Power glow plugs thru a switch straight from the battery?

[jonleroy2506]

Hey all,

I just bought a 1990 7.3 with an ATS turbo. Haven't had one of these trucks in years because, unfortunately, I bought my first one as a stupid 18 year old and ruined it. So I sold it to a guy who wanted the zf-5 out of it. And I've kicked myself over that ever since. But now I have this one, and I intend to take MUCH better care of it. Plus I can't afford to not take care of it. Anyways, I may have a really stupid idea of how to wire up a manual glow plug switch on it.

The problem is that the turbo sits right on top of the glow plug controller/relay. I would like to wire up a manual glow plug switch in the dash, but I can't even see the relay, much less get my hands back there to wire it. I would really hate to have to pull the turbo off to wire up a pushbutton, but it looks like I may have to.

Unless I can skip the controller and relay all-together. I was looking at the wiring diagram in a shop manual (I'll try to add a picture of it to this post to help me explain myself here).

Would it be stupid to run power straight from the battery to one side of a dash mounted button (With an inline fuse of some sort) and run the 2 10ga brown wires shown in the wiring diagram to the other side of the switch? Or maybe even pull power from somewhere in the cab to the positive side of the switch?

I'm really not a wiring guy, so forgive me if that's basically the stupidest idea you've ever heard. It does sound quite simple though, if its even realistic. The way I figure it, I should be able to find those two 10ga brown wires without having to take the turbo off.

Side note, I realize I went back and forth between saying 'switch' and 'pushbutton' several times in this thread. I'll likely use a momentary toggle switch so I don't destroy the plugs.

Any thoughts or criticisms would be greatly appreciated. If this is a stupid idea, has anyone else tried to do this with a turbo right on top of the relay and found success without having to pull the turbo off? Or will I just have to suck it up and pull the turbo off?

Thanks folks.

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[IDIBRONCO]

First off, that's a bad idea. The glow plugs pull A LOT of power through the wires. That's why people activate the relay which, in turn, activates the glow plugs. Second, you activate the ground off of the controller to manually control your glow plugs. I believe that it's the white wire on the controller. Easily done plus no need for a fuse. Third, you don't have to remove the turbo to access the glow plug controller. You do have to remove the air box though. You should familiarize yourself with doing that because you'll have to remove it in order to work on things like injector removal, pump removal, return line work and, possibly glow plug replacement. It seems intimidating, but it's not all that bad once you do the job once. Fourth, welcome back to the IDI world!

 

[Old Goat]

Usually with a Turbo, the GP Relay/Controller is move over onto the Pass side V/C as I remember.
The GP`s pull something like 200amps, so running that through a toggle, wouldn`t be a happy time for you as it starts smoking, and other exciting things.

Yeah welcome back to the IDI world.

Goat

 

[IDIBRONCO]

Usually with a Turbo, the GP Relay/Controller is move over onto the Pass side V/C as I remember.

All of the early kits didn't do that. I've seen a lot of glow plug controllers underneath the turbo.

 

[jonleroy2506]

Thanks for the info. I guess I was right, stupid idea. Figured it was worth asking though.

So if I understand you correctly all I have to do is run the white wire off the relay to one side of the switch, and ground the other side of the switch somewhere under the dash?

Also, I assume I want to cut the white wire and extend it to the switch, not just add a second wire to that terminal on the relay?

I'll have to post a picture of the engine when I get the chance. I had the airbox off yesterday to check the glow plugs, I'm fairly certain I can't gain access to the relay without moving the turbo. It's dead center on the motor left-to-right and all the way up against the firewall. My 91 had the turbo offset a bit to the drivers side, so this setup is new to me

 

[IDIBRONCO]

So if I understand you correctly all I have to do is run the white wire off the relay to one side of the switch, and ground the other side of the switch somewhere under the dash?

Yes. That's it.

Also, I assume I want to cut the white wire and extend it to the switch, not just add a second wire to that terminal on the relay?

Yes. That way, if your controller is working, it will only power the glow plugs when you want it to. If you don't want to cut that wire, at least unhook it from the place where it's grounded and wrap the eyelet end of the wire with electrical tape to make sure that it doesn't ground accidentally.

I'm fairly certain I can't gain access to the relay without moving the turbo.

Since I can't see your turbo, I have to go by your descriptions. A centered ATS turbo should be either a 085 or a 088. The ATS 093 does sit off to the passenger's side.
You may have to get creative with this one. When the air box is removed, if you can see the bolts for the relay, you should be able to get them loose. You may have to use a 1/4" drive socket, swivel, and a long extension to reach them. You also may have to reach one bolt from the driver's side and the other from over the top of the intake where the turbo hat bolts on. If you can remove the mounting bolts, you should be able to move the controller over toward the driver's side and be able to reach the wires easier.

 

[jonleroy2506]

IDIBRONCO, thanks for all the help. I'll have to mess with that when i get the chance. For now the controller and relay are doing their jobs, so I'm in no hurry

First I have to get the gas out of the rear tank that my wife accidentally put in there... but that's a whole other thread lol

 

[nelstomlinson]

Another option would be to abandon the existing relay in place, and install a heavy duty relay where you can reach it, light gauge control wiring runs to the dash, heavy gauge power from the battery through the relay then to the glowplugs.

I would put it on the driver side, and pull power from the driver side battery, since it'll supply less than half the amperage for the starter.

 

[BeastMaster]

If you go Nel's route ( which I have already done the same ), I would upgrade to the White Rodgers #586-902 ( Emerson ) industrial contactor.

Several of us here ( me included ) have been having issues with the later relays malfunctioning. I had two incidents of contacts welding shut.

The White Rodgers is a lot beefier construction. Wes of Classic Diesel Design uses these for his kits.

Keep the existing ballast resistor in the circuit. That's that big piece of twisted ziz-zag metal strap connecting the existing relay and the output terminal on the existing Glow Plug Controller module. If you wire direct, you will over voltage your glow plugs and take out your alternator should you rev the engine before cutting GP power ( ask me how I discovered that! ).

Even after rewiring your GP to manual, nothing says you can't use your old GPC module as a mounting block for that resistor.

You can even use that one big stud on the existing relay as a tie point. Just disconnect the other wiring to avoid sneak discharge paths. I used #6AWG wire for wiring the power circuit.

For good measure, I installed a six inch length of four #16AWG fusible link wires, twisted together, wired in parallel, sleeved, and soldered into the battery connector ring and butt connector to the #6AWG feed to my White-Rodgers contactor, just for good measure, to make sure that the fuse wire, in an easy to get to, easy to replace, easy to measure, ( and easy to cut! ) in case my glow plugs fix failed.

So far, 2 years post fix, I have had no further issues.

Wire Combination Calculator

Fusible link wire is typically chosen 4 gauges lighter than the wire it is to protect. I am protecting #6AWG. That means #10AWG fuse wire. I don't have any. But I do have a 100 foot spool of #16AWG fuse wire.

So I used it. Right at the battery lug. Hanging right up in the air. Where I can get to it fast should I note my ammeter ******* again.

It will be a lot easier to fix my fusible link than it will be to replace my glow plugs again!

Or having to deal with melted #6AWG wire in my wiring harness after I got it all prettied up.

Should I ever re-do it, due to thermal cycling of the fusible link, it's probably going to go to #4AWG feed wire and 6 #16AWG fusible link in parallel.

Solder recommended because of the importance of keeping all currents in the parallel links equal. ANY resistance in the connection will only shift the current flow to the remaining wires and cause a cascade failure. The solder acts as an electrically conductive water and corrosion displacer.

 

[chillman88]

Even after rewiring your GP to manual, nothing says you can't use your old GPC module as a mounting block for that resistor.

For what it's worth, this is exactly what I did, although still in the stock location as of now. It's tight, but the White Rodgers solenoid can be fitted to the factory controller in place of the original. Keeps everything nice and tidy.

I THINK the wire for the wait to start light needs to be grounded to illuminate but that's from memory so I could be mistaken.

 

[BeastMaster]

I think you are right about the WTS light.

Mine now lights when I ground the coil lead to my White-Rodgers contactor ( The small white wire ), which is now also connected to the blue? wire that illuminates the WTS indicator. The small red wire, fed from key-on power, sources 12V switched power to the hot side of the contactor coil.

So grounding the cold side of the contactor coil both energizes the coil and illuminates my WTS indicator lamp.

Since I finally bit the bullet and ditched the existing part, after making two expensive replacement attempts, I have had no further incidents.

I remain convinced that someone at the factory monkeyed with the relay design and designed in a lot of problems for the rest of us.

 

[jonleroy2506]

Thanks for all the advice. Sounds like I have quite a few options here that I'll have to look into. I'm in no rush to get this project done at the moment, considering the current automatic system is still functioning, and I have a few more pressing projects to take care of on the truck before I start on the modifications.

 

[IDIBRONCO]

That's the best way. Take your time, decided how you want to go, and then have the parts on hand for when something does happen.