"ABS failure" and "PSM failure" warnings

[RJFabCab]

During some "spirited" driving on the track I received a "brake fluid level low" warning. The brake fluid level in the reservoir was half way between the Min and Max lines. So, I topped it off with some ATE Gold (TYP 200) to just under the Max line. I have had this happen before and topping off the reservoir gets rid of the low level warning. I'm sure it's all the G's sloshing the sensors around.

Anyhow, another trip out I received an "ABS failure" warning and then "Drive to workshop" message. Sure enough, the ABS was "out" :drive: , but I always had good pedal feel and braking performance.

A restart on the car reset the ABS failure warning, however, on the next session the ABS failure warning returned and was followed by a new "PSM failure - Drive to workshop" message.

It was like driving an 'ole 911! :thumbup:

Another restart and everything was back to normal. Braking control and pedal feel never changed. The electronic aids including ABS just disappeared. No brake fluid overflow at the reservoir and no leaks in my system that I am aware of.

Does this sound like a computer glitch or a faulty ABS/PSM module? Anyone have any ideas?

Cheers

Edited December 5, 2004 by RJFabCab

[Tool Pants]

Here is a PCA article. http://www.pca.org/tech/tech_qa_question.a...7-9B3D2D31F8C8} Search on ABS and/or PSM and you will find more.

[RJFabCab]

Here is a PCA article.  http://www.pca.org/tech/tech_qa_question.a...7-9B3D2D31F8C8}  Search on ABS and/or PSM and you will find more.

<{POST_SNAPBACK}>

Jeff, thanks for the link. I had a little trouble searching Renntech due to the 3 character limit of ABS and PSM.

Here's another Q. If I had a compromised brake pad wear sensor (it appears that the wear sensor is a continuous wire loop that eventually is broken by the worn pad), would this lead to the same "ABS failure" or "PSM failure" warnings on the display screen?

I will keep you all posted. Thanks for the help!

[wwest]

If you are somehow working the ABS and PSM really hard/continuously, it is entirely possible that the abs pumpmotor is close to overheating and the system is disabling those functions to prevent a permanent failure.

Toyota/Lexus disables the AWD/Trac functionality of their systems after about 45 seconds of continuous use, say wheelspinning to get out of a mudhole.

rOn T/Ls Restart and drive about 100 yards and the failure indicators extinguish.

[RJFabCab]

If you are somehow working the ABS and PSM really hard/continuously, it is entirely possible that the abs pumpmotor is close to overheating and the system is disabling those functions to prevent a permanent failure.

Toyota/Lexus disables the AWD/Trac functionality of their systems after about 45 seconds of continuous use, say wheelspinning to get out of a mudhole.

rOn T/Ls Restart and drive about 100 yards and the failure indicators extinguish.

<{POST_SNAPBACK}>

wwest, I thought about the scenario you mention since I had no faults in the morning sessions except the fluid level alert. We have ample cool down time between runs and I had no alerts during parade laps during which I hardly used the brakes. Shortly thereafter within 2 laps of really moving, I had the alerts back.

I was working the ABS out there, but it didn't seem like anything extreme compared to my usual track sessions. I had fresh ATE in the system and never lost pedal feel/response.

Perhaps once the system "heated up", it never really had a proper chance to cool down enough under all the duress.

[Tool Pants]

ABS/PSM for street cars is designed for us idiot drivers under slippery conditions and panic situations. Not for maximun braking on a dry race track. From the PCA tech articles, when you take a street car on the track with consumer gadgets and shove it around you can get things to happen as the systems were not designed for the track.

Here is the main link to the PCA tech section if my specific link to the same issue did not work. I am not a member but can see all the messages. You should search on ABS and PSM there - I did not mean on renntech.

http://www.pca.org/tech/index.html

From reading some of the messages ABS can stop working as it is confused as to what is going on. My pad wear sensors are also out and tied to the brake lines. The wiring diagram does not show any connection between the wear sensors and the ABS/PSM control unit.

[RJFabCab]

Jeff,

Thanks again for the help. I will review the PCA information.

Cheers

[wwest]

Remember that the ABS pumpmotor supplies pressurized brake fluid for many functions, "virtual" LSD, BA (brake assist), traction control, lateral (yawing) stability, and finally, ABS.

ABS pumpmotor is usually about the same size and fractional HP 12 volt DC motor used to run your windshield wipers. Heating is not detected, presumption of overheating is deterministic based on amount of use over time.

[ncbob]

During some "spirited" driving on the track I received a "brake fluid level low" warning.  The brake fluid level in the reservoir was half way between the Min and Max lines.  So, I topped it off with some ATE Gold (TYP 200) to just under the Max line.  I have had this happen before and topping off the reservoir gets rid of the low level warning.  I'm sure it's all the G's sloshing the sensors around.

Anyhow, another trip out I received an "ABS failure" warning and then "Drive to workshop" message.  Sure enough, the ABS was "out"  :drive: , but I always had good pedal feel and braking performance.

A restart on the car reset the ABS failure warning, however, on the next session the ABS failure warning returned and was followed by a new "PSM failure - Drive to workshop" message.

It was like driving an 'ole 911!  :thumbup:

Another restart and everything was back to normal.  Braking control and pedal feel never changed.  The electronic aids including ABS just disappeared.  No brake fluid overflow at the reservoir and no leaks in my system that I am aware of.

Does this sound like a computer glitch or a faulty ABS/PSM module?  Anyone have any ideas?

Cheers

<{POST_SNAPBACK}>

I had the same problem with ABS/PSM lights. However, my mind went into panic mode because I chipped my TT and those lights also come on when the MAF sensor goes bad. I did not notice any performance problems, so I thought it might be a wheel sensor. Took it to the dealer and it turned out to be the ABS module. Car was tied up for four days. Module replaced and no lights since.

[RJFabCab]

Update on my ABS/PSM problem. "Fault Code 5525".

The dealer replaced the air mass sensor. This is the second time my MAF sensor has been replaced. The first time I was having rough idling and depressed throttle response. This time the engine response was perfect but I received the ABS/PSM failure warnings.

Why does the MAF sensor affect the ABS/PSM systems? Perhaps I'll be able to dig the answer out of my technical manuals.

NCbob, thankfully no modules needed replacement.

There is no doubt that the ABS/PSM were "off" when I got the warnings! :drive:

Cheers

Edited December 15, 2004 by RJFabCab

[frenchy]

Update on my ABS/PSM problem.  "Fault Code 5525".

The dealer replaced the air mass sensor.  This is the second time my MAF sensor has been replaced.  The first time I was having rough idling and depressed throttle response.  This time the engine response was perfect but I received the ABS/PSM failure warnings.

Why does the MAF sensor affect the ABS/PSM systems?  Perhaps I'll be able to dig the answer out of my technical manuals.

NCbob, thankfully no modules needed replacement. 

There is no doubt that the ABS/PSM were "off" when I got the warnings!  :drive:

Cheers

<{POST_SNAPBACK}>

Are you using a "K & N" or similar type of air filter?

They are known for contaminating the MAF sensor (did that to mine)

Jean

[RJFabCab]

I am well aware of the issue concerning the cotton type filters. I was running the BMC filter (straight out of the box, not re-oiled) when my first MAF went out. The BMC may have had something to do with the first failure, but I know guys who have run the BMC's for years with no issues at all.

So, I switched back to the stock element which has been in place ever since. And my reward? A second MAF failure! :P

I just have to accept the fact that the MAF sensor is a unit prone to contamination/failure.

Edited December 16, 2004 by RJFabCab

[KarlS]

I don't see how a failed MAF would affest the ABS or PSM systems. It would throw a check engine light but I don't think it would affect braking or traction control.

I suspect that what was happening on the track was you were threshold braking in a rough or bumpy part of the track. This will cause the ABS to go crazy cycling to try an regain traction. Eventually, it will give up and throw the ABS light. Since the same sensors are used for PSM, it makes sense that you could see a warning light there as well.

Did you notice if the ABS warning was coming on in the same braking zone each time?

Karl

[RJFabCab]

I don't see how a failed MAF would affest the ABS or PSM systems. It would throw a check engine light but I don't think it would affect braking or traction control.

I suspect that what was happening on the track was you were threshold braking in a rough or bumpy part of the track. This will cause the ABS to go crazy cycling to try an regain traction. Eventually, it will give up and throw the ABS light. Since the same sensors are used for PSM, it makes sense that you could see a warning light there as well.

Did you notice if the ABS warning was coming on in the same braking zone each time?

Karl

<{POST_SNAPBACK}>

Karl, I've been tracking for some time now with the same setup and have never had ABS/PSM issues before. There was no consistency to when the faults showed up. Heck, the second PSM fault showed up while moving at good speed down a straight with no heavy braking immediately prior. It was strange.

The first faults showed up under heavy load, so I thought I may have been confusing the electronics or overstressing the system. However, the other two alerts occurred during relatively stress free driving.

NCBob apparently had a similar incident. The dealer told me that the faulty MAF somehow creates an electrical issue that affects the system. I don't understand the situation, and I have not had the time to review my tech manuals yet!

The faulty MAF code definitely showed up on the PST2, though.

I'll keep you all posted if I find out something interesting...

Cheers

[RJFabCab]

OK, here's Joel Reiser's excellent explanation of the relationship between the air mass sensor and the ABS/PSM.

Tech section pca.org

[pioneerporsche]

Hi, I had the same issue with ABS/Brake fluid, I had changed the fuse and it is fine now. when you turn the ignition on all lights go on, starting the car everything is fine. try the fuse abnd see if it works.

During some "spirited" driving on the track I received a "brake fluid level low" warning. The brake fluid level in the reservoir was half way between the Min and Max lines. So, I topped it off with some ATE Gold (TYP 200) to just under the Max line. I have had this happen before and topping off the reservoir gets rid of the low level warning. I'm sure it's all the G's sloshing the sensors around.

Anyhow, another trip out I received an "ABS failure" warning and then "Drive to workshop" message. Sure enough, the ABS was "out" :drive: , but I always had good pedal feel and braking performance.

A restart on the car reset the ABS failure warning, however, on the next session the ABS failure warning returned and was followed by a new "PSM failure - Drive to workshop" message.

It was like driving an 'ole 911! :thumbup:

Another restart and everything was back to normal. Braking control and pedal feel never changed. The electronic aids including ABS just disappeared. No brake fluid overflow at the reservoir and no leaks in my system that I am aware of.

Does this sound like a computer glitch or a faulty ABS/PSM module? Anyone have any ideas?

Cheers

[phillipj]

That thread is 6 years old now. Hopefully he has fixed the problem

[mas430]

Hi, I had the same issue with ABS/Brake fluid, I had changed the fuse and it is fine now. when you turn the ignition on all lights go on, starting the car everything is fine. try the fuse abnd see if it works.

Daft question but do you mean the abs fuse ?

[pioneerporsche]

I open the fuse box, and the changed the fuse, located at the bottom left to the clutch.

Hi, I had the same issue with ABS/Brake fluid, I had changed the fuse and it is fine now. when you turn the ignition on all lights go on, starting the car everything is fine. try the fuse abnd see if it works.

Daft question but do you mean the abs fuse ?

[pioneerporsche]

oops, i hope so.

That thread is 6 years old now. Hopefully he has fixed the problem

[pioneerporsche]

maybe you can help, I had replace my battery and now the Rdio won't turn on, it a Decker CDR 220, I do have the code.

Thanks;

oops, i hope so.

That thread is 6 years old now. Hopefully he has fixed the problem

[SpawnyWhippet]

I have had this problem. Durametric throws faullts for stop light switch, so I replace the switch on the pedal. This didn't fix it, so I took the car to a specialist who advised it was the pressure sensor / switch on the ABS PSM hydraulic pump. It is a seperate part to the pump, but the shop seemed unable to locate a replacement part, other than buying the whole pump for many $$.

 

I've been unable to find a part number for this switch, can anyone advise if it is possible to buy it seperately?

 

 

Edited March 13, 2015 by SpawnyWhippet

[JFP in PA]

I have had this problem. Durametric throws faullts for stop light switch, so I replace the switch on the pedal. This didn't fix it, so I took the car to a specialist who advised it was the pressure sensor / switch on the ABS PSM hydraulic pump. It is a seperate part to the pump, but the shop seemed unable to locate a replacement part, other than buying the whole pump for many $$.

 

I've been unable to find a part number for this switch, can anyone advise if it is possible to buy it seperately?

 

Year and model would always be helpful, as would recognition that not all parts are sold separately, either by Porsche or the aftermarket.

[SpawnyWhippet]

Sorry, forgot. 2001 996 C2 with PSM

[JFP in PA]

Sorry, forgot. 2001 996 C2 with PSM

 

From what I can find, that pump is only available as a complete assembly, and retails for around $3K:

 

ABS PUMP ASSY - 2001 Porsche 911 (996355955BX) List Price: $3,428.24

• You Save: $586.74 (17% off)
• Sale Price: $2,841.50
• Core Charge: $772.84 

 

Genuine Porsche Parts

• Manufacturer: Porsche
• Part Number: 996-355-955-BX
• Part: ABS PUMP ASSY
• Replaces: 996-355-955-52, 996-355-955-54, 996-355-955-62
• Part Notes: 2WD, W/STABILITY MNGMT

  PARTS: Order by description.