Massive parasitic current leak in stereo/nav circuit

[Multibeemer]

Quicksilver,

I don't see what you're referring to. All I see above "new posts" and "search" is a Wells Fargo ad

I went ahead and measured the current drain by placing a 1 ohm, 10 watt resistor across the connectors for the #75 fuse after I removed the fuse, and measuring the voltage drop across this resistor. Since it's a 1 ohm resister, the current equals the voltage (I = V/R, where R = 1.0). I measure about 800 mA, which is a massive amount of current, about 16 times the typical limit of 50 mA. No wonder my battery is going dead if I don't drive the car for about two days.

[Quicksilver]

Look for "online references" Right between How To's and FAQ. http://www.xoutpost.com/e53wd.php

Originally Posted by Multibeemer

Quicksilver,

I don't see what you're referring to. All I see above "new posts" and "search" is a Wells Fargo ad

[Multibeemer]

Quicksilver,

I don't see anything between "How-To's" and "FAQ", but thanks for the link. However, I get error messages when I try to open the wiring diagrams for the nav system. I'll keep playing with it, but to be honest, I think I've reached the limit of my skill level with this stuff, so I will probably take the car to somebody with experience with this type of problem, unless anyone has any advice on anything I could do to further narrow down the source of the problem.

Correction on the degree of current drain: I went through the process of checking to make sure there are no other sources of parasitic current drains other than the nav system by connecting a 1 ohm (10 watt) resistor in series between the negative post of the battery and the cable that connects to it (there is essentially zero current drain from any other sources, which is good news), and then measured the voltage after re-connecting fuse #75 for the nav. It read a whopping 1.4 volts, which translates directly into 1.4 amps! I'm surprised the battery doesn't go dead during a trip into the grocery store!

[Quicksilver]

Sorry: Premier membership may be required.

[Multibeemer]

Update on my battery drain problem. I located a wiring diagram, so I was able to identify all of the components in the circuit protected by fuse 76, across which I'm seeing a parasitic current flow of 1.4 amps. I disconnected each of the components in the circuit, one at a time, and measured the effect on the parasitic current. In no case was I able to reduce the massive parasitic drain.

So, I came up with the following work-around: I located a source of +12V when the key is in the on position, located in the rear fuse block, very close to fuse 76 (it's a connector to an unused relay). I confirmed that there is no voltage at this connector whenthe key is off. I then bought a simple relay, and connected the source of +12V to the connector to the energizing magnet on the relay, and connected the switch connectors of the relay in series with the circuit with the drain. So, when the key is on, the relay is energized, the switch is closed, and current flows in the circuit. When the key is off, the switch in the relay is open, shutting off the parasitic drain. Everything fits neatly under the right rear panel, so nothing is visible. It works like a charm - the car can sit indefinitely, and it cranks strongly, and all the accessories work. Yes, I admit it's a bandaid, but a pretty darn effective bandain, if I do say so myself .

[Zulu95]

Or you could have just swapped the switched +12 V from the spare fuse holder for the fuse 76 supply.

[Multibeemer]

Originally Posted by Zulu95

Or you could have just swapped the switched +12 V from the spare fuse holder for the fuse 76 supply.

???? Sorry, I'm not following you. The problem is (was) a missive current leak in the circuit protected by fuse 76. I basically inserted an interruption of this current flow in the form of a relay that's actuated by the +12V source that's only hot with the key is turned.