How do I know if my glow plugs are working?

[AMP762]

I wouldn't take this to the bank.... You are reading the voltage drop on the wire going to the glow plug. If it was designed right and is fairly new, no bad connections this drop could easily be less than a volt and won't light the bulb. Iffy test at best...

Say again /forums/images/graemlins/confused.gif with the test lite hooked to the bat.+ you have taken the wire out of the circuit,right?

 

[cp1969]

If the glow plugs are wired in parallel and you don't disconnect them, won't the current find it's way through to any working glow plug? Maybe I missed something, but I think you have to isolate glow plugs to test them and this means disconnecting their wires.

 

[LeRoi]

Maybe I wasn't too clear on this procedure.
This test is done if you are already reading 12 volts at the glow plugs feeding from the wiring harness. You're not reading the voltage to the glow plug, You are reading the glow plug resistance. No resistance, no glow (means the glow plug is open and should be replaced.)
On edit yes the glow plug harness has to be disconnected from the glow plug.
Hope this clears up any banking confusion /forums/images/graemlins/smile.gif
Leroy

 

[mopacman]

you need to know your system. their are different voltage systems. My old kubota has 10.5 volt glow plugs, my iseki has 9.5 volt system. they have a resistor to drop the voltage. I think Ford uses two different voltage systems in their trucks.