006 by rb4door

[Mandingo]

Try another launch see if it happens again.

(any excuse for a launch )

[rb4door]

^^^^ yeah i've since tried in the dry and

everything completely normal - no more A-LSD light.

[govich]

In the dry it probably doesn't spin hard enough/long enough to set off the fail mode.

[smurf80]

I was told that if you continue to slip the wheels for 20secs or longer the computer goes into safe mode and it becomes an open wheeler does anyone know if this is true or not? And yeah as everyone has stated the ALSD light only goes on when there is a problem.

Chris

[rb4door]

^^ would seem to tie in with what I experienced.

However I would have thought a GT-R is a little bit

tougher than to chuck a dummy spit at one decent launch with

some possible wheelspin in the wet.

I still think there must be an error with my ecu or the A-LSD itself

[MANWHORE]

I may haev done this on a few occassions on my own private road. It didn't go into fail safe mode on my car.

[mark morris]

Interesting... I have a fairly modded 33vspec and have done numerous heavy launces with alot of wheel spin and even done doughnuts in fwd, and never had ATTESA or ALSD lights on, other than at start up.

So I would say these lights only come on when there is fault, like the rest of the fault lights on the dash.

[paulr33]

correct the a-lsd light will on come on when it fails.

failure can be electronic signal problem from the ecu (it needs tps signal) or it can be its locking for too long and gives up. if you lock it for say 25 seconds it usually gives up and a-lsd fails

[rb4door]

Finally found my GT-R manual....

A-LSD Warning Light:

If the light comes on with the engine running

it may indicate that there is something wrong

with the active limited slip differential system.

Have the system checked by your Skyline GT-R dealer.

If an abnormality occurs in the system,

the A-LSD function will cease and the differential

will operate conventionally.

I dont like the way its worded - still very open to interpretation

"may indicate there is something wrong".....

[paulr33]

yes as i said. if a-lsd comes on while driving it means the computer in the boot has detected an error and gives up. this means the system will not lock the diff when traction is lost. slip will NOT come on if a-lsd is light up. you need to reboot the car to correct it.

common causes for a-lsd coming on that i have seen:

running the pump manually (computer doesnt expect it to run)

doing a long burnout (over 30 seconds, a-lsd will fail)

tps signal to a-lsd computer not clear or disconnected

[paulr33]

this is my 2 page thread on manally override the a-lsd pump

http://www.skylinesaustralia.com/forums/in...howtopic=128917

[rb4door]

just read it all - thanks for the link....

The FAST schematic you have put up

looks exactly like the pump on the back on my diff housing -

so that part is the pump that runs A-LSD?

I have always been told the hydraulic fluid reservoir in the back

right access panel in the boot is the reservoir for the ATTESA 4wd

system on GT-R's - so i'm not sure if this is a shared reservoir on mine

and only for A-LSD on your GTS-T?

I can also hear an electric pump at the back upon startup of my car,

seems to run for about 4 or 5 seconds then turn off - like its

pressurizing. Do you think this would be the ATTESA system or the A-LSD?

Edited August 14, 2006 by rb4door

[paulr33]

the resivour in the boot right hand side is the a-lsd fluid.

when i turn my pump on via the hardwired switch we can see the fluid level drop instantly. its definetly a-lsd fluid resivour. the diagram is from nissan fast which shows the a-lsd pumps, resivour and return systems. it attaches to the diff via an oil feed (in the diagram). the diff has the vspec finned cover despite being in a gtst skyline.

i have ecr33 gtst skyline with a-lsd option fitted. what car do you have?

the a-lsd in fast is listed as the torque split system.

nevermind just read you have series 3 gtr33. my bad.

yeah so gtst with vspec diff and a-lsd have that same resivour in the boot right side

[rb4door]

hmmm, I wonder if its a shared reservoir in mine (ie for both ATTESA & A-LSD)

If you leave yours in automatic mode (computer control)

do you also hear a pump running when you immediately

start the engine?

I'll have to get a friend to start my car while I am listening underneath

at the back - see if I can work out if its the ATTESA pump or the A-LSD.

Edited August 14, 2006 by rb4door

[paulr33]

yes at car boot up it sends a 12v signal to the pump

its basically a preload pressure and diag check

if the pump doesnt respond the a-lsd fails and the a-lsd light will come on