If you think you have short that is draining the battery but not blowing a fuse, take a close look at the glow plug relay. A while back mine went bad. While the engine was running it would come on by itself and there is nothing to indicate this is happening other then there is a big drain and the alternator. I had to hook voltmeter to one of the glow plugs and drove around. When I the battery would start doing a heavy discharge, the voltmeter said 12 volts at my glow plug. I new this should not happen. Also, while this was occuring, the glow plug light acted like it normally would and never came on when the engine was running.

TimK

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EPA 609 & 608 HVAC Certified
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83' 300D Turbo - 300K + Miles
00' 1.9L TDI Beetle
85' 6.5L Turbo, GV-OD, GMC Suburban,
67' 2.5L Diesel NA - Land Rover Series IIA

Here's what you do if it's so cold your diesel fuel gels. Smear some on some toast and stay inside until it warms up outside.