Just thought I'd give you an update as well. Recall I have been dealing with code 4460 for over 2 years. The car was at an Indy shop for 4 months, they concluded it needed a new ABS/PSM module. I had the car transferred to a dealer and they also concluded it is the ABS/PSM and the high pressure pump (They said they don't know which one failed first and whether that impacted the other part). They scavenged another car they had to test and the replacement parts seemed to take care of the issue, so now I am replacing those parts...big $$$, but don't want to skimp on brake systems.

 

Another update, with similar outcome.
My indy shop was able to finally resolve the issue. In the process the ABS module was replaced with a used module from a 4S, and new high pressure pump, yaw sensor, and a wheel speed sensor was replaced. Even after doing all this, and with no error messages showing, the front brakes were not pulsing properly. Finally voltage drops were checked in many areas and the brakes now work. I believe we had a multi-faceted issue that is finally resolved. Phew!

 

What was done to resolve the voltage droops?

 

Replaced connectors and ensured proper contact wherever there was a connector. As I did not do it myself I am not sure which.

 

Hi all,

appreciate your expert advise. Have a 996 turbo that had a burnt ABS module (electric side). After much struggle, was able to find and replace it with a module from 4S and also replaced wiring harness connecting to pump as it was burnt along with the pump at the place where they connect. Now, all seems sorted and all connections done with all warnings also gone.
The issue now is that the car seem to automatically engage brakes / engage traction when it is on a sharp turn (not on normal turns or on straight line). Any help / suggestions are most welcomed. Thank you

 

I’ve hit a similar issue where on windy roads and the track, especially during strong left turns, PSM would pinch the front right brake. Drove me nuts. It seemed to correlate with whenever I would swap tires out in pairs instead of all fours … for instance, rears would wear out roughly twice as fast as fronts and so I’d pair fresh rear tires with older fronts that still had plenty of life. Over time the issue would abate, which I surmised was due to tire wear evening out resulting in less of a front/rear speed differential for the PSM to get touchy with. But I have no solid data for that short of a gut feel.

Ensure all your wheel speed sensors are clean at their tips? They tend to collect ferrous debris after some time.

If any warning lights latch on and persist, a Durametric tool can scan them out and give you clues about whether it’s a voltage issue or an implausible sensor signal issue. Just know that if you turn off the car, the PSM module codes often clear and the clue codes are lost… so try and scan out before turning off ignition.

 

Also, see this post about replacing the wiring harness running to the front wheel carriers. You can see the error codes that the module throws. But as I recall, the intermittent brake pinch during hard turns was never really associated with the harness issues because those would latch an error light that persisted for the rest of the drive.

 

Amazing. Thank you for your advice. It’s exactly reacting the way as you described - The right front brake seems to be engaging when turning left even at slow speed. But all 4 tires are new and stock spec 😔 so that suggestion can be ruled out. Will get the speed sensors cleaned - have been asking the shop to do that but they keep saying that it should not help. I will ask them to do it irrespective. No harm exhausting all possible reasons. Also, there are no codes comig up in the PIWIS to detect any fault. Though the steering angle sensor was checked, the shop tried replacing it with another sensor to make sure the reading are same. In the process, seems like they triggered the airbag activation and now disconnected the battery to keep it overnight and hopefully they connect again for that issue to go. Coming back to the other possible causes, considering that the ABS is from a 4S, the PIWIS keeps showing the VIN no of the car from where it was taken. They keep trying to erase it and put my cars vin in it. While it takes it, it reverts to that other cars vin (from where the abs module came) after 5-7 seconds. Do you think this could be a potential reason - am getting a professional coding / programmer to help clean the vin from the Abs module and add my car vin to this abs (if possible). Hoping this and cleaning sensors will work 🤞🏻. Thanks again for your feedback and advise - do pls let me know what you think of the above 🙏

 

Interesting. I also have the same issue of front right brake pinch on street driving. It actually intervenes much less on the track. I have replaced a leaking hydraulic block on the ABS module in the past. I have replaced all speed sensors previously and even replaced the front right wiring harness in hope that was causing the behavior. The car does have a modified suspension and fairly aggressive track alignment (GT3 bits, -2.5 camber, lowered to GT2 ride height on JRZ coil overs.) I contemplated putting the alignment back to a street friendly setup to see what changes, but sounds like others are experiencing this with a fairly stock setup. I've just been turning the PSM off on the street lately, as its quite annoying unless you stay on throttle for those left turns.

 

Yeah, best I’ve narrowed the left turn pinch root cause down to, after addressing everything else I could think of, was it happens most often with mismatched tire age. Rear tires tend to get replaced twice as often as fronts, and any time I slapped new rears on while keeping the old fronts as they had plenty of tread left, this pinch would rear its head and then slowly go away as the rears wore down. Never seemed to experience it when all 4 tires were changed at once. I also found disabling the PSM via dashboard button did not help. Did you find it to help?

 

Yeah, if I turn off PSM via the dash button, it does not intervene on me. Honestly was thinking about just unplugging the PSM pump at this point.

 

I found that I had too much PSM intervention on track even with PSM disabled on dash. I think through this forum, I was advised to just put a switch on the power to the pump. This disabled the PSM but did not disable ABS or EBD. All good, and rear brakes not overheating on track.