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Honda CRV car alarm goes crazy

I inserted my key into the ignition of my 2007 Honda CRV and the car alarm went off. I was in a parking lot. It finally stopped. I tried the key again. Car alarm again. The navigator screen is blinking and the CD player is making repetitive sounds. I feverishly paw through the manual while I’m waiting for the alarm to stop. It stops. I get out of the car and use the key fob to lock and unlock to door. I try the ignition and all is well. I drive home. About 4 hours later that same evening, I go to start the car and the battery is dead. We jump it and take it to the mechanic. He can find nothing wrong. Any ideas?

Was the engine-off-state battery current measured? If so, what was the value in mA?

The mechanic tells me the battery is “good”.

That isn’t a test of the battery. It’s a measurement of how much current the car is drawing when it’s off. All modern cars have a slight constant current draw to operate the clock, the security system, etc. If there’s a problem and the current draw is too great, it kills the battery.

I agree with George’s suggestion. In this case, I’d suspect that the security system has a malfunction, or there’s a high-resistance short circuit to ground somewhere in he circuitry, possibly the security system circuitry or some circuit that if shorted will trip the security system.

If the security system can be disabled by pulling the fuse, you may want to try that. If not, you may want to take the car to a shop that specializes in automotive electrical systems.

Thank you both so much for your comments! This gives me something to ask the mechanic tomorrow. The mechanic mentioned that Honda’s security system has some kind of proprietary protection that only Honda dealers can access and fix. Also he said that the only thing drawing on the battery when the car was off is my iphone charger. Reading your thoughts, I suspect the mechanic is thinking along the same lines. Would you be afraid to drive the car?

“… the only thing drawing on the battery when the car was off is my iphone charger.”

Where is that plugged in?

The iphone charger is plugged in to the center console below the dashboard.

So this receptacle is “ON” all the time, even with the car off? If so, I would hesitate to leave anything plugged into it that would drain the car battery.

The mechanic did mention it is on all the time but doesn’t draw enough power to drain the battery, so he ruled that out as the culprit. It was a revelation to me that a cord plugged into that receptacle draws a small amount of power when the car is off even though it couldn’t charge a phone when the car is off.

if it won t charge the phone when it is off I doubt its drawing any current

And if it won’t charge a phone when it is off, then it is OFF! Total confusion here.

I agree that there’s some misunderstanding here. The charger port is either off when the engine is off, which means it draws no current at all even if you plug the charger in, or it’s “on”, which means it is capable of powering the charger IF one is plugged in, but it will still not draw current unless something is plugged into it. It functions exactly like the socket on your wall at home. The socket itself draws no power, only the device plugged into it draws power.

UNLESS it’s always “hot” and its wiring has a high resistance short to ground. However, that should NOT cause the symptoms you describe, except for the drained battery, so I doubt if it’s the source of your problem.

If your mechanic of choice can’t solve it, I still think a shop that specializes in automotive electrical systems is your best choice. There should be one in the yellow pages.

All the Hondas I’ve owned turn 12V receptacles OFF when the car is off and key removed.

Are all the battery and ground connections clean. They can trigger the alarm if you have an intermittent connection of either power or ground.

I have absolutely no idea whether the receptacle in my Scion stays hot when the car’s off. I’ve never had any reason to find out. I’ve never plugged anything into it.

In addition to a power port, my Scion also has a cigarette lighter. I have no idea if that stays hot either. I recall in the early '70s when I smoked using the lighters in my cars to light cigarettes even when the car was off, but that was a very long time ago.

Whether the socket is hot with the engine off depends on the car. Both of our Camrys the power socket is off with the engine/ignition off. But the Caravan has 1 socket that is always on and 1 that is switched with the ignition.

Additionally, in some vehicles you can choose whether it’s switched or always hot.

Whew! The Honda Dealership found a loose wire on the alarm sensor. Cost to repair: $33! All is well. Thank you for your comments! The dealership chimed in on the charger’s ability to drain the battery, said it is off when the car is off so would not affect the battery.