PSM activation oddity baffling

[jyoteen]

I have been chasing this issue for a while now, trying to figure out what the hell is the cause. I'm trying to go about it methodically partly because there's so much stuff tied into the PSM/ABS system.

I'm getting PSM activation/intervention when the car is turning left on an off/on ramp or a curve at speed. The speed itself isn't really at play (doesn't happen when making a left turn on the street, for example) but almost always activates on the higher speeds of a highway curve (whether the surface is at an incline up/down or level).

So far, we've checked the tires, ABS speed sensor, steering angle, yaw sensor, brake switches.

I had a ABS/PSM light as well, but that turned out to be the brake switch which is now fixed, yet the PSM problem persists. The steering wheel angle was reset and calibrated. The yaw sensor shows readings that are not out of range.

I cleaned the MAF and seems to be fine (It was fine beforehand but just in case, I cleaned it). I also got a new Battery just in case.

What else could it be? Help would be appreciated.

It only happens when car is turning to the left. Normal operation to the right. Is there something I can buy that logs the driving conditions and record PSM activation? maybe it's a particular speed that needs to be reached, a particular steering angle or yaw combination? What other sensors are on-board that affect this?

Edited May 19, 2011 by jyoteen

[Loren]

Did you check your brake lights too?

[jyoteen]

yes, they were actually functioning before I replaced the brake switch which was odd. I was just getting the ABS/PSM failure notification in the instrument cluster, which is now cured with the new switch.

This has me completely baffled.

Did you check your brake lights too?

[Loren]

Hmm... same switch? loose connector? bad switch?

[judgejon]

I have been chasing this issue for a while now, trying to figure out what the hell is the cause. I'm trying to go about it methodically partly because there's so much stuff tied into the PSM/ABS system.

I'm getting PSM activation/intervention when the car is turning left on an off/on ramp or a curve at speed. The speed itself isn't really at play (doesn't happen when making a left turn on the street, for example) but almost always activates on the higher speeds of a highway curve (whether the surface is at an incline up/down or level).

So far, we've checked the tires, ABS speed sensor, steering angle, yaw sensor, brake switches.

I had a ABS/PSM light as well, but that turned out to be the brake switch which is now fixed, yet the PSM problem persists. The steering wheel angle was reset and calibrated. The yaw sensor shows readings that are not out of range.

I cleaned the MAF and seems to be fine (It was fine beforehand but just in case, I cleaned it). I also got a new Battery just in case.

What else could it be? Help would be appreciated.

It only happens when car is turning to the left. Normal operation to the right. Is there something I can buy that logs the driving conditions and record PSM activation? maybe it's a particular speed that needs to be reached, a particular steering angle or yaw combination? What other sensors are on-board that affect this?

[jyoteen]

The PSM activation issue has been going on before the ABS/PSM instrument cluster warnings lit up. On searching I assumed there was a connection between the two issues, but apparently there is not. At least there doesn't seem to be one.

Obviously, the most expensive route of either the ABS pumpmotor or ECU hasn't been ruled out, but those are more expensive and I can't imagine it'd would cause only one side to activate, but I don't know enough about these cars.

Hmm... same switch? loose connector? bad switch?

[judgejon]

You mentioned checking the tires. Are you running different tires on front/rear? Need to run same tire brand all around. This has been noted by others here, including me, with similar problems. Can't cross brands with the psm.

[jyoteen]

nope. Same tire, OEM size on OEM wheel. I even tested it with factory tire pressures. Nothing has changed

You mentioned checking the tires. Are you running different tires on front/rear? Need to run same tire brand all around. This has been noted by others here, including me, with similar problems. Can't cross brands with the psm.

[RFM]

Do a shock absorber test, it may be that one of the left shock absorbers performs less than the others, hence less pressure on the road in curves at speed result in PSM intervention (spinning wheel, inside curve)

[WillardWest]

The PSM activation issue has been going on before the ABS/PSM instrument cluster warnings lit up. On searching I assumed there was a connection between the two issues, but apparently there is not. At least there doesn't seem to be one.

Obviously, the most expensive route of either the ABS pumpmotor or ECU hasn't been ruled out, but those are more expensive and I can't imagine it'd would cause only one side to activate, but I don't know enough about these cars.

Hmm... same switch? loose connector? bad switch?

This could be wrong, probably is. But I seem to remember rear L/R height detectors/sensors (anti-rollover..?) as a part of PSM.

[schmidty]

Has anyone come up with an answer to this problem? I have an 02 tt which is behaving similarly. Drives fine at slow speeds, drives fine when pushed a bit, but just cruising along on a long left hand turn the abs activates on what feels like the left front tire unsettling the car and the driver. The speeds are not at all high typically 50 ish ( happened while following a 80s Toyota pickup through the corner once- his car worked fine :) ) and it doesn't happen every time just a fairly high percentage on specific corners and always a left hand turn. If you push the car a bit in the same corner it's fine, which is what makes it so frightening. It happens when you are just relaxed driving.

No codes are visible with either durametric or and Indy shops program. An independent Porsche shop owner drove the car and had it happen to him, his words were to the effect that it scared the snot out of him an that it is not normal.

I have replaced and swapped wheel speed sensors and the problem never changed. I have inspected the wiring harness into the body and there are no signs of damage. Car has never been in an accident. Steering wheel sensor has been recalibrated with no effect. Suspension is factory, car has less than 25k miles. The car has oem wheels and tires in the correct sizes. Rears have less than 3000 miles on them fronts have nearly the same tread depth. Tires are contisportcontact 2s. The only snafu is that the fronts are not N-Rated. The rears are nspec. Rolling diameters are matched and there is no evidence of damage to any wheel or tire. Tire wear is even.

I called The dealer who told me that no codes means unlikely to find a fix as replicating the problem in their suburban location is nearly impossible-hmmmph

Anyone with any thoughts on what to check next or any experience? Yaw sensor is over a grand and I dont want to willy nilly replace parts unless they are needed. Love the car but am getting tired of looking at the trees on a left hand corner and wondering...

Thanks, Schmidty

[fpb111]

Pull fuse B9 (or equiv.) until you puzzle this out?

[efs]

Has anyone come up with an answer to this problem? I have an 02 tt which is behaving similarly. Drives fine at slow speeds, drives fine when pushed a bit, but just cruising along on a long left hand turn the abs activates on what feels like the left front tire unsettling the car and the driver. The speeds are not at all high typically 50 ish ( happened while following a 80s Toyota pickup through the corner once- his car worked fine :) ) and it doesn't happen every time just a fairly high percentage on specific corners and always a left hand turn. If you push the car a bit in the same corner it's fine, which is what makes it so frightening. It happens when you are just relaxed driving.

No codes are visible with either durametric or and Indy shops program. An independent Porsche shop owner drove the car and had it happen to him, his words were to the effect that it scared the snot out of him an that it is not normal.

I have replaced and swapped wheel speed sensors and the problem never changed. I have inspected the wiring harness into the body and there are no signs of damage. Car has never been in an accident. Steering wheel sensor has been recalibrated with no effect. Suspension is factory, car has less than 25k miles. The car has oem wheels and tires in the correct sizes. Rears have less than 3000 miles on them fronts have nearly the same tread depth. Tires are contisportcontact 2s. The only snafu is that the fronts are not N-Rated. The rears are nspec. Rolling diameters are matched and there is no evidence of damage to any wheel or tire. Tire wear is even.

I called The dealer who told me that no codes means unlikely to find a fix as replicating the problem in their suburban location is nearly impossible-hmmmph

Anyone with any thoughts on what to check next or any experience? Yaw sensor is over a grand and I dont want to willy nilly replace parts unless they are needed. Love the car but am getting tired of looking at the trees on a left hand corner and wondering...

Thanks, Schmidty

Hi!! I have exactly the same problem with my 05 Boxster S...:(

I just ordered two front tires. I´ll fitt them tomorrow.