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Discussion Starter #1
Hi guys, relatively new g8 owner. I recently started the car(08 gt) and had the dic show a brake warning, not a parking brake warning. Its not low fluid, no abs light, no braking issues driving the car, just an annoying light. It comes on every time I start it, disconnected the battery, no change. Tried searching, no luck, anyone have any ideas?
 

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Could be the brake switch on the pedal. Check to make sure the brake lights operate properly while pressing the pedal... Also check 3rd brake light

Sent from my Nexus 6 using Tapatalk
 

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I've never had a problem yet that has caused some type of display in the DIC referring to the brake system. But if you meant the red "BRAKE" icon in the cluster, I can't see it being anything but a faulty parking brake handle position switch, or a faulty (or telling the truth) low level sensor in the brake master cylinder reservoir. You can (if its that icon display) isolate either or both to either prove out or eliminate as the source.
 

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Discussion Starter #4
I will check the brake lights this morning, but I the shift interlock works, although that could use a different sensor on the pedal, I havent looked. Im pretty sure I can rule out the parking brake and the fluid level, when the parking brake is pulled it literally says "parking brake" on the dic, when I drop it back down it just says "brake". Fluid level is good and I pulled the sensor to bypass it, no change. Also the car will beep at you if it thinks you still have the parking brake on and start driving, this doesnt. Ill check brake lights and report back. Is there anything else in the system that can trigger the idiot light? Low pad sensors like german cars? Does this system store codes that can be pulled to help diagnose it, or just a light?
 

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Son of a gun, there are 3 things that can cause the "BRAKE" tell tale light to illuminate, as well as display some sort of animation in the MFD. Plus causing a general warning chime to sound off (must be to get your attention of a possible problem). You said you eliminated the low level sensor. They way I read it, if it was the parking brakes fault, you would only get the MDF animation once the car exceeds 6 mph. The fluid level, and the 3rd item would cause the animation to display from the get go. Kinda reads like you may be able to confirm or eliminate the parking brake circuit (based on the 6 mph rule). The 3rd item is the EBD (electronic Brake Distribution) circuit. It regulates the brake fluid pressure delivered to the hydraulic brake wheel circuit. It is located within the ABS module (not good if that's the cause).
 

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Discussion Starter #7
For clarity, I have no chime, that only happens if I leave the parking brake up. So it seems to me that option 3 is most likely, any way to test that unit or confirm? Would it prevent abs from functioning? Not real sure exactly what its doing.
 

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If you have had other things along with the brake light and its associated DIC display (like ABS or Stability Control) there might have been some further checking I could have posted. But not having any other symptoms, that info probably would not help. Its beginning to look like you will have to have GM's Tech 2 hooked up to properly T/S those 3 circuits. All the electronic stuff that takes place *within* that EBCM, is way over my head.
 

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At this point you must get a scanner and check, on rare occasions the inst. Cluster will keep it on also, after checking abs systems first, you need to go into body system data to IPC data and see if the brake light is being commanded on, if no = faulty cluster.keep in mind the sensors are not hardwired to cluster it all happens by data streams, keep us posted
 

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Any update?
 

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Discussion Starter #11
Havent had it scanned yet, will update when I do. Going to do it soon because it annoys me that it disables cruise control.
 

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Not knowing when you would be able to get your car checked (for a possible fault code or codes), you could easily try/test this. >>>>> Remove an verify the condition of fuse F1-10A (labeled comm/enabled). If proven OK, reinstall the fuse, an swap the R12 relay (comm/enable) with the R5 relay (fog lights). This to verify that the comm enable circuit is *not* causing the problem with the brake warning light, an the loss of the cruise control circuit. Those components are located in the underhood fuse box.
 

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Any updates on this?

I have a similar issue and the dealer said they would have to replace the master cylinder because the sensor inside was bad and I guess you can't just replace the sensor. They said it would be over $500. Just curious what you found out or if what I heard sounds reasonable?
 

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^^^^ I think you need to post up exactly what the brakes are doing when you step on the brake pedal. An, if you are getting any displays/warnings prior to or after applying the brakes. I'm finding it hard to blame the master cylinder at this point, since it does not contain any wiring or pressure sensor.
 

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^^^^ I think you need to post up exactly what the brakes are doing when you step on the brake pedal. An, if you are getting any displays/warnings prior to or after applying the brakes. I'm finding it hard to blame the master cylinder at this point, since it does not contain any wiring or pressure sensor.
The brakes (and brake lights) themselves work fine. I have a warning that says (BRAKE) in the DIC and the brake light illuminates in the instrument cluster. They are on pretty much all the time now, but when the problem first started (a month or so ago) they would randomly come on and randomly go off at different times.

Earlier in this thread, you mentioned it could be the "low level sensor in the brake master cylinder reservoir" which is what the dealer is saying as well. If that is what it is, do they have to replace the whole brake master cylinder or is there a way to just fix the sensor. Does the price they quoted me sound right?

Thanks.
 

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Discussion Starter #16
Sorry guys ive been living with it so i have no info for you. Other than the abs still works, which is interesting.

For your problem that the dealer just wants to throw parts at, if they KNOW its just a failed low level sensor thats at least a great start. If its not a separately replaceable part(not sure, but i know it is on gm trucks), the price seems reasonable, actually id venture to say cheap. Price of new master cyl + labor to physically replace + labor to bleed the whole system + labor to scan to clear code + fluid/shop supplies, at what $100/hr seems reasonable.

Please let us know how you make out.
 

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Other than a possible mess with the brake fluid (if not completely removed from the reservoir) prior to removal, it looks like a very simple job. The *bad*, is that they say you can no longer order an buy the reservoir with its built in internal low level sensor. When it was available, the P/N assigned to it was 92213570. What you have to do now, is buy a new OEM master cylinder (which also includes the complete reservoir). That P/N is 92213566 for about $167 plus the usual shipping an possible state tax. All you would have to do is install the new reservoir on your existing master cylinder an stow the new cylinder for future use (if it ever becomes necessary). For now (to avoid that annoying warning light), once you verify that the existing reservoir is full of fluid, just disconnect the connector from it. That will create the same condition as a properly working sensor. If your VIN # is lower than 8L136054 there might be a problem with the P/N above
 

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Rock Auto has Centric and Raybestos brands for much less and some Centric parts are re-boxed Aisin's.
 

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Discussion Starter #19
Not knowing when you would be able to get your car checked (for a possible fault code or codes), you could easily try/test this. >>>>> Remove an verify the condition of fuse F1-10A (labeled comm/enabled). If proven OK, reinstall the fuse, an swap the R12 relay (comm/enable) with the R5 relay (fog lights). This to verify that the comm enable circuit is *not* causing the problem with the brake warning light, an the loss of the cruise control circuit. Those components are located in the underhood fuse box.


FYI I tried all things here, no change.
 

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Curious, is your traction control also turned off? (Not by you, automatically)

I ask because if the MAF is malfunctioning or unplugged it can cause this very warning. It happened to me years ago, and I suspect it was the reason for the lingering Brake Warnings and TC being off after starting for the first time after the DOD Delete.

Unplug the MAF and check the connectors. Clean them with an electronics cleaner; there are aerosols for that. Clean the MAF while you're at it. Plug it back in and drive for a while. It should eventually go off.

An OBD Scanner of sorts would tell you if the MAF is malfunctioning as well.

It's worth a shot.
 
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