Brakes / ABS problem

kanujunkie · January 9, 2008, 10:58

doh! your right, so the only way to totally disable it with no warnings but to still keep the speed signal functioning would be to pull the 2 fuses and to cut the output from the ABS ECU block B pin 11. That would leave the ABS ECU functioning but disable the actuator and it can complain all it wants but it wont matter, nobody would be listening

aaronjb · January 9, 2008, 11:08

Yep - although I do wonder - if those two fuses (ABS1 and 2) are supplying power to what appear to be the actual ABS actuators (they're listed as 'solenoid' and 'motor'), removing power to those should leave you in fail-safe non-ABS mode.

Not that I want to be the first to try it, but..

I'll let Nathan do that.. s:lol: :lol: s:lol: s:oops: :oops: s:oops: s;)

s;)

kanujunkie · January 9, 2008, 11:31

no ABS sounds great to me personally, i personally think its about as much use as a dead dog on the 2, not that ABS is useless, just that the 2's ABS is so hyper sensative that it fires when you go over a small pothole and is verging on the dangerous in itself IMHO

aaronjb · January 9, 2008, 12:03

Strange - mine hardly ever comes on.. Only if I'm trying really, really hard - standing on the brakes and hitting a metal grating, for example..

ChrisGB · January 10, 2008, 00:38

Odd that the occasional times mine comes on are when I am not trying hard. Monday's triggering was on the approach to a junction over very broken surfaces and as wheel control was temporarily lost in wheel patter, the ABS kicked in,When I am properly on it, the abs very rarely triggers at all. It even smokes the tyres if I give it a really hard stop.

Still reckon I would prefer the car without it to be honest.

Chris

kanujunkie · January 10, 2008, 08:09

ditto on mine, the annoying part is that this then increases your stopping distance and i've almost had a couple of accidents in the past because of it s:(

s:(

hence why i'd rather do without the ABS

philster_d · January 10, 2008, 15:28

Mine does that too, I just learned to break much earlier and be more progressive.

ChrisGB · January 10, 2008, 16:55

I found the key to getting the early ABS intervention to let the car brake heavily again is to get fully off the pedal than then back on it again. The problem is once wheel patter kicks in, it can sort of keep resonating with the ABS sometimes, leading to the experience a few of us have noticed.

Since going to the harder springs and damping, the problem occurs less often and lasts for less time before sorting itself out. I reiterate that this happens on other cars too, but due to the flexible nature of the MR2 shell, you notice the wheel control problems more.

Chris

kanujunkie · January 10, 2008, 17:57

tell you what i'll try removing the fuses when i'm on track next which is the 26th, safest place to do it i reckon, i'll then do a couple of less agressive laps and see what happens and report back

heathstimpson · January 10, 2008, 21:31

Quote from: "kanujunkie"tell you what i'll try removing the fuses when i'm on track next which is the 26th, safest place to do it i reckon, i'll then do a couple of less agressive laps and see what happens and report back

Good idea Stu s:wink: :wink: s:wink:

ChrisGB · January 10, 2008, 22:17

Quote from: "kanujunkie"tell you what i'll try removing the fuses when i'm on track next which is the 26th, safest place to do it i reckon, i'll then do a couple of less agressive laps and see what happens and report back

The only potential problem I can see to this is losing power steering scaling. It may end up too light, or it may end up with no assistance. If the latter, there is the possibility of having the gearing taking all the steering load instead of being hydraulically assisted which may stress the rack gears.

Chris

aaronjb · January 10, 2008, 22:19

Quote from: "ChrisGB"The only potential problem I can see to this is losing power steering scaling.

If Stu pulls the two fuses we mentioned earlier (ABS1 & 2) then why would he lose the PS scaling? The ABS ECU will still have power and be operating as normal - the only things without power will be the actual actuators inside the ABS module.

ChrisGB · January 10, 2008, 22:36

Quote from: "aaronjb"
Quote from: "ChrisGB"The only potential problem I can see to this is losing power steering scaling.

If Stu pulls the two fuses we mentioned earlier (ABS1 & 2) then why would he lose the PS scaling? The ABS ECU will still have power and be operating as normal - the only things without power will be the actual actuators inside the ABS module.

Makes sense. Got to be worth a try. For anyone thinking of this for the road, take a moment to consider potential insurance complications in the event of an incident.

Chris

aaronjb · January 10, 2008, 22:41

Quote from: "ChrisGB"For anyone thinking of this for the road, take a moment to consider potential insurance complications in the event of an incident.

Oh yes, I could see an insurance company nailing someone to the wall over it..

heathstimpson · January 11, 2008, 05:30

Quote from: "aaronjb"
Quote from: "ChrisGB"The only potential problem I can see to this is losing power steering scaling.

If Stu pulls the two fuses we mentioned earlier (ABS1 & 2) then why would he lose the PS scaling? The ABS ECU will still have power and be operating as normal - the only things without power will be the actual actuators inside the ABS module.

I would agree with this Aaron s:wink: :wink: s:wink:

heathstimpson · January 11, 2008, 05:31

Quote from: "ChrisGB"
Quote from: "aaronjb"
Quote from: "ChrisGB"The only potential problem I can see to this is losing power steering scaling.

If Stu pulls the two fuses we mentioned earlier (ABS1 & 2) then why would he lose the PS scaling? The ABS ECU will still have power and be operating as normal - the only things without power will be the actual actuators inside the ABS module.

Makes sense. Got to be worth a try. For anyone thinking of this for the road, take a moment to consider potential insurance complications in the event of an incident.

Chris

I think that's why Stu said he will try whilst on a track. Some cars don't run with ABS so I cannot see this to be a issue as the brakes will still function.

kanujunkie · January 11, 2008, 08:07

if logic plays any part in all this though then we should be looking at the theory of what would happen if the pump failed, its exactly the same thing, you couldn't have cars crashing on the road just because a pump or a fuse failed, that would be stupid

aaronjb · January 11, 2008, 09:53

Oh I've no doubt you won't crash - the brakes will work as per non ABS brakes.. (Actually that's only true of modern Bosch ABS units - original Bendix units had a pressure accumulator, and if that blew you had.. no brakes!)

But the insurance angle would be - you've modified something that was standard fitment.. and it would be fairly easy to tell (the big, solid, black lines would give it away s;)

s;) )..

Maybe we're (Chris and I s;)

s;) ) just overly paranoid - but you know insurance companies will step over their own mothers to avoid paying out...

kanujunkie · January 11, 2008, 10:39

i only really want the ABS disabled on track so pulling 2 fuses is good enough and then re-instate them for road use

Anonymous · January 11, 2008, 17:44

OK, left work early - before it got dark. No cars about.

Pulled out the first fuse. Started her up. ABS light stayed on.

Drove until about 30km per hour. Hit the brakes hard - no ABS. Fronts (and rears) locked up and I skidded to a stop (pulling to the left). Tested a few times with the same result. Jumped out and checked the psi of my front tyres - they were at 29psi and 24.5psi. Set both to 24.5psi.

Tested the brakes several times on the way home. Once balancing psi o the tyres, braking was more even but certainly not perfect.

Difficult to comment on any effect to the power steering as my max speed was less than 70kmph, but it did feel slightly lighter at speed.

OK concerning my braking problem: The car stops very similar to when the ABS was working! I can deduce that the ABS is fine. The tyres slide rather than grip, with no screeching. I am now sure that the tyres are at fault (although I haven't ruled out the discs)

My Toyo's have arrived and I will be fitting them on Monday.

Nathan

kanujunkie · January 11, 2008, 18:22

well no great surprise that the ABS light stayed on or that slamming the brakes on hard will now lock em up with no ABS.

as for your little problem mate, i think were looking at a case that these ABS units are wildly different in their abilities on car to car, and then you add in us chucking different tires, brakes and suspension, your looking at all sorts of wierd results, i'm going to lay money that you wont cure this and that you'll be looking at haveing to live with this or deactivate the system altogether

ChrisGB · January 11, 2008, 23:33

Ok so you ave eliminated the ABS form the equation, next thing to do is to check for differences between braking on a smooth surface and braking in a broken surface. If you only get the problem on broken surfaces, you can eliminate the tyres.

This is to be expected to an extent as no car will brake as well over broken surfaces, however, if you get wheel patter excessively, you can point the finger at dampers getting tired.

Chris

Anonymous · January 15, 2008, 15:12

OMG - it's cured!!

The new Toyos are fitted - and although i have only driven 30km with them the car is back to normal. I had forgotten how well she hugged the corners and she now stops so hard that the seatbelt has to hold me in - with not a hint of ABS! Funny also that the ride is much quieter and slightly less firm - although more grippy than I remember. I cannot wait for them to bed in over the next few km.

I just wonder if the last two very hot summers here in Greece had simply perished the tyres.

loadswine · January 15, 2008, 15:18

Pleased that it worked Nathan. s:)

s:)
I wouldn't mind betting that the heat has had an effect on the previous tyres. The tarmac must reach phenomenal temps in July and August. I know the air temp is very high normally in the Summer on Corfu.

heathstimpson · January 15, 2008, 15:36

Quote from: "Agni"OMG - it's cured!!

The new Toyos are fitted - and although i have only driven 30km with them the car is back to normal. I had forgotten how well she hugged the corners and she now stops so hard that the seatbelt has to hold me in - with not a hint of ABS! Funny also that the ride is much quieter and slightly less firm - although more grippy than I remember. I cannot wait for them to bed in over the next 500km.

I just wonder if the last too very hot summers here in Greece had simply perished the tyres.

Don't forget that it takes quite a few miles of use to wear the scrubbing agents of a new set of Toyos matey s:wink: :wink: s:wink: