JimOz

Hi Guys

My 97 C4S has been off the road for 6 weeks with alarm and immobiliser issues.

It all began with the immobiliser not being able to be turned off to start the car - new battery remotes etc. did not solve the problem, so I locked it up using the key and had it towed home.

Charged the battery etc and the alarm double flash problem is still there. Borrowed a scan tool and could not get it to 'talk' initially then discovered a whole other secondary alarm system present in the car that i never knew existed.

After removing the secondary system and returning all the wiring to standard including removing all the taps into the loom I could get the scanner to talk but the double flash remains. ( a friend who is an electronics engineer has done the work)

A kind RL is going to send me a copy of the wiring diag so we can go through the inputs etc but this has turned into a nightmare.

Have approached and explained my problem to the local dealer who basically said our cars are extremely frustrating to work on to fix such problems and the key procedure needs to be repeated until it finally recognises the coding.

I have read the articles posted by others and will let you guys know how I go but this is really getting to me now. I am reluctant to take it to shops with extremely high charge out rates with no guarantees.

Any assistance from those that have experienced a similar problem in the past would be extremely helpful.

Cheers
Jim

Spokes

I had Alarm, and central locking system issues too. Couple of questions:

Do the internal lights and Frunk Lights come on when door, or Frunk opened?
Central lock attempt to work?

Possible checks:

Earths, wiring loom damage, reset all systems (disconnect the battery).

If all above fails to resolve the problem, it is probably the ACU.

Good luck.

TheBen

How about deleting the immobilizer? You have a 97 so you can do so.

Steve Weiner-Rennsport Systems

Jim,

I gotta ask,......how old is the car's battery?

nine9six

Double binks are usually ground faults to one or several of the following...Trunk light, glove box light, engine bay light, inside cabin lights, trunk micro switch, door light micro switches.

Check each of these by pulling all bulbs and see if you still have the double blinking door lights. If not, you have a short in one or several of these lights.

I replaced bulbs one at a time to identify where my short existed (trunk light)

Hope this helps...

JimOz

Thanks for the replies battery is a few years old but has been charged and tested for voltage.

Next step was to check for shorts as described by nine9six.

Want to get rid of the alarm problem so can move on to the immobiliser.

regards

jim

orangecurry

1) first thing is to replace the earth-strap - this metal has a hard life and over time the resistance builds to a level that causes many different electrical issues. At the same time clean-up the chassis connection point.

2) junk the entire 1990s alarm system and fit something modern that would stop a modern thief.

Lorenfb

There're two ECUs involved in the immobilizer function:

1. The immobilizer ECU that receives the remote's signal and controls the
DME ECM and the alarm ECU. It's under the driver's seat.
2. The alarm ECU that controls the alarm function, e.g. locks, alarm horn,
lights, and starter signal. It's under the passenger seat.

nine9six

Jim,
Once you id and fix the alarm issue, you may find that there is no problem with the immobilizer. As Loren indicated, both ECU communicate with each other...Once one starts talking, the other may listen

Best to you!

hoggel

The installer of your aftermarket alarm may have disconnected the factory alarm horn. If it is not connected the system will fault and double flash.

Spokes

Lots of good suggestions above. My Alarm flashing light and associated issues such as central locking, interior lights not working was resolved last week, just as I was about to order a new ACU....

It involved swapping out the standard seats for hard back seats. The battery was disconnected for a week during the swap. I have no idea why the ACU started working again! Probably an earth problem.

Frustrating chasing this fault - good luck.

JimOz

Update

Thanks for the suggestions guys.

Got the car running today using the key programming procedure. Hooked up a scan tool and car showing no faults but the alarm is still double flashing and the key fob procedure came up empty.

Extremely frustrating to say the least but it was nice to hear the car purring in the garage at long last.

Will give the service manager at the dealer a call to see if they have any ideas.

Feel free to offer any further suggestions.

regards

Jim

ReinerFink

I would have your dealership run the codes, as the alarm codes may not be readable by an standard ODB scan tool.

For my part, every single time I plug in my PST2 to my car it always has a stored alarm code of "implausible position of drive elements" or such. Makes me chuckle as I have never had any issues with the immobilizer but I clear the code each time.

-reiner

dombeau

I 'm having a similar problem here. My input might help but I also need your help.
The PO for some reason pulled out the fuse from the ACU under passenger side. That ended up having to lock and unlock the car with the key. Alarm was dead. Unlock button in central console not working either. I still had to use the fob to clear the immobilizer.

What I did this winter is put a new fuse in the ACU. Now alarm and center console switch work. Locking the door with the fob works after several pushes on the button, but last week, at the grocery, I could not unlock with the fob. I tried with the key, alarm went off… blah blah blah…

Problems so far: lights (frunk and cabin) won't turn off, ending in a battery drain every 2 days. Pulled out the two door microswitches and they seem fine (only one wire that makes contact with the car body when door is open) a. the loop stays open because there is a ground/earth cable that is faulty? (if yes, where can I find that cable). b. something else..


Cues: on the relay for horn (36 if my memory is correct) someone soldered a black wire that goes under the fuse box and I don't know what it connects to but I bet it is related to that alarm delete from a PO. Should I cut it….

Other question: where is the frunk microswitch? Is there a light in the engine bay and if so, where is it located… ?

nine9six

Try replacing the battery in your fob, the issue above sounds like a battery thats running low

This is your trunk microswitch needing adjusting or replacing if bad. Once your microswitch is properly adjusted, the trunk switch will complete the circuit, and turn off the cabin lights.

The black wire you're speaking of is a Porsche upgrade/fix. DO NOT CUT THE WIRE. It has nothing to do with an alarm delete. It is soldered jumper inside one of the relays, but I did not trace it back under the fuse board after discovering its origination.

Do a search on trunk microswitch location...Its by the latch I believe.
Yes, the light in the engine bay is located on the deck lid that is raised for access to the bay. just look up a the deck lid while kneeling at the engine bay