Active LSD light on, tried bleeding, no luck

[jacobzking]

My active LSD light is on.  I dont think the active LSD pumps are even trying to do anything, but I could be wrong.  I've tried bleeding both bleed valves (on pump and on LSD), but the light still comes on.  Tried using an air pump on the reservoir, but nothing.  Any test I can do to try and get this thing working?  Any diagnostic codes anywhere?  Stock ECU.  Does this thing have its own ECU?  In my trunk I have the any skid ECU and HICAS ECU.  Maybe the skid is same ECU?

Is there a fuse for it somewhere?

[joshuaho96]

14 minutes ago, jacobzking said:

My active LSD light is on.  I dont think the active LSD pumps are even trying to do anything, but I could be wrong.  I've tried bleeding both bleed valves (on pump and on LSD), but the light still comes on.  Tried using an air pump on the reservoir, but nothing.  Any test I can do to try and get this thing working?  Any diagnostic codes anywhere?  Stock ECU.  Does this thing have its own ECU?  In my trunk I have the any skid ECU and HICAS ECU.  Maybe the skid is same ECU?

Is there a fuse for it somewhere?

The "skid ECU" is also responsible for controlling the Active LSD. Pull the codes from that module. 

[jacobzking]

21 hours ago, joshuaho96 said:

The "skid ECU" is also responsible for controlling the Active LSD. Pull the codes from that module. 

Oh!  There's a light!  62, 65, 66 are the codes:

62 FR and RR G sensor 2 and circuit

65 G- sensor 2 power supply and circuit

66 Side G sensor and circuit

Now what, lol.  I have no idea what those G sensors are or how to trouble shoot them.

Edited April 25, 2023 by jacobzking

[joshuaho96]

1 hour ago, jacobzking said:

Oh!  There's a light!  62, 65, 66 are the codes:

62 FR and RR G sensor 2 and circuit

65 G- sensor 2 power supply and circuit

66 Side G sensor and circuit

Now what, lol.  I have no idea what those G sensors are or how to trouble shoot them.

There's a g sensor under the center storage box that the skid control CU uses to modify the resulting lockup curve. Less lateral g and you will get more LSD lockup. More lateral g and you will get less lockup. From the skid control CU pin 40 is Vcc, pin 43 appears to be ground. Pin 41 is "Horizontal g sensor" and pin 42 is "Sidev g sensor". That's a horrific translation and I wish someone could just send me the original FSM in Japanese instead of trying to guess at what that means. Check the Vcc to ground voltage, it should be something like 8V supply and 2.5V signal voltage for both lateral and longitudinal signals sitting still.

[jacobzking]

1 hour ago, joshuaho96 said:

There's a g sensor under the center storage box that the skid control CU uses to modify the resulting lockup curve. Less lateral g and you will get more LSD lockup. More lateral g and you will get less lockup. From the skid control CU pin 40 is Vcc, pin 43 appears to be ground. Pin 41 is "Horizontal g sensor" and pin 42 is "Sidev g sensor". That's a horrific translation and I wish someone could just send me the original FSM in Japanese instead of trying to guess at what that means. Check the Vcc to ground voltage, it should be something like 8V supply and 2.5V signal voltage for both lateral and longitudinal signals sitting still.

Your'e amazing!  Do you think it may be easier to just swap out the G Sensor?  Possible that fixes all 3 codes?  Thank you!  I'm determined to get this working.

[Duncan]

What's the bet the g sensor is not plugged in, given that list....

Assuming it is the same as 4wd chassis, it will be under your centre console

[joshuaho96]

43 minutes ago, jacobzking said:

Your'e amazing!  Do you think it may be easier to just swap out the G Sensor?  Possible that fixes all 3 codes?  Thank you!  I'm determined to get this working.

The sensor is expensive so I recommend diagnosing first. Start by checking you have power to the sensor. If it turns out the 8V supply to the sensor is dead you're going to waste a lot of money to not fix your problem.

[joshuaho96]

2 hours ago, Duncan said:

What's the bet the g sensor is not plugged in, given that list....

Assuming it is the same as 4wd chassis, it will be under your centre console

It is basically a cut down version of the ATTESA ETS Pro system so yes it will be under the center console. The R34 Skyline manual throws all of the ATTESA/ABS/traction control diagnostics into the same section of the service manual. 

[GTSBoy]

I'm trying to work out how anybody knows what car we're talking about here. The OP's listed R32 can't have the shitty A-LSD, and there's no mention of an R34 in any text here. Were there even any R34 RWDs with the shitty diff?

I guess that means that it should only be an R33. Was gibts?

[joshuaho96]

1 hour ago, GTSBoy said:

I'm trying to work out how anybody knows what car we're talking about here. The OP's listed R32 can't have the shitty A-LSD, and there's no mention of an R34 in any text here. Were there even any R34 RWDs with the shitty diff?

I guess that means that it should only be an R33. Was gibts?

I knew it was an R33 GTS25T because he posted the same exact question on a Facebook group but whenever possible I prefer to reply on something that isn't an information black hole.

[Duncan]

lol I just assumed it was a 33 gtst because there was no mention of 4wd not working.

Imagine how much easier it would be to help if people listed their car, and their location, in the fields called "car" and "location" in their profile!

[GTSBoy]

56 minutes ago, Duncan said:

Imagine how much easier it would be to help if people listed their car, and their location, in the fields called "car" and "location" in their profile!

I'd agree with you if it wasn't against my internet policy to do such things. Also, my car is a bitsa now, and I've never anywhere near it, so my location is moot!

I'll happily give such information when it's helpful though!

[jacobzking]

7 hours ago, Duncan said:

lol I just assumed it was a 33 gtst because there was no mention of 4wd not working.

Imagine how much easier it would be to help if people listed their car, and their location, in the fields called "car" and "location" in their profile!

Fixed! Sorry, haven't been on this page in about 8 years (last time I owned a Skyline).  Just updated car to R33 GTST

[jacobzking]

14 hours ago, Duncan said:

What's the bet the g sensor is not plugged in, given that list....

Assuming it is the same as 4wd chassis, it will be under your centre console

Just checked, G Sensor IS plugged in.  Probably unrelated, but the white wire going to the parking brake cable was cut from harness and ran under the carpet (not sure where to).  On the plug to the G sensor, which wire should get 8 volts?

[Duncan]

Does the brake dash light come on when you put the parking brake on?

Anyway.

I don't have a 33 A-LSD wiring manual, but the R32 GTR manual shows all the wiring at the g sensor comes directly from the boot control unit

So, at this stage it seems like your gsensor probably has an issue because:

1. We know it is plugged in

2. The control unit must be at least partly working because you saw error codes on it (ie, it has enough power and earth to fire up)

Next I would use a multimeter to check continuity of each of those 9 wires from the g sensor to the control unit.

If they are all OK, assuming there is not another g-sensor handy to swap in and check, it is probably time to buy a replacement. I believe midori make one, and probably others.

[joshuaho96]

5 hours ago, jacobzking said:

Just checked, G Sensor IS plugged in.  Probably unrelated, but the white wire going to the parking brake cable was cut from harness and ran under the carpet (not sure where to).  On the plug to the G sensor, which wire should get 8 volts?

Unplug the g sensor, use a multimeter in resistance mode and see which pin has zero resistance to the chassis. That will be a ground pin. Switch the multimeter to voltage and reference the other pins against the chassis. One pin will be 8V and the other should have no voltage as you haven't plugged it into the g sensor. If you can't find 8V anywhere then it's a power supply issue. Then plug it in and try to probe the backside of the harness pins if you can to see if you get 2.5V relative to ground.

[jacobzking]

Quote

If they are all OK, assuming there is not another g-sensor handy to swap in and check, it is probably time to buy a replacement. I believe midori make one, and probably others.

You guys are awesome!  I wish Midori made one for the RWD A-LSD, but I think they only make it for the AWD system.  The RWD sensor only has one plug (I think 4 wires).  I'll keep you posted.  This is what mine looks like BTW.

[Duncan]

Thanks for the pic, that is good info for next time.

There is every chance the 4wd sensor is the same wiring plus the additional sensor with additional wiring, maybe ask midori or others if A-LSD Is supported

[joshuaho96]

32 minutes ago, jacobzking said:

You guys are awesome!  I wish Midori made one for the RWD A-LSD, but I think they only make it for the AWD system.  The RWD sensor only has one plug (I think 4 wires).  I'll keep you posted.  This is what mine looks like BTW.

I would definitely try hard to get an aftermarket sensor to work if you can. A new OEM sensor is 1.6k USD which is absolutely insane pricing. Of course I would also recommend making 100% sure it's a dead g sensor to begin with.

[BK]

I have a spare 33 gtr one here, but I see Jack Philips JDM in Melbourne has an 33 one with the single plug in stock - $220

https://jpjdm.com/shop/index.php?id_product=3160&rewrite=nissan-skyline-r33-acceleration-gravity-g-sensor-98805-20u05&controller=product