Brake booster warning troubleshooting

[ciaka]

Well, last few days, got the brake booster warning on the instrument cluster.

I read the existing thread(s) on here and elsewhere on the topic, but still need some help with pd.

Here are my observations:

- Obvious brake booster warning on cluster

- After reset, warning comes back within 5-10 minutes of driving

- No other errors are present (using Durametric)

- When I turn the car on, and turn off radio/ac, whenever I press the brake pedal, I can hear the vacuum pump (I assume - the silver canister on passenger side, near the washer fluid reservoir) activating for about 20 seconds or so ,and then it turns off.

The pump will activate whenever I press the brake pedal (assuming the pump has stopped already before I press the pedal again).

- I visually inspected pipes near the vacuum pump and did not see any obvious breaks in line.

- Braking does not seem to have diminished at all despite the warning light

- When I press the brake pedal when the car is on (fast press), I hear a slight hiss coming from area of pedal inside cabin (not sure if this is a normal behavior as I do not normally listen for this and do not abruptly step on brakes either - with slow depress I do not hear that hiss)

Here is what I would need help with:

1. Someone to give me a good overview of the components involved, starting at the brake pedal, all the way through vacuum pumps, etc, where the issue may reside (I would like a good understanding of the components involved)

2. Possible places to look for issues

3. Anything else to help me fix this.

Greatly appreciate. Thanks in advance.

[Molitoth]

I feel your pain. I'm still driving around with this issue, and without replacing all of the hoses 1x1 or taking it to a mechanic that will charge me lots of money I'm kinda stuck.

[EleCTriCT]

Hey there...

Last time I ran into a Cayenne with a brake booster fault, it was a fault for the pressure sensor I believe..

If my memory serves me correct, it is part of the booster and not replaceable on its own.. To fix the fault I had to replace the entire booster that is stuffed into that cowel :(

I have also done this 3 times on a 997...

Can you scan it and pull the actual fault codes before you go any further?

[ciaka]

...thats the thing, there are no faults. I ran through all sections with durametric and had no codes thrown at all. The only thing i see is the warning on the instrument cluster. "Brake Booster Faulty" message.

When I reset faults in the ME7.1 section in Durametric, the error goes away, but returns shortly thereafter with no other errors registering.

Hey there...

...

Can you scan it and pull the actual fault codes before you go any further?

Edited July 12, 2012 by ciaka

[Loren]

Best find someone with a PIWIS tester - if there is a fault displayed then there has to be one in the control module or the cluster too.

[ciaka]

FOUND THE PROBLEM AND SOLUTION.

Note: This solution is just one of many possibilities in this system. There is some piping involved in the brake system and several locations exist, which coiuld be the issue. My isue was just one of several (so keep in mind when troubleshooting - check this location to see if this solution will work for you).

Problem: Found a pipe cracked near the firewall (aboiut 2 inches before the pipe enters the firewall, at the joint between the plastic pipe and a joining connector from another pipe which goes into the hose).

See pictures.

Solution: Used high heat electrical tape to tightly wrap up the cracked area. Used several 3 layers as the area expands when trying to insert hose connector into it. After wrapping, used 3 small zip ties (not shown in pics), to reinforce the crack area to prevent it from spreading when inserting the hose connector.

After putting everything together, used Durametric to reset the faults. DONE.

Other comments:

This area contains other hoses, so be careful when working here, as you may accidentally crack other attachment points.

Hope the pics help to show what I fixed in my case of this warning.

[Molitoth]

Thanks for that writeup ciaka. I will be checking this hose soon.

[EleCTriCT]

Hey Everyone, Just verified ciaka's repair on a recent cayenne myself.

Mystery Brake Booster Faults/Warnings

Brake booster fault on screen of instrument cluster. (tell tale sign on this vehicle was a "stiff" brake pedal)

No faults detected with scan tool again... ??? Using both a PIWIS and Durametric.

Found broken pipe by pass side airbox underneath vacuum pump - similar to above photos inn ciaka's post

Replaced necessary parts - clear all faults regardless

Warnings gone and normal bake operation restored.

Cheers!

[Molitoth]

Thanks for that writeup ciaka. I will be checking this hose soon.

This is exactly where my problem ended up being! To fix it, I cut about 2 inches of some rubber hose and slipped it over the cracked plastic hose for a tight sqeeze. If I recall it was 1/2" hose. I then put a hose clamp on it and wrapped it with electrical tape.

After I found this cracked hose and applied the fix, my Faulty Brake Booster light still came on. I spent another 30 minutes looking around for more cracks and possible problems before I gave up. THEN I took the car for a drive around the block and the error message went away.

Very Important: If you have this problem and fix the cracked tube, take your car for a drive!!! Don't waste your time expecting the error message to go away without driving your car around like I did.

[ciaka]

Good job molitoth.

If you have no errors thrown, the light will go off after drivinv for a few minutes (sensors report to control units which adjust warning lights - takes time).

Those who have durametric, just reset the lights to get same result.

Great to see you have yours fixed.

[mckiggan]

Thanks from me too ciaka, your post was a great help in tracking down the P1455 error code to the split plastic hose problem. In my case I gave two turns of electrical tape then used two layers of heat shrink tubing (shrink the first on with a suitable soldering iron working around it) then repeated the process over it to reinforce the connection. I hope the problem is now OK until I source the correct replacement hoses for the Aussie model. I have to find out if the dummy firewall come shielding comes away readily to give access to the booster, I have never seen a vehicle with so many covers and panels to get in your way for maintenance.

[ciaka]

you are welcome.

..." I have never seen a vehicle with so many covers and panels to get in your way for maintenance" - but is sure looks nice thought, right? lol

Thanks from me too ciaka, your post was a great help in tracking down the P1455 error code to the split plastic hose problem. In my case I gave two turns of electrical tape then used two layers of heat shrink tubing (shrink the first on with a suitable soldering iron working around it) then repeated the process over it to reinforce the connection. I hope the problem is now OK until I source the correct replacement hoses for the Aussie model. I have to find out if the dummy firewall come shielding comes away readily to give access to the booster, I have never seen a vehicle with so many covers and panels to get in your way for maintenance.

[ARModen]

I have found the exact same problem with mine.  I'm also going to fix it the same way, however, does anyone know the part number for this hose that is cracked?  Mine is exactly the same as in the pictures, where the vacuum hose comes down and plugs into the other one.

 

There are two part numbers, 95535557751 and 95535557951 both with the same description.  I'm going to have to go back under the hood there because with how jumbled it is in there, it's hard to picture which is which. 

Edited October 4, 2015 by ARModen

[Jay Pacquing]

I found the crack in my system and fixed it but the brake booster light is still on.  Does this error need to be cleared first?... and is the Duratech scan tool required to clear this error?... because I don't see the error display on my scan tool I picked up from Pep Boys.  

[Loren]

I think you mean the Durametric scan software.

Yes, you need to clear the error (in most cases) then retest to make sure.

 

I am removing your duplicate post with the same question -- please re-read the board Guidelines/Rules that you agreed to when you registered here.

"Please post your messages in one forum only. Crossposting, double posting, triple posting, etc. are all a waste of time and valuable resources. If you post the same message in multiple times or in multiple forums, we will delete the ones we feel are inappropriate."

[ciaka]

I found the crack in my system and fixed it but the brake booster light is still on.  Does this error need to be cleared first?... and is the Duratech scan tool required to clear this error?... because I don't see the error display on my scan tool I picked up from Pep Boys.  

 

You would need to reset.  Likely would need Durametric tool to do this (as I am not sure Pep Boys would sell tools that can do this for Porsche cars).  Then you need to drive for a bit to make sure light does not return (I found a few hundred yards would do).

Good luck.  

[ciaka]

If you find that you cannot or do not want to fix the issue by patching the hose(s), you can order the OEM part from multiple places to replace the entire section of hoses in that area.  

The entire 'brake booster vacuum hose' assembly will get you what is needed to replace cracked hoses in that area (passenger side under hood).

 

I ended up getting the part to replace the whole assembly (to make it 'proper' looking I guess - although the fix was holding fine).

 

The part number I ordered was:  955 355 579 51

This was for my 2005 Cayenne Turbo.  Purchased from ebay (OEM Porsche part) for total of $113 shipped.

Part was a perfect fit, replaced in a short time (I think I have DYI for this too somewhere - at least pics and instructions).

 

Thanks again.

 

I have found the exact same problem with mine.  I'm also going to fix it the same way, however, does anyone know the part number for this hose that is cracked?  Mine is exactly the same as in the pictures, where the vacuum hose comes down and plugs into the other one.

 

There are two part numbers, 95535557751 and 95535557951 both with the same description.  I'm going to have to go back under the hood there because with how jumbled it is in there, it's hard to picture which is which. 

Edited January 3, 2016 by ciaka

[Jay Pacquing]

Is the vacuum pump supposed to be a bit loud when you press the brake?... I'm asking because on mine you can easily hear from inside the cabin while I'm driving and it's pretty annoying because it sounds like a constant electrical hum of some sort.  
So far I've found 4 different leaks in my brake booster's vacuum system that I've fixed.... what a pain!
 

[Jay Pacquing]

alrighty then...

[ciaka]

Sorry for late reply. I do not hear my pump while driving. It is possible that the pump is noisy because of being overworked (due to multiple leaks and trying to compensate). If things work you are set. If the pump goes off you will know and will also know what to replace next. Thank you.

[TT955MTL]

Solved this issue on my 2004 CTT last summer.  I used a brake bleeder pump (similar to the picture below) to diagnose the leak.

 

 

I disconnected the pipe going to the brake booster pump and connected it to the bleeding pump.  When depressing the bleeding pump I was not able to build up any vacuum in the brake booster system.  That test confirmed me that there was indeed a leak.  When no leak is present you should be able to build up and keep a vacuum in the system.

 

A visual inspection did not allow me to properly locate the leak, so I did a smoke test. I didn't had a professional smoke generator at hand but I had a pack of cigarettes.  By blowing smoke in the hose disconnected from the brake booster pump, I was able to correctly identify where the leak was.  I used JBweld the seal the leak and did another vacuum test with the bleeding pump to confirm the repair was holding on.  

 

I never had the "brake booster failure" code in the cluster since then.

[Ddavidoff]

Fixed this today. 08 CTT. Didn't get the codes yet, but was having some rough idle that I thought was vacuum issues. Mine didn't have the silver pump. Maybe it was moved for the 08 version.




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[rahul singh]

Hello.... I have problem with porsche cayenne-2006. It was a no-start problem earlier, Actually some wires were damaged nearby to engine fuse-relay compartment side, 1st we fixed them & some other guy also screwed with the wiring from fuel pump side, we fixed that problem. They had already replaced ABS hydraulic unit, brake booster & DME.... We checked all these components, and observed that the gap between the holes of vacuum hose and distance sensor was less in new brake booster, compare to the previous booster...... Everything was o.k, We succeed to start the car, but now gearshift lever was struck into parking........ One fault was also appearing on instrument cluster regarding brake proportioning failure....When pressing the brake pedal, vacuum assist was working properly, but pressing pedal was lot more easier....... I mean it was going down really fast & easily.
Also checked for water intrusion, looks ok. there,
 Any advice on this kindda problem, Please help..?

[MikeBike]

I also get a "Brake Booster Faulty" on my Cayenne 2005 (V8 Turbo) . I took off the plastic shields and checked for breaks on the pipes. Everything looks OK (very fresh).

Everything is exactly as Ciaka describes - OK. A also checked the connection quite carefully that he (and Davidoff) had problems with and it looks OK. 

 

But one strange thing: My vacuum pump is hot. It works and goes on when pushing the break pedals, but it is hot.

Is that normal?  (It is working, Could it be breaking down?)

 

[dpatel710]

Hot is normal if the pump has been running for awhile. I had the same issue, all the visible connections were fine and I had jb welded them.

 

If all the normal locations check out, there is one connection under the wiper motor assembly which is not visible for inspection. That's where my crack was and I caved and ordered new lines and an updated vac pump from an audi (same part #, diff letter at the end for newer revision).