Glow-Plugs

[lindsaym]

I'll start this off by saying that this is my last resort because I know I'll probably get hammered for asking a common question or missing something stupid. However, I would really like it if i could get my M1009 to start. The second thing is, I have followed to TM/threads as best as I can with my limited base of knowledge. There, now let's do this!

Today, my M1009 decided not to start. I have tested the input and output terminals on the relay and they get voltage. Nothing to the GPs, though. I'm by myself so testing the wires is a pain, so I took out a couple GPs, plugged them in and turned the battery on. Nothing. Didn't even get warm. I did all my checks again and the relay is getting voltage. Just now, I took the 'output' wire and held it to the input terminal while I was holding the GP (not in my hand!). Again, nothing.

I have tested the GPs a couple different ways and they're working. Power seems to be getting to the relay, and to the output side, but not to the GPs.....and I have no idea what that could mean, other than something could've happened to my wiring system? Okay guys, unleash ****.....

 

[porkysplace]

Have you tested the GP's with a multi-meter ?
this should help Testing Glow Plugs

 

[Warthog]

The power comes out of the relay via the two large orange wires. Near the engine head the wires breakout into four green wires that are fusible links.

In order for the plugs to "heatup", they have to be grounded.

 

[Triple C]

Take your test light or ohm meter and check for current between the glow plug terminal and the ground. If you don't get current when you cycle the glow plug controller but you do have current at the controller under the same conditions, you have most likely burnt one or more of your fusible links. I find it easiest to use a cheap test light so you can see if it lights up from inside the cab when I am working alone. Good luck and keep us posted.

 

[gimpyrobb]

Hold the tip of the glow plug in your fingers and touch it to bare metal on the block. Then read what the DMM says.

 

[lindsaym]

On a couple. And got around 1.3, but it's hard to get a good reading so I took them out and connected them to battery via wire and they were orange in less than 3 seconds, which I'm told is a solid test.

 

[doghead]

The controller reads the voltage drop, to control the GPs correctly.

If they do not measure the correct ohms, the controller cannot operate optimally.

Just because they glow, does not mean they are functioning properly.

I do not understand what is hard about getting a reading. (I've never experienced this)

 

[doghead]

So, if your GPs all glowed.

And you have power coming out of the GP relay.

Your wires must be bad(possibly bad fusible links in the GP harness). Or, you could have dirty connections.

I do not recall anyone ever posting this issue in the last 7 years.

To diagnose for this, use your ohm meter and measure between the ring terminal(at the GP relay) and each of the 4 GP terminals on each side of the motor.

 

[lindsaym]

Doghead, I'm heading home now to continue diagnosing this. If my wires test bad, are there detailed instructions anywhere for making a new set? I called NAPA and they said that wire was discontinued. O-Reilly's doesn't have them either. They both say I'll have to make it from scratch.

 

[Warthog]

You will have to custom make the GP harness if needed. No instructions. There are hundreds of videos on YouTube on how to work with fusible link wire.

Used is your other option.

 

[lindsaym]

I tested each wire, they came back .5 to .7, which I'm told is good. Now I'm really lost....

 

[doghead]

So, let's back up and start over.

Is your GP relay supplied with 12 or 24volts(stock)?

Did you follow the step by step GP troubleshooting procedure in the -20 TM?

Have you changed any parts lately?

Which brand of GP do you have?

 

[lindsaym]

Napa ST85

i tested GPs, all at 1.3 - 1.5. Tested voltage at relay got 12v (was converted to 12 before I got it). Tested wires, they're good.... But the GP will not fire up, even if I bypass the relay and controller.

 

[lindsaym]

I have not changed any parts. I did switch out the connectors on one of my battery terminals, and I removed my instrument panel to tinker with my voltmeter.

 

[doghead]

Does your engine have a good ground?

Do you have a jumper cable you can use to temporarily connect the block to the front battery negative terminal?

Does your engine crank over well?

 

[lindsaym]

Yes, it cranks fine. I will try the jumper now.

 

[lindsaym]

No change. Is there a particular spot I should put the jumper cable on?

 

[doghead]

Nope.

 

[lindsaym]

Okay, I put it right next to where the grounds run into. Didn't seem to change anything.

 

[doghead]

Try this, with your multi-meter set on DC volts, and each probe on the large terminals of the GP relay and the key on(to energize the relay), what does your meter say?

Also, with one probe on the hex of a GP and the other on the large GP stud (input side), what do you get with the key on?

And one more test, same as above but with the probe on the other large GP stud, with the key on.