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#1
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Reversed polarity
Hi, I did something really stupid and by mistake reversed polarity when installing new battery on 87 300td.....got a big spark for a moment when wrong terminals touched....
After that incident I lost completely any tachometer reading and ABS light is now on (was not before). I checked all the fuses but could not find any burned and also not the one that would be related to the instruments. Would maybe someone know where I should start to troubleshoot this; what would be the first most likely thing that would burn from reversed polarity and make Tacho and ABS stop working? Thanks a lot, Robert |
#2
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Reversed polarity most likely cooked/fried the tachometer and possibly the pickup, same goes for the ABS module and sensors.
You’ll probably find that the alternator winding is fried too, along with a multitude of other electrical parts (the Starter and blower motor will be fine though)
__________________
'92 Dakota : OM617 Swap '73 Duster : 8-71 Blown 426 |
#3
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The OVP relay may have done its job and saved some of your electronics. Look for a blown fuse in it's top, or replace the OVP relay if it's cooked.
Expect some failed electronics in things like the cruise control amplifier or HVAC system. I strongly suspect someone connected a battery backwards in my SDL at some point in its life due to the unusual number of cooked electronics I've repaired in that car.
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Current stable: 1995 E320 149K (Nancy) 1983 500SL 120K (SLoL) Black Sheep: 1985 524TD 167K (TotalDumpster™) Gone but not forgotten: 1986 300SDL (RIP) 1991 350SD 1991 560SEL 1990 560SEL 1986 500SEL Euro (Rusted to nothing at 47K!) |
#4
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Hi, great, thanks, did not even think about OVP relay! Puled it out and yes, the fuse is burned. Changed the fuse and all is back, working perfectly!
Thanks a lot; I guess I was really lucky! |
#5
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Quote:
Lesson learned (I hope) with out any serious consequences!
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
#6
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Glad you were lucky. Thanks to the good old MB engineers.
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#7
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Dodged the bullet this time .
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-Nate 1982 240D 408,XXX miles Ignorance is the mother of suspicion and fear is the father I did then what I knew how to do ~ now that I know better I do better |
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