Please confirm this test.
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Junior User
Joined: Apr 2002
Posts: 72
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Please confirm this test.
From what I have found in the search this is how i can test my glow plugs,
1) Use a test light from the POS on the bat to the tip of each plug, lighting up indicates prob good.
2) Use ohm meter between plug lead and plug terminal. Put IGN swith in on position and check reading, should fall between .6 and 1.8 OHMs
Just want to be sure,
thanks
1) Use a test light from the POS on the bat to the tip of each plug, lighting up indicates prob good.
2) Use ohm meter between plug lead and plug terminal. Put IGN swith in on position and check reading, should fall between .6 and 1.8 OHMs
Just want to be sure,
thanks
Post Fiend
Joined: Nov 2004
Posts: 5,638
Likes: 1
From: Manitoba
Test 1 is a good one but test 2 I have not heard of. Normally you use an ohm meter to the tip and the base if you get .5 to 1.0 ohm they are good. One point keep fingers off the lead tips as the body has an ohm reading too.
Here is a bit of info I like..........for solid state controllers.
If you have 2 or more bad GPs, the controller may not cycle at all.
Two problems that occur with the solid state ( 1987 to 1994 IDI engines ) GP systems. If a GP burns out ( circuit resistance goes up ), the controller cycles the GPs at a faster rate which doesn't let them get to max operating temp. If 2 or more GPs fail, the controller may not cycle the GPs at all ( very rapid or no clicking heard ). When you check the GPs, use an ohmmeter. A high resistance ( not necessarily burned out ) GP can cause circuit resistance to go up and the controller will then cycle the GPs too fast. You probably will not find this problem with a test light. Resistance spec for GPs = .5 to 1 ohm cold. Second problem. A poor controller ground ( black wire attached to valve cover stud ) will cause the controller to leave the GPs on longer, often damaging or failing them. If you are having mulitple GP failures, I would check closely the controller ground. Now the confusing part. Bad ground --> longer GP on time ( slower cycling ). Burned out GPs --> faster cycling If you have both situations, it may appear that the controller is cycling the GPs at the proper rate. Bad ground slows it up while the burned GPs speed it up ---> normal cycling. The system acts/sounds like it's working normally, but you have a hard starting concern.
Glow plug torque is 12 ft lbs, I always use antisieze on the threads.
PLC7.3
Here is a bit of info I like..........for solid state controllers.
If you have 2 or more bad GPs, the controller may not cycle at all.
Two problems that occur with the solid state ( 1987 to 1994 IDI engines ) GP systems. If a GP burns out ( circuit resistance goes up ), the controller cycles the GPs at a faster rate which doesn't let them get to max operating temp. If 2 or more GPs fail, the controller may not cycle the GPs at all ( very rapid or no clicking heard ). When you check the GPs, use an ohmmeter. A high resistance ( not necessarily burned out ) GP can cause circuit resistance to go up and the controller will then cycle the GPs too fast. You probably will not find this problem with a test light. Resistance spec for GPs = .5 to 1 ohm cold. Second problem. A poor controller ground ( black wire attached to valve cover stud ) will cause the controller to leave the GPs on longer, often damaging or failing them. If you are having mulitple GP failures, I would check closely the controller ground. Now the confusing part. Bad ground --> longer GP on time ( slower cycling ). Burned out GPs --> faster cycling If you have both situations, it may appear that the controller is cycling the GPs at the proper rate. Bad ground slows it up while the burned GPs speed it up ---> normal cycling. The system acts/sounds like it's working normally, but you have a hard starting concern.
Glow plug torque is 12 ft lbs, I always use antisieze on the threads.
PLC7.3
Senior User
Joined: Aug 2003
Posts: 269
Likes: 0
From: Cleveland/Akron, Ohio
Test one is OK only if you disconnect the wire from the gp 1st.
That is all you need to do, when they go bad, they open up, and have infinite resistance. When they are good there is basically no resistance ~ 0 ohms, digital ohmmeters will flutter around 0.
Think of it as a light bulb - filament burns out, it won't light up anymore.
That is all you need to do, when they go bad, they open up, and have infinite resistance. When they are good there is basically no resistance ~ 0 ohms, digital ohmmeters will flutter around 0.
Think of it as a light bulb - filament burns out, it won't light up anymore.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
Test 1 is a good quick test that will spot 92% of the bad plugs
It takes a good digital ohm meter to do test 2, but that is the best one. I have seen them short to the case when they burn out. This causes 0 ohms resistance which will still light the light. When you do this test the glow plug should be unplugged from the harness as with the first test. When the harness is plugged in you are testing all the glow plugs at once which messes the readings up.
It takes a good digital ohm meter to do test 2, but that is the best one. I have seen them short to the case when they burn out. This causes 0 ohms resistance which will still light the light. When you do this test the glow plug should be unplugged from the harness as with the first test. When the harness is plugged in you are testing all the glow plugs at once which messes the readings up.
Senior User
Joined: Nov 2004
Posts: 202
Likes: 0
look if the little dash light goes off to quick or you have really good white smoke on startup, and or hard cold morning starts then just replace all 8 plugs, in the time that it takes to test and retest the plugs you could just replace and be done with it, also if one goes then it is the beging of the end for the rest of them, they all have about the same service life.
