[DFrank]

So I had a friend install new GPs and I had him use the snow plow relay that I had read about here.

Everything worked great at first, but then the truck stopped starting again.

I can now start it only with ether or when plugged in.

I tested the posts on the relay, and learned the following:

one side is hot always.

Turn the key for WTS, and the other side becomes hot.

It stays hot after the WTS light goes off, and stays hot even while the truck is running.

I assume either the relay was bad, or more likely the computer is telling the relay to stay engaged.

I further assume that my brand new glow plugs are now toast.

My buddy who did the work for me says that even if the relay were installed backwards, it should have no effect.

How can I further trouble shoot / diagnose the root of this problem?

This guy is a 20+ year diesel tech, though mostly with the Dodge. He thinks this may need dealer type computer diagnostics, but I figured that I would start here.

Thanks,

 

[bugman]

The relay will stay on for up to 2 minutes after you turn the key on to run before it will shut off. So if it is staying on past this time frame then there is a problem with the wiring or the PCM. The PCM provides the ground signal to the relay.

What brand of glow plugs did you install. Most have found that the only ones to use are the Motorcraft ZD-11's.

 

[Patrick Feeley]

Also, what brand of Glowplug relay was installed? If the relay is not a case-isolated type (meaning none of the posts, large or small, should have any continuity with the base), the plugs will also not turn off. Cheers!

 

[DFrank]

Thanks guys. The relay did shut off after a couple minutes. I did not check to see if it had any continuity with the base.

What else can I self diagnose with just a multi meter?

It wouldn't even think about starting at 40 degrees without being plugged in. Plugged in it starts immediately, but that heater must pull a lot of amps. If I have much else going, it blows the 20 amp fuse.

 

[bugman]

What brand of glow plugs did you or your mechanic install?

Have you tested them through the valve cover gaskets to see if they are bad or not?

How is the under valve cover wiring?

I would also do a voltage test on the relay to make sure that it isn't burnt or bad.

The heater is 1000 watts and the formula for converting watts to amps escapes my mind right now but it will be around 10 amps.

 

[ArcticDriver]

Thanks guys. Plugged in it starts immediately, but that heater must pull a lot of amps. If I have much else going, it blows the 20 amp fuse.

How long is your extension cord and what gauge is it?

Amps = Watts / Volts

 

[DFrank]

I don't know what brand he used, aside from that they came form NAPA.


He did replace the wiring.

I do not know how to test the plugs themselves.

I should probably run a shorter cord, but it is a 12 gauge 100 foot cord. . I wouldn't think that would add much resistance to the load. 30 ' would do the trick.

The pig tail coming out of the hood looks like a 14 if not 16 gauge cord, and it is green, which I assume is not OEM.

I can't really see where it might be spliced in, but it doesn't look to be adding any length.

People act like 1000 watts isn't that much power. Most of my light bulbs in my house are 40-60 watts, if they are not CFLs, which probably only draw 15 watts.

1000 watt load is the equivalent of leaving 20, 40-60 watt bulbs running, which I try pretty hard not to do.

This is a second or third vehicle for us, with a big camper on it. Leaving it plugged does not need to happen very often, but I sure as heck can't drive it up skiing right now and expect to drive home.

 

[ArcticDriver]

I should probably run a shorter cord, but it is a 12 gauge 100 foot cord. . I wouldn't think that would add much resistance to the load. 30 ' would do the trick.

People act like 1000 watts isn't that much power.

A 100' 12-gauge cord is rated to a max of 14-15 Amps. My OEM Block Heater pulls 15-16 Amps continuous use. I would agree with you that a shorter cord would do the trick.

Many forum members keep their block heater on a timer set to turn on 3-hours before they need the truck.
But that won't help at the ski area.

 

[bugman]

While NAPA stocks glow plugs that will work in our trucks they don't stock the factory ones and there has been problems with just about any glow plug other than what is stock for our trucks.

So I would test them through the valve cover gaskets and if they are bad then I would replace them with Motorcraft ZD-11 glow plugs and nothing else.

 

[ArcticDriver]

While NAPA stocks glow plugs that will work in our trucks they don't stock the factory ones and there has been problems with just about any glow plug other than what is stock for our trucks.

So I would test them through the valve cover gaskets and if they are bad then I would replace them with Motorcraft ZD-11 glow plugs and nothing else.

Bugman,
Are the UVCH connections a problem on these earlier 7.3's like they are for my 2000 MY ?

 

[bugman]

No the harness is no problem keeping them connected but they just like to cook the harness connections at the valve covers. International used to make a repair kit for them but I don't know if the kit is still available.

 

[ArcticDriver]

No the harness is no problem keeping them connected but they just like to cook the harness connections at the valve covers. International used to make a repair kit for them but I don't know if the kit is still available.

OK.
Since the OP has new GPs and his GPR tested good, is it possible there is a problem with the harness connection you mention?

 

[bugman]

For some reason these trucks don't like aftermarket glow plugs, they tend to eat them. I don't know if it is the extended time that they are on after starting or what. So if they are indeed dead or bad he needs to replace them with some ZD-11's.

All this can be figured out by testing them. It also sounds like he is depending on his mechanic to do the work.

 

[DFrank]

Thanks guys. Can someone point me towards how to test the glow plugs? Seems the relay is acting as it should.

Hard to believe they would be burned out after jut a couple hundred miles, if they are not stuck on.

 

[Snowtow]

http://www.google.com/?gws_rd=ssl#q=Powerstroke+glow+plug+test

 

[Patrick Feeley]

For checking the injector/glowplug wiring: From each valvecover gasket connection's outermost pins (2 per connector) to ground you should get 0.1 to 2 ohms (indicates good plug and wiring). From each valvecover gasket connection's center pin to each immediately adjacent pin, you should get around 3 ohms (indicates good injector solenoid and wiring). You should not get any continuity from any of the outer pins to the 3 inner pins (indicates no shorts between injector and glowplug wiring). You should also get 0 to 1 ohms from each of the external harness connectors outer pins back to the Glowplug Relay's large terminal on the GP side (indicates good wiring from external connections back to the relay).

To check the glowplug relay (GPR), measure the voltage drop across the GPR's large terminals. While the GPR is active (up to 1.5 to 2 minutes after the key is turned to Wait-to-Start) put your meter leads on the large terminals (one lead on one large terminal and the other lead on the other large terminal). The measures how much voltage is being "lost" across the relay. A reading of 0.3V or more indicates a bad relay.

Cheers!

 

[DFrank]

Thanks for your help folks.

Snow, I watch some of the Utube stuff that came up on your google search.

I think I've learned that my valve cover wiring is suspect.

When I put the Ohm meter to the GP points in the valve cover, I get no continuity to the neg battery terminal on any of the passenger side gps.

I didn't try the driver side, as the plug didn't want to cooperate, and I didn't want to risk cracking it.

Can anyone direct me to a reliable, value oriented vendor for getting these?

I've got a buddy who is going to help me do this next weekend.

I think I should probably have a new set of GPs on hand just in case, but it seems likely that my new ones are still good.

The guy who did this work for me, knows that he got Motorcraft GPs from NAPA; he does not remember if they were the ones you guys have suggested.

Anything else I should be replacing while the valve covers are off AGAIN?

 

[bugman]

The first thing that I would do is to pull the valve cover off and take a look at the wiring and then measure the glow plugs with out having the harness connected.

For parts I would go with Motorcraft only. Parts stores stock Dorman gaskets and wire harnesses but this is one thing that you only want to do once. K-Manns Parts stock everything that you would need if you decide to go with Motorcraft and their prices are not that bad.

If you pull one of the valve covers you may be able to eliminate the costly gaskets and perhaps the plugs themselves if it is the wire harness. Other than that I would purchase the glow plug replacement kit that they have for $369.00 which has everything in it.

 

[DFrank]

Tore into this last night with a mechanic friend.

I bought new glow plugs and the valve cover gasket/ wire harnesses ahead of time.

Found 7 of 8 glow plugs dead. (eighth one might not have been plugged in tight enough to have been engaging at all.

gaskets and wiring looked and tested great, but I put the new ones in just to be safe.

He did the first side, while I did the driver's side after watching him start.

The hardest part, aside from the bolts in the rear that were hard to reach, was pushing the plug wire back onto the glow plugs.

Got it back together and realized the signal to the relay was not shutting off, at least not always, hence the brand new burnt plugs.

Seems like an obvious thing to test, but maybe that isn't SOP?

It was getting late, and diagnosing the cause of that problem was not on the agenda.

We rigged a switch to the control wire, so I can cut power to the relay once its started.

So far so good. I'm getting a Momentary switch that requires holding down, to ensure it cannot be left on.

I am wondering how I would diagnose the issue that is leaving the control wire to the relaly hot, after WTS goes off.

I am also thinking that I should just bypass that power source entirely and make the power to the relay fully manual via the monetary switch.

Any reason not to do that?

I know the GPs cycle on and off while warming up. How important is that? How long and often would I hold them on to mimic that?

What does it accomplish aside form reducing emissions? (nothing reduces this thing's emissions, yet it passed with no issues.)

Thanks,

Dave

 

[ArcticDriver]

Dave,

The GPR can cycle ON & OFF for atleast 90 seconds after the Wait To Start light turns off and the engine is running.

It does this by design.

Are you sure this is not all that was happening?