Okay, here's the basics: I've got an '85 6.9 - the previous owner put a manual glow plug switch in.

The glow plugs have never worked as long as I've had the truck and frankly the fear of snapping them as they came out scared me off swapping them and fixing.

Finally getting around to it. Couple of questions.

1.Is there an easy way to test if this manual controller/switch system still works? What voltage should I be looking for where?
2. Looks like folks prefer the Motorcraft ZD1a - correct?
3. Is there any chance that the controller/switch would require a different glowplug from the ZD1a? If so how can I figure that out?
4. Best practices for removing these glow plugs? I've got a couple of days because I'm waiting on other parts.

Thanks so much for the help!

Anthony

UPDATE:
1. Sorry for double posting!?!
2. Also discovered I asked half of these questions back in 2014!?!? Any input still greatly appreciated.

UPDATE #2:
Okay, looks like I may have been overly spooked by the glow plug research. Just tried taking two out of the truck and they came out without incident (one had a popped tip but that seems to have happened ages ago because there was no tension or trouble sliding them out).
Don't have time to pull the rest now but hopefully that part won't be an issue.

Which knocks out (fingers crossed) question #4.

So what's the best way for me to test the wiring? Since this is a manual push button that the PO put in - is it as simple as testing for 12v at each spade connector with the button pushed? Or is there something more complicated about the wiring?

Assuming the wiring works and it is a manual pushbutton - am I best to replace with the Motorcraft ZD1a's or is there something better for this setup?

THANKS!

 

Frankly, if the push button is working and wired reasonably the dash light will come on. If it isn't check the wiring. Connect the two wires from the push button and see if the light comes on. Perhaps a bad switch.

Beru plugs are internet-preferred and seem proven. There are other plugs that have an internal dohickey that mitigates issues associated with manual-button folks holding the button for too long. YMMV. Internet says Beru (motorcraft) and I have yet to see a complaint.

 

I don`t know how your manual GP set up is wired.
This is the way I wired it on my 86.
Next to the Brake Booster is the factory fuel water separator.
Most had a problem with them eventually sucking in air, and
they were disconnected and the 2 rubber hoses looped together
as mine was.

There is an electric plug for the filter and one is a hot with key on,
think the red one.
I connected a wire to it, ran it through the Firewall to a Toggle Switch,
then from the switch back out and across the Firewall along the big
AC hose to the passenger side to the GP Relay.

The GP Relay is mounted the the flat of the inner fender. The small
purple wire activates the relay. The wire connector just pushes onto a
threaded stud. Pull it off and attach your wire to it.

With the key on, you push the Toggle and it activates the GP Relay for
as long as you hold the Toggle down.
Our days have been getting up to 100 and nights high 50`s low 60`s.
In the morning I hold it and count to 6 and the engine lights right up.
Never need to use it the rest of the day.

I did add a inline fuse at the red wire, don`t remember the amperage.
This wire just activates the Relay, and it carries the big power to the GP`s.

I buy Heat Shrink tubing in 4ft lengths, I slide this over my new wires and
shrink it to cover up the various color wires., and zip tie things down.

I use ZD1 Motorcraft plugs for the past 3 years and all has been good.

One way to test ea plug, use one of those Ice Pick test lights. Remove
the wires from the plugs. Connect the alligator clip to 12V positive, and
the other end to the end of the plug. If they light, it is good.
To test the GP harness, connect the alligator clip to ground, and touch the
connector as some one activates the GP Relay. The light should come on.
If not, maybe a fuse able link blew.

Be sure to slop some Anti Seiz on the threads of the new GP`s.


Charlie

 

Thanks both for the reply and details.

So if I'm understanding this correctly a manual switch/button still typically goes through the GP relay, yes?

I've disconnected all the spade connectors. Should I be able to test them one by one or do the one's I'm not testing need to be connected to glow plugs?

I'll likely test with meter rather than bulb. Assume I'm looking for 12v, yes?

Thanks for the help.

 

Yes, the switch activates the GP relay. As long as switch/button is pushed or held,
the Relay will send power to the Glow Plugs. You release the Switch, and the relay
turns off. The switch is doing the job of the GP Controller.
Having the manual set up has it`s draw backs if other people drive your truck. They
hold the switch on too long, and "can" burn out the plugs. This is where having the
Controller in the system is a good idea.

A new Controller is around $100. On the 6.9 (83 - 86) it screwed into the block at the
back of the engine on the drivers side. It is aluminum and the block steel, they can
become one with corrosion, I pulled 3 at PNP, 2 snapped off and one unscrewed.

I haven`t used a meter so not help there. Just pull the wires to expose the Spades and
and check ea one.
Best way to see how the tips get hot. remove the plug, hold the nut part with a pair of plires
or VG, and put 12v to the electrical end. Then see how red the tips get. With a test light, the
light may come on and look good. But seeing the tip light up tells a different story. I have
seen some that get red, but the tip is cool. it`s working, but on the way out. They are a heating
element like your electric stove.


Some good info here.
https://www.ford-trucks.com/forums/1...tech-info.html

Here is a Google search.
https://www.google.com/search?q=test...w=1138&bih=536


\Charlie