Glow screen (11 Viewers)

[monton]

I have an HJ61 with a 12HT motor. I understand that it has a glow screen and not glow plugs. I understand what this does... just not quite sure on how it works. I have a glow light that has never worked since I got the truck. Would this be a fuse or a simple bulb? Anyway, as I don't have a light to let me know how long is long enough, what is the recomended time to warm up the glow screen. I usually do it for 10 seconds on a cold start and less on a warm start. Is this right? How do I fix the glow light?

Thanks.

 

[Greg_B]

I have an HJ61 with a 12HT motor. I understand that it has a glow screen and not glow plugs. I understand what this does... just not quite sure on how it works. I have a glow light that has never worked since I got the truck. Would this be a fuse or a simple bulb? Anyway, as I don't have a light to let me know how long is long enough, what is the recomended time to warm up the glow screen. I usually do it for 10 seconds on a cold start and less on a warm start. Is this right? How do I fix the glow light?

Thanks.

Have you put in a push button override for the glow?

If not, I do not understand how you can do it for 10 secs...

The glow system for the 13BT and 12HT typically will not cycle till getting close to 0C. Even then it only cycles for a few seconds at best. The colder it gets the longer it will glow. There is a thread on bypassing the system with a push button so you can "fool" the system and control the glow when temps are around 0C.

Read this: https://forum.ih8mud.com/showthread.php?t=29462

And this: https://forum.ih8mud.com/showthread.php?t=24480

If I have read all this, and you have done the mod, then chances are your bulb behind the cover is burnt out. Simply replace.

hth's

gb

 

[monton]

yes, that helps. I only mean that I hold the key on for 10 seconds before I start it. I guess as I park in underground parking, maybe the glow light has never had to come on.

 

[Tim-HJ61]

Monton,

If the glow light isn't coming on and it's not around freezing, don't waste your time holding the key on start for 10 seconds - just fire it up - holding the key won't make any difference.

The mod is easy to do, but make sure you get a NC switch, normally closed. It's only when the switch is open that it triggers the circuit, and only then if the circuit is 'open' prior to the start lights come on, and only then for as long as the timing circuit allows.

Tim

 

[brownbear]

Monton,

The mod is easy to do, but make sure you get a NC switch, normally closed. It's only when the switch is open that it triggers the circuit, and only then if the circuit is 'open' prior to the start lights come on, and only then for as long as the timing circuit allows.

Tim

That sounds backwards with the switch. The switch should be open when not pressed down. Otherwise you always have continuity thru it. And pushing it in would be breaking the circuit.

Normally open, no continuity(open circuit)
Normally closed, closed circuit= continuity.

 

[Stone]

That sounds backwards with the switch. The switch should be open when not pressed down. Otherwise you always have continuity thru it. And pushing it in would be breaking the circuit.

Normally open, no continuity(open circuit)
Normally closed, closed circuit= continuity.

Nope...it's correct. You need a normally CLOSED push button switch that is momentarily openwhen you push it. Reason being is you're trying to fool the glow screen timer into thinking it's very cold outside. The wire that you run the switch inline with is to the temp sensor on the thermostat housing. When it's very cold, the variable resistor in the sensor starts to produce resistance until the coldest setting, which would see infinity in that wire. So, by pushing a normally closed switch to open, the wire sees infinity and fools the timer to thinking it's very cold outside and kicks the glow screen on for the full cycle. If you leave theswitch alone, it sees continuity and everything works as from the factory.

One thing to note about that mod is that if you want the glow screen to kick in (override), you have to have the switch pushed in prior to turning the key to ON...otherwise nothing will happen.

Thanks again to Stickboy for this simple but effective mod.

 

[Tapage]

Reading your post Stone I'm little confused .. this is the same system that use m y 2H .. ? I thought no ..

 

[brownbear]

Reading your post Stone I'm little confused .. this is the same system that use m y 2H .. ? I thought no ..

Thanks Stone, I was thinking a totally manual set up, I never read Stickboys thread..

Tapage, you don't have a glowscreen, you are like my 3b( I think) where you want to go with the milson switch idea in other threads, then As I described above you want a NO switch.

Sorry Stone and others above, I did not realize you were just going between the tmer and the coolant temp sensor.

But one thing come to mind... Why do that? Why not go fully manual and have a switch that runs a relay to your glow screen. Too dangerous for over doing it on the glowscreen?

My timer was about as good as scrap metal. Waay to fawkin short. garbage. Only good if you live on the equator.

 

[Stone]

Brownbear:

The mod as I described above works for the 13B-T and 12H-T. The great thing about doing it this way with these engines is that the setup remains 100% factory if you don't touch the switch, but you can force it to glow anytime you need to. I find that my engine really wants a little bit of glow when ambient temps are between 0*C to around +3-5*C, but the glow timer doesn't even kick in until ambient temps reach below 0*C.

For the 3B and 2H, I would imagine that the superglow system would be the way to go.

Cheers.

 

[M John Galt]

To test the glowscreen on the 13BT unplug the temperature sensor lead at the thermostat housing. The preheater light should come on with the key in the "ON" position, and the glowscreen should be energized.
If the temp sensor is left unplugged, then one has as much preheater as they want by how long one leaves the key in the "ON" position before starting. No mods required.

 

[Stone]

To test the glowscreen on the 13BT unplug the temperature sensor lead at the thermostat housing. The preheater light should come on with the key in the "ON" position, and the glowscreen should be energized.
If the temp sensor is left unplugged, then one has as much preheater as they want by how long one leaves the key in the "ON" position before starting. No mods required.

Which is great...until your glow screen burns out.

 

[M John Galt]

Which is great...until your glow screen burns out.

ROTFL... You're in lotus land, here in the north it makes for smoother starts on cold mornings.
The timer still limits the max on time to the 14 sec factory spec, so the glowscreen isn't any more likely to 'burn out' than normal winter usage.

 

[Stone]

ROTFL... You're in lotus land, here in the north it makes for smoother starts on cold mornings.
The timer still limits the max on time to the 14 sec factory spec, so the glowscreen isn't any more likely to 'burn out' than normal winter usage.

Northern specific mods? Meh...

That's a good point.

 

[Tapage]

Tapage, you don't have a glowscreen, you are like my 3b( I think) where you want to go with the milson switch idea in other threads, then As I described above you want a NO switch.

Yes you are right .. I need to keep my keys in " glow plug " podition to run it.

But one thing come to mind... Why do that? Why not go fully manual and have a switch that runs a relay to your glow screen. Too dangerous for over doing it on the glowscreen?

I thought the same thing .. my system is very easy, after 10 or 12 secs my glow light comes off and I'm ready to start .. off course I only use it in really cold ( to me ) mornings ..

 

[Duane]

Thought I would ask all of you about glow screens since this thread came up on a search.

on an 84 BJ60 3B engine. there is one bus that connects the 4 glowplugs together and then there is another bus that runs perpendicular to that one which connects to some other device that has 2 wires on it which is screwed into the intake.
What is this thing?? Is this a glow screen for preheating air or just an intake air switch or something else?

I am new to a 3B engine compartment thus the silly question?

 

[cody c]

i had one of those on my 83 bj60 as well. after i killed the motor i swapped one in from a bj42 (i think thats what the fella said) and it didnt have one on the intake manifold. not sure but guessing some sort of glow screen myself!

 

[JohnnyBoy]

is there a way to test that intake heater? i just replaced my glow plugs, because they were toast. could the intake be gone too?

 

[Stone]

is there a way to test that intake heater? i just replaced my glow plugs, because they were toast. could the intake be gone too?

You don't have one in a 3B. Glow screens are for the direct injected 13B-T engines in the B series family.

 

[Duane]

Hi Stone.

If a 3B doesn't have a glow screen(intake air heater) have you any idea what this device is then?

regards

 

[UpsideDown]

1984 BJ60 with a 3B:

The function of the electrical connection that's on the intake manifold, protruding into the #4 intake runner is a glow plug resistor (FSM RM035E).

The operation of the super glow system generally follows this pattern - the glow timer measures engine coolant temperature and determines the amount of glow time needed to provide a clean start given that the correct glow plugs are installed. The timer provides power to two different circuits; the first circuit provides full current to the glow plugs, the second circuit provides reduced current to the glow plugs.

The pre-glow (full current) is short, it allows the glow plugs to fully light; power does not pass through the resistor. The post-glow keeps the glow plugs hot in order to keep the engine running cleanly during initial warm up; the current to the glow plugs passes through the resistor to reduce the current to the plugs to prevent burnout.

Super glow systems rely on a few things to work properly: correct functioning of the coolant temp sensor, correct timing of the glow plugs, correct functioning of the glow plug relays, having glow plugs with the correct values installed (commonly, errors occur here). In general this is a simple system that should work well. In reality, there are often small problems that crop up with age that makes the cost of repair greater than the cost of installing a "wilson switch" to just provide a manual glow to the plugs.

Manual glowing requires the operator to have an idea of how long it takes for the installed plugs to fully light and apply the switch for that amount of time, and have the wherewithall to provide post-glow touch ups to keep the initial start up clean. It's not tough to do... before 1982 (afaik) all Land Cruisers used such a system with a small glow screen (visible to the driver) to judge the glow plug lighting time.

Another question might come up: if you're moving from a super glow system to a wilson switch, I'd recommend that you obtain the correct values for such glow plugs (they will not be much lower than your vehicles system voltage (ie: a 12V truck will get 10.5V plugs and a 24v truck will probably get 20.5V plugs) and determine glow time under real world conditions. I would also recommend that the glow plug resistor is bypassed in such a system.

hth, and corrects previous information.

~John