83 300SD electrical issues - PeachParts Mercedes-Benz Forum

matt s · #1 02-17-2009, 09:43 PM

hello everyone,

I've been reading the threads for awhile to try and target the electrical problems but am still curious and would appreciate some input...

1983 300SD turbo diesel only 140,000 miles, just bought it a few months ago. Recently lost all speedo and odometer function (I plan on checking the cable this weekend) tach used to bounce around, now it doesn't work at all...fuel gauge stopped working and turn signals don't work at all. This all basically happened at the same time just before the alternator seized up and broke the belt. I changed the alternator and belts last weekend with no avail to these electric problems.
Thanks a ton for any info.

Brian Carlton · #2 02-17-2009, 10:09 PM

Welcome to the forum.

Go into the fuse box (underhood right in front of the driver)...........find fuse #12 and replace it. The current condition is irrelevant.

matt s · #3 02-17-2009, 10:26 PM

Thanks Brian
I really appreciate the quick response, will replace the fuse ASAP when I get back home in 2 days, and I'll let you know.
One other question: Why does the alternator (65 amp) have 2 pulleys? What does the 2nd pulley and belt go to. Thanks matt

Brian Carlton · #4 02-17-2009, 10:33 PM

Quote:

Originally Posted by matt s

Thanks Brian
I really appreciate the quick response, will replace the fuse ASAP when I get back home in 2 days, and I'll let you know.
One other question: Why does the alternator (65 amp) have 2 pulleys? What does the 2nd pulley and belt go to. Thanks matt

Two pulleys has been standard issue for the alternator on all the 617 turbo engines. A bit of an overkill if you ask me, but it allows you to have fairly low belt tension to do the job. The belts need to be a matched set, however.

matt s · #5 02-17-2009, 10:42 PM

interesting... so running one belt off the alternator is fine?

Brian Carlton · #6 02-17-2009, 11:25 PM

Quote:

Originally Posted by matt s

interesting... so running one belt off the alternator is fine?

I never tried it..........but, I'm sure it would work fine in a pinch. Long term durability at maximum alternator loads might be questionable........depending on belt tension.

matt s · #7 02-21-2009, 01:01 AM

thanks again
When I originally looked at the fuses there was an auxillary wire a previous owner had hooked up to fuse 12 so I couldn't see that the tip of the fuse was blown.
Not only did changing the fuse fix the lights, the tach, the fuel and oil gauges and clock now the heater works! and it never did before... the speedometer and odometer both kicked in too.
Thanks a MILLION, what an easy fix now that I know.

bgkast · #8 02-21-2009, 02:28 AM

Did the fuse look OK?

Brian Carlton · #9 02-21-2009, 08:57 AM

Quote:

Originally Posted by matt s

thanks again
When I originally looked at the fuses there was an auxillary wire a previous owner had hooked up to fuse 12 so I couldn't see that the tip of the fuse was blown.
Not only did changing the fuse fix the lights, the tach, the fuel and oil gauges and clock now the heater works! and it never did before... the speedometer and odometer both kicked in too.
Thanks a MILLION, what an easy fix now that I know.

Excellent.

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