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Discussion Starter #1
Folks, I think I have confused my Hicas controller - can anyone shed some light on this?

The battery went totally flat for a day and I recharged it.
I have also installed an amp and rear shelf speakers.

Here is the problem:

When driving in as straight a line as you can on the isle of wight, apropo of nothing the back end of my GTR33 skips. Now this is not a 'over drain wobble' but it is literally as if someone has steered the car via the rear wheels. It is quite pronounced and a tad alarming!

It is not tramline or the back end wobble my 300zx used to suffer from but it feels as though the hicas is moving the rear wheels.

I find this real strange as I would not have thought the HICAS system could move the wheels the amount needed to make the car feel like this.

Strange....

Any help gratefully pondered upon... soz to chuck this in here, did run search:):)

Thanks
 

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I have exactly the same problem with mine but only when I turn the stereo up to approx 3/4 volume or above. It has done this ever since I had the car nearly two years now a R33 1998 UK car.

I know that does not help you, but at least you are not alone!
 

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does this happen at the same speeds each time ?

I had a problem where the rear end would jerk to the right at exactly 120 mph, nearly shat myself when it first happened !!

it also happened at slower speeds and at about 140.

I lived with it for a while thinking it was a "feature" but it frightened the life out of me so I took it to my mates garage.
it is a Nissan dealership and one of the top guys there said he remembered a similar thing with the 300zx's (which also use Hicass) it was a bit of play on the rear tracking rod.

Sure enough we lifter the car up and there was a barely discernable bit of play in the rear track rod arm. Up and down.

What it looked like was the car had been curbed at a slow speed in a car park (by me...Doh) and this pushed the track rod towards the ball joint it sits on. It was slightly compressed and resulted in a gnats **** worth of movement. This is picked up by the Hicass computer at high speed as a fairly sudden change of direction and hence the tail end snapping about.

new track rod ( about 60) and an hour later it was fixed..

the play is so slight as to be barely noticeable so get someone to have a lok at that who knows how it feels.

hope this is it because it is an easy one to fix.

cheers
Steve
 

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Thats why...

this forum is so useful.

Good work fellas!
 

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hicas

hicas is voltage sensitive - if your hi-fi is dropping the car voltage (loud bass?) it can do some odd stuff.

It would be worth looking at where your hi-fi is getting its power from - you may want to take a lead from the battery itself.
 

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may also be...

It could also be that the HICAS controller hasnt setup straight...
When you reconnect the battery the HICAS ECU resets its self and it _assumes_ that the front wheels are straight, if they arnt, the rear wheels will point slightly in the wrong direction...
to cure it you just need to disconnect the battery again, and make sure that the front wheels are straight when you reconect it...
 

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HICAS TWITCH

I can related to what s2gtr has to say, again I have a 98 UK car and it does exactly the same if the music is up to load.

We've had the car on the ramps where if you turn the volume up then you can see the rear wheels doing a little jig.

TOMIE do a HICAS lock which I'm considering at the moment, but I'd rather just loose the volume.

No track rod movement, I had that checked to confirm, but yes it either voltage related or thump of the speaker related.

Tesh
 

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120 Twitch

I have a similar problem to Steve C, except it's a twitch to the left. Occurs at about 120, also occasionally under hard acceleration. On all occasions, the stereo has not been on. Thanks for the post as, like Steve, I thought it was 'one of those things'.
 

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I have the same

but the back end feels funny if i'm in 5th & floor the right foot
at 18-2200 revs like the wheel isn't properly connected to the
car.

Weird Feeling !

Weston
 

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Hicas

Hi


I have had the same problem with my 33GTR.

I even took the car to Middlehursts who reset the battery and checked HICAS using Nissan diagnositic. No problem found.

This back end sensation ( Its proper brown trouser material - Feels like someone is driving back end of car ) is more commonly found where people have installed uprated hi-fi equipment. Even factory uprated cars ( with Kenwood Amp ) have this fault.

I was told that this fault is known to be caused due to vibration of a sensor located within the handbrake area ( think its this area ) which causes Hicas to play up. I know of several cars that have had this fault.

I will investigate further and try and find how to correct.

Hope this info helps

Pete
 

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put mine on a consono and no fault, the chaps looking at the car then looked at me like I was mad so I took one them out. He also nearly shat himself.

Changed the component and all is good.

I get the odd twitch now and then but nothing like it was (this could be related to the stereo as I do have it loud sometimes..

scary stuff.

/Steve
 

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Re: Hicas

peatough said:
I was told that this fault is known to be caused due to vibration of a sensor located within the handbrake area ( think its this area ) which causes Hicas to play up. I know of several cars that have had this fault.
Yeah thats true, because when I run my wires through the centre for my CD changer wire, I noticed a box which said something like "Caution do not touch/vibrate/move".

I'm sure its what your on about aswell, and its near the handbrake.

This has put me off doing my audio system.
 

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Hicas problems

1) the hicas computer is near the speakers
2) the g-sensors are near the handbrake

Would have some bearing on this I would think:)
 

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Hey...same problem

This happened to me coming down the M76 yesterday. It occurred on a particular part of the motorway (concrete pavement, v uneven). Scared the shit out of me (again felt like the read end steering itself). It cleared up after I hit asphalt and didnt reoccur...

I put it down to the pavement quality...maybe not

She does have an after market stereo fitted....
 
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Discussion Starter #15
Wow

What a response, I think we have hit upon something here.

I really thought it was something to do with my stereo install but couldn't see how Nissan would allow vibration to disturb the HICAS distribution - the reason is that before I installed a big amp and huge (ooer) sub in the boot I didnt have this phenomenon.

I have also installed a second amp (routed though the center console past the gearlever)..

The sub creates huge vibration, so much so that the mirrors vibrate as does the dash and all exterior trims etc.

Driving to work with sub on, rear wheel shuffle... I hadnt read these replies before setting out home but I figured I'd listen to the engine and exhaust note on the way home (better than any music!) and no rear end steer at all.

Im going to go out tomorrow and test this with big bass noise and then none at all.... Ill let you know:)

Thanks for all your replies... top forum, top people:)

Peace,
 

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I've got a 10" sub, mounted in a free air configuration directly below the HICAS computer, the magnet can't be more than 2" away from the computer housing. I'm driving it with abt 400w and the amp is mounted in the space beside the battery.

I have not experienced any problems with the HICAS on my car (GTS25T) and think htis maybe point more to the centre gauge as the source of the problems you folks are experiencing.

Just my 2p worth, interesting topic BTW, be nice to hear how you get on tomorrow Senna.

Have you tried it listening to anything else than Steps and SClub though ? ;)
 

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Hicas

Hi


Further to my email above I have checked with a Ex Middlehurst techn.

This HICAS fault we have described IS due to a G Sensor located within the handbrake assembly.

Resonance from add on base units causes this. Also poor condition handbrake assembly ( mine was knackered ) plus wear and tear also contributes.

Hope this helps

Thanks

Pete
 

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Info on G-sensors

The following thread links to an interesting article where someone has modified the signal from the g-sensors to play with the handling of the car. There was only one reply to the post... from me. My car is fixed now by the way and the traction control unit broke so has been removed:)
G-sensor link
 
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Discussion Starter #19
you got a pm

SteveC said:
does this happen at the same speeds each time ?

I had a problem where the rear end would jerk to the right at exactly 120 mph, nearly shat myself when it first happened !!

it also happened at slower speeds and at about 140.

I lived with it for a while thinking it was a "feature" but it frightened the life out of me so I took it to my mates garage.
it is a Nissan dealership and one of the top guys there said he remembered a similar thing with the 300zx's (which also use Hicass) it was a bit of play on the rear tracking rod.

Sure enough we lifter the car up and there was a barely discernable bit of play in the rear track rod arm. Up and down.

What it looked like was the car had been curbed at a slow speed in a car park (by me...Doh) and this pushed the track rod towards the ball joint it sits on. It was slightly compressed and resulted in a gnats **** worth of movement. This is picked up by the Hicass computer at high speed as a fairly sudden change of direction and hence the tail end snapping about.

new track rod ( about 60) and an hour later it was fixed..

the play is so slight as to be barely noticeable so get someone to have a lok at that who knows how it feels.


hope this is it because it is an easy one to fix.

cheers
Steve
Steve, You got a pm from me.
 

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This is an interesting one. Dave, Emailed you back.

I do occasionally get a shimmy still and I do have a 12" rockford fosgate sub in the boot so this could clear it all up.

I always wondered why it only happens when I am driving slowly(relatively) and when I boot it it doesn't happen but I always turn down the sounds when I give it some ( I don't like the distraction) so that explains it.

The fault I had with the track rod arm was like it but a LOT more violent. If it lasted for more than the split second it did I had the feeling I would have crashed the car.

cheers all.

/Steve
 
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