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Old 09-14-2007, 11:36 AM
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Join Date: Aug 1999
Location: Florida / N.H.
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<-> From post #8 above, the indication is that the ignition switch is faulty - are there any other reasons for no voltage at the middle terminal post for the heater motor wiring harness??? Any easy way to confirm that the ignition switch is to blame???

Thanks, Ian>>

There is a very simple test to see if you have a fuse problem or an ign. sw. problem:

With a 12v test lamp, one lead to a good ground ..w/ other lead , test for 12v on each side at the strip fuse/F-15 [ under small cover near the left strut tower] with key in the ON position..
If you have power to only one side , you have a bad fuse/connection...if you have NO power to either side , you have a suspect bad ign sw contactor bar [ inside ign sw]
The Blower gets it's constant HOT 12v from Bat > ign sw > fuse...
The three wire connector[ X-69 ] is after the fuse and ign sw, so you want to be testing right at the fuse to differentiate fuse or ign sw ..this test will do just that............
One problem with a bad ign sw is that they are usually erratic, so it is best to do this tests when condition exist..I hook the test lamp up and then go wiggle the sw . along with repeated ON/OFF rotation while watching the test lamp to coinside.
And on the fuse test, you want the blower on full position [ Defrost] while doing the test b/c I see these pass a NO LOAD test just fine , but as soon as there is an Amp demand [ Blower] , they will fail..that goes for any poor connection.

Lastly, for those who hang everthing but the kitchen sink on their key-chain, a premature failure of ign sw/tumblers is a the consequence you will be looking at sooner or later ..

Last edited by Arthur Dalton; 09-14-2007 at 12:00 PM.
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Old 09-16-2007, 02:11 PM
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Join Date: Sep 2007
Location: Mid-West
Posts: 2
Thumbs up Replaced the Infernal MB Strip Fuse!

Thanks - It was actually the first thing that I checked and it looked fine and passed the digital multimeter continuity test.

After much time and head scratching I ultimately removed it and found a practically invisible hairline crack (continuity still checked out OK but obviously the fuse couldn't handle the 10-20 A load from the fan and was the cause of the blower's intermittent operation.

With no dealership nearby, it proved surprisingly difficult to find an exact replacement for the troublesome 30A strip fuse. Had to use a widely available "Cooper Bussman FLD-30 Fusible Link" which required slight modification to narrow its mounting hole distance and decrease its overall length. Also used a utility knife to cut a clearance hole (window) through the top center of the Mercedes strip fuse housing.

In any case it is now fixed and working fine. Total cost out of pocket was $10 for new motor brushes and $4 for the new and better designed fuse.

- - -
One note on the 300E blower motor R&R procedure: if re-installation of the wiper assembly seems tricky, it may be because the top weatherstripping can easily catch under the base of the windshield. Once this weatherstripping is properly seated, the wiper assembly should align properly and mount very easily. Whole job probably should have only taken a couple of hours, but for the first time do-it-yourself mechanic, figure about double that time.
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Old 09-12-2012, 12:54 AM
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Join Date: Aug 2012
Location: north new jersey
Posts: 7
wich fuses?

Originally Posted by jeff (moose) View Post
This would be a metal strip type fuse mounted inboard of the fusebox?
Hi, just bought my first mb. 1998e300. already the blower motor stopped and sunroof stopped. My mechanic said the regulator looks new. if thats the case I want to start by checking the fuses. Which ones and where are they located? If they are good what would be my next step. Thanks
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