JDM93

Hi Everyone,

First-time poster in this forum, and relatively new owner of my very own 993 - i'm still giddy when walking back to the parking lot from the grocery store. I have an issue that has been plaguing me intermittently, and I think it has to do with the immobilizer, but i'm not sure how. I'll list the facts, and the provide some examples of scenarios when i have the no-start with contextual evidence. My hope is to get some direction in diagnosing the issue (even my trusted mechanic is scratching his head a bit).

Good-start, baseline case:

1. The car battery is at least 12.5V
2. I have 2 car keys, both of this have the Fob
3. The Fob battery is good, and when the button is depressed, the red light illuminates
4. When the Fob is pushed, the door locks cycle along with the red-illumination on the door sill bulb.
5. When putting the key in, if the fob has not been pushed - the immobilizer light is on. If the fob is pushed, the light goes away. the car starts
   1. if the fob has been pushed, the light is not one
6. The engine bay, frunk, and cabin dome lights are connected and are NOT illuminated except for when the doors are opened.

I will drive around, do my thing, park, lock (or not) the doors, and then come back and the car starts just fine.

No-start, Specific Cases:

Weird electrical glitch

1. Car started with Baseline Case and, during a long drive, when using the driver-side AND passenger-side window switches, the doors locks cycled, I lost A/C, and the central warning light came on! (WHAT?!!)
2. Continued to drive home and, after parking the car and turning off, the car would not re-start. no gauges would illuminate, absolutely nothing.
   1. As i was turning the key to OFF, it looked like the battery light on the dash was illuminated, but i can't find evidence of whether this is a possible illumination case.
3. Returning to the car the following day, the car starts just fine. (i repeat: WHAT?!)

Weak door-lock sound:

1. Car starts with Baseline Case and, drove a short distance (< 1 miles) to the store. Exiting the car and pushing the Fob evinced a "weak" door lock sound. Thought "that's weird" and kept going.
2. Returning to car, the doors don't open with Fob. Key had to be used to enter vehicle.
3. Upon a start-attempt, no lights showed on the dash panel, no start at all
4. Repeated cycling of the Fob, followed by attempted starts began to exhibit relay sounds (i think fuel and other things?) but not lights showed.
5. When cycling the fob, and turning the key to ACC and then back to OFF, the Immobilizer light Illuminates. it does NOT flash. That's weird...
6. The car COULD not be jumped. It displayed a battery of approximately 12.5 V, but would seemingly NOT charge? (how is that even possible?)
7. Between unplugging the battery, removing and re-installing the accessory lights (frunk, cabin dome, etc.,) and cycling the fob while opening and closing the doors my problem was solved. It was during a particular instance of cycling the cabin dome that i noticed the glovebox light became....brighter. I was then able to start up the car without issue.

The shop i go to, Bauerworks in Oakland, has attempted a fix (didn't spend too long on it as i only have so much i can spend any one visit) by replacing Relays. That appeared to fix the issue until these recent events. My DME relay has also been replaced. Also the immobilizer light has NOT flashed thus far, so if there is something wrong with it, the system does not currently know...

pretty car

the weird illumination of the immobilizer when turning the key all the way to OFF after attempting to start.

pp000830

Hi JDM,
Pull the battery straps off the battery and inspect them. Clean and reattach them to the battery.
Also check the other end of the negative battery strap connection to ground.
Andy

jay@EZimmoblock.com

Rather than trying to chase down a bunch of seemingly unrelated symptoms (window switches, door locks, battery light, immobilizer light), pick one, because they’re probably all related. Start with this:

“Upon a start-attempt, no lights showed on the dash panel, no start at all.

NO dash lights at all when you turn the key on is highly unusual. The battery itself sounds like it’s up to snuff (even if it weren’t, you’d get some illumination). Besides, the car does eventually crank (strongly I assume?) and start. So this doesn’t sound like a battery voltage or charging system issue. Could be flaky connections at the battery terminals, or ground strap cable or connections - easy to check.

Next time you’re in the “no-start-no-dash-lights” situation, turn the headlight switch on and see if they come on normally, dimly or not at all. That’ll help narrow down the problem and lead to the next troubleshooting step.