[W126 Coupe] Long term Battery drain problem

[Vance Rowley]

Hi Guys,

  I hope that some of you guys have had some similar experience to the one I have had regarding this intermittent battery drain problem (and solved it). This has been going on now for years. As a reminder for those not seen my previous posts, I am getting an intermittent current draw from somewhere that will drain the battery enough not to start the car after 2 or 3 days standing parked. I have had months of testing and circuit testing, It has come down to a proven fact without any doubt something  being fed by fuse #2. All the usual lights  (trunk light, battery, alternator, starter motor etc) have been ruled out, plus the fact, this is not a constant current draw, this is intermittent. The head unit for the stereo system is also on this fuse, but I have done considerable testing of the head unit which for memory takes no more than 70ma with ignition off which is fine with a 100Amp/Hour Battery (which has been recently been drop tested again). Other items on this fuse are the hazard warning system, (which can take up to 6.5Amps while active) but I have never seen them come on, by themselves. I am currently in the process of trying relay "B in the fuse box which I have removed. I have ruled out the stereo head unit and the stereo amplifier unit (as I had the amp unit disconnected completely from the system for over a week). Fuse #2 in the fuse box  feeds several circuits. These being 1. Diagnostic terminal #6, 2. Hazard warning system, 3. clock, 4. Front roof light, 5. Electronic Radio (this is now the memory feed to the aftermarket stereo head unit which takes no more than 70ma in off mode), 6. Vanity mirror light (which both work as they should). The only things I don't quite understand are the last two circuits by there description. They are 7. Relay comfort circuitry term 86, and 8.electr illum control. 
Relay "B" is a combination Relay for Turn signal, Hazard lamps, Wiper / Washer system. I have currently replaced fuse #2 and removed Relay "B". 
BTW just to clarify, with fuse #2 removed, the battery does not drain off. It is most definitely one (or more) of the above which is the problem.

So, if there is anyone out there that has had any similar experience with one of these circuits fed by fuse #2, please let me know.

All the best, (and banging my head against the wall)
Vance