tom_993

Some time ago I made a post about my car lighting the ABD and Anti-Lock warning lights simultaneously (and the “!” light). Well, it happened again yesterday and this morning. Yesterday I was putzing along in traffic. There was nothing to engage either ABD or ABS. This morning, I was mere feet from my driveway. In all cases, the lights go out after turning the car off then back on. At home last night, I retrieved the codes from the ECU by the “Press the accelerator for 5 seconds” method, as documented <a href="http://batauto.com/Porsche.html" target="_blank">here</a>. It flashed 15, which I'm hoping means 1500, or "No codes stored."

Does anyone have any clues as to what would light both of these lights simultaneously? I have no reason to believe there is anything wrong with my ABD or ABS. I tested the ABS this morning by standing on the brakes. I felt the pulsation through the pedal as I should. I was thinking something along the lines of a wheel speed sensor. One of them might be on the fritz. I’m imagining one sensor sending the correct speed, while the other sends either 0 or infinity. The difference in speeds is “out of range” so the computer lights the warning lights rather than engage the ABD or ABS. Does anyone know how I could confirm this theory?

TIA,
Tom

Ray Calvo

[quote]Does anyone know how I could confirm this theory?<hr></blockquote>

Bring it into the dealer and let them trobleshoot the system is all I can think of - I think you need the fancy multi-thousand $$$ Porsche decoding tool. If you do a panic stop and ABS kicks in, then that system is possibly all right (when a wheel speed sensor went on old Audi Coupe, ABS shut down completely). You might have a software bug in the computer brain or a poor connection.

Jeff 993TT

Are those the only lights that are on? It could be a problem with low battery voltage, causing those lights to fire.

At the track once, I broke my alternator belt and those lights came up instantly. In my case, the alt belt was obviously broken, but if you have a weak battery, it will cause that also.

Jeff

tom_993

Thanks Ray and Jeff.

Ray, yes, I suppose I should get the codes read with the right tool. My local mechanic has the tool, so I should be able to avoid a trip to the dealer. The problem is, it's intermittent. After I reset the lights (by turning the car off) this morning, they haven't come back on. This included my morning commute and lunch hour errands. Also, the ABS test I did this morning was with the lights off (e.g. computer reset). I suppose I should wait until they come on again, then test the ABS before the computer gets reset. It's possible that with the lights on, the pooter shuts down ABS like Ray's Audi, but turns the ABS back on when the lights are off. There might be a poor connection someplace. They can be intermittent.

Jeff, no, no other lights (besides the ! ). There also shouldn't be a problem with low voltage. My battery is relatively new, as are the alternator belts. There is also a separate alternator light that did not come on. Perhaps I could get the battery tested, just to rule that out. When you broke your alt belt, were those the only two lights that come on, or were there others?

Thanks again,
Tom

tom_993

Ah Ha! I just had another thought, along the lines of the low voltage suggestion. Due to my lightweight flywheel, sometimes the RPM’s drop precipitously when I press the clutch in. The engine catches it right away, and then idles fine. It never stalls. Most of the time these drops are small, to 700 or so, but sometimes it goes as low as 500 or 600. I wonder if one of these drops in RPM could lower the output of the alternator enough to momentarily cause the pooter to pick up a low voltage condition. My question would be, why light the ABD and ABS lights and not the alternator light? There is nothing in the owners manual about the ABD and ABS lights coming on simultaneously. Has anyone else with a lightweight flywheel experienced this?

Jeff, when you broke your alternator belt, did the alternator light come on? What about the belt light?

Jeff 993TT

[quote]Originally posted by tom_993:
<strong>Jeff, when you broke your alternator belt, did the alternator light come on? What about the belt light?</strong><hr></blockquote>

Yes, in my case the alternator light came on, but I for some reason, I just focused on the abs/abd lights. Having your battery checked out seems like a good idea. Perhaps you could just swap batteries for a bit with another 993 owner.

Jeff

Ray Calvo

[quote] Ah Ha! I just had another thought <hr></blockquote>

Tom, you're dreaming, Bring it in to a shop with the right diagnostic tools.

E. J. - 993 Alumni

I will say like Jeff that I had the same lights come on once when I had a bad battery. Came to a stop at a light and the 2 lights you meniton come on. Like a dumb ***, I figure I will reset them by turning off the car and starting it again. Of course, with the bad battery, the car didnt start and I was dead in a center lane in my hard to hide SY 993 1 block from work at a major intersection. Of course, it was one of my co workers that gave me a jump and I limped to the office parking lot. Had Interstate deliver a new battery that day and had to change it with the lame *** tools in the tool kit in the rain. No more problems. I might start by checking the water level in the battery and then checking the battery with a volt meter. Certainly this is easier to check than the service tech.

Good luck,

E. J.

Jeff 993TT

[quote]Originally posted by E. J.:
<strong>Had Interstate deliver a new battery that day and had to change it with the lame *** tools in the tool kit in the rain.</strong><hr></blockquote>

EJ, are you saying that you are dissatisfied with the 993 toolkit?

<img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

Jeff

Steve Weiner-Rennsport Systems

Hi Tom:

LOL,..well sir, you don't need me to tell you that intermittents and non-logged faults are tough to find and resolve,....

If you were here, here are some of the things I might do:

1) Clean all of the wheel speed sensor connectors and treat with Wurth electrical spray. This stuff puts a conductive coating that helps prevent oxidation and corrosion.

2) Check resistance of the sensors.

3) Plug in my Hammer and put the car on the Dynojet for some "rolling road" testing on the off chance that I might trigger the fault. This also permits me to watch this in real time on the Hammer screen.

There is no question that any underlying system problem; battery, cables, voltage regulator, alternator and wiring, will generate the same kinds of things.

Its "Sherlock Holmes" time,.....

tom_993

Thanks everybody, I really appreciate the suggestions. It seems that from “those who have seen the two lights” that the battery/alternator is the area to look at. Plus, it’s pretty easy to get a battery checked, so it’s the logical first thing to check or rule out.

I might also dig around behind the wheels and check the sensors, just to see if they’re full of gunk or loose or something.