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Discussion Starter #1
Hey peeps. As is the story with almost all the ZCars, the second you fix one problem, another develops to take its place. :) Here's whats going on now that has me confused.

The little red "Brake" idiot light on the dashboard. Well, it has taken to the habit of lighting up for a few seconds every time I release the brakes and accelerate. It started coming on for a few seconds only after making a quick right turn from a stop (why right only? i dunno). Now its all the time, whenever I release the brakes and punch the gas, the light comes on for about 3-5 seconds.

As far as I knew, the only sensors that would trigger that brake light to come on are the handbrake, and the fluid meter in the master cylinder resovoir. Both of these locations are in check. The fluid is at the MAX level, and the previous owner tack welded the handbrake down, so I know neither of those could cause it. Does the 82 ZXT have a sensor down in the wheel that goes off when the pads get worn?? Something like the squealer..but electronic? I do need to change the pads as the squealer on the right front has started to make noises. Anybody have any ideas as to what I should do to cure my beloved Z of this ailment?

That idiot light is seriously tickin me off. :)

Thanks.
-il82
 

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Re: Dash "Brake" light on crack? Or is

Hoping this will help.

On the 240z later model, there was a sensor mounted in the Brake System that alerted to low fluid and low vacuum. From the symtoms you are reporting, light flickering during acceleration, it sounds like your Master is showing either too much or not enough vacuum. One of the other guru's here I'm sure will help more, but you might check that out.

The other point to check is that the switch on the parking brake handle is a simple pull to ground switch. If the PO of your car welded the brake down, it's possible that that switch is now grounding itself. May be way off base here, since you report the problem on right hand turns, (could your car body / frame have THAT much flex?) and under acceleration (you're actually accelerating so faat that the switch is coming on due to inertia?)

For what it's worth
 

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Re: Dash "Brake" light on crack? Or is

I have had that happen twice.

First time low braje fluid. WHen I opened the container it looked like it showed at MAX, I added some anyway and that fixed the problem.

Second time it was the beginning to an alternator failure.

ROb
 

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Re: Dash "Brake" light on crack? Or is

There is a circuit braker under the leather brake handler cover. If it is bent, you would have that problem. Check that out.
 

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"brake" light

I'm learninga bout this right now.. in my 260 the breaks have developed a certain ammt of play. Anyway it does the same thing.. spontaneously it will go through and not light up.. then it will. As far as i can determine it if a certain ammt of pressure isn't being maintaned the light goes on. Do your breaks feel "mushier" than normal? Do they respond better the harder you hit them? These are signs that you either a vacuum problem or a bleeding problem Which according to the FSM would cause the brake warning light to come on. Hope this helps!
 

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Discussion Starter #7
Hmm..

Okay, so far I've seen low fluid, and too much/too little vacuum within the master vac. I wasnt aware the master vac had a vacuum sensor within it.

Well, to explain a little further.. the brakes do feel a little different. Part of it may just be the need to change pads. The pedal travel is slightly longer (pedal goes further before resistance), and it feels like the same amount of pressure doesnt stop the car as well as it used to, which leads me to believe thats just the pads causing that "lack of stopping power". It isnt a large dropoff in stopping power..just enough to be noticable. Maybe seeing the light come on like this has got me paranoid and I'm imagining the different feeling. I dunno.

So, I'll put a little more fluid into the resovoir and see if that makes it stop. If not, can someone instruct me in a way I can test my master vac to see if it is getting either too much or too little vacuum? FSM anyone? :)

Thx.
-il82
 

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Discussion Starter #8
Sweet!

I totally forgot about the pressure differential switch. I guess that would sorta describe the feeling of the same pedal travel not really stopping the car as good as it used to. So, what..when I replace the pads, I should re-bleed the system and it'll all go away? That is, of course, if everything else is in order?

*makes note of those links*

Sweet...thanks.
-il82
 

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Re: Hmm..

As the posts that I referenced suggest, check each of the several sensors that could cause the brake warning light individually. Although it's most likely just low fluid (pull the caps to check because they are probably too dirty to see into), it could be something more serious. My guess is that it's the brake pressure differential switch, this is the "something is very wrong" indicator in the system. Since your parking brake lever is welded (WTF?), then their is no chance that the rear brakes are adjusted properly (since they self adjust when the parking brake is pulled.) Because the rear is so far wrong, then the differential switch activates under heavy load. You could try adjusting the rears though the inspection holes, but that would only be a temp fix. In the end you will HAVE TO fix the parking brake. This goes for you people with automatics also, if you don't yank the parking brake several times a day then the brakes will never be properly biased.

ConorP

Dangit!!! I wrote all that and just noticed that you're a ZXT (rear disks right?) ... but most probably still applies.

I'll throw in a "Buy a FSM" and "RTFM!!!" just for fun.
 

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Funny ...

Funny ... I just bitched at you in the other thread. Looks like you found the info I was talking about.

ConorP
 

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Re: Adjusting Rear Brakes...huh?

Adjusting the rear brakes by using the parking brake is a new one to me. Not doubting it, but had never heard of this.

I was told that the rear drum brakes adjust themselves when you apply them when travelling in reverse. Apparently the backwards pull on the pads causes the sproket that is used in a manual adjust to click over, and therefore tighten the brakes. I got told this with a 62 Chevy Bel-Air, and again with a 70 Chevy Nova, as well as a 76 Ford LTD. Just figured since they're brake drums that the Z would be the same.

Can someone confirm / deny this?

Re: the original post, upon reading that there is a change in the amount of travel required to stop the car, it points almost specifically to a leak in the system someplace. I would get underneath while someone steps on the brakes real hard and see if you have any leaks in the hoses to the wheels. Of course, this is after checking the reservoir, look inside it, a little bit of dirt can trap the reservoir fluid and not let it drain into the master.
 

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Re: Dash "Brake" light on crack? Or is

Mine was a simple fix after I finally found it. The wire from the switch by the handle that runs under the passenger seat was cut and I guess grounding itself and would come on at odd times once I found it a splice on the cut fixed it.
 

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Re: Adjusting Rear Brakes...huh?

On 1987 Nissan Pulsar, 1987 Bronco II and 1990 Pontiac 6000 LE the rear (drum) brakes are adjusted when the vehicle is in reverse and the foot brake pedal (hydraulic) is depressed. The adjusting mechanism is also activated each time the parking break is applied and released.

From the 1979 280 ZX FSM:

"Rear Disk Break.

Rear disk break does not require adjustment under normal conditions since the pad-to-rotor clearance is automatically adjusted by depressing the foot break pedal. Break pad-to-rotor clearance is properly adjusted if break pedal stroke is constant."

Now having said that I just pushed the "Toggle Lever" on a rear caliper assembly I am working on and as the "Outer Piston" moves forward. When the "Toggle Lever" is returned to its normal position the "Cam" allows the "Push Rod" to retract and the "Adjusting Nut" turns inside the "Outer Piston". To get the "Outer Piston" back you have to screw the outer piston back in clockwise.

So the answer here is both.

Wayne Monteath
Masham, Quebec.
 
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