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Turn signal fuse keeps blowing. 87 300d
Seems like I have a short to ground that I cannot find. I measure ground to L and R pins in the hazard socket and get 22 ohms or so. I've pulled all the front turn signal plugs and got the same reading at #3 pin on those. At fuse #6 (the one that blows) I get the same 22 ohms from the top. What is confusing to me, I get 22 ohms across + and - battery terminals with battery removed.
Thoughts? This followed an IP swap and some vacuuming in the engine bay. I also found some rat droppings and a half eaten block of poison in the bay as well. (I had left the car outside for a week).
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http://superturbodiesel.com/images/sig.04.10.jpg 1995 E420 Schwarz 1995 E300 Weiss #1987 300D Sturmmachine #1991 300D Nearly Perfect #1994 E320 Cabriolet #1995 E320 Touring #1985 300D Sedan OBK #42 |
#2
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Interesting problem. Rat poison should have more than 22 Ohms resistance.
Suggestion: remove all turn signal bulbs, front and rear. Make sure nothing is touching any of the contacts in the lamp housings and that the wires in the immediate area of the lamp housings all looks OK. Now turn on the ignition and try the turn signal lever. Obviously the turn signals won't work and you should get a bulb-out warning but does the fuse still blow? If the fuse doesn't blow, you know it has something to do with one of the bulbs / sockets. Add bulbs one at a time until one causes the fuse to blow. There is your problem. If the fuse still blows you know it isn't related to the bulbs and their sockets. It then could be the turn signal switch in the steering column, the combination relay N10 in the fuse/relay box (included the flasher circuit), the lamp-out warning relay (also in the fuse/relay box) or the wiring in between. Jeremy
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"Buster" in the '95 Our all-Diesel family 1996 E300D (W210) . .338,000 miles Wife's car 2005 E320 CDI . . 113,000 miles My car Santa Rosa population 176,762 (2022) Total. . . . . . . . . . . . 627,762 "Oh lord won't you buy me a Mercedes Benz." -- Janis Joplin, October 1, 1970 |
#3
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Quote:
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http://superturbodiesel.com/images/sig.04.10.jpg 1995 E420 Schwarz 1995 E300 Weiss #1987 300D Sturmmachine #1991 300D Nearly Perfect #1994 E320 Cabriolet #1995 E320 Touring #1985 300D Sedan OBK #42 |
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?????
Not sure what you mean. Fuse 6 powers a number of things -- it's wired to S7 the horn, S6 the hazard flasher switch, p4 the outside temperature display, N2/4 the warning module and possible others. But yes, with the ignition off and key out there should be nothing on the load end of Fuse 6. You should not get any resistance to ground -- it should measure infinite on an ohmmeter.
Jeremy
__________________
"Buster" in the '95 Our all-Diesel family 1996 E300D (W210) . .338,000 miles Wife's car 2005 E320 CDI . . 113,000 miles My car Santa Rosa population 176,762 (2022) Total. . . . . . . . . . . . 627,762 "Oh lord won't you buy me a Mercedes Benz." -- Janis Joplin, October 1, 1970 |
#5
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Fuse 6 also powers the bus bar I believe that is hidden behind the dead pedal, mashed/cut up wires there can cause a dead short.
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2012 BMW X5 (Beef + Granite suspension model) 1995 E300D - The original humming machine (consumed by Flood 2017) 2000 E320 - The evolution (consumed by flood 2017) |
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Power strip
Quote:
Jeremy
__________________
"Buster" in the '95 Our all-Diesel family 1996 E300D (W210) . .338,000 miles Wife's car 2005 E320 CDI . . 113,000 miles My car Santa Rosa population 176,762 (2022) Total. . . . . . . . . . . . 627,762 "Oh lord won't you buy me a Mercedes Benz." -- Janis Joplin, October 1, 1970 Last edited by Jeremy5848; 01-29-2013 at 04:04 PM. Reason: Add diagram of X30. |
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right - sorry bout that,
need some tea. ..
__________________
2012 BMW X5 (Beef + Granite suspension model) 1995 E300D - The original humming machine (consumed by Flood 2017) 2000 E320 - The evolution (consumed by flood 2017) |
#8
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An old electrician/controls field engineer trick for finding a short:
Use a bulb in place of the fuse. Try a double ended bulb like in the glove box or dome light. This provides a safe series impedance to help find the fault without hurting things. And it stops glowing when you found the short.
__________________
The OM 642/722.9 powered family Still going strong 2014 ML350 Bluetec (wife's DD) 2013 E350 Bluetec (my DD) both my kids cars went to junkyard in 2023 2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles) 2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles) 1998 E300DT sold to TimFreeh 1987 300TD sold to vstech |
#9
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Quote:
__________________
http://superturbodiesel.com/images/sig.04.10.jpg 1995 E420 Schwarz 1995 E300 Weiss #1987 300D Sturmmachine #1991 300D Nearly Perfect #1994 E320 Cabriolet #1995 E320 Touring #1985 300D Sedan OBK #42 |
#10
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That trick has saved me more times...
You might have to pull the turn signal relay in the relay box, and jump pins 8 and 10 when trying this trick. The bulb may present too much series impedance to allow the turn signal relay to function correctly.
__________________
The OM 642/722.9 powered family Still going strong 2014 ML350 Bluetec (wife's DD) 2013 E350 Bluetec (my DD) both my kids cars went to junkyard in 2023 2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles) 2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles) 1998 E300DT sold to TimFreeh 1987 300TD sold to vstech |
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And according to the ETM, the turn bulbs are not supervised by the external lamp monitor. At least not directly like the other bulbs. The turn signal flasher monitors the bulb current and if it doesn't have the load of 2 bulbs it flashes fast.
There is a tap to the monitor relay from the output of the flasher, maybe this is a special input to the monitor that looks for the fast flash pattern to turn on the warning light?
__________________
The OM 642/722.9 powered family Still going strong 2014 ML350 Bluetec (wife's DD) 2013 E350 Bluetec (my DD) both my kids cars went to junkyard in 2023 2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles) 2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles) 1998 E300DT sold to TimFreeh 1987 300TD sold to vstech |
#12
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Quote:
__________________
2012 BMW X5 (Beef + Granite suspension model) 1995 E300D - The original humming machine (consumed by Flood 2017) 2000 E320 - The evolution (consumed by flood 2017) |
#13
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The 1xx chassis is an electrical dream to work on. Except for some bad choices in wire strand counts across hinges, the wires are nice and solid. You can actually maintain the connectors or worst case rebuild the harness with a soldering iron. Or you can do neat tricks like convert from a 4-pin to 5-pin OAT display without having to cut or splice any wiring.
You can actually still buy the housings and the pins and sockets.
__________________
The OM 642/722.9 powered family Still going strong 2014 ML350 Bluetec (wife's DD) 2013 E350 Bluetec (my DD) both my kids cars went to junkyard in 2023 2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles) 2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles) 1998 E300DT sold to TimFreeh 1987 300TD sold to vstech |
#14
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Quote:
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Brian 87 300Dturbo 180K #14 head still running R-12 SOLD 12/2017 02 F350 Powerstroke 180K 05 Chevy Express 1 ton w/Royal Utility box 120K 08 Infiniti FX-35 40K 15 Golf Sportwagen TDI 35K 10 Sprinter 3500 chassis with a Class A Winnebago on it. 56K |
#15
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The lamp test is a neat idea. Seems to me I remember seeing long ago fuse holders with a lamp built in. If the fuse blew, the lamp would glow so you immediately knew which fuse was bad.
Jeremy
__________________
"Buster" in the '95 Our all-Diesel family 1996 E300D (W210) . .338,000 miles Wife's car 2005 E320 CDI . . 113,000 miles My car Santa Rosa population 176,762 (2022) Total. . . . . . . . . . . . 627,762 "Oh lord won't you buy me a Mercedes Benz." -- Janis Joplin, October 1, 1970 |
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