Glow plug system

[T J]

I tested the glow plugs individually and all were okay.

I checked each of the three individualy

 

[T J]

Dude. this morning I connected volt tester ground to battery ground, put positive end on bar that conncts the three glow plugs, turned on switch. Glow plug light lite, no voltage to glow plugs.
any more suggestion.

 

[rScotty]

Sounds like your glow plug relay has two contacts inside - one for the glow plug indicator light and one for the glow plug voltage.

The glow plug side is probably fused, so check the fuses first. That will probably be the biggest rated fuse in the fuse holder. If the fuses are OK, next thing to check is the glow plug relay. Those glow plug relays go bad; they don't last forever.

To find the relay, trace the wire that connects to the bar feeding voltage to the three glow plugs. Follow that wire and make sure it is good & not burnt up. Following that wire should be easy as it has to be a fairly heavy gauge wire.

Anyway, check that wire back to the relay which is a pill box size box probably under the dashboard. That under-dash box ought to be the glow plug relay.

Expect that relay box to have 4 wires: the one to the glow plugs, another heavy gauge wire back to the fusebox, a smaller wire up to the glow plug light, and a medium wire to the ignition switch to power up the whole system when you turn the key.

When you turn the key, putting the negative voltmeter lead to the frame, and the positive meter lead on any those other wires should show 12 volts give or take an volt. If one of them doesn't show voltage either the relay or the wire - or the key switch itself - is bad.

rScotty

 

[T J]

TJ, when you say they tested good individually do you mean you removed the wire from each and measured the resistance of each one or that they each are getting hot?

Yes

 

[T J]

Scotty
Ill try that Monday, thamks

 

[rScotty]

Scotty
Ill try that Monday, thamks

Sure enough. The other check is to make sure the battery is a good one with good connections to the battery cables.
If the temperature is about 30 or 40F or above, even a worn diesel should start right up if the starter cranks it over at normal speed. It should start without needing any help from the glow plugs at all.

 

[skipmarcy]

Sometimes, as on my Mahindra, the power to the glow plugs is protected by a fusible link, not a fuse. A fuse protects the RELAY control side but not the power wire to the glow plugs.

 

[WranglerX]

Trace wiring back from buss bar on GP's to source of power for GP's (key switch) ... Some where along the way you will find a malfunction (bad relay/bad fusible link/bad fuse/loose connection)... Wiring diagram from factory service manual would be big help....

 

[T J]

As to my Mitsubishi MT15D tractor. I am still working on glow plug issue. I have checked all that has been posted, and then some. Thank you
However, still not functioning. The person I bought from installed a new ignition switch. I do not know if it is wired correctly. I have Southern Global MT15+ book, with a wiring diagram.
So, the question I have today is: Did this original ignition system switch have a turn back position for glow slugs, or did the key turn to start position, wait a few moments and then start engine?
Currently, when I turn switch on, before starting, the glow plug light does not light. I wait a few seconds and it cranks and starts but takes several cranks to do so. I have two other tractors so am used to diesel operation.

 

[LouNY]

On my older F2000 mower the glow plugs are activated by the key switch being held inbetween the run and start position.