Glow Plug help?
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Joined: Sep 2015
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Glow Plug help?
I have no ground going to my glow plug relay. I have 12 volts on one big plug and when I turn the switch to "on position" both little wires get 12 volts. One should be ground but it's not. Where do I start looking? Thank you very much.
Hotshot
Joined: Jan 2011
Posts: 18,849
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From: Puget Sound
First thing.... "switch to on"? Are you referring to the ignition switch? If the engine is already warm or the environment is warm, you'll get just a few seconds of GP on time. The only way to catch that is to have the meter leads clipped to both of the little wires and the meter display in view when you turn the key. The "big" ground is the glow plugs themselves, so you will see a ground on one of the big wires when the GPs are off.
When I test my GP system, I clip my meter leads across the large studs on the GP relay. When the GP relay fires, I should see the voltage across the large studs go from battery voltage to about zero volts (good contacts in the relay).
When I test my GP system, I clip my meter leads across the large studs on the GP relay. When the GP relay fires, I should see the voltage across the large studs go from battery voltage to about zero volts (good contacts in the relay).
Elder User
Joined: Aug 2013
Posts: 588
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The Base of the Relay is the Ground for the high amperage. The Coil Circuit of the relay (the switch on/off) is Ground Switched by the PCM. Glow Plug ON time is dependent on oil temperature and altitude. The Glow Plug relay comes on between 1 and 120 sec. and does not come on at all if oil temp is above 131 F.
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spicker
1999 - 2003 7.3L Power Stroke Diesel
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Jun 22, 2010 03:08 AM
