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#1
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My 1985 300CD has developed an annoying habit of late. After 3 or four days of driving or sitting (it doesn't seem to make a difference), the battery runs down and won't start the car. I have replaced both the alternator and the battery (both tested bad) and the problem persists. I hooked up an ammeter between the disconnected positive battery cable and the battery post. The only draw was 2 amps lasting for about 5 seconds out of every 30 seconds. I suspected that was the clock, and disconnecting the fuse for the clock circuit ended the draw. Please, this is making me crazy!! Any helpful suggestions you can make would be greatly appreciated. ------------------ kjcalhoun Bosch certified DFI Tech 20 years experience MBCA Member, Southern Stars |
#2
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It is somewhat common for the Pre-glow relay to stay on after starting the car. Since the glow plugs take about the same amount of current as the alternator can put out the battery will go dead. Other than testing the charging system after every start or disconnecting the glow plug harness, replacement is a good bet.
------------------ MERCEDES BENZ MASTER GUILD TECHNICIAN ASE MASTER TECHNICIAN 27 YEARS M.B. TECH |
#3
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Rest current draw on this model should be no more than 30mA. 2a draw from the clock? This test is best done neg termal to neg post. Connect ampmeter leads then touch the termnal to the post for aprox 15sec. to cycle every thing off. Key out of ign and doors closed.
Good Luck. |
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