Intermittent Battery and ABS Light on

[sak_27]

Recently I started my 99 Boxster and noticed that the ABS and Battery Light came on.  I had this issue last year when my alternator failed so I hurried home as to make sure I didn't stall on the side of the road. I made it home and checked my voltage readings on the battery.  With the engine off the battery read 12.5 and with the engine on the reading was 14.44.  When I went to start the engine to check voltage, the lights were not on.  Drove couple of days and the two lights came back on, but when I shut the engine off and restarted, the lights went away. 

 

Anyone have experience with this type of problem?  Could this issue be caused by thin brake pads setting off the brake wear sensor?  

 

Any advice/help is appreciated.

 

Thanks

 

Andy

[sak_27]

Just realized I put this in the wrong sub-forum.  Sorry about that.  

[JFP in PA]

Recently I started my 99 Boxster and noticed that the ABS and Battery Light came on.  I had this issue last year when my alternator failed so I hurried home as to make sure I didn't stall on the side of the road. I made it home and checked my voltage readings on the battery.  With the engine off the battery read 12.5 and with the engine on the reading was 14.44.  When I went to start the engine to check voltage, the lights were not on.  Drove couple of days and the two lights came back on, but when I shut the engine off and restarted, the lights went away. 

 

Anyone have experience with this type of problem?  Could this issue be caused by thin brake pads setting off the brake wear sensor?  

 

Any advice/help is appreciated.

 

Thanks

 

Andy

 

I seriously doubt your brake sensors would cause this.  My first inclination would be to scan the car with a Porsche specific scan tool (Durametric, PST II, PIWIS), looking at both active and pending codes.  Low voltage excursions are know to cause these types of problems, yours may be intermittent, which would be why the MIL would clear itself.

[sak_27]

Just hooked it up to a Durametric and there are no active codes.  How do you check for pending codes?

 

Thanks

 

Andy

[RFM]

It is more effective if the voltage is measured when the ABS and/or the battery lights are lit, this works more effectively. 

[JFP in PA]

Just hooked it up to a Durametric and there are no active codes.  How do you check for pending codes?

 

Thanks

 

Andy

 

Any pending codes would have appeared with the active codes.

 

I would have to agree with RFM's assessment, you may have to test voltages when the fault appears.

[Ahsai]

I always recommend this handy tool to monitor the voltage. This is very useful as it shows you the voltage in real-time extremely accurately. It can also show you any battery drain overnight if you leave it plugged in and check the voltage in the morning.

 

http://www.amazon.com/INNOVA-3721-Battery-Charging-Monitor/dp/B000EVWDU0/ref=sr_1_1?ie=UTF8&qid=1427393920&sr=8-1&keywords=inova+battery+tester

Edited March 26, 2015 by Ahsai

[sak_27]

Just happened again.  The voltage on the battery reads 14.34.  Is this low enough where it would trigger the ABS and battery light to turn on?

[RFM]

Just happened again.  The voltage on the battery reads 14.34.  Is this low enough where it would trigger the ABS and battery light to turn on?

14.34V is  more than a good result, the load is thus sufficient. Of course still remains the actual condition of the battery and/or maybe a loose connection between alternator and battery (+ or -), a lot of other things as, faulty brake switch, throttle body, MAF, etc. remain possible also.

[JFP in PA]

Just happened again.  The voltage on the battery reads 14.34.  Is this low enough where it would trigger the ABS and battery light to turn on?

 

That voltage should be more than enough.  One item to  consider is your brake light switch; there have been multiple reports of failing brake light switches causing ABS and/or PSM faults which promptly went away when the switch was replaced.