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#1
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All power does not disconnect when key is turned off
Anyone have a suggestion as to why some of the curcuits would still be hot even with the key off? I've changed the electrical portion of the ignition switch, but that was not the problem. I'm changing and checking fuses, etc trying to find out what the cause is.
Battery, brake, and brake pad wear indicator lights stay on when the key is turned off. Thanks. KRW ps. The car is an 83 300D Turbo Diesel Sedan
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1991 350SDL 350k+ miles |
#2
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Alternator Light On Key Off
1984 300d Turbo 147k
Pull The Plug On The Alternator, Check If The Warning Light Is Off Its The Diode In The Alternator, Replace Alternator |
#3
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Quote:
Or, just replace the regulator. Only one plug and two screws. $30-40 bucks. Jim
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14 E250 BlueTEC black. 45k miles 95 E320 Cabriolet Emerald green 66k miles 94 E320 Cabriolet Emerald green 152k miles 85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles |
#4
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The alternator is a Bosch 115 amp unit off of a late 80's model SAAB. It bolted right up. However, it is not just the battery light that is staying on. There is also the brake light and a few of the accessories, but not all.
Also, when the car starts, everything is working normally. But when I turn off the engine and remove the key, the indicator lights come on and the aux fan will keep running as well (if the engine is warm enough). Thanks for your help. I will check the alternator and make sure the voltage is correct. KRW
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1991 350SDL 350k+ miles |
#5
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Check the fuses?
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91 350SD 14 F150 Eco 19 Fusion Hybrid 11 GT500 |
#6
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A number of circuits are "Hot at all times" by design. Turning the key off will have no affect on those circuits.
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#7
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All current is not shunted through the key switch electrical contacts on a lot of cars. . There might be a load relay that has stuck or welded contacts. Does anyone remember if these cars have one? The key switch normally turns a cars load relay on and off again if it has one. At this point if there is one in your model it is the best suspect. Does this jog anyones memory?
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#8
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Not on an 83 not part of the brush pack
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BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif 15 VW Passat TDI 00 E420 98 E300 DT 97 E420 Donor Car - NEED PARTS? PM ME! 97 S500 97 E300D 86 Holden Jackaroo Turbo D 86 300SDL (o\|/o) |
#9
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Quote:
How many screws and plugs on an external regulator? |
#10
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Pic of external regulator
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BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif 15 VW Passat TDI 00 E420 98 E300 DT 97 E420 Donor Car - NEED PARTS? PM ME! 97 S500 97 E300D 86 Holden Jackaroo Turbo D 86 300SDL (o\|/o) |
#11
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Current events
Quote:
Aha! Page 108 of the circuit diagrams in the FSM [attached] shows that the charging light and the brake warning lights are interconnected through the "warning system," a complicated electronic relay that involves the door-open, key-in-ignition, and seat-belt buzzer. The warning system is a little metal box located under the dash and just to the right of the parking brake pedal. I can't find its schematic in the FSM; the index says "next index" and then the next index says "previous index." If I had to take a guess, I'd replace that warning system thing. I had a problem with the analogous module in my '87 300D-T (W124, OM603) in which all kinds of screwy things were wrong in the dash. Replacing the warning module fixed the problems. 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 |
#12
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It's the backout diode inside the alternator on the inner diode plate. When it fails it allows power to flow back through the system that's why you are getting some idiot lites illuminated with key off.
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BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif 15 VW Passat TDI 00 E420 98 E300 DT 97 E420 Donor Car - NEED PARTS? PM ME! 97 S500 97 E300D 86 Holden Jackaroo Turbo D 86 300SDL (o\|/o) |
#13
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On my american car, when the regulator failed like this, the alt. would get warm, and pull a wrench to it with a magnetic field in the alt.
Was a quick easy check. Whould be the same here right?
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83 300SD Dark Silver Dark brown inside |
#14
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Thanks so much for the info. I will check these things tonight and post what I find. KRW
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1991 350SDL 350k+ miles |
#15
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More Clues!!
When I turn the key on, then off again, the following 6 circuits stay hot when they are not supposed to.
10 - heated rear window 12 - stop lamp, turn signal lamp, inst cluster, cruise control, (relay window lift term. 86, tachometer) 14 - back up lamp, warning monitor term 8, emission control, horn, overload protection (autom transmission, relay auxillary fan term 86, control unit/water pump/heating water valve for climate control system) a - (window lift front right, rear left) b - (window lift front left, rear right) d - (sliding roof) I also find that if I disconnect the battery, then connect again, these circuits stay off (as they should) until I turn the key on. Then when I turn the key off, they all stay on. I also disconnected the wires leading to the warning contol box under the dash and nothing changed. Same problem either connected, or disconnected from the warning box. I can't figure out what is causing it but it acts like a relay of some kind. I think this because when the battery is disconnected, the circuit breaks until the key is turned on again. (I have already changed the electrical portion of the key switch, but I'm wondering if the new one is bad too). KRW
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1991 350SDL 350k+ miles |
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