I understand Bob's concern, too. My thoughts are, if you're running a manual switch to control the GP activation time, it is now your responsibility to ensure the GPs are run often enough and long enough to prevent/reduce carbon buildup, instead of the PCM.

If your GPs are functioning properly, it doesn't matter if they're controlled manually or by the PCM, they should be capable of preventing carbon buildup. It's when the GPs fail that carbon buildup becomes problematic. If the GPs are not functioning properly, carbon buildup will occur.

So, IMHO, no matter how you control your GPs, they will need to be properly cycled on a regular basis, especially during the warmer months when we think the GPs are not needed. I like to the idea of being to control the GP function, but also realize I would need to become the "manually operated PCM" to ensure I don't cause additional problems due to the switch installation.

 

You also have to remember to turn them off!!!!!!!!!!!!!!!!!

I had a 81 VW diesel on a manual switch and forgot to turn it off once

 

Exactly! If I were to do this, my preference at this time would be the SPST switch that madpogue suggested. That way, the "GP Off" is controlled when the switch is "Off" and the PCM would control the GPs when the switch is in the "On" position.

The momentary switch controls the "GP On" time. The longer you hold the switch, the longer the GPs are activated.

I would prefer a combination of these two functions. Have one switch position be "Normal" (GPs controlled by PCM), one position turns the GPs "Off" and one position turns the GPs "On" manually.

 

Exactly, this is the way I have mine. If I go to the corner store or just want to move the truck in the driveway, I don't want the GP's running all the time. I defiantly let them run on the first start of the day though.

 

I wonder how you would wire up a switch like that? I would think using a switch to control the power to the GPR would be something like this:

I imagine a switch being "on" would complete a circuit, for regular PCM operation of the GP's, and "off" there would be a break in the circuit, where the manual control and external power would need be used to trigger the GPR. You would never have to worry about turning it on or off since power to the toggle would be supplied by the PCM control wire to the GPR. Which is only active when you key over right?

Both switches are tied together, but the manual activation power wire would come from external 12V power, tied into the trigger wire of the GPR past the break in the switch. Maybe I'm just over thinking it.

 

I'm not sure how to wire this and I'm guessing that either two switches, or possibly a three-position toggle or rotary switch, would be needed.

If a three-position switch is used, it would need to be wired in such a way that one position is "Off" for no GP activation, "On" for continuous GP activation, and the final position would the "Normal" PCM-controlled GP operation.

If two individual switches are used, the same scenario above applies, but instead of the "Normal" PCM-controlled GP operation, that position would energize a momentary switch for manual GP operation.

Now, how does one do that? I have no idea. If I cut a wire, I can reconnect it, add a light to it, (if it's a power wire), or add a simple switch to it. If the above scenarios are not part of a switches designed function, I'd have to ask someone else how to properly connect the switch. They'd have to draw me a diagram of what goes where, provide their email, cell phone, and parent's email and phone, just in case I have a question at 2:00 AM about something I did and now my truck is on fire.

I'm good at coming up with ideas, but when it comes to electricity, I need the help of folks that know what they're doing.

 

You guys are losing me. Cut one of the small wires at the GPR, run two wires into the cab to a toggle switch. Its been a long time ago that I did this but I think the little wire is for ground. With the toggle switch off, no ground, no action. With the toggle switch on, we have ground for action. I really don't understand why you would want 'continuous GP activation'? Isn't 90 to 120 seconds under normal operation long enough?

 

Under "Normal" operation, 120 seconds should be fine. It sounded to me like folks are turning off their GPs and not allowing the PCM to control their operation. I'd want continuous operation to help burn off the carbon buildup from the GPs not being run normally.

A running engine won't burn off the carbon buildup on the GPs, so something needs to be done to prevent the carbon buildup. The continuous operation function would be used for that purpose.

 

Main reason that I hooked up the manual switch is to be able to turn off the glow plugs while the starter is cranking. It just seems to me that the current draw of the GP's is sucking voltage and RPM's away from the starter.

As long as the glow plugs are preheated and hot the engine seems to fire faster than with the original system, even though the glow plugs are off while the starter's cranking. One of these cold mornings I want to use AE to watch the RPM's while the starter is cranking with no glow plugs and see what it does when I switch them on.

If it stays the same then it's back to the drawing board.

I agree that normal engine operation probably does little or nothing to burn off GP carbon deposits and we should be aware of the need for manual "cleaning cycles."

Bob

 

I'm not sure what the deal is with my subscriptions because this is definitely not the first time I have responded in this thread and it didn't come up on my subscriptions that the thread was up and running again.

What you guys are talking about is a HOA (Hand, Off, Auto) switch for the Glow plugs. In the "Hand" position the GP's would stay on as long as you leave the switch on. In the "Off" position, the GPR would be disconnected from the PCM so the glow plugs won't run at all, and in the "Auto" position the PCM will have its way.

That's a pretty simple thing to wire and I'll be more than happy to draw a wiring diagram for anyone who wants to do this. The cat's meow would be if we could find a HOA switch that has a momentary "On" position so the GPs won't be forgotten. Then again, I suppose you'd have to hold the switch the whole time. Honestly I don't see why you'd want to keep them on longer than the 150 seconds or so that the PCM will burn them for when it's cold outside.

 

Basically, what you need is a SPDT switch. Here is a picture to help it make sense.


The wiring is pretty simple. You only have three poles. The center terminal (pole) is where you will connect the wire from the glow plug relay. Connect the wire to the PCM to either of the outside terminals, and a wire to a good ground to the other side terminal.

With the switch in the center the GPs are disabled. Flip it one way and you connect the GPs to the ground and they stay on until you move the switch again. Flip it the other way and you connect the GPR back to the PCM and it runs the show.

Does that make sense?

 

I think it does, Nate. Thank you. I'm going to have to think about connecting the wiring for a bit to make sure I understand.

I tried to rep you, but couldn't.

 

I think I'd put a momentary contact switch in series with the manual glow plug "On" position. That way you wouldn't be able to leave the glow plugs switched on. Sooner or later they'd get left on if it was up to me to remember to switch them off.

You'd put the SPDT switch in the glow plug manual "On" position but nothing would happen until you press the momentary contact switch or button. I'd connect it that way right now if it wasn't such a pain in the rear to run wires and add switches to the dash.

Bob

 

Agreed. You could do that pretty easily. Put it right next to the SPDT switch for that "aircraft look" haha.

 

Here's a link to the most thorough DIY glow plug control system I've run across. Not a simple one hour task like adding a manual switch into the circuit.

He uses a temperature switch so that the glow plugs are automatically disabled when the engine is warm. He also adds a relay to automatically disable the glow plug circuit while the starter is cranking.

www.rosewooddieselshop.com/DZLJIM/Ford/GPR1.htm