996 TT ABS PSM warning light

[Allan.adams]

2001   came on. Long story short, every shop(non Porsche) said the pump/computer was bad and needed replacement 4,000.00>. I don’t have a Porsche dealer anywhere around so I just listened and watched. Come to find out the tire pressure was low, adjusted pressure and lights went out. 

Question, how did it know the tire pressure was low, there is no TPMS system that Iam aware of???  Curious and new to Porsche. 

 

1st Porsche I have owned and concerned about the car diagnostic,   Best to invest in Durametric Diagnostic Tool.  

[Paul in WI]

The flat tire’s circumference changed causing it to turn at a different speed than the rest. 

[Allan.adams]

Wow...those Germans....it knows the tires are low without a TPMS system. Wish it would light up something else BUT I am  impressed.

 

Thank you very much. So glad I found this site. 

[Allan.adams]

Hello all- quick question...tire pressure on front and back. Book said 36/44, would the 8 lbs difference cause a ABS/PSM light to come on?  Iam in the mountains and temp differences cause tire pressure to lower. Shop here  said all tire pressure should be the same? 35 psi. This seems wrong to me. 

First time owner and this tire pressure is causing these false abs readings when down/up the mountain.  

Any suggestions would be greatly appreciated.  

 

Thanks in advance. 

[JFP in PA]

 That slight a tire pressure difference should not be enough to trigger this problem.  More often than not, battery/charging system issues can trigger "ghost" ABS/PSM codes in these cars, so I would start by checking them first.  I would also scan the car with a Porsche specific scan tool to see what faults are indicated.

[Allan.adams]

Thanks for the information. Is there a way to test the battery/charging system?  Car is on a tricycle system, and seems ok, but I am in the mountains far from civilization..  maybe meter the battery?? Or voltage from the alternator?  Car drives fine but concerned about driving down the mountain. 

 

Thanks again, much appreciated. 

 

[JFP in PA]

3 minutes ago, Allan.adams said:

Thanks for the information. Is there a way to test the battery/charging system?  Car is on a tricycle system, and seems ok, but I am in the mountains far from civilization..  maybe meter the battery?? Or voltage from the alternator?  Car drives fine but concerned about driving down the mountain. 

 

Thanks again, much appreciated. 

 

 

You can read the alternator output with a digital multimeter, but the battery should be load tested.

[Allan.adams]

Thanks, greatly appreciated.