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Hello-

Had a close call the other morning and its time to straighten things out. My GP relay light only stays on for a split second when its less than 0 out. Other wise the whole system works fine. I would like to wire up a manual switch. Can anyone tell me what I need to do? My truck is a simple push button normally closed switch that runs to ground. That set up would be nice,

Thanks,

Bill
 

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I installed a push button which is located above my left knee. Its wired through the amber indicator light. I used a Ford truck solenoid as I didn't want to run that many amps to the switch which is 15 amps from Napa. It works fine, eliminating the relay and one less thing to go wrong. Oh, this is on my 79 240D, which has the later style GPs using an 80 amp fuse.
 

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If you want to keep the stock Relay the below is from another forum:
Glow Plug Relay Voltage at connector pins
The glow plug system from that era is an electronic timer on the left front fender ahead of the wheel well. Under the cover are 2 connectors. The forward connector goes to the glow plugs, either 4 or 5 wires depending on whether you have a 240 or a 300. The rear connector has 4 wires, it is tagged C130 in the diagrams.

I assume this is the wires that go to the connector
Pin 1 hot with key in pos 2 or 3
Pin 2 hot with key in pos 3
Pin 3 +12 V supply to bulb in cluster
Pin 4 ground

On my Volvo I just used what people call a Ford type Solenoid that I got at the Junk Yard and a push button switch.
The Solenoid handles all the high ampeage so that you do not pull that ampeerage through the switch.
The heavy red wires to the left bottom of the picture go to the + Battery Terminal.
 

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This sounds like an awesome setup. I've always thought it'd be nice to be able to leave the glow plugs on for a bit longer first thing in the morning to help the engine warm up and even out faster.
 

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This sounds like an awesome setup. I've always thought it'd be nice to be able to leave the glow plugs on for a bit longer first thing in the morning to help the engine warm up and even out faster.
I would like that also but if I installed a toggle switch I would surely forget and leave it on.
Also it is claimed that the Stock Alternator is not up to that; especially if other things like the Blower and the Head Lights are on.

The system would need to have a timer on it to avoid trouble.

Some of the later models have something called Afterglow that keeps the Glow Plugs going for about 2 minutes more. Again you need an Alernator that can handle it.
I do not know if the Glow Plugs for afterglow use fit a 617.952 Engine.

I forgot to mention that the pic in my last post is from my Volvo Diesel that has a 6 Glow Plug System.

I am going to mention the for those new to Mercedes Diesels.
In cold weather:
If you keep the Key in the Preglow Position and ignore the Glow Plug Light the relay will stay on for another 20 seconds. Wait until you hear the Relay click off before you start.
If your Battery is up to it you can also cycle the Key again and start another Preglow cycle.
The Glow Plug Relay will stay on about 30 seconds before timer shutdown.
 

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My push button system came with an after glow AP, I just hole the button in a little longer:D

I have heard it said that a solenoid that was designed for more extended use (as in needing it longer than for starting a car) would be a better choice than the Ford truck one. Could be but mines been in use for about 8 years and I have another as a spare, also they are cheap and readily available.
 

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Pardon my ignorance here, but why couldnt the existing switched lead to the relay be diode-protected, and then an alternate 12V source just be wired to the existing relay via a switch? Essentially just a fused, switched hot lead?

Of course this relies upon the existing MB relay to be working, but if it is the case, wouldnt it be a viable afterglow solution?

And maybe use a switch that is somehow timed itself (mechanically would be preferable).
 

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Theres probably lots of ways to do it. My goal was to make it simple, I can operate the button with my left hand and turn the key with my right. why use a timer switch, just hold the button longer.
 
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