Alarm going off - AFTER bypassing

[AdamKaz]

Hey all - I'm rebuilding my '88 Carrera Coupe but at the moment it's no fun because she won't shut up!

Dissembled the car for a complete bare-metal paint job. I seem to remember the alarm going off once I disconnected/removed the doors. Well now it's back from paint and the doors are back on (including the wiring harnesses) but the alarm keeps on going off whenever I connect the battery.

Okay - No problem - I'll just bypass the alarm...

Well it's still going off. I followed this walkthrough from another thread:

Originally Posted by Jeff

1. Remove the negative battery cable.
2. Remove the fresh air handler in the front trunk.
3. Looking into the trunk, the alarm module will be on the left side of the car. Mine had 10 wires coming from it.
4. Find the blue and blue/red wires leaving the unit. They are located in the #61 terminals. Cut these wires and connect the ends that lead away from the alarm (make a good permenant connection, you don't want to have to take the air handler out again). Cap off the ends at the alarm module.
5. Cut the black wire leaving the alarm module. It is in terminal 87A. Cap off the end at the alarm module. Connect the end leading away from the module to another piece of wire and connect that to the bottom of the #8 fuse (which is actually the 11th one back, counting from rear of car to front).
6. Reconnect negative cable on battery and start the car.
7. If you want to put a manual "kill switch" in, install an in-line toggle switch on the black wire before the fuse box.

and all the others I've looked up look similar or identical.

So what's going on? Why is my alarm still going off? Both the electricity and fuel pump are cut, and the horn is beeping intermittently. I don't really care whether I chase down the problem or disconnect the alarm, but I can't move forward with my rebuild until I solve this...

Any ideas?

[schoward]

If your alarm has the key switch in the driver side door jamb, I would check the wires running to that switch to make sure connections are not lost, wires broken etc. I am not sure and going off memory a bit but I think that switch provides a constant resistance that the alarm module is expecting to 'see' even when alarm is not in use. If the connection is interrupted it can cause strange behavior and I once read that it is a safeguard to detect tampering with those wires / switch (sets off alarm).

I personally had an issue with this and had an alarm that would randomly sound on my SC. In my case though the alarm would sound but car would still run, but obviously extremely frustrating and embarrassing.. I found the two wires running to the door switch passed through a plug behind the hood strut/master cylinder area in the frunk en route to the door that had corroded which was giving an intermittent connection. Fixed that and fine for 10 years plus now. I posted the fix way back when if you search my user ID posts.

No idea how the bypass helps or hurts here. And not sure if same problem but the fact that you say this started when you removed doors has me thinking the connections to the door switch may be area to check and/or make sure your bypass job didn't essentially cut this connection.

[AdamKaz]

The door switch was indeed taken off by the painters, but they never touched the wires and neither have I since reinstalling it.

Regardless, I'll check the wires thoroughly tonight as far as I can trace them.

I can't get my key to rotate the tumbler on switch, so maybe it's armed and the bypass isn't helping this?

[schoward]

I could be way off but the key not turning in the switch does not sound good. Who knows perhaps, that switch got dropped or something in the process. If not turning perhaps the whole switch is now bad... Perhaps others will chime in but still thinking key switch related.

[86 911 Targa]

O.K., here's what I think.

The alarm module needs to see a resistance from one of
the two resistors in the alarm lock.

This is built in theft prevention step to prevent
some one from cutting the alarm wire & taking the car.

I suspect that that:

1. There is an open connection in the two wires that
run from the alarm lock to the module.

2. One of the resistors in the lock is damaged.

Good luck,

Gerry

[86 911 Targa]

^^^^^
Here you go.

Best,

Gerry

[AdamKaz]

Excellent, I'm on the case! We'll see what I can find out.

Anyway to bypass the switch? How do I get resistance on a wire?

Thank you all.

[86 911 Targa]

Originally Posted by AdamKaz

Excellent, I'm on the case! We'll see what I can find out.

Anyway to bypass the switch? How do I get resistance on a wire?

Thank you all.

^^^^^
Here.

Gerry

[AdamKaz]

Fixed! (At lease for now...)

As is often the case, it was something stupid and fairly simple.

The door switch and it's wires were fine, and I was doing the bypass correctly. The fault was right here:



These connectors were a bit old and corroded, and in the process of pulling them apart before paint and putting them back together afterwards, 2 of the male connectors got pushed down into their recesses, thus were not making a connection. I got some needlenose pliers in there to pull them up, then liberally WD-40'd all the wire ends to hopefully provide a good connection.

Total success, even after I removed the alarm bypass.

So note: this problem still set off the alarm even after the bypass!