Have a battery discharge problem in my 87 190D 2.5 N/A. I have installed a rebuilt alternator and new OPTIMA red top. The Alt charges well, but the BAT discharges over the course of 2 weeks or so when I am on the road. I have checked the mA drain and it is about 75 or so, I removed all the fuses and relays and no change detected. It is obviously intermitent. I have been having some issues with Central Locking Sys; it is flat after a few days. I may have a small leak causing the elec. vac pump to cycle on but the books says it only runs for 1 or 2 minutes and then shuts off...for how long, it doesn't say. The question is 1) Can the vac pump cycle enough to run a BAT down over the course of 14 days? 2) Is there an easy way to disable the system? Just pull fuse 12? Also, there appears to be VERY little info about the peculiarities of the W201 CLS. Anyone have any similar problems? Solutions? Thanks.......

The pump runs one way to create vac. to close the locks etc and runs the other way, to make air pressure to open things. Why would a leak in the system cause the pump to cycle? Is there some parts of CLS that need continuous vac.?? I understand it is independent from the other vac, systems because of this bi-rotaional function. Sounds like a neat system...until it SNAFU's. Any insight would be great!

I'm not understanding how you could have measured the battery current drain at 75 m.a., yet removing fuses didn't isolate the circuit that is responsible. If this were true, then you must have something connected to the battery that does not go through the fuse box. This is a real no-no. I'd suggest removing the fuses again while watching the current draw with an ammeter, to make sure you didn't overlook the correct fuse. And if it is really true that removing fuses does not stop the current draw, then look for something that is connected to the battery but does not go through the fuse box. For example, is there any half-vast stereo or burglar alarm installation involved?

There was a problem with the early 124 CLS pumps draining the battery (changed mid-MY'87), but I'm not aware of a problem in the 201.

The pump is under the RR seat, you can unplug the electrical connector to see if that helps.

__________________

Gone to the dark side

- Jeff

The only thing not fused is the alternator. There might be a problem with that new alternator, try disconnecting it and see if the current draw disappears.

__________________
Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C

That is what I was going to say!

Also, how did you measure the current? Why do you say it is obviously intermittant?

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra