81 GTSi I put a new battery in 2 weeks ago. I went to drive a week later, and it's dead. After recharging, I took the + off the battery to test for sparks with the key off, and I got some pretty good ones. while leaving the + off, I went to the fuse block to find which circuit the problem was in. (Thanks Birdman) # 16= Horn, lighter, clock, lamp socket, buzzer. The fuse block has a piggy back connector and one has 3 wires, and the other has 1. The connector with 3 wires was the culprit. Large guage red, and large guage blue, and a smaller guage white with green trace. I'm thinking the red is for the horn and the blue is for the lighter. The last small wire is probably for the clock. Here is what makes this an interesting problem, when I went back to put the + back on, there was a rather large spark, I touched the cable to the battery again, and the spark was smaller, less intense, after touching it sveral times, the sparking almost went away. Checking it with my meter, I find that after leaving the cable off of the battery for a few mins then, when the battery is connected the drain is 560 ma, and it decreases slowly, all the way down to 10 ma where it stabilizes. The behavior indicates a capacitor is charging, and when charged is leaking to ground, possibly through a leaky diode. The horn works, the lighter does not, and the clock does not. Before I start tearing it apart, I was wondering if anyone is aware of any capacitors in the clock, that could be causing this problem. The clock was working until month or so ago. Thanks guys, Rob
Sehr interessant, mein herr. How about placing a voltmeter on the car side and observing how quickly the voltage decreases when you pull the cable? No way the clock will contain a cap big enough to make a visible spark. There are numberous 'radio suppression caps' (on coil and alternator) but even they are too small. Anything less than a microfarad will not make a spark and those are mostly 0.05ufd. Might someone have added a capacitor for a long gone stereo amplifier? Those are commonly up to a farad and will definitely require substantial current when applied. Next step, pull all fuses and repeat.
I pulled all the fuses, and the drain was still there. With the + cable off, I checked the resistance between + and -. There is definately a large capacitor across the line, and it is leaking to ground. Did the factory put any on, if so where would it be? Thanks Rob
The lighter was my problem! Even when you pull out the actual lighter the socket may still be shortby dirt shorting the receiving portion. I found it the hard way when it malted the black wire...It is worth a look.
On your car it's not too difficult to isolate the problem. There is a terminal board at the bottom of the relay panel which distributes voltage and that's where to disconnect wires to isolate the problem. Once those red and white wires are removed from connection to the battery, only the starter and alternator remain connected (as it left the factory). That terminal block gets voltage from the battery through heavy red wire to the starter. The battery itself connects to the starter with a large black wire. If you have difficulty getting the wires off the terminal block and are able to get under the car easily, you might wish to attack the problem that way. I'd start in the dash first. Focusing on the terminal block, voltage comes in a the heavy red wire. Three red wires go to the fuse blocks, the 3 whites go to relays. The odd red wire goes to the ignition switch. GL _________________________ http://www.ferrari308gtbi.com/
