When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
993 mods that may affect alarm/immobilizer function:
- ECU w/ Rennsport tune, immobilizer defeat, and ECU Doctors ROW flash.
- fixed deck lid grille with spoiler module under dash disconnected (https://rennlist.com/forums/993-foru...ol-module.html)
Yesterday I unfortunately spilled about 5oz of liquid on my center console (mostly passenger side). After getting home I removed the passenger mat and used a Bissell carpet spot remover to clean the area. Later that night I went down and my remote did not work to unlock the doors; I unlocked from the driver's door manually and was able to start the car with no issues. I locked the car manually last night and this morning when I unlocked manually the alarm went off and I was unable to disable it with the 'unlock/lock/unlock+position 2 within 15 sec method' mentioned in a previous thread or through just manually unlocking the door as mentioned in ECU Doctors' video. I then disconnected the battery to spare my neighbors. Since then I have discharged the positive terminal and also replaced my remote's battery as advised by a friend but with no luck; every time I re-connect my battery, the alarm continues to go off. I wanted to reach out to members for any advice on what I can try from this point. Thank you
Hi Peter,
Here is a page used to sort out the alarm /immobilizer. I would check the system for an electrical fault before going under the seats as it is a bit of a job to get to the controllers: https://993servicerepair.blogspot.co...-lighting.html
If you have ruled out other issues related to the alarm you can pull the seats and inspect the alarm & immobilizer modules and see if they got wet.
Also on the left-hand side, the controllers are covered by a metal shield with tamper-proof rivets.
Here are the steps to gain access to the Immobilizer/Fob receiver and the DME controller:
1) Disconnected the car's battery before starting the procedure.
2) Remove the driver's seat on left-hand drive cars, see the above instructions for this.
3) Drill out the security rivets on the cover over the controllers under the driver's seat.
4) Use a vacuum to clean out the metal shards left from drilling before unplugging the controller to avoid contaminating the electrical connections.
5) When done replace the cover when finished with some self-tapping machine screws as it may be providing some required electrical shielding.
If there is evidence of moisture flooding I would disconnect the car's battery and unplug the controllers open them up and hose them out with CRC QD electronic cleaner spray.
If it looks like just a little moisture is present one can consider just disconnecting the battery and hosing off the modules' connectors and the plugs for them that are part of the wiring harness. Then reassemble the plugs, reattach the battery and test to see if it addressed your issue before putting the seats back in.
I hope you find a way through this issue and resolve it,
Best of luck,
Andy
Last edited by pp000830; Aug 25, 2022 at 06:51 PM.
Once the alarm is triggered, the only (easy) way to silence it with the FOB. It's a 993 catch-22 - use the key to unlock the door..... because the FOB doesn't work and then can't turn the alarm off.... because the FOB doesn't work. The procedure in the ECU Specialists vid I believe only works on some 95's. The "unlock/lock/unlock+position 2 within 15 sec method" you mention is the emergency start procedure - you use it to unlock and start the car when the FOB doesn't work, using the 4-digit code. It's not designed to silence an alarm that's already been triggered. If you're taking the passenger seat out anyway to inspect the alarm unit, you can turn the alarm off manually by momentarily GROUNDING the BR/GN wire out of the alarm unit. That'll keep you neighbors happy and give you time to figure out why the FOB stopped working. Sounds like it happened right after the spill, so have a good look at the Alarm unit.
Thank you both for the wealth of info, especially the 993 catch-22 (which was very frustrating). I have removed the passenger seat and the ACM (cleaned contacts and re-installed but the alarm continued when reconnecting the battery so it’s completely out at this point). The majority of the spill was in that area (right of the center console between the passenger seat); I am currently trying to source a used replacement ACM and will update this thread with my results. Wish me luck.
If you're convinced the failure of the FOB to unlock the car is correlated with the liquid spill, I'd open the Alarm unit and see if anything got in there. Unless the liquid was molten lava, not likely it could permanently damage the ACU, so dry it out real good, plug it in and clear the alarm by grounding the BR/GN wire. Then see if the FOB can lock and unlock the car. Be a shame to buy a new ACU when such a simple fix is possible. It could be a coincidence that the problem started with the liquid spill and the problem is actually the FOB. In that case, buying a new ACU makes even less sense. If you have another FOB, try that one. If you don't, clean the contacts on the one you have, bend them in so they grip the battery tightly, install a new bat and give it a try. On my 97 I installed a hidden momentary switch to GND on the BR/GN wire to silence the alarm in just such situations.
Last edited by jay@EZimmoblock.com; Aug 29, 2022 at 10:02 AM.
First of all, thank you to @jay@EZimmoblock.com for the immense amount of help this morning through e-mail correspondence.
After his last response, I asked for clarification of certain steps and acronyms as I am not electronically inclined and he responded with:
"Before you do any of this, make sure the inside of the ACU is clean and dry.
The wire you want to locate is on PIN 2 of the Yellow connector (II). It’s the only BR/GN wire going to the unit, so you can’t get the 'wrong' one. (BR/GN means Brown wire with Green tracer). That wire goes between the ACU and the immobilizer under the driver’s seat. When you press the FOB to UNLOCK the door, the immobilizer receives the radio command and pulses this line to ground. You’re going to simulate that by manually forcing that line to ground. You have to do this the ACU plugged in. What I would do is get your ground wire set up before you plug the ACU in so that you can quickly silence the beast. I’m not sure if you can get at the exposed pin at the connector or not. If you can, then get a length of scrap wire, connect one end to a good ground point on the car. Any bare metal on the chassis will work, and certainly the negative post on the battery will do as well.
With the ground end of the wire connected, plug the ACU in and just touch the other end of the wire to the ACU BR/GN wire. Nothing critical on how long you do this – the immobilizer pulses it low for 1/10th second so anything more than that will work. If you can’t get to the pin from the back of the connector when it’s plugged in, just strip a little insulation off the BR/GN wire and touch your ground wire to that bare spot. (Tape it up when you’re done).
That should silence the alarm. Then check if the FOB can lock and unlock the door.
The real issue is why you couldn’t open the door with the FOB. It can only be 3 things:
1) the FOB stopped working
2) the immo stopped receiving the FOB
3) the FOB and immo are working but the ACU is not responding to the unlock command from the immo
This test will help point to where the problem is."
I followed his instructions to silence my alarm and it worked like a charm. At that point my FOB functioned properly but soon after its performance became intermittent. He then shared this thread about FOB range: https://rennlist.com/forums/993-foru...this-easy.html
At this time my FOB does work from ~5 ft as it did previously so I am holding off on swapping caps but I wanted to post this wealth of information for anyone in the future to be able to search.
Last edited by c2_peter; Aug 29, 2022 at 05:33 PM.
"At this time my FOB does work from ~5 ft as it did previously"
Hi Peter,
Perhaps the coffee finally dried up leaving the system good-to-go?
Replacing the capacitors is a good idea and will significantly lengthen the transmit distances, in the case of my car it increased to over 30 feet.
Removing and replacing the capacitors is relatively easy if you are handy with a soldering iron however the circuit board is a two-layer board with wire traces on the front and back so be sure to use a low watt pencil-style soldering iron 35 Watt max, use care not to overheat the board and solder the replacement capacitors to both the front and the back sides of the circuit board's mounting holes. The traces are very close, so use a magnifier to check that the solder joints are good and you didn't inadvertently jump and join an adjacent wire trace.
Andy
This procedure can also be used on the 928/964 alarm ECUs, since they're basically the same ECUs with minor variations of the flash memory of the alarm ECU's processor chip.
Last edited by systemsc; Aug 30, 2022 at 09:09 PM.
Awesome @systemsc , thank you for the additional information. I unfortunately did not find that in my search but hopefully it helps someone in the future.
Yeah, not good. From the recent spill? I've seen a few with the "green death", (mine included) but this has to be the worst. If you need some caps, let me know I keep them in stock.
@jay@EZimmoblock.com Yes it seems like it was from the recent spill because I cracked open the immobilizer case and the board looks ok; my friend will do a more thorough inspection. And thank you for the offer but I already purchased 5 of each and sent them directly to my friend's place so he can do the swap while I am out. I'll keep the spares on hand to offer to other owners I meet locally that happen to have the same range issue.
Update: Caps have been replaced per Jay's old thread and 'green death' has all been cleaned properly. With everything buttoned back up, my FOB range has improved from ~5 ft to ~30 ft (haven't had the chance to properly test in a large open space). Everything is functioning as it should.
Porsche's Top 5 Most Questionable Naming Decisions
Slideshow: For a company obsessed with engineering precision, Porsche has occasionally named its cars in ways that left even loyal enthusiasts scratching their heads.
Pogea Racing's 964 Porsche 911 Reimagination Stands Out in a Crowded Field
Slideshow: Pogea Racing's latest Porsche 964 project blends carbon-fiber construction, modern chassis upgrades, and up to 500 horsepower while keeping the air-cooled 911 experience firmly analog.
Talos Takes Your 991 Porsche 911 GT3 to the Next Level for a Cool $1.13 Million
Slideshow: Talos Vehicles has transformed the Porsche 911 GT3 RS into a carbon-bodied, race-inspired machine that costs well over $1 million before the donor car is even included.
9 Vehicles Porsche Helped Engineer that Aren't Porsches
Slideshow: Long before engineering consulting became trendy, Porsche was quietly helping other automakers build everything from supercars to economy hatchbacks.
9 Features and Characteristics That Only Porsche People Understand
Slideshow: Some brands build cars. Porsche builds traditions, obsessions, and a few habits that stopped making sense decades ago but somehow became part of the charm.
Alarm Will Not Shut Off
