Scrumpy

Car is a '95 993 coupe. Just bought it a month ago and drove it on and off for a couple of weeks. Before heading out of town on vacation around the holidays, I tried using the fob to unlock it and there was no response. So, I unlocked the car with the key, which set off the alarm and prevented me from starting it. I think this is the point at which I notice the door LEDs are double-flashing (something that wasn’t happening previously).

Of course, I only received a single fob and a single key for it from the PO.

Thinking the fob probably just needed a new battery, I ordered a couple of new batteries online and then headed off for vacation. Upon return (about 10 days later), I replaced the battery in the fob, but the car still will not respond. I actually tried both new batteries, but no difference. They read 11.9V on the multimeter, so they are relatively fresh, but no luck in fixing anything. The LEDs on the doors are still double-flashing and it alarms whenever I unlock it and open the door with the key.

So, I start reading through all the posts of woes people have with the alarm / immobilizer system on their 993s and found the great document (key fob setup procedure-10-1.pdf) by Andy (pp000830) on how to program / associate a fob with the car. So, thinking I might just try and re-associate the fob with the car I tried going through the procedure, but I haven’t been able to get past the 2nd step:
“B) unlocked, lock, and unlock the door using the ignition key all within five (5) seconds. –the alarm horn will sound momentarily, go to next step.
C) Open the door…”

Whenever I can actually get the car to momentarily sound the horn after step B, when I open the door the alarm immediately sounds. No chance (10 seconds as defined in step D) of getting close to getting the key in the ignition to get it into programming mode. Of course, it alarms in every attempt I've made that ends in me opening the door.

Thinking my first problem might be the double-flashing of the door LEDs, I have gone through the following items to diagnose:
1. Opened fob, cleaned battery contacts, re-bent them to better make contact with the battery.
2. Reflowed solder between battery contact arms and lands on the circuit board (didn't seem to be an issue there, but thought it wouldn't hurt).
3. Checked charge state of car’s battery. The battery was replaced shortly before I bought the car (within a few months). To be safe, I placed it on the trickle charger for a few days just to make sure it was topped off. This did not help. Still getting the double flashing and alarm as soon as I try to open the door.
4. Checked ground cable on battery. It’s still the original one, so I checked its resistance and cleaned the contact / connection to the body. This didn’t change anything either.
5. Checked to ensure both the frunk and engine compartment lights turn off when I close the lids. No issue there.
6. The passenger compartment dome lights turn on and off when the doors are opened/closed, so there doesn’t seem to be an issue there.
7. Checked the glove compartment switch, bulb, and wiring between the two. These were correct and without any problems (that I could find).
8. It has an aftermarket radio, so I checked for the ground connection that should be disconnected (floating). It was, but I added insulating tape just to make sure. No difference.
9. Checked fuse 11, was not blown.
10. Checked the connectors and fuse on the alarm module under the passenger seat. No issues there either.

So, now that I’ve set off the alarm countless times attempting to fix things, I’m running out of ideas. The other things I've not checked include:
i) ignition switch
ii) immobilizer module (under driver's seat)

The only other thing I can think of is that I turned off the dome lights to be less annoyed with flashing while it was alarming. Not sure if the system needs to "see" the resistance of the bulbs in order to get into programming mode --seems unlikely.

So, the door LEDs continue to double flash and I can’t start the car. Should I just purchase a new fob and get it towed to the stealership to get both old and new fobs programmed? Risk is that it’s something else and they take me to the cleaners to fix it.

Other ideas on what else I should look for? Doesn’t seem like my issue is quite the same as others posted in that my door LEDs are double flashing (other posts weren’t clear on that). Sorry for the wall of text, just wanted to be clear as possible.

pp000830

Double flashing suggests your problem is not with the fob, make sure the engine lid is fully seated. I would detach one of the battery leads and let the car sit for a few min. Reattach and check the battery voltage as above 12.2 volts, then try the fob again.
Andy

mpruden

Seems like you've done your homework. Two things to try, one easy, one hard.

Easy - confirm that the radio alarm wire is not grounded. If grounded, you get the double flash. There is a green wire that attaches to the factory radio cage. When the factory radio is inserted, this wire is insulated from ground by some tape on the radio. If the radio is slid out of the cage, the wire will short to ground triggering the alarm. This wire is commonly grounded due to a misunderstanding when working on the radio. Just disconnect it. You may be able to see it without removing the radio, but just in case, I'd pull the radio.

Hard - find someone with a tester that can connect to the alarm module in the car. Even if that means towing it to a shop. A Bosch Hammer, PST2, or the UDT999 can all do this. Unsure on a durametric.

These will allow you to test the various alarm module inputs, view any stored fault codes, and hopefully conclusively identify the source of the double flash so you can turn off the alarm and reprogram new fobs.

Edit: Do you have any indication that there has been a spill under the seat that would have damaged the alarm module itself? Are you getting any other weirdness with hazard lights, central locking button, etc? These things are all controlled by the alarm module and if it is failing (uncommon?) it may show other symptoms.

Scrumpy

Andy: Interesting. I was wondering if the double flashing would prevent any reprogramming. Battery voltage sits just under 12v at rest without load (something 11.8). Thought this was usual for lead-acids where charging voltage is closer to 14. I've tried going through this routine with my trickle charger (set at 1.5A max) connected. I could try again with the trickle charger set to a higher current limit (10A). This is something relatively easy to try. Of course, doing this I've had the hood completely closed (and verified the light turns off). Have also left the leads disconnected over night while working on it and this didn't seem to change anything. I may make an attempt tonight again with the trickle charger connected at a higher current to verify the voltage doesn't dip while I'm playing with it (though I couldn't imagine it would very much). Guess I should run my multimeter leads out of the hood along with the AC line for the charger and monitor it.

mpruden: I've checked the connector behind the radio. It was not connected, but I further isolated it by wrapping it in electrical tape just to make sure it didn't become a problem in the future. I may resort to trying to flush out the codes for more clues. Unfortunately that would involve a tow to a shop with said equipment.
Also, I had removed the passenger seat to check the alarm module and didn't see any evidence of corrosion or wetness in the past. The connectors looked clean, but when I reassembled I did apply some dielectric grease to the connectors. Of course, I didn't pry it open to check for water ingress inside. Do you know if it's potted? I could open it and check for corrosion or bad solder joints and perhaps some component/circuit checks. I have not removed the driver's seat to check the immobilizer unit for evidence of wetness or issues with connectors / visible harness problems.
Edit: I didn't have any issues with the central locking , hazard lights, or other electronics that I could tell in the handful of times I've actually driven it.

Scrumpy

Left battery disconnected for the last 20 or so hours and verified it provides 12.38V, pretty close to what Andy had suggested. I then reconnected it back to the car, connected the trickle charger set to 2A (lowest setting) and waited for it to finish alarming, which is what it was doing when I disconnected it. Verified that the door LEDs are still double flashing. Voltage without trickle charger connected (with car alarming) was 12.25V and voltage with trickle charger attached set to 2A is 13.3V.

Sounds like the next step is to get more clues with a tester. Anyone know for sure if a durametric would provide the alarm codes? Perhaps now is the time to make the investment in one (1 month into ownership).

pp000830

The alarm/immobilizer is sensitive to low voltage. You may want to have your battery charged to bring it up to 12.5 volts at rest to rule out this issue. An inexpensive 1.5 amp charger will do this over night.

Davis Pan

I went through a very similar issue with my 993 a few months ago. I had lost my key fob and had to program a new one, but I couldn't get rid of the double flashes and the alarm would go off after opening the door after step B, as in your case. I did the same checks you did, to no avail. I ended up flat-bedding it to a shop who claimed they could diagnose and fix the problem. They couldn't fix it either, so I had them send the ECU, immobilizer and alarm to ECU doctors so they could rebuild and reprogram the system. I had to pay $1k to ECU doctors alone to have them fix the problem ($575 immobilizer, $425 alarm). I'm not a big fan of ECU doctors (too expensive and didn't fix an intermittent battery contact problem in my fob, something I fixed in 5 minutes), but they seem to be the only place in the US that can repair 993 immobilizers/alarms:
http://www.ecudoctors.com/porsche-993-1993-1995.html

Good luck with your debugging. It would be great if you find a less costly solution.

Davis

pp000830

My durametric doesn't see the alarm module. It is reasonable to consider removing the module and cleaning its plug contacts. If you plan to do this raise the seat to the highest setting and put a few drops of penetrating oil on the seat Mounting bolts and let them sit overnight. Use a fresh Allen wrench fully seating it in the screws and pop them loose.

Scrumpy

Davis: Ouch. ECU doctors would be a last ditch option for me. I'd rather pay to get a blinker fluid flush. Did you ever have codes read out?

Andy: Good to know about the durametric's lack of capabilities on this one. Guess I'm back to the potential towing scenario.

Letting the battery charge overnight to see if I can get the voltage to stay up in the 12.5 range. Will try playing again tomorrow.

nine9six

Scrumpy,
As I understand things, the double flashing door top leds indicate that there is an issue in the handshaking between the alarm module and immobilizer...

In addition to the switches you checked, there are microswitches in each door, as well as one in the clutch pedal box that need to be verified as functional.

BTW, You may want to contact rennlist member, Lorenfb, of Systems Consulting. The man knows what he's doing!

Scrumpy

Checked the clutch microswitch and it is functioning properly. It changes from less than 0.5 ohm to open circuit when actuated. I had disconnected the spade connectors from it to measure it thinking perhaps the connections could be flaky too. No difference.

Out came the driver's seat without any drama (thanks for the tip about the penetrating fluid Andy). Harness going to the immobilizer box looked great. Connector was seated firmly into the receptacle on the back of the box. Removed the box and figured since it had screws, it must be telling me to inspect some solder joints and components. So, I did.

Didn't see any component on the board that had let out its smoke, nor did I see any cold solder joints, or lack of good wetting of solder on the joints.

Checked all the diodes and resistors and they all measured as I would expect (measured them in circuit and I don't have a schematic, so actual values measured couldn't be verified, but none were open, and none were short except those that were 0-ohm resistors. For diodes, forward voltage drops were all within reason 0.55-0.7V). Also did a quick (non complete) check on the SK14 metal oxide varistor, but it measured open (as expected when not energized) and had an extremely low capacitance (also as expected). Again, no discoloration on any of the components and didn't smell anything that would hint at smoke or overheating in the past.

Here's a few pics:



Immobilizer Label (993.618.159.02)




Component side of board assembly




Evidence of hand soldering on several components. D4 shown




Leftover flux found on/around many of the hand soldered components

Upon re-assembly I sprayed down the connector (male & female side) with some Deoxit D5 contact cleaner. My experience with it has been good in making old contacts stay alive. Reconnected the battery (voltage at 12.45 when disconnected from car), waited for alarm to stop and then waited another 10 minutes to see if the alarm system would reset itself. Nope. Still double flashing on the door LEDs and no response from the fob.

(sigh)


Edit: Also forgot to mention that I believe the door microswitches are good since when I open either one of the doors, the alarm is triggered. Presume that means it can tell when the door is open or closed.

Davis Pan

>>Did you ever have codes read out?
No, I didn't have access to a scan tool. I assumed the mechanic I used did, but he didn't say one way or the other. Given my other not-so-great experiences with him, I wouldn't be surprised if he didn't either.

nine9six

Scrumpy,

I believe this to be correct. You have to solve the handshaking pretest, before you will be able to successfully enter into programming mode.

Could you please try this...Prior to going to step B; will your fob lock the car? If so, please post outcome. If not, lock the car up with the key and let it sit for 5 min.

Now, try step B and please post results.

Step:B) unlocked, lock, and unlock the door using the ignition key all within five (5) seconds. –the alarm horn will sound momentarily, go to next step.

The car must be locked and sitting for 3 mins for the auto alarming function to attempt to initiate.

Please post your results.

If all lights and microswitches check out, the only unknown is potentially the mechanical portion of ignition switch making proper contacts.

P.S. I would recommend PM'ing rennlist member, Lorenfb and sending him a link to your post, for his thoughts...He is a professional

HTH!

Scrumpy

nine9six: Fob will not lock the car (or do anything else other than flash it's little fob light when I press the button). Still getting the double flashing on the doors. However, your suggestion helped in that it at least gives me a little different situation than I had before:
The car had been locking itself while alarming, so I hadn't been able to actually physically move the lock from unlocked to locked with my key. Whenever I tried locking it, it was already in locked state due to the alarming. Tonight, I waited for the alarm to stop, then waited another 5 minutes, then physically locked it with the key. Perhaps I just wasn't waiting long enough for it before, but the directions had said for the car to be locked (and it was) so I had assumed what I was doing was fine.

So, tonight I locked it and waited for an additional 4 minutes after the alarm stopped (and no lights flashing), then tried going on with Step B "unlock, lock, and unlock the door using the ignition key all within five (5) seconds. –the alarm horn will sound momentarily, go to next step." This worked and I was able to go through the whole procedure with the immobilizer light in the clock flashing as it should. Of course, during this procedure the door LEDs were still double flashing... At the end, when the immobilizer light was flashing I pressed and held the fob button for at least 10 seconds, but wasn't sure if it was acknolwedged by the car since the door LEDs continued double-flashing as they had throughout the whole procedure. I turned off the ignition after and the fob still doesn't work.

But that's ok. I made it another step closer (or at least it feels that way, so I'll take it).

I need to order a new fob and see if I can go through the programming procedure with a new one. It is very likely that my old fob is just no longer functional. Of course, the question still remains in my mind whether the door LED double flashing will prevent any fob (new one or my old one) from being programmed.

nine9six

I wouldn't buy a new fob just yet, or any time soon for that matter...With my car, I had some non functioning lights (frunk, engine bay, and glove box) in addition to a non illuminating immobilizer/alarm indicator in the clock. Once I solved the non functioning lights, (frunk, engine bay, and glove box), the immobilizer/alarm light in the clock worked!

The issue with my lights was chaffed wires in the (frunk, engine bay, and glove box), all which were solved with lengths of double shrink wrap in the chaffed areas.

Since you claim no light or microswitch issues, I might tend to lean towards the ignition switch, and I suspect just the portion that is held in place by a single Phillips head screw on the back of the ignition assy.

If you could borrow one for test purposes, that would be ideal...At least you could confirm/rule out the last item in the circuit.

I think you are getting closer too!

Again, if all else fails, try www.systemsc.com
HTH...