Glow Plug off switch

[dieselman29200]

I am wondering if anyone has put an on/off switch on their glow plug controller? Im not talkin about a manually controlled GP's, I just want to be able to turn on and off my glow plug controller. Any thoughts on this?

 

[91f2504x4]

First of all, Nice Avatar.

Secondly, yes some people have even used a 3 position switch, one position off, another On Automatic using the controller and the third position (momentary) is manual glow plugs. Some people have also made setups so that their glow plugs are only used on cold starts and not every warm start of the day, but you could use a manual off switch for this to preserve glow plug life.

 

[LCAM-01XA]

Sure thing man:

1. install an SPDT (Single Pole Double Throw, aka your regular on-off-on) switch at a convenient location on the dash.

2. disconnect the thin white wire from the GP relay, cut the ring terminal off, extend the wire to inside the cab, and connect it to one of the end terminals of the SPDT switch.

3. that stud on the GP relay that you just removed the white wire from, run another wire from that stud to inside the cab and to the middle terminal of the same SPDT switch.

4. finally run a wire from the other end terminal of the SPDT switch to a good ground.

How all this works is that in the middle ("off") position the stud that's used for grounding the relay (and triggering it to power the GPs) ain't connected to nothing so the GP won't come on.

Then in one of the "on" positions the GP relay gets connected to the controller, to resume its automatic operation.

Then in the other "on" position of the switch the relay gets grounded and triggered without the controller, this is your manual override mode and you should never leave it on for more than 10-15 seconds.

All this is assuming you have the '87-up solid-state glow plugs system...

 

[dieselman29200]

Thanks M.L.S.C.,

I only want to use a single on type switch as I dont want to manually turn on the plugs. I would rather the GP controller handle the job. I just want to be able to turn on and off the controller.

 

[EMD_DRIVER]

I wonder if anyone else has thought of this.... Run a relay (Powered by the high idle solenoid wire) and have the GP controller ground go through the relay. When the engine coolant temp is above 112, the controller would have no path to ground and would be effectively disabled. Whenever the engine was cold, the GP controller would function normally!

 

[LCAM-01XA]

I only want to use a single on type switch as I dont want to manually turn on the plugs. I would rather the GP controller handle the job. I just want to be able to turn on and off the controller.

The manual controller override is handy for those few occasions when in the dead of winter you're out at your buddy's place in the middle of nowhere and when you go out to leave you realize that 3 of your plugs just died - the controller can somewhat tolerate 2 dead plugs, but any more and you will have fun starting that engine - with the manual override you can manually glow the remaining good plugs for 10-15 seconds, and the engine will start much much easier. If you don't want that feature tho, just install a simple on/off switch instead of the SPDT one, and skip step 4 of my previous post.

I wonder if anyone else has thought of this.... Run a relay (Powered by the high idle solenoid wire) and have the GP controller ground go through the relay. When the engine coolant temp is above 112, the controller would have no path to ground and would be effectively disabled. Whenever the engine was cold, the GP controller would function normally!

Now that's a great idea, I think I'll go work on this tomorrow

 

[dieselman29200]

I worked on hooking up the switch today, and I found that the black wire is the ground, not the white one, not too sure what the white one is for but it didnt kill the plugs. So I ran a wire from the black ground wire into the cab and found a ground under the dash to connect to the switch. It works good just controlling the ground, Thanks for all the input!

 

[LCAM-01XA]

Well, that black wire is the ground for the controller, the white wire is a switched ground for the relay - the way I was telling you to wire it the controller will try to do its thing, but with the switch off the white wire is effectively disconnected from the relay so the control circuit will not close and the relay will not power up the plugs. What concerns me in your setup is that the controller is known to glow the heck out of the plugs if the ground quality ain't to its liking, so I have no idea how it will react to having no ground whatsoever - are you sure the plugs really shut off that way?

 

[dieselman29200]

As a test I disconnected the white wire, and I could still hear the gp"s cycling on and off, so I decided to disconnect the controllers ground and the plugs did not work as I had to crank the engine quite a bit to get er started. With the swich controlling the ground, in the off position, there is no drain on the batteries from the gp's, When I turn the switch on, there is a noticable drain on the batteries according to the volt gage. I am assuming that if the gp controller has no ground then it cannot work, am I wrong?

 

[LCAM-01XA]

Well, guess disconnecting the main ground does shut it off - whatever works man, but that white wire disconnect not shutting the GPR off still bugs me...

 

[LCAM-01XA]

I wonder if anyone else has thought of this.... Run a relay (Powered by the high idle solenoid wire) and have the GP controller ground go through the relay. When the engine coolant temp is above 112, the controller would have no path to ground and would be effectively disabled. Whenever the engine was cold, the GP controller would function normally!

Well, I did it, however I made some changes in the circuitry:

1) I'm taking power off the cold advance solenoid, as I have a manual switch for the high idle, and I don't want the glowplugs controller powering up when I'm running the high idle for lighting or whatever else purposes.

2) I wired in the new relay inline with the white wire between the controller and the main glowplugs relay, and retain factory power and ground to the controller itself, this way the controller can only trigger the main relay when the engine temp is under 112F. I didn't wanna mess with the factory ground for the controller because the controller is actually pretty sensitive about that one too - the more resistance it feels there the longer it keeps the plugs engaged, and the extra wiring associated with the new relay would adds 0.4 ohms to that circuit's resistance (yes, I measured it, lol).

Overall I'm pretty happy about it, it works flawlessly - regular 15-second glow cycle with the engine cold, then once she drops off the high idle and the cold advance if I shut her off upon restart the glowplugs stay off and she lights off almost instantly

 

[Andylad13]

I like the relay concept because i dont have to put another stupid switch in the dash somewhere. I will probably be doing this exact thing in my rig. Sometimes I have to start the truck to move it 10 feet, and it would be nice to not cycle the plugs and not load the batteries if the truck cant run long enough to get the charge back up.

MLSC, what is the wire color off the cold advance that you tapped into, and how big was the relay you ran?

 

[LCAM-01XA]

Andy, the wire was a red one with a light green stripe IIRC, but because it's almost entirely covered with that black plastic mesh insulation the factory put on it, about the only place you can splice in it would be right next to the plug that slips onto the tab for the advance solenoid - actually I just cu that plug off and replaced it with a new one, thus splicing the two wires together in the plug's end.

 

[Andylad13]

Nice, and how about the relay? Would a 10 amp be okay?

 

[EMD_DRIVER]

Well, I did it, however I made some changes in the circuitry:

1) I'm taking power off the cold advance solenoid, as I have a manual switch for the high idle, and I don't want the glowplugs controller powering up when I'm running the high idle for lighting or whatever else purposes.

2) I wired in the new relay inline with the white wire between the controller and the main glowplugs relay, and retain factory power and ground to the controller itself, this way the controller can only trigger the main relay when the engine temp is under 112F. I didn't wanna mess with the factory ground for the controller because the controller is actually pretty sensitive about that one too - the more resistance it feels there the longer it keeps the plugs engaged, and the extra wiring associated with the new relay would adds 0.4 ohms to that circuit's resistance (yes, I measured it, lol).

Overall I'm pretty happy about it, it works flawlessly - regular 15-second glow cycle with the engine cold, then once she drops off the high idle and the cold advance if I shut her off upon restart the glowplugs stay off and she lights off almost instantly

That's exactly what I had in mind, but may not have expressed it properly. In my head (Lots of room in there!) I figured I would put the relay between the GP relay's white wire terminal and the white wire itself (Same thing you did)

I am also going to wire myself a high idle switch in the cab. Doing my mod this way, will not interfere with the operation of anything, except the GP relay operation. Did you happen to take any pictures of your mod?

Nice, and how about the relay? Would a 10 amp be okay?

10AMP would be perfect for this application. It doesn't take much power to actuate a relay.