Some Glow plug info I found in the Service Manual
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Fleet Owner
Joined: Apr 2012
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From: Spanaway
Some Glow plug info I found in the Service Manual
All this information comes from the 2006 Service Manual.
Glow plug on time is dependent on oil temperature and altitude. The GPCM will
command the glow plugs on for 1 to 120 seconds. The GPCM does not operate
if the oil temperature is above 55C (131F)
It looks like the GPCM is really 2 units in one box.
Glow plug to ground 0.1~2 Ohms
Glow plug connector to GPCM connector Less that 5 Ohms
Pin #3 on both is the VBattery
Green connector
pin #1 is gp#5
pin #2 is gp#7
pin #6 is gp#1
pin #7 is gp#3
pin 8 goes to the PCM
pin 9 goes to the PCM
Black connector
pin #1 is gp#6
pin #2 is gp#8
pin #6 is gp#2
pin #7 is gp#4
pin 9 goes to the VPwr
Enjoy
Sean
Glow plug on time is dependent on oil temperature and altitude. The GPCM will
command the glow plugs on for 1 to 120 seconds. The GPCM does not operate
if the oil temperature is above 55C (131F)
It looks like the GPCM is really 2 units in one box.
Glow plug to ground 0.1~2 Ohms
Glow plug connector to GPCM connector Less that 5 Ohms
Pin #3 on both is the VBattery
Green connector
pin #1 is gp#5
pin #2 is gp#7
pin #6 is gp#1
pin #7 is gp#3
pin 8 goes to the PCM
pin 9 goes to the PCM
Black connector
pin #1 is gp#6
pin #2 is gp#8
pin #6 is gp#2
pin #7 is gp#4
pin 9 goes to the VPwr
Enjoy
Sean
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All this information comes from the 2006 Service Manual.
Glow plug on time is dependent on oil temperature and altitude. The GPCM will
command the glow plugs on for 1 to 120 seconds. The GPCM does not operate
if the oil temperature is above 55C (131F)
It looks like the GPCM is really 2 units in one box.
Glow plug to ground 0.1~2 Ohms
Glow plug connector to GPCM connector Less that 5 Ohms
Pin #3 on both is the VBattery
Green connector
pin #1 is gp#5
pin #2 is gp#7
pin #6 is gp#1
pin #7 is gp#3
pin 8 goes to the PCM
pin 9 goes to the PCM
Black connector
pin #1 is gp#6
pin #2 is gp#8
pin #6 is gp#2
pin #7 is gp#4
pin 9 goes to the VPwr
Enjoy
Sean
Glow plug on time is dependent on oil temperature and altitude. The GPCM will
command the glow plugs on for 1 to 120 seconds. The GPCM does not operate
if the oil temperature is above 55C (131F)
It looks like the GPCM is really 2 units in one box.
Glow plug to ground 0.1~2 Ohms
Glow plug connector to GPCM connector Less that 5 Ohms
Pin #3 on both is the VBattery
Green connector
pin #1 is gp#5
pin #2 is gp#7
pin #6 is gp#1
pin #7 is gp#3
pin 8 goes to the PCM
pin 9 goes to the PCM
Black connector
pin #1 is gp#6
pin #2 is gp#8
pin #6 is gp#2
pin #7 is gp#4
pin 9 goes to the VPwr
Enjoy
Sean
Josh
Lead Driver
Joined: Jul 2004
Posts: 6,950
Likes: 510
From: Foothills, CA
I'm illiterate here, so excuse maybe a stupid question: I always thought the dash lamp was telling me when the glow plugs were on and when the cylinders were warmed enough to start. But that certainly doesn't jive with the service manual... 
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Fleet Owner
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From: Spanaway
I would like to know how the calculation is done regarding the amount of on time.
I think it would be a good use of the Xgauge for the glow plug on time so see.
It did not say it but I bet that the outside air temp is also in the mix.
I'll read more in the book and see if I can find any thing more.
Sean
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Joined: Aug 2001
Posts: 14,441
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The red statement is also my understanding too.
I would like to know how the calculation is done regarding the amount of on time.
I think it would be a good use of the Xgauge for the glow plug on time so see.
It did not say it but I bet that the outside air temp is also in the mix.
I'll read more in the book and see if I can find any thing more.
Sean
I would like to know how the calculation is done regarding the amount of on time.
I think it would be a good use of the Xgauge for the glow plug on time so see.
It did not say it but I bet that the outside air temp is also in the mix.
I'll read more in the book and see if I can find any thing more.
Sean
Josh
Fleet Mechanic
Joined: Aug 2012
Posts: 1,760
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The glow plugs are a two stage unit. The first stage they get very hot for a few seconds, second stage they get warm for up to two minutes or so. The glow plugs are controlled by the GPCM, and the GPCM is controlled by the PCM. You can see the vehicle volts on the ScanGauge2. The alternator does not produce charging volts (14vdc) until the glow plugs turn off.
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Fleet Owner
Joined: Apr 2012
Posts: 27,307
Likes: 549
From: Spanaway
Today I watched the on timer with the SGII. On one restart I was at
177F EOT and altitude of just over 400 feet air temp about 48F
and I got 45 seconds on time. So one question is if the altitude
is lower how would that effect the on time?
I have not had time yet you do more reading and as soon as I do
find the answer if I ever do I will report it back.
How did you come about that info that there are 2 levels of power
for the plugs? I would like to read it if you can point to a link.
Sean
177F EOT and altitude of just over 400 feet air temp about 48F
and I got 45 seconds on time. So one question is if the altitude
is lower how would that effect the on time?
I have not had time yet you do more reading and as soon as I do
find the answer if I ever do I will report it back.
The glow plugs are a two stage unit. The first stage they get very hot for a few seconds, second stage they get warm for up to two minutes or so. The glow plugs are controlled by the GPCM, and the GPCM is controlled by the PCM. You can see the vehicle volts on the ScanGauge2. The alternator does not produce charging volts (14vdc) until the glow plugs turn off.
for the plugs? I would like to read it if you can point to a link.
Sean
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Fleet Mechanic
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This is from my notes:
*************************************************
Install an inductive ammeter on one bank at one of the two harnesses at the
Glow Plug Controller Module (GPCM). You can get up to 200 A at first, but then should stabilize around 35-45 A. Check the other bank with the inductive ammeter. Both sides should read the same. If not, check the amps to each individual glow plug to determine which one (or ones) is bad. Each glow plug should draw 10-12 Amps.
Also - you can disconnect the glow plug harness and test the resistance of each plug. Each plug should read 0.1 to 2 ohms resistance. The harness should read 0 to 1 ohm resistance."
**************************************************
The glow plugs draw up two 200 amps (per side, 400 amps total) at first then stabilize to about 40 amps. Per glow plug that is up to 50amps at first, then down to 10amps. Maybe more of a cycle then stages.
So it sounds like glow plugs get more current draw for the first second or two. More current draw equals more heat.
I could be wrong about this, or I am missing something, but this is how I understand it.
*************************************************
Install an inductive ammeter on one bank at one of the two harnesses at the
Glow Plug Controller Module (GPCM). You can get up to 200 A at first, but then should stabilize around 35-45 A. Check the other bank with the inductive ammeter. Both sides should read the same. If not, check the amps to each individual glow plug to determine which one (or ones) is bad. Each glow plug should draw 10-12 Amps.
Also - you can disconnect the glow plug harness and test the resistance of each plug. Each plug should read 0.1 to 2 ohms resistance. The harness should read 0 to 1 ohm resistance."
**************************************************
The glow plugs draw up two 200 amps (per side, 400 amps total) at first then stabilize to about 40 amps. Per glow plug that is up to 50amps at first, then down to 10amps. Maybe more of a cycle then stages.
So it sounds like glow plugs get more current draw for the first second or two. More current draw equals more heat.
I could be wrong about this, or I am missing something, but this is how I understand it.
Posting Guru
Joined: Dec 2012
Posts: 1,644
Likes: 3
From: SW Ohio
Today I watched the on timer with the SGII. On one restart I was at
177F EOT and altitude of just over 400 feet air temp about 48F
and I got 45 seconds on time. So one question is if the altitude
is lower how would that effect the on time?
I have not had time yet you do more reading and as soon as I do
find the answer if I ever do I will report it back.
How did you come about that info that there are 2 levels of power
for the plugs? I would like to read it if you can point to a link.
Sean
177F EOT and altitude of just over 400 feet air temp about 48F
and I got 45 seconds on time. So one question is if the altitude
is lower how would that effect the on time?
I have not had time yet you do more reading and as soon as I do
find the answer if I ever do I will report it back.
How did you come about that info that there are 2 levels of power
for the plugs? I would like to read it if you can point to a link.
Sean
It should drop slightly when the key is turned to the on position engine off while waiting for the GP to cycle. I have never seen less than 11.0-11.5 volts.
Start the truck and you should see around 13.0ish on the volts at idle until the GP's turn off. Then you should see 14.0 and up.
Posting Guru
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That charging cycle is what I see as well, the alternator is on as soon as the engine starts but the current draw to the glow plugs keeps the voltage low. The in-rush current to the glow plugs is just their initial heating cycle, as soon as they get hot they draw the lower amount of current. It's not really a dual power or temperature thing, they draw the high current when they are cold, and as soon as they reach operating temperature they draw less current. The glow plugs are left on after the engine starts to reduce pollution emissions while the combustion chambers are still colder than normal.
Fleet Mechanic
Joined: Aug 2012
Posts: 1,760
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This was another reason I was thinking it was a two stage system.
Page 67: Electrical Components
Not really sure how a resistance coil can "control heat at its peak". I think this done at the GPCM.
Page 67: Electrical Components
Not really sure how a resistance coil can "control heat at its peak". I think this done at the GPCM.