brake booster faulty

[royxaxa]

mine was broken when I did the timing chain job.

i replaced the T with a copper fitting from Homedepot. lol

[Molitoth]

Problem Resolved: See this thread.

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.

[Roli Savvaris]

I had the same brake booster faulty and it had nothing to do with the hoses in my case,...

My friend checked if there was power going to the brake booster when the brake was applied in stationary.

He then opened the fuse box which is located in the engine compartment up close to the winscreen on the side, close to the left hand door as we see from sitting in the car (this is so that people don't get confused if left hand drive or right hand drive vehicle)

The fuse which I believe was a standard 30 was blown so he replaced it and finally the car is braking as it should for a supercar,...

[ALEV8]

Just got this now on the way to Home Depot..... ****. Going to check hoses tonight....fingers crossed.

Edited January 9, 2013 by ALEV8

[ALEV8]

Sure enough I removed the engine cover on pass. side and the upper hose above the check valve was cracked where it mounts on check valve barb. Gorilla tape and small ziptied it until I can order an OE hose assy. P/N anyone....? I'll be searching. My thought is it's the hose described as the upper hose in this thread.

What I can deduce is the hardware above the clip retainer, etc is ok. The split hose was a shiny PVC IIRC no part number on it, perhaps not OE parts? Exactly the same as the linked to thread by forum used with issue at firewall and whom removed pump to access it.

The valve appears ok but maybe I should swap out everything while I'm in there?

Edited January 9, 2013 by ALEV8

[ringnalda]

Same 'brake booster faulty' warning, was quoted $1500 for new brake booster: "Yes Sir, we checked and even smoke tested the vacuum line..." Went home, found the crack in the line and replaced it for $120 with a new vacuum line from Porsche. Happy Days. Time to find new mechanic...

Jan

[ringnalda]

Problem Resolved: See this thread.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.

Or reset the code with PIWIS...

[ALEV8]

Everybody needs money these days.... That's what scares me.

[Andrei Marton]

I see this problem appears on 955 TT cayenne models. Any ideea if someone with 957 S or other engine had this problem??

[ALEV8]

Finally ordered this *****.

[Ignited]

Finally found my third vacuum leak yesterday! It was same as ohboy's...there is a "T" under the torque mount. I did the same slathering epoxy with a long thin screwdriver and let it dry overnight. The split in the hose was right on top and easy to see and reach. No more fault light!! This is the first day in 2 years my '04 CTT has not had some kind of warning light on! I also wrapped it with foil tape to protect it from heat.

Tim in Ft Worth

Edited April 26, 2013 by Ignited

[bluedog]

Does anyone know if the vacuum pump has a relay?? I have had the brake booster light on and off for a month. Yesterday I went to push the brake and it was all leg to stop the 6k lb. I have read most forums and checked all the hoses, pressure tested the line, etc. I took the vacuum pump off and cleaned it, and tested it with a 12v powersupply and it ran well. However, when the pump is connected to the car it turns on just after start up for 5 sec or so and shuts off. This is even if the vacuum line is disconnected from the pump. Ergo, is there a relay that is not doing its job to tell the pump to run longer or at all?

Thanks

[ciaka]

Is there a fuse for the brake booster? I thought there was one, probably under the hood, under the cover near the brake fluid (driver side). Check the manual and look at the fuses to make sure not blown (although you did say it worked on/off which would not be in line with blown fuse). Just another place to check. Relay would make sense though, if getting stuck sometimes.

Does anyone know if the vacuum pump has a relay?? I have had the brake booster light on and off for a month. Yesterday I went to push the brake and it was all leg to stop the 6k lb. I have read most forums and checked all the hoses, pressure tested the line, etc. I took the vacuum pump off and cleaned it, and tested it with a 12v powersupply and it ran well. However, when the pump is connected to the car it turns on just after start up for 5 sec or so and shuts off. This is even if the vacuum line is disconnected from the pump. Ergo, is there a relay that is not doing its job to tell the pump to run longer or at all?

Thanks

[VIPNiSS]

04 TT, same fault, "brake booster warning".Same problem as TopGun2000. the hose/plastic pipe is cracked at the connection (bottom end). Most likely due to heat exposure. Wrapped electrical tape (for now), i guess 3/4" heatshrink will also do.P/N is 7L5-611-931 G. Cleared code, seems ok.it is under pass side engine cover (remove blue washer lid, remove torx screw at lid, loosen rubber gasket around, remove that "+" screw lock thingy, remove plastic cover, and it's right under the plastic cover.)15 minute job total.Thank you Renntech, thank you Durametric!

I found the problem: a cracked vacuum line (on the top of the hose at the "931" mark)!!! :cheers:DSC_0012.JPGObviously there was another old leak which was fixed by the previous owner in a JB Weld way. :jump:DSC_0010.JPG :renntech:

Thank you very much!!! i have the same issue and it was this hose. I will order a new one.. thx everyone who contributed!

[VIPNiSS]

The one that is pictured above is part # 955-355-579-51 for the piece that included the check valve. from the pump to the "Y" split and to the engine and firewall" I paid $133.34 probably cheaper online tho, if u dont mind waiting.

thanks!! just what i needed.

[ALEV8]

Well the fault has returned. I gave the vacuum lines a cursory look and didn't see anything split. Also I replaced the bulk of those lines with the new part as in the beginning of the thread. Going to take it to the independent now..... Dear Jesus.....

[mcbit500]

05 turbo went again after I sold the car to a mate, 110k km and 3 years later.

[ALEV8]

Indy can't come see me until Monday. I checked the fuse for the vacuum pump and it's fine. Vac pump runs perfectly on startup and stops after about 30 seconds. No sucking or hissing sounds detectable with engine running. Maybe shut the engine off and listen for noises coming from the vacuum line area next? I'll also check the line behind the pump, and tee lines at firewall and beneath the torque mount, although I think I replaced these as part of the full hose assembly replacement earlier in the year.

Edited November 24, 2013 by ALEV8

[Ignited]

Just got back from my indy mech who ran the smoke test. Would not have found these leaks otherwise. In addition to the bulkhead leak another was found by way of the smoke test done by the local garage. It seals the entire vacuum system and pumps vapor into an open port. Leaks can't hide from this test! The other leak, much smaller, was the check valve underneath the engine's torque arm. The bulkhead leak was massive and was plugged to discover the other much smaller leak in the check valve.

Tim

[slaskowski]

Thanks for the post. I had the same brake booster alert with my 2004 CTT with 85K miles. Low and behold the same hose was cracked at the lower base, I just ordered one from Sunset Motors for $85 (love those guys).

I am looking forward to not seeing that warning alert anymore as well as my ex-wife no longer threatening to take the car to the local Porsche dealership to fix it :)

[Ignited]

hey Slaskowski, what hose was cracked at the lower base? Where was it located? And did you order the entire hose assembly from Sunset for that price? My error light came back on last time as soon as I hit boost, so I'm wondering if my problem might be a check valve and not a cracked hose. Does whatever you ordered include new check valves?

Tim in Ft Worth

[slaskowski]

Tim- I went to my mechanic today to put the new hose in, he started taking apart the hose and then told me to wait a minute. He came back wtih some hose from the back, he cut it to length and installed it. Brake Booster problem went away.

I asked him what I owed him, he shook my hand and said that it was on the house.

I am thinking it was either good karma and/or the holiday, either way I am taking it :)

[mcbit500]

Good result! :cheers:

[ALEV8]

Well mine is at the Indy now and there's a leak at the cowl, which I'm assuming means the firewall, in the hose running to the booster itself. Looks like a straight piece terminating at the booster pressure sensor from the diagrams I've studied. Anyone replace this one yet? If so please indicate p/n. I've already replaced everything on the passenger side connecting to the pump and the air box as I stated earlier in this thread....

[5thlilpiggy]

Here are the hoses:

http://www.ecstuning.com/Porsche-2004-Cayenne-955-Turbo-Sport_Utility-V8_4.5L/Braking/Master_Cylinder/Brake_Booster/

This one has the pressure sensor:

http://www.ecstuning.com/Porsche-2004-Cayenne-955-Turbo-Sport_Utility-V8_4.5L/Braking/Master_Cylinder/Brake_Booster/ES1446344/