okay i check 3 or 4 on the driverside not sure i am doing it right or not? set my ohm meter to 20 then took the red one and touched the tip and touched the black one on the intake then battery now i had my truck plugged in soit was warm and i did not get a very high reading i think it was 1 or 2 mabye 3 ohms max what is the best way to test them and what is good or bad? it seems to fire better when she is plugged in so i figure there must be some bad ones
another glow plug ?
- Thread starter braveops
- Start date
I think the last time we talk about this some said the best way is get a test light on the positive (+) terminal of the battery and the other end on the top tip of the GP and if the light comes ON then that one is good.
Twin_diesels
Twin Diesels
That method is a quick and dirty way to find one with a major fault. The way it works is that when the GP's get warmer, the resistance goes up. That resistance is what the controller senses to shut them off before they burn up. I dont know what the range is for resistance of a good one. Someone else with a little more knowledge should pipe up shortly.
F350camper
BOOST!
yep, you should see 1 - 3 ohms on each plug if the plug is good. Put one lead on the tip of the GP, and one to a good ground (neg battery post). A bad gp will be totally open aka infinite ohms to ground.
Twin_diesels
Twin Diesels
Things are a little warmer, so the plugs don't have to run as long to get up to temp. Sounds like they are ok, just is cold. The diesels are a little tempermental in the winter if ya aren't familiar with em. If you can keep it plugged in, thats better anyways. The oil circulates a little better right away, because everything is a little warmer too.
Sometimes the plugs aren't the only culprits. Anything in the system to increase the resistance will cause the controller to cycle down. Slip a stand of fine wire under one of the glow plug connectors, and set your volt meter to Volts. Put the black probe on ground, and the red probe on the fine wire, and have somebody turn the ignition on. You should see 7 volts slowly climb towards 11 or so, over the course of about 10 to 12 seconds. It should then start switching off and on for a while. If the voltage starts out higher, or the cycle time is shorter, you may have a high resistance connection somewhere, or the controller may be bad, if all the plugs check out.
That certainly works as a quick testExekiel69 said:
but IMHO it's better to use an ohmmeter if time allows, or if problems crop up after a successful test-light check. IIRC it isn't common, but it is possible for glow plug to short out and fail "closed", wherein the plug passes electricity through itself but there isn't any resistance at all in the plug, so the plug doesn't heat up. But, since current will go through the plug, the test light will still illuminate. I remember someone going through this a long time ago and got really frustrated, before finding out that a few of his plugs had shorted out...The 1 to 3 ohm range certainly works...but a plug at 0 ohms can also be a bad plug.
