adding ON/OFF switch to control glowplug relay
 

To avoid having to buy a new relay right now, i'd like to hook a switch up in the car that turns the power going to the relay on and off. Does anyone know where I can interrupt power that controls the relay, or preferably where the ground is that I can splice into? If I take off the smaller plug on the relay (I believe it has 4 pins) then the light goes off and i'm guessing theres no power going to the relay then. So insted of having to go under the hood to unplug the relay after I get the car started, id rather just flip a switch and shut it off. Plus its kinda a theft deterrant because if its cold and u have the switch off u can crank the car all u want but the battery will just die and badguy wont get ur car!

Is there a certain size amperage switch I will have to use?


In a previous post I had stated that my glow plug light comes on while i'm driving sometimes (more often now) and according to my volt gauge I installed the relay is for sure warming up the plugs. The relay still lights up the plugs just fine, and the car starts up just fine when cold. Its just after the car is running or driving the relay kicks on and warms up the plugs up which is no good.

to avoid having to buy a new relay right now id like to hook a switch up in the car because the relay still does its job but it doesnt know when to quit! :)

All you need is a switch to control the relay. The switch, and its wiring will carry verry little current, because the relay switches the heavy load ( that is what they are for).
Lots of Ford IDO owners have done this as they have 6 volt GP in a 12 Volt vehicle. I its how they get the fast start). The Ford controller is designed to cycle them, because after about 12 to 15 seconds of 12 volts, all the GP are toast.

I do not see that having them come on in the MB will harm anything.

Because your glow plug relay is sticking on, I don't think you can use the 'on' switch on the existing relay. You'll need to introduce a different relay controlled with a switch to the cabin. forcedinduction has a picture on here of such a system that he installed in his car activated by a push button (I think). Any adequate amperage relay should work. You will have to tie in the new relay to the existing wiring harness.
My view is that a manually controlled relay is superior to the OE automatic one. Afterglow can be achieved by continuing to hold the button.

I have had a push button switch for a few years and love it. I used Ford truck solenoid wired through the GP indicator light and a 15 amp push button switch from Napa. Its mounted above my left knee so I can glow and crank the engine conveniently. Solenoid is mounted on the passenger side fender, forward of the battery. A "continues service" type solenoid might be a better choice but a spare one from my old F250 works fine for me.

How did you connect the power from the new solenoid into the existing wire harness to the plugs?

I just wired in at the strip fuse on the fire wall if I remember right. I can go out and have a look if need be.

Ok, that makes sense on the older systems. The newer systems would require getting power to the 5 (or 4) pins that plug into the OE relay on the left fender liner.

Yes, I guess I'll figure that out when my 85 needs a relay, in a way I hate to depart from "stock" with a nice Euro but.. ....the push button is "one less thing to go wrong", which is one of the reasons we drive em:P

simpsons did it! put a switch to power on the violet wire. don't forget a diode if you leave the wire connected to the starter!

http://www.superturbodiesel.com/std/w123-w116-w126-om617-afterglow-mod-t-335.html#pid6058

If he does that, won't he still have the problem of the relay sticking on that he already has since all he's doing is replacing the keyed switch with another switch?
If he wants to use the existing relay and wiring harness without modification, wouldn't he have to interrupt the heavy power supply wire to the OE relay with another relay so that all current to the OE relay is cut off with the new switch/relay combination?

simpsons did that too.

http://www.peachparts.com//shopforum/showthread.php?p=1463485&highlight=napa+relay#post1463485

well my relay works fine when i first turn the key and start the car, the plugs glow and light up just fine its just that when running the relay keeps kicking the plugs on so i want to put a switch in to turn off the relay after the car is started then when i turn the car off i can leave it off for a security device and turn it back on when i go to start my car again... theres got to be a wire i can just tap into for a switch, i dont need anything fancy i just want to add a switch to the relay i already have

If your GP relay is sticking on then interupt pin #31 in the small connector at the relay with a switch to grnd. Close (pin31 to grnd) the switch to glow.

You can open the connector and get to the wire. Run one small 14-16 gauge wire to the cabin switch. This way the system can be put back to original when you or new owner obtains a replacement relay.

does it say the pin numbers on there? and is pin 31 a ground?

First of all is a used glow plug relay from a salvage or pick and pull yard cheaper and easier? Few cars land up there because they have a bad relay.