R32 Gtr G Sensor Fix

[xiaorpowr]

Hey Jeff,

Ur a legend mate, I followed your instructions and got my unit to work momentarily. Here is what happened:

1. Measured the voltage, one of the 3 points measured 1.7 volts.

2. Adjusted it as high as possible to 2.2 volts

3. Turn the car on, 4wd and abs light remained on.

4. Turned the car off and adjusted my after market torque splitter higher (more front wheel bias setting). I'm guessing this increases the voltage too??

5. 4wd and abs light went off and all was working well.

The unfortunate thing is that it stopped working this morning any idea what I néed to replace on the board to get it to 2.5 volts and remain there??

Ps good on u for taking the time to trial build a new unit mate. I think there r a lot of ppl who desperately want to fix their gtrs. After all driving an expensive 1500kg gts-t is not much fun is it

[YunisA]

Hi Jeff, good to hear that you are looking at new ideas, look forward to seeing how things progress. Would love to get my unit working again as the car has been in 2wd for a while now.

BTW mine too does not go above 1.6v, I think one of the voltage pots is buggered up.

[xiaorpowr]

Jeff,

i reckon if you build a working new unit, you could retire off it lol, theres that many GTRs limping in 2wd!

update on mine - works if I start the front of the car facing up the hill. haha, better than nothing i guess!

[Bozz]

I'm willing to do the same if someone has a 32GTR with this fault in Melbourne, I'll also investigate why the values are drifting to see if the root cause can be fixed.

[Matty Sherlock]

Did a tutorial on actually getting to the g-sensor the other day. Here's the link if anyone is interested..

http://www.skylinesaustralia.com/forums/topic/376142-r32-gt-r-lateral-g-sensor-check-and-more/

[Bozz]

Without seeing whats on the other side of the PCB, the underneath pictured is very simple - three quad op-amp chips taking input from what I'm assuming are the G sensors on the other side of the board.

Surely someone has a crook one here in Melbourne that wants it fixed....

[datsun_1600]

Hey Jeff,

Ur a legend mate, I followed your instructions and got my unit to work momentarily. Here is what happened:

1. Measured the voltage, one of the 3 points measured 1.7 volts.

2. Adjusted it as high as possible to 2.2 volts

3. Turn the car on, 4wd and abs light remained on.

4. Turned the car off and adjusted my after market torque splitter higher (more front wheel bias setting). I'm guessing this increases the voltage too??

5. 4wd and abs light went off and all was working well.

The unfortunate thing is that it stopped working this morning any idea what I néed to replace on the board to get it to 2.5 volts and remain there??

Ps good on u for taking the time to trial build a new unit mate. I think there r a lot of ppl who desperately want to fix their gtrs. After all driving an expensive 1500kg gts-t is not much fun is it

Hey mate. Not sure why it would start then stop working unless the pot moved just a tiny bit and flipped the bias voltage low. Might have happened as you set it really close to max... So it would only take a tiny bump...

Awesome to have Bozz onboard. The accelerometer is actually a really cool old school design. Is uses a magnetic pendulum suspended in about 30000~40000 weight silicon lube (for dampening) and a hall effect sensor to measure its position. Not sure witch components drift over the years... I'm guessing the hall effects. But they are moulded into the housing. I think (if I remember correctly) they there were the only components on the back side of the PCB. But when I pull it out again. (Hopefully this weekend) ill check. I was more interested in going digital so I could fiddle with settings on the fly etc, I kinda didn't look into the root cause of why the sensors drift and die. Does anyone have a broken unit that maybe they could donate/lend to Bozz or myself?

If you need a better quality image Booz of the top drop me an pm with your email.... There were also some resistors on a little side PCB between the output of the top PCB and the header... Didn't look like it did much so I didn't take a pic. Originally the pic was just for myself so I knew what it looked like before I fiddled with components.

I think the op-amps have gone are EOL but there might be a drop in ??? (haven't looked...)

Awesome to have somebody else gett'n into this.

Just landed back in Adelaide yesterday.... so I should be able to take a look at stuff as needed...

Jeff

Sent from my HTC

[Bozz]

I'm in two minds about a digital accelerometer - the R32 4WD system is well known to be shit on a track and all the aftermarket stuff does is feeds different signals into a slow and shitty controller to try make it less shit in some situations.

An awesome project would be to replace the 4WD control system (leave the factory ECU doing ABS) with a MEMS accelerometer such as the ADXL335 coupled to an Arduino Duemilanove. $40 gets you the new sensor, new controller running at 16MHz and you can make it do whatever you want, track, drift, playstation

But back on topic, it would be good to play with a broken sensor as it's unlikely all three axis are broken so I could spin it up and plot the force/voltage and pretty easily make a new unit with a MEMS accelerometer. After the design work, I reckon a replacement adjustable accelerometer could be manufactured for under $100.....

Sent from my laptop using Firefox

[YunisA]

Excellent stuff guys, very interested to see how this will come along. If new units can be produced and used as a replacement for the orginal design, I am sure many people would be happy to buy it.

[datsun_1600]

I'm in two minds about a digital accelerometer - the R32 4WD system is well known to be shit on a track and all the aftermarket stuff does is feeds different signals into a slow and shitty controller to try make it less shit in some situations.

An awesome project would be to replace the 4WD control system (leave the factory ECU doing ABS) with a MEMS accelerometer such as the ADXL335 coupled to an Arduino Duemilanove. $40 gets you the new sensor, new controller running at 16MHz and you can make it do whatever you want, track, drift, playstation

But back on topic, it would be good to play with a broken sensor as it's unlikely all three axis are broken so I could spin it up and plot the force/voltage and pretty easily make a new unit with a MEMS accelerometer. After the design work, I reckon a replacement adjustable accelerometer could be manufactured for under $100.....

Sent from my laptop using Firefox

Yeah I totally get what you mean. I'd love to have the time to totally replace the controller with something better, but as i'm always so busy with work I don't want to start something I'll never get around to finishing. I agree, def would be the better choice... I'd love to have the source code of the current controller, just looking at the maths would be sweet. I think to start with i'm gonna stick with just a digital replacement for the G-sensor. But, if you wanna have a crack at replacing the controller I'd sure be interesting in lending a hand (if you want it).

My bro is also in Melbourne (sort of) and has a R32-GTR i'm sure avail for testing etc.

Just started the schematic etc for the digital G-sensor. I use the latest Altium Designer but can release it in whatever file type ppl want when it's done. (Maybe just the Gerbers so ppl can order the PCB's etc ??) The unit i'm building is a little overkill as I'm also going to use it for another project, but yeah I reckon around too that about $100 would be about right for a cut down unit just to replace the G-sensors.

Jeff

[R32 TT]

subscribed. Be interested to see where this goes guys.

[datsun_1600]

All the schematic and PCB footprints are done, FPGA's came in.... Didn't get time to pull my G-sensor as I was driving my car all weekend...

Jeff

[Bozz]

You're on a roll, I haven't even put any thought into it yet.... Great work!

[datsun_1600]

Almost ready to send the PCB away... Just wondering does anybody have an R32 G-Sensor (a really good one) they I could borrow for some testing ? I think mine is ok, but i've done some tweaking so i'm a little unsure how "original" the outputs now are. I'll be at SAU Nationals (Just the Race Day - spectating) I can post it back after i'm finished with it... I don't plan on opening it up or anything so nothing *should* get damaged - I just want to monitor the output against my new replacement when it's up and running.

Cheers,

Jeff

[scotty nm35]

My mate has a 32 with a cracked g sensor, its probably had a large shunt. Can this be repaired? Otherwise he will be interested in your board design if it works as planned.

[datsun_1600]

My mate has a 32 with a cracked g sensor, its probably had a large shunt. Can this be repaired? Otherwise he will be interested in your board design if it works as planned.

If the G-Shock indicator has gone red then it's probably still fine (or might just need the bias voltages adjusted as per my pic at the start of this thread) If the whole unit has cracked and the silicon dampening fluid has leaked out of the hall effect / magnet pendulum cavity then it's prolly NFG. I'd take the top off and adjust the bias voltages first. If it's been hit the worst thing that can happen is that the magnets mounted on the small pendulum spring will be bent a little (ok) or bent a lot (nfg unit) inside it looks like this

Just pretend the magnet is a rock mounted on a piece of string. (Really it's a magnet moulded in a lead weight mounted on a spring all sitting in some thick fluid.)

"x"'s = Fluid

----------------------------------------------- (PCB)

xxxxxxxx|xxxxxxxx

xxxxxxxx|xxxxxxxx

xxxxxxxx|xxxxxxxx

xxxxxxxx|xxxxxxxx

xxxxxxxx|xxxxxxxx

xxx(Magnet)xxxx |Hall effect sensor|

As the car undergoes g-force the magnet moves closer or further away from the sensor.

After years of movement or an impact they look like this (Dramatised) (Edit - this should look bent to the right - added x's so the alignment works)

----------------------------------------------- (PCB)

xxxxxxxx|xxxxxxxx

xxxxxxxxx|xxxxxxx

xxxxxxxxxx|xxxxxx

xxxxxxxxxxx|xxxxx

xxxxxxxxxxxx|xxxx

xxxxxxxx(Magnet) |Hall effect sensor|

And therefore the output of the op-amps feed from the sensor needs to be re-calibrated, the bend in the spring taken out, or the unit replaced.

Hope this helps a bit and that the text pics look ok

Jeff

Edited October 12, 2011 by datsun_1600

[YunisA]

How are you guys getting on with this? any more updates or developments?

[jessehu]

can i just ask a stupid question,

i never know r32s have g sensor, what is it for and where is it located?

thanks

[Madaz]

it helps determine if torque should be shifted to the fronts wheels

[xiaorpowr]

Thats an awesome explaination Jeff.

Still keenly watching this thread hope to hear from you soon!