Hello Everyone,
I am the new owner of a 1984 380 SL looking for help with a battery drain problem with the ignition key off. I disconnected the positive lead at the battery and hooked up a test light from the cable to the battery terminal. The light is on showing a draw from the battery. I removed each fuse and found the draw on fuse #12. When I removed fuse #12 the light went out. Fuse #12 protects the clock (not working), trunk light, interior lights, hazard warning system, radio and antenna, as well, I don’t know if my car has this or what they do - the warn. Monitor term 5, and the diagn., I have checked all lights including the trunk and they are off. The hazard warning lights are off but I wonder if a relay or a switch could be causing the draw. The radio is off and the antenna is not moving or making any noises.
Any help diagnosing this problem is greatly appreciated.

Should I be posting these questions on the SL forum?

Thank you. Daryl Miller

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Daryl Miller
84 380 SL
51 Ford
61 Chev 409 project
62 356
80 928
88 928 S-4
97 528
03 Forerunner

That sucks. How many amps is it drawing? Sometimes the glovebox light or trunk lights don't go out. The clock may stick and be draining even moe than it's supposed to, still it would very little. Maybe check the radio to see if it's warm, that or check each of those items directly for power use. I'm assuming your battery is good?

Take the bulb right out of the trunk light and recheck. I had mine with the leads to the bulb reversed. This killed the battery too.

__________________
1986 560SL
2002 Toyota Camry
1993 Lexus

I would check and see if the antenna is warm or hot to the touch. I had an electric antenna on a BMW, that seemed to work fine, but it drew current when the motor was shut off. Enough that you could almost burn your hand if you touched it.
Battery would drain down enough that it wouldn't start overnight.

IF YOU CANNOT FIND THE PROBLEM, BUY A "PRIORITY START UNIT" WHICH CONNECTS TO BATTERY & MONITORS DRAIN. WHEN BATTERY REACHES 11.9 VOLTS THE UNIT DISCONNECTS THE BATTERY. WHEN YOU ENTER CAR AAND TURN KEY, THE UNIT SENSES THE DRAW AND RECONNECTS BATTERY SO YOU CAN START AND DRIVE CAR. I WOULD BET ITS IN THE RADIO, THE ANTENNA MOTOR OR AMPLIFIER IF YOUR CAR HAS ONE. TRY TO DISCONNECT EACH PIECE AND THEN USE PROCESS OF ELIMINATION. I USE A DIGITAL VOLTMETER AND MONITOR CURRENT LEVEL AT BATTERY. MY PROBLEM CAME DOWN TO BEING THE RADIO RECEIVER IN TRUNK BUT I DONT THINK YOUR CAR IS SET UP THAT WAY.

If voltage (as measured @ battery) with a volt/multi meter is
11.9 ... you may have trouble successfully engaging starter
and completing ignition process!

Thank you all for the replies. I am on to checking the radio and antenna.
Does anyone know of a web site that explains how to remove the center console? I think I need to do this to get to the radio and I don’t want to damage anything in the process.
I will let you know what the problem is once I find it.

__________________
Daryl Miller
84 380 SL
51 Ford
61 Chev 409 project
62 356
80 928
88 928 S-4
97 528
03 Forerunner

I started at the antenna. Just disconnected the power plug at the power antenna and problem solved. I don’t understand why just yet as there doesn’t appear to be a power draw at the antenna (it's not hot to the touch or making any noise) and works as it should. Further investigation should produce the answer.

__________________
Daryl Miller
84 380 SL
51 Ford
61 Chev 409 project
62 356
80 928
88 928 S-4
97 528
03 Forerunner