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'86 280GE won't turn off!

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dayj
Posts: 7

'86 280GE won't turn off!

Post#1 » Sun Jan 10, 2021 12:24 pm

Hi! Yesterday, I arrived to a campsite and turned my ignition switch to off but my engine (and everything else) stayed on. I found an article on the web that walked me through: 1) determining it wasn't "dieseling", 2) disconnecting the white plastic connector that's on 2 of many cables that come off the back of the ignition lock (I didn't pull apart the 2 sides of the black ignition housing), 3) disconnected the fuel relay and that turned things off but left the engine oil, brake, and battery lights on.

After more investigations today, pulling apart the 2 sides of the black ignition housing wouldn't turn it off and that the fuel relay in my car is for an SL (#001 545 0705 aka not a G part). After more staring, I realized I had the rear defroster on for the first time and left it on. With the rear defroster off, everything went back to operating as normal.

A few questions:

a) If the rear defroster is on when you try to turn off the car, is it expected behavior to not allow turn off? Seems unlikely to me, what might be causing this? And do you recommend I fix?

b) Should I replace the SL fuel relay with the OEM G wagon fuel relay—I know some Mercedes parts can do as temporary replacements, but feels like yes to me.

PS: My first post here, didn't realize I had been accepted and could start posting! Thanks to everyone who contributes and has made this an invaluable resource for someone new to G Wagons!

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AlanMcR
Posts: 7729

Re: '86 280GE won't turn off!

Post#2 » Sun Jan 10, 2021 3:20 pm

(Caveat - I know nothing of the 280GE)
In the W463 case, the rear defroster is switched by a relay and the power for the relay coil comes from the D+ line instead of B+ (the battery +12). All of the other accessories get their power from the ignition line. All I can figure is that this is designed that way to prevent drawing lots of power when the engine isn't running.

If someone miss-wired that so that the D+ backfed into the ignition line then it would keep the ignition on.
...Alan

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EHKO
Posts: 1595

Re: '86 280GE won't turn off!

Post#3 » Sun Jan 10, 2021 3:55 pm

Alan, this was similar to my issue with my transplant. Apparently the older starter wouldn't backfeed but the newer one on my M119 does. I originally had it wired as shown in the 230g wiring diagram this caused a similar issue as above. Seems that the defrost switch when on is backfeeding the ignition.

User avatar
dayj
Posts: 7

Re: '86 280GE won't turn off!

Post#4 » Mon Jan 11, 2021 4:12 pm

Interestesting, I'll have to investigate this some further next time I'm working through all the electricals. Thanks!

TorontoPuch
Posts: 207

Re: '86 280GE won't turn off!

Post#5 » Sat Jan 16, 2021 8:43 pm

I have a similar issue with my 1992 Swiss Army 230GE. The engine will not shut off when the ignition is shut off if I have the headlights on. Turning the headlights off then shuts the engine off.
3 x Swiss Army Puch 230GEs, Agate Grey, Tangerine Orange, and China Blue
+ 2 Swiss Army Puch 230GE sold.

User avatar
EHKO
Posts: 1595

Re: '86 280GE won't turn off!

Post#6 » Sun Jan 17, 2021 7:01 am

I guess that's one way to prevent you from leaving lights on.

dcurbet
Posts: 6454

Re: '86 280GE won't turn off!

Post#7 » Sun Jan 17, 2021 7:41 am

:lol:

User avatar
dayj
Posts: 7

Re: '86 280GE won't turn off!

Post#8 » Tue Jan 26, 2021 10:08 pm

That’s a great way to never leave them on! Ha! I read in the manual there should be a buzzer for that—hooked up to ignition switch and when in a specific position. My buzzer doesn’t buzz though—not sure if it’s dead or disconnected somehow. Pretty low on my to do list for now!

goat
Posts: 1794

Re: '86 280GE won't turn off!

Post#9 » Wed Jan 27, 2021 10:42 am

TorontoPuch wrote:I have a similar issue with my 1992 Swiss Army 230GE. The engine will not shut off when the ignition is shut off if I have the headlights on. Turning the headlights off then shuts the engine off.

Same with my W460 280GE but I realized that it was a good reminder to never leave the lights on and drain the battery so I left it the way it was.
G less
2008 Lexus GX470
2015 BMW X-5 35D

G Nome
Posts: 7766

Re: '86 280GE won't turn off!

Post#10 » Thu Jan 28, 2021 7:23 am

Gives new meaning to an "Idiot Light"!

Love it.

Kent
Kent
If you need help...I usually have extra zip ties and duct tape.

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