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#1
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what is an overload protection relay
1992 300 D
I am told that I need to replace the overload protection relay! What is it? What does it do ?
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Wayne Jockers 1992 300D |
#2
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Actually, its the overvoltage protection relay, and it keeps voltage spikes or a runaway alternator from frying the electronics. Cuts the voltage to all sensitive circuits when the voltage gets too high.
It also tends to get "tired" and cut the current when it's not supposed to as well, probably the reason you need to replace it. Usually just cracked solder joints, but can also be burned contacts. Peter
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1972 220D ?? miles 1988 300E 200,012 1987 300D Turbo killed 9/25/07, 275,000 miles 1985 Volvo 740 GLE Turobodiesel 218,000 1972 280 SE 4.5 165, 000 - It runs! |
#3
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is there a way to test the relay?
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Wayne Jockers 1992 300D |
#4
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Where are the W123 experts? I'm 90% certain your car doesn't have an OVP relay.
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Rick Miley 2014 Tesla Model S 2018 Tesla Model 3 2017 Nissan LEAF Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro Chain Elongation References |
#5
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1992 300D is a 124 body...
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Wayne Jockers 1992 300D |
#6
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Oops. I read 82, not 92. Sorry about that. The OVP should be between the two firewalls on the passenger's side, and should have a fuse on the top of it. I've never seen a procedure for testing, most people just replace them.
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Rick Miley 2014 Tesla Model S 2018 Tesla Model 3 2017 Nissan LEAF Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro Chain Elongation References |
#7
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thanks for the reply...the dealer wants 135.00 I ckd fastlane there price was more reasonable
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Wayne Jockers 1992 300D |
#8
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Testing procedure is thump it with the handle of a screwdriver and see if it starts working again! When it fails the ABS light will always come on and the engine may run rough, stall when D is selected or become hard to start when hot.
But seriously, you can open them up and re-solder all the pcb joints - it worked for me and the car ran fine for another 2 years before I sold it.
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Mick J '08 Chrysler 300CRD (MB OM 642 engine) '95 E220 estate '89 230TE (R.I.P.) |
#9
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what is an overload protection relay hmmmmmm
its a belt with a buzzer in the buckle.
If you eat too much it goes off BUZZZZZZZZZZZZZz ![]()
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"Know other lessons I need to learn? TELL me. Tired of learning'em the hard way". Glow Plug Wait: [i} Time of silence in homage Rudolph Diesel. Longer you own a diesel. more honor you give". [/i] Life; SNAFU Situation Normal All Fouled Up, & FUBAR: Fouled Up Beyond All Repair -Now: Snafued Jeep TJ w/OM617 2Be daily driver & building SS M1079 w/Ambo boxed /live in Adv. Truck, Diesel KLR conversion -Sold 62 UNIMOG Camper w/617 Turbo, 85 300SD |
#10
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69.00 from the dealer with my MB club card....yahoo
The fuse is good...and now I broke the plastic shield between the battery and the firewall....
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Wayne Jockers 1992 300D |
#11
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[quote=wayne2970;523006]69.00 from the dealer with my MB club card....yahoo
quote] Forgive my ignorance but what is the MB club card? Do you mean the MB USA membership card?
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Strelnik Invest in America: Buy a Congressman! 1950 170SD 1951 Citroen 11BN 1953 Citroen 11BNF limo 1953 220a project 1959 180D 1960 190D 1960 Borgward Isabella TS 2dr 1983 240D daily driver 1983 380SL 1990 350SDL daily driver alt 3 x Citroen DS21M, down from 5 3 x Citroen 2CV, down from 6 |
#12
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New Overload protection relay from Parkplace Midcities 69.00
self install saved 108.00 a happy wife...PRICELESS power restored, I am assuming the relay does a alot mor than originally suspected. Thanks for everyones input!
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Wayne Jockers 1992 300D |
#13
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Our friend the OVP keeps expensive electronics from turning into toast.
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ASE Master Mechanic https://whunter.carrd.co/ Prototype R&D/testing: Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician. Noise Vibration and Harshness (NVH). Dynamometer. Heat exchanger durability. HV-A/C Climate Control. Vehicle build. Fleet Durability Technical Quality Auditor. Automotive Technical Writer 1985 300SD 1983 300D 2003 Volvo V70 https://www.boldegoist.com/ |
#14
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Ovr
I just replaced mine awhile back...but before replaced my tach would fall down to nothing and it appeared that the turbocharger wasnt working. Darn lights on the cluster acted like a pinball machine. So I took the forums advice and replaced it with an OEM relay and sha...zam it worked...no more odd stuff has happened since... I cracked my plastic shield upon reinstallation also..oh well
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1993 300D 2.5L 240,000+ miles |
#15
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Quote:
Quote:
It is sometimes known as a 'crowbar' circuit, from the idea that you protect the circuit by throwing a crowbar across the incoming line, causing a short circuit that guarantees that the fuse melts and protects the circuit. After all, OFF is safe... ![]() That is a method of preventing electronics developed before electonics coud withstand any voltage that the alternator can reasonably produce. For many cars the OVP is no longer needed. |
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