clicking in the tower speakers

A friend just bought a Malibu and had tower speakers and amp installed by the local car stereo shop next to the dealership. When he turns the key to ignition, there is a clicking in the tower speakers. Not in the boat speakers. The audio tech thinks it has something to do with the depth finder, but can't seem to fix the problem. Note: this is before he starts the enhgine, so I don't the the alternator has anything to do with it. Any ideas or help????

IS the amp wired directly off the battery? or thur the fuse panel? Why does he think it's the depth finder? A common problem in cars/boat is a "popping" sound when the car is started or tunrned off., is this what yoru referring too?

Yes it is wired directly to the battery, but the ignition wire goes to the HU.
No, the clicking sound continues when the key is switched to ignition. It is a fast click that seems to slow up a little the longer the key stays in the ignition position. The clicking continues if the engine is started.
I thought maybe the ignition wire that comes off of the amp is running too close to the depth finder or the HU is grounded incorrectly. But again, the interior speakers do not have this problem.

We have run into that problem a few times. It sounds like the depth finder is the culprit. We have seen some noisy/faulty transducers and depth finder equipment. Make sure the wiring for the depth finder is in good shape, especially the ground. Also, make sure all the grounds to the radio and amps are in good shape. This is a very difficult problem to remedy. High quality RCA cords might help and also a ground-loop isolator or noise filter may help in a worst case scenario. good luck.

We'll check the grounds. Thanks for the input!

Possibly the fuel pump and it slows as the pressure builds in the fuel rail?? Does it do it in the accessory possition too?

I second the "check the grounds" comment.

In fact, do more than check them, beef them up!

It is easy to create a "ground" problem when the head unit is operated off of the boat's main electrical system and the amps are wired directly to the battery. The amplifier's job is to take a tiny signal comming from the head and turn it into a large signal. The problem is that the amplifier references everything to what it considers to be "ground", which is usually a very close approximation of what is on the battery due to some really beefy cables connecting it to the battery.

The head unit, on the other hand, generally picks up its version of "ground" from up under the dash, after is has run half way around the boat, through the engine compartment, through the cable harness that connects the engine to the dash, and then a distribution panel. Any surge of current (like a pulse from the depth sounder) will create a slight shift in the "ground" voltage due to the voltage drop in the wiring. The amplifier seens this and can't distinguish it from signal.

The solution is to make a direct ground connection between the head unit and the amplifier. If you can get up behind the head unit then there is usually a good spot to connect a ground to, often doubling as a rear mount to hold the back of the head unit up. Use something like #12 or #14 wire and then run it to the Negative terminal of the amplifier.

Bob,
My first thought was it might have something to do with the fuel pump.Or just the electrical connection to it. When I turn boat switch to ignition I hear the pump in the engine compartment. Yes, the stereo is connected to an Acc. switch.