Changed out the glow plugs, now relay is whining..

I finally got around to changing the glow plugs in my 94 E350 with a 7.3 NA

Before the new GPs were installed, when turning on the ignition key I would get the WTS light,
then a rhythmic clicking of the relay, and the volt meter on the dash would move back and forth with the clicking.


After the GP swap, I had the dog house off when I went to start it.

Turned the ignition key, got the WTS light, and heard what sounded like what can best be described as a 'key in ignition buzzer' and thought., "huh never heard that before".

After a few seconds it went from a 'rrrrrrrr' sound to a rising pitch 'weeeeeee' sound like an old camera flash with a strobe bulb. (like something building up a high voltage charge)


When I turned the ignition off then on again, I could tell noise was coming from the relay on the back of the engine.


Is this new sound "normal" and the previous sound/ticking was NOT normal?
Or was the old way normal and this new high pitch sound is NOT normal?
(Or are they both sounds of problems and I need to fix something larger?)

I have not had time to pull out the multimeter and check the terminals yet.


Anyone with more experience than me care to share their thoughts/insights?

Thanks!

The new sound is not normal.

The old sound was normal.

I would just get rid of the controller altogether, and go with a manual setup.

Wes sells a complete setup...

Thanks Selahdoor!

Is there anything I could have done while changing the glow plugs that would have caused the relay to fail? (Did I break it?)

I don't really know how you would break it.

Unless you crossed some wires somewhere?

But if I were you, I would at the very least disconnect the thing RIGHT NOW. Don't let it cycle again. That whining noise is the sound of disaster headed your way.

I would disconnect and tape up/isolate every wire, right now. Then either install a manual system, or replace the controller and solenoid.

this is why I can't have nice things...

The truck has a battery disconnect switch, so everything is isolated from power at the moment.

I've heard many of the 7.3 style controllers make that rising pitch whining noise. I've never heard the buzzer noise though.

Did you clean all the connections at the glow plug relay? And the cable connection at the post on the hot side of the starter relay and then the wire headed to the positive terminal on the battery? That's where the voltage originates. It could be that new additional load on the relay with bad connections is causing the controller to behave strangely as the voltage is dragged down too low for it to function properly. It's also possible that the actual relay on top of the glow plug controller is damaged internally from age and starting cycles and the new load is pushing it over the cliff. I would start by making sure all the connections are clean and good at the controller and back at the starter relay and then the source wire from the battery terminal. If all the cables are in good condition then maybe replace the gp relay first and then the controller. The controller needs a minimum voltage of like 7 or 8 volts to run the electronics on board so bad connections or wires feeding a new increased load will definitely lead to reduce voltage to run the controller.

Thanks AggieDiesel01

I didn't check the relay. I just changed out the plugs.
(I suppose a look-see/once over of all the connections would have been the smart move)

The afterthought was the new glow plugs might be pulling more current through the relay and causing some new behaviors

I recently went through a similar problem. I replaced the controller unit assembly on the back of the engine only to find out the relay on the fender wall was bad.
I also have a switch that activates the relay on the controller to turn off the glow plugs when not needed.

Noiseydiesel said:

I recently went through a similar problem. I replaced the controller unit assembly on the back of the engine only to find out the relay on the fender wall was bad.
I also have a switch that activates the relay on the controller to turn off the glow plugs when not needed.

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Just fyi, the one on the fender is for the starter. Maybe you already know that, just trying to clarify before confusing anyone.

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The way it was, is how they act with several bad plugs. You should have a much longer time now before the clicking starts. I have heard many make all kinds of weird whining noises that functioned properly. And it would be loud with the doghouse off. If you are worried about it replace the relay.

Mine's been squealing for years and works fine FYI

I haven't a glow plug controller, I just have a manual push button for cooler starts, and my glow plug relay whines, or "sings" with an increasing pitch when I activate it. Starts the truck beautifully though. I keep my starter and gp relays in an ammunition box, keeps things drier in that fender top area.

Matt Leaman said:

I haven't a glow plug controller, I just have a manual push button for cooler starts, and my glow plug relay whines, or "sings" with an increasing pitch when I activate it. Starts the truck beautifully though. I keep my starter and gp relays in an ammunition box, keeps things drier in that fender top area.

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Click to expand...

Well, I know what I’m doing with my ammo cans.