Author Topic: replacing low fuel/reserve bulb  (Read 391 times)

Charles 230SL

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replacing low fuel/reserve bulb
« on: June 27, 2025, 00:20:39 »
it's been a few years since I had my dash apart and removed the center cluster.. is it possible to replace the fuel reserve bulb without removing the center cluster? Its been a few years and I can't remember whether its possible. One thing I DO remember is it's no fun taking the tach, cluster and speedometer out. thanks all, Chas 

clunker

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Re: replacing low fuel/reserve bulb
« Reply #1 on: June 27, 2025, 03:56:14 »
I think the cluster does have to be removed to access the bulbs, so the tach has to come out, so radio or steering wheel too, etc. If cluster removed maybe replace all bulbs with LED so it puts off doing it again.

That said, note from tech manual:

“ The low fuel warning lamp fitment appears too small to accommodate (currently available) BA9s base red LED.
Since this is a (presumably) very occasionally lit bulb it can expect to have a long life even as an incandescent and can be replaced by and original style incandescent. “

If you do find an LED that fits, maybe update tech manual. 

Are you sure the low fuel bulb is gone? Have you checked the feed circuit if you think it not lighting? Probably easier to check that before you pull out the cluster.
Charles
1969 US 280SL 4-speed Red/Black
DB9 / 981 S / G300 SWB / CB750 / etc

Paul99

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Re: replacing low fuel/reserve bulb
« Reply #2 on: June 27, 2025, 08:34:53 »
one thing to remember is that if you replace the bulbs with LED bulbs, don't replace the red charging bulb. I am sure that has to stay as a standard bulb otherwise the charging system wont ignite.

yves

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Re: replacing low fuel/reserve bulb
« Reply #3 on: June 27, 2025, 10:16:26 »
+1 as say Paul..... ask me why....!
Happy owner of a 69 blue 280SL ,  63 FHC  osb E-type , 55 FHC XK 140 to be restored...

lpeterssen

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Re: replacing low fuel/reserve bulb
« Reply #4 on: June 27, 2025, 10:29:08 »
it's been a few years since I had my dash apart and removed the center cluster.. is it possible to replace the fuel reserve bulb without removing the center cluster? Its been a few years and I can't remember whether its possible. One thing I DO remember is it's no fun taking the tach, cluster and speedometer out. thanks all, Chas

Dear Charles

In theory it is possible to replace central instrumentation light bulbs without removing the central instrumentation.   That if the printed circuit board that is in place behind it has still the original central hand tighten nut.   You just unscrew that nut from behind with small hands and pull out the circuit board.  Then disconnect that from the 12 pin female connector below steering wheel and work then in the confort of your bench.

Remove the rheostat knob as well.

Look at picture attached

 Best regards
Leonardo Peterssen
Www.wiredoktor.com



clunker

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Re: replacing low fuel/reserve bulb
« Reply #5 on: June 27, 2025, 12:54:56 »
Leonardo, thanks that is a very useful tip. I assumed that the holding nut was unreachable. Definitely worth a try, dexterity permitting (I updated the tech manual with this.)

Paul, Yves - check the tech manual for details on what resistor to install if you use an LED on the charging light. see https://www.sl113.org/wiki/Electrical/InstrumentLights
« Last Edit: June 27, 2025, 13:23:12 by clunker »
Charles
1969 US 280SL 4-speed Red/Black
DB9 / 981 S / G300 SWB / CB750 / etc

BobH

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Re: replacing low fuel/reserve bulb
« Reply #6 on: June 27, 2025, 14:18:32 »
Easy to check the circuit feeding the lamp, just link between the brown and blue/green wires in the plug on top of the fuel sender in the boot/trunk, with the ignition on
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Charles 230SL

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Re: replacing low fuel/reserve bulb
« Reply #7 on: June 27, 2025, 15:30:48 »
In theory it is possible to replace central instrumentation light bulbs without removing the central instrumentation..if the printed circuit board that is in place behind it has still the original central hand tighten nut. You just unscrew that nut from behind with small hands and pull out the circuit board.  Then disconnect that from the 12 pin female connector below steering wheel and work then in the comfort of your bench..
Thanks gentlemen, and thank you Leonardo for that bit of hope.
Easy to check the circuit feeding the lamp, just link between the brown and blue/green wires in the plug on top of the fuel sender in the boot/trunk, with the ignition on
Thanks Bob, before my original posting I had already unplugged the fuel sender and grounded the W & G terminals, and the R lamp didn't illuminate. Palo Alto Speedo restored the gauges about 13 years ago and I'm sure they would've replaced the R lamp. It's worked fine those (very few) times I needed a reminder to stop and get some fuel.
thanks again guys, vr, Charles

 

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