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#1
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'84 300D washed engine compartment...uh-oh!
Shined her up this weekend - even spray-washed under the hood. Now I have an electrical problem - go figure.
Has to do with the brake light and turn signal circuit. When I first start it up everything seems to work properly until I press the brake pedal or flip the turn signal. Then my tach, coolant temp., fuel gage, windows, brake lights and turn signals cease functioning. The fuse for that circuit is in the number 12 slot in the fuse box but it never blows. I then turn the ignition off and restart it and everything works again until I use the brake or turn lights. Every time I repeat this cycle it works until the brake or turn lights are used then BAM! - out she goes. Its got me baffled. Obviously, water has gotten in to something somewhere. But since it happens instantaneoualy only when the brakes or signals are used, that would seem to point to an issue in just the brake and signal lighting wiring. Any ideas? |
#2
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Try cleaning the contacts of the fuse and fuse holder.
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For Sale: 1982 MB 300TD 1995 Chevrolet Suburban 6.5TD Sold: 1980 IH Scout Traveler- Nissan SD33T Diesel |
#3
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Also, clean all the grounding points.
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RRGrassi 70's Southern Pacific #5608 Fairmont A-4 MOW car 13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete. 91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K 90 Dodge D250 5.9 Cummins/5 speed. 400K |
#4
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Ditto, grounding points......check the engine-to-chassis ground. (near the starter)
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Sam 84 300SD 350K+ miles ( Blue Belle ) |
#5
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After everything dries out it may return to normal.
As a mechanic I worked with the local school district for about 3 months. I kept getting vehicles with a lot of electrical trouble. Cars with 3-4 exterior bulbs burned out and cars with several dash bulbs burned out. This puzzled me as it is abnormal to replace more than a bulb or 2 in a whole year and very seldom a dash bulb. Yet I was getting a lot of cars with multiple bulbs no good. I got a hint but it did not register with me at the time. I found a car that had a lot water inside of the turn signal. Since is was very low on the bumper I thought it was from a puddle. Later when I worked at another job I listened to my Boss talking about a same electrical problem at the Oil Refinery we had a contract with. The electrical problems were being caused by people who were using a hose to was off their Company Cars (same at the school district) which they were responsible to keep clean. They were directing the water flow at the lights. The pressurized water was getting into the light circuits and causing all kinds of electrical problems as well as a lot of burned bulbs. At the Oil Refinery they were instructed not to direct the water at the lights and ect. and their problem disappeared. I never figured this out for myself when I worked at the school district.
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84 300D, 82 Volvo 244Gl Diesel |
#6
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I'll be checking it this weekend as I am having to drive the other vehicle unitl I can get to it. Seems likely water may be the culprit and in something somewhere, lights, wiring, switch, etc. Its kind of wet here now so don't know if a few days sitting will get it back to normal or not - but hope so. Will try to post the results of my trouble-shooting efforts soon.
Thanks for all the advice! |
#7
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In the future, follow my example. I often clean under the hood with the pressure spray at the car wash. First I take some small grocery plastic bags and cover as best I can the fuse box and all electrical junction boxes. For the most part, those are only dusty anyway. It's the oil and engine grime I want to remove to make working under the hood less of a clothes ruining exercise.
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Charles 1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html |
#8
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engine wash / electrical woes
Well - guess what it was... a fuse in the fuse box must have gotten damp letting corrosion build up on the fuse tips enough so to cause a resistance in that circuit. Nothing ever blew but after jiggling each fuse and finding one that had some corrosion on the ends - Walla! No more problems!
Will definitely cover the fuse box and anything else that looks like it could cause me trouble with water ingress. I learned a lot about my MB300D from that incident! |
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