The old '94 was left alone to it's own devices for a few days, and when I finally gave it some attention, the battery was dead. Completely. Oh well, it's 6 years old on a 60 month battery. I had a new 72 month Interstate installed and *thought* all was well.

Until yesterday. My wife was home and said the alarm kept going off. Huh. All doors were latched tight as was the hood and trunk. Yesterday evening while watering the plants, she noticed the lights were flashing, but no horn alarm.

So I looked at it, and the led on top of the dash is showing solid red, all the time. Locked, unlocked, running, it's on. ???? So today she went out and left the car unlocked (at my direction), and came back, and the lights were flashing again. Hmmmmmm.

Again, I checked the doors, hood, and trunk, all was well. So I walked off, and the horn and lights went off. ????? I unplugged the alarm horn so as not to piss of the neighbors, left the car unlocked, and the lights started flashing again.

I'm starting to think the alarm killed the battery, since it was fine until left un-driven for a few days.

So what's going on? How do you troubleshoot this alarm system, or completely disable it?

Ron

Thanks Klaus and Ozark Lee. The alarm has been disabled, and now I can also diagnose it, if it needs that.

I'm starting to think the alarm is a symptom, not the problem.

To recap, my 5 year old battery went flat after a couple of days, and cranking had been getting weak anyway, so I replaced the battery. A few days later, my wife kept hearing a car alarm going off, only to find out it was the 850. Nothing was wrong, hood was closed, doors, trunk, etc. Leaving the car unlocked did not stop the alarm from going off. So I disabled it per Ozark's post.

Well, the battery is still going dead, so obviously something else is wrong, and that will be this afternoon's job. The glove box light has been removed, and the trunk light unplugged, yet the battery still goes flat in a couple of days. So I guess I'll put an ammeter in the circuit and start pulling fuses until I find the offending circuit and go from there.

Here's another question on this: On old cars with mechanical voltage regulators, the contacts could get stuck and drain a battery. I don't suppose there could be a similar problem with electronic regulators could there? How about a bad diode in the alternator? Could that drain a battery with the car off? (The car charges fine, though I've not tested voltage yet)

Lee is right, check for a short. When my alternator diode board failed, the ALT light would stay on even when the car was turned off and the battery drained in a matter of hours.

You will need to pull one fuse at a time. And don't forget to trickle charge the battery for at least 24 hours for a complete charge.

Klaus
--
I still miss my 164

So here's what I found this afternoon:

with all doors closed, etc ( and the alarm system relay is out still) the current drain is 9.5 mA, with pulses every couple of seconds to 14.75 mA. With fuse 7 out ( radio) it drops to 8.4 mA, steady. Pulling #6, (central locking) drops another 2mA, but no other fuses make any changes. We do have remote unlocking, so the 2 mA seems reasonable to me.

What now? The total draw does not seem bad to me so I guess whatever is draining teh battery is intermittant? Or is 9.5 mA too much?

Your parasitic draw is just fine.

How are your battery cables? There are a couple of different styles. On my '94 all of the cables are molded into the battery terminal, on the '96s the "secondary" cables bolt onto the main battery terminal. On my son's '96 the secondary ground was a tad loose and it was corroded (I bought the car as a non running vehicle). I cleaned the connections up and the car has run, for the most part, like a top ever since. Particularly if you have the bolt on style cables take them apart and clean up all of the surfaces.

...Lee

Mine has only a single ground, but a bolt-up secondary set on teh positive. I'll clean them, but doubt it could cause the battery to drain over a couple of days.

I'm more afraid I have an intermittant fault, which will be a RPITA to locate.

Ugh.

>>I'm starting to think the alarm is a symptom, not the problem.<<

I think you are correct. The alarm always seems to get triggered when the battery is removed and replaced so I would imagine a low battery condition would result in the same thing.

>>So I guess I'll put an ammeter in the circuit and start pulling fuses until I find the offending circuit and go from there.<<

Good plan.

...Lee

I have a pdf on the alarm system if you want it. Is it possible that the hood was not closed properly and the alarm system keeps trying to arm itself and failing?
Leaving the car unlocked and the alarm on is a little weird.

I'll send you the pdf anyway, watch for it.

Klaus
--
I still miss my 164

Chasing down an intermittent problem is always tough but I can tell you how to disable it.

Remove the lower dash panel on the drivers side of the car (3 T-25 Torx)and look to the left of the steering column, high on the firewall, for the lower central electrical unit. It is just below your fuse box on the inside of the car and it is a bunch of relays.

Once you locate it find relay 210/211 and remove it. This disables the alarm but it also enables the immobilizer and the car will not start. Look on the base of the 210 side of the relay and molded into the plastic you will find pin numbers. Locate pins 50e and 50f. You will need to make a jumper wire to fit the socket positions associated with those 2 pins to get the car to start again.

The dealer can get you a replacement dummy relay number 210 that has the jumper wire built in. It is part number 3545333 but I have no idea what they charge for it.

...Lee

Thanks. Given our neighborhood and the age of the car, I don't think it's much of a target for theft or break-in. Locking it is more habit than necessity.