Another Immobilizer/Alarm Thread
 

I've searched here and in the owner's manual and gotten nothing but confused, so bear with me through another immobilizer/alarm thread. This is on a 1996 model. Car hadn't been run for a few months, so I went to fire it up this morning. Long story short, the fob battery and the back-up battery in the glove box were old (both measured 12.2V) and probably the start of this downhill run when I couldn't seem to get the ignition unlocked. The car door locked on me and I made the mistake of opening the door with the key so I could get into the trunk to check the car battery (12.8v at rest). At some point (not sure which part of this saga), the fob light on the clock lit up intermittently, but isn't lighting now. Now the alarm is sounding and the fob isn't operating anything even with a new battery installed. Disconnected the battery ground for an hour, but no reset and alarm continues to sound. Door lock light on sill is flashing rapidly. I've tried various combinations of things to no avail.

I have two codes from the dealer- one is "ignition lock/alarm system code" and the other is "immobiliser code". Seems like a lengthy, complicated process and the instructions I have are vague at best. The first instruction is to switch off the alarm by unlocking, locking, then unlocking the door. Tried that and alarm didn't shut off, so I don't think I'm on the right path.

Can anyone clarify what my next steps should be and which code (if any) to use to shut the alarm off and start the car?

This sequence should work if all is up-to-snuff in the electrical system. That said, a weak/failing car battery can cause all kinds of weird symptoms including flashing dash lights, etc. If it was my car, I'd remove the (car) battery and take it somewhere to be load tested. Then recharge or replace it as needed. I'm betting that with a new fob battery and a new/fully-charged car battery you'll be able to stop the alarm and start the car using the process stated above.

If you unlock the door with the key the alarm will sound and the door LEDs will flash rapidly, so what you're seeing is normal. The alarm should stop if you press the FOB but if your FOB isn't working, you may be stuck. So focus on the FOB(s) for the moment.

A couple questions:

1) What's your history with the FOBs? Did they work reliably in the past? (every time and at reasonable range?)
2) Do you have 2 FOBs and do they both not work?
3) You changed the FOB battery but have you tried cleaning the battery terminals on the FOB circuit board? Open the FOB and try cleaning them real good even if they look ok. (The red FOB LED should be bright and steady).

12.8 volt vehicle battery is plenty high to unlock the doors.

Let us know how it goes.

There is just the one fob. Never had any real trouble with it before. Range has never been a lot- maybe 10 to 15 feet tops. Already had cleaned terminals, plus measured voltage on the board terminals with battery installed and got the same voltage- 12.75. LED is bright and steady. The old fob battery seemed to work a little.

Should pressing the fob button stop the alarm? At this point, nothing happens when the button is depressed- doors don't lock/unlock, alarm still sounds.
When I try the unlock/lock/unlock sequence, it almost seems like it's thinking about shutting off the alarm as there is a minor hesitation.

It's a 3 year old AGM battery that is always on a maintainer and it's putting out ~12.8v, but it couldn't hurt to take it in for testing- I'll do that. If I can get the alarm to shut off with either the fob or the unlock/lock/unlock sequence, which of the two codes should I be using (if any) to reset? ("lock/alarm" or "immobiliser)

The fob does not lose its mating to the car from sitting. Jay is right to start here.
If the fob battery is fresh its contacts are clean and making good physical contact;
And the light illuminates on the fob when you press the button the fob is good to go and your problem lies elsewhere.

If the car's battery at rest is at 12.6 volts or more the remote should actuate the door locks and disable the immobilizer. The Reserve capacity of the battery is not relevant as the door lock/Alarm/Immobilizer system doesn't really draw any current to speak of. Unlike the starter.

If the dome lights in the car won't go out or the door LEDs flash in couplets or the remote fob icon in the clock flashes you have an alarm/immobilizer system fault:

Here is a process to try at home to sort out these faults:
https://993servicerepair.blogspot.co...-lighting.html

If the fob's light won't illuminate with a fresh battery it is non-functional and can be replaced with one from the dealer or from ECU Doctors.

Here is how to program the alarm/immobilizer to mate to your fob or its replacement fob if this is your issue:
https://993servicerepair.blogspot.co...ming-made.html

Good luck with this.
Andy

PS after sorting things out get yourself a second key with fob, by having just one you are asking to be stranded somewhere.

Sounds like the FOB could be ok but just to be sure - when you checked the voltage on the FOB PCB terminals were you pressing the button? (The FOB draws no current until the button is pushed). 10-15 feet range is ok. Bright LED sounds good. It's unfortunate you don't have a second FOB - would be a good test.

It does on my 97. But if you can't even FOB lock/unlock the doors, RF comms between the FOB and immobilizer don't seem to be working. No comms, no alarm reset.
The vehicle battery is probably fine - if it has enough uumf to blow the alarm horn, it can easily run the immobilizer, alarm control unit and open the door.

Was any work done on the car since the FOB last worked? Anything removed, modified or disturbed?

Took the car battery in for testing and it passed load and voltage. 12.91V . Dome lights flash in sync with alarm horn and door LEDs flash rapidly. The fob icon on the clock lit up a couple of times earlier and I don't recall it flashing , but it may have also been flashing at some point- not sure. The fob icon on the clock is not lighting at all at this point.

I also opened up the fob and manually pressed the switch that the button would normally depress, but that did do anything other than to light the fob's LED.

With the battery installed and the voltmeter leads touching their respective fob terminals, the voltmeter will read any voltage present as the terminals are just an extension of the battery. I was just making sure that the voltage was making it past the contact points with the battery.

Nothing has been done to the vehicle since it was last running. At that point, everything was running fine.

Is the comm problem likely on the car end or the fob end? How would I check the car's comm? Fuse? Relay?
Is your immo-block a solution here, or does the comm/alarm/block system first need to be fully operational ? Always was annoyed with the damn thing, and this might put me over the top!

Don't know if this means anything, but the alarm goes off just as the key begins to turn in the ignition. Nothing else happens, however- no interior or warning lights.

You did good by testing at the PCB side of the terminals. However...unless the FOB is drawing current when you make the measurement, dirty contacts will go UNDETECTED. You should repeat the measurement on the terminals while the FOB button pushed, otherwise you're just testing an open circuit battery.

Without a second FOB, hard to say which end of the link is at fault. The immo is pretty reliable and unlikely to suddenly develop a fault especially just sitting there. If it had been flaky in the past, i.e., intermittent or very short range, it might be the case where it was marginal and just finally gave up the ghost, but you say that's not the case. Grasping at straws here, but try putting the FOB right down in front of the drivers's seat to see if there's any difference. That's about as close as you can get to the immo receiver.

The IMMO BLOCK eliminates nuisance double fobbing and let's you start the car without the FOB but the FOBs will always be required to lock and unlock the car (as you've discovered).

Am I understanding this correctly- that any one of the three things you mention are symptoms of an immo system fault and that the fault is caused by one or more of the interior lights (including frunk and engine lights) not working? IOW, the whole immo fault problem lies with an interior light(s) that is not functioning properly?

All of the interior/frunk/engine compartment lights flash on/off with the alarm system, so how do I determine if they would shut off normally?

Maybe I'm not looking correctly at the door LEDs flashing in couplets- is this flashing relatively slowly? Looking closely (or maybe it's my imigination) the LED seem to be brightest on the first flash, not as bright on a second flash and not bright at all on the third flash (or possibly not lit at all), then the sequence starts again. But it's a fast sequence. I'd include a video, but the file is too large (can't figure that out, either!)

Sorry, figuring out electrical stuff is not my strength.
EDIT: It occurred to me that maybe the alarm may need to be de-activated before finding lighting faults. The unlock/lock/unlock sequence with the key in the door lock doesn't seem to be working (is there some timing trick to that that I'm not understanding?), but will the alarm and the flashing lights eventually turn off after a certain amount of time elapses? If so, how long?

any one of the three things you mention are symptoms of an immo system fault and that the fault is caused by one or more of the interior lights (including frunk and engine lights) not working?

--Yes, 99% of the time, and their switches.

All of the interior/frunk/engine compartment lights flash on/off with the alarm system, so how do I determine if they would shut off normally?

--Your problem I have not encountered. Does the alarm terminate at some point and go quiet? If not I see no way to test the switches with my published procedure. I would pull the controller from under the seat and have it tested or just replace the dielectric capacitors internal to it as they can dry out and so age out. I would also clean the contacts on the controller and its harness plug with some electronic spray cleaner. Not sure these are root causes but could help. Grasping at straws a little here.

Maybe I'm not looking correctly at the door LEDs flashing in couplets

--If normal the flash in an even cadence that slows down over time;
If a fault the flash in an uneven cadence two quicker flashes - pause two quicker flashes- pause - two quicker flashes.
I have never seen a situation where their brightness varies.

the alarm may need to be de-activated before finding lighting faults.

--Yes, or at least the noise should stop while sorting things out

The unlock/lock/unlock sequence with the key in the door lock doesn't seem to be working (is there some timing trick to that that I'm not understanding?),

--If you speak of how to initialize the system to program the fobs and or start the car as outlined in the procedure No, it should work if you do it all within a couple of seconds and immediately move to the next step.

will the alarm and the flashing lights eventually turn off after a certain amount of time elapses? If so, how long?

--The alarm horn should time out after a few minutes.

Andy

The lights flashing is not the source of your problem.

Again, the flashing lights is a secondary issue, so focus on the immobilizer.
Just open the driver's door and quickly insert the key and turn it to the run position while monitoring the immobilizer light. It should come on immediately and go out after about 15 seconds.
If this occurs, you have entered the remote programming mode. Now enter the four digit code. If not, you probably have an immobilizer problem or you may have an ignition switch problem too.

Since you don't have second remote, which would also be helpful given your situation, consider buying one.