glow plug controller

[gunnie]

Hey guys,
I'm having some trouble figuring out my controller issue. A couple weeks ago my wait to start light was staying on for a shorter length of time but I could tell the glow plugs were getting power since my volt meter was pulling down. I thought I had a couple bad glow plugs so I bought a new set, before I got around to installing them my wait to start light quit coming on and the controller clicks after about one second and the volt meter showed no draw. I installed them today with no change in cold starting. I pulled the cover off the controller and with a short piece of wire jumped off the hot post to the small post and the relay clicked but immediately clicked again. I put a test light on the number 1 glow plug lead and again jumped the hot post to the small post on the controller relay and the test light lit for about 1 second and as soon as the relay clicked the test light went out. Is my controller bad or am I missing something? After a new set of zd9's I really don't want to just keep throwing money at this until I have some input from you guys. Oh by the way all 8 of the zd9 plugs I pulled out were good.

Thanks for the input,
gunnie

 

[motox tech]

check your plug harness, any bare spots or corrosion? I have the same issue, and have purchased two controllers, both just click. Think, after some testing, that the harness itself is faulty. have not had the time to make new one, but thats my next step. weird thing is my previous controller worked for about two solid weeks after doing that click click click crap for about a week and a half prior. after the flawless two weeks it just quit alltogether. I feel your frustration, dont know if this helps, but if you figure it out let me know.

 

[Cincinnati Guy]

If The controller is bad go to uhaultruckparts.com many of us buy there and have good and decent priced parts.

 

[gunnie]

I found a 3 part test on our site that Mel had written, so according to the test instructions I have a bad relay. I'll go to ford tomorrow and pick up a new one and give you guys my results as soon as I get it installed.
Thanks for the input
gunnie

 

[Cincinnati Guy]

Can you wait and buy online? Stealership prices are up there...

 

[gatorman21218]

heres what happened to my glowplugs. http://www.oilburners.net/forums/showthread.php?t=46330

may not be your problem but then again its a wise upgrade

 

[gunnie]

thought I should get a relay from ford as Mel stated the others may look the same but are inferior. this one lasted 21 years so I really have no room to complain.

 

[gunnie]

CORRECTION
After rereading Mel's 3 step instructions I realized I had not followed them correctly. My relay is definitely good, but I still have the same problem after rechecking all connections on the relay. Should I just run a new wire to my relay hot side and say heck with it? Could it be something else?

 

[franklin2]

Follow the controller wiring(along with the rest of the engine wiring) from the top of the engine over to the pass side inner fender. Along the way you will find harness plugs. The main power feed for the glowplug system goes though these plugs along with the smaller wiring. These plugs are too small to handle the current of the glowplug system, and it's very common for them to melt around the glowplug wiring.

I just cut the two large yellow wires off the plugs till I had 4 pieces, and then crimped ring connectors on the ends and bolted them together. This was handy when I went to change valve cover gaskets and was able to unbolt them for access.

 

[gunnie]

guys,
something about this just doesn't make sense to me, sometimes I can be a little slow to pick up on the obvious so bear with me.
I have power to the hot always post on my relay and i followed Mel's instructions on checking my relay and it works and I have new glow plugs, why wouldn't the glow plugs work properly? I know some have suggested the wires feeding the always hot post could be corroded or overheated and melted, but how could I have power to always hot if the wires are corroded or melted? I don't understand this portion.
thanks again
gunnie

 

[gatorman21218]

the plugs take a LOT of amps. Itll be like having a 16 gauge battery cable. yes that cable will give you 12 volts at the starter, but it wont allow enough current to flow.

I was jump starting/charging my truck with a volvo S70 once and had a brick on the throttle revving the swedish 5 banger up to 3k rpms. After say 20 mins of this, with the volvo still humming, I went and cycled the glowplugs and it bogged the engine down to 2000 rpm. That was just the plugs not starting or anything.

 

[gunnie]

Gatorman,
when you rewired your always hot, did you use an inline fuse?

 

[gunnie]

so if i run a 4 or 6 ga awg wire from the battery directly to the always hot post this will verify if my wires are the problem correct? Nothing permanent only as a test.

 

[gatorman21218]

No I did not use a fuse, but it wouldnt hurt anything. It just has to be very big. Id say just make it permanent. It may or may not help your problem but it will cure the melting harness problem, which could lead to a fire.

 

[franklin2]

guys,
something about this just doesn't make sense to me, sometimes I can be a little slow to pick up on the obvious so bear with me.
I have power to the hot always post on my relay and i followed Mel's instructions on checking my relay and it works and I have new glow plugs, why wouldn't the glow plugs work properly? I know some have suggested the wires feeding the always hot post could be corroded or overheated and melted, but how could I have power to always hot if the wires are corroded or melted? I don't understand this portion.
thanks again
gunnie

This is an important concept that will get you in trouble with more than the glowplug wiring. You can think of the 12v power like a garden hose, where the water flow is current, the water pressure is voltage. Ever have a kink in the hose and when you open the nozzle it squirts good for about 1 second, and then goes to nothing? That's exactly what happens when you have a poor connection in wiring. The voltmeter draws hardley any current, so it reads through the bad connection, and gives you 12v. But when you go to use the glowplugs, a lot of current is flowing, and it can't get through the bad connection(the kink in the hose) so the voltage drops. So the key to checking circuits like this is to put the meter at your test location and then activate the circuit with the meter in place. You will then see the if the voltage holds or it drops down to nothing.