12HT Intake Heater / Glow Screen help (1 Viewer)

[Crimson Cruiser]

Last spring I did a 12HT swap into my HJ60.
It's starting to get colder and I want to hook up my glow screen/intake heater.

I've purchased a Hella 24V 60amp relay and set up a push button/manual switch circuit.

My question is, I'm not sure what terminal on the glow screen I should be hooking up the 24V to.
The front (right in the pic) or back (Left in the pic)?
The back has a black wire attached to the screen and the front has a red wire attached to the screen.

Do they both need 24V?
Is there two screens in the intake?
What have others done?
FWIW, My 60 is 24V and the 12HT is 24V as well.

Thanks

Mike

 

[amauri]

Yes, there are two screens.

You can switch both on together or switch on only one (with two solenoids).
Here's diagram showing the factory automatic timer system.

I just used a manual two position momentary toggle switch on my 12HT conversion.
Flip it one way to turn on one element, flip it the other way for both.

 

[Crimson Cruiser]

Thanks for the info.

So... when it's really cold you would activate both screens?

I have that schematic but something doesn't add up.
Is each screen 24V or are they 12V each wired in series?

Does each post go directly to each screen then the screen are grounded in the intake?

 

[lostmarbles]

I suspect 24V cruisers run them in series and 12V cruiser run them in parallel.

And I'm suspicious of the wiring diagram too..

 

[HJ61 12HT]

That drawing has never made sense to me either, I figure there is two 12v elements, so if you have a 24volt cruiser they are wired in series.
My cruiser only has one big relay to switch it on, not the two as in the drawing...

 

[amauri]

Thanks for the info.

So... when it's really cold you would activate both screens?
On the factory installed automatic system, when you first turn on the key you are acticating both screens until the glow light turns off. Then when you start the engine, the system continues running one screen for a few minutes until the right temperature is reached. This is called "afterglow"

I have that schematic but something doesn't add up.
Looking at your first photo, you can see a red wire and a black wire.
Don't remember without looking inside but when you apply 24v to one wire you are heating both screens. If you apply 24v to the other wire you are only heating one screen.
On the front side of the heater you can see that the red wire connects to both screens thru a jumper strap.
If you remove that jumper strap you can control the screens individually, that's what I did on mine.

Is each screen 24V or are they 12V each wired in series?
Each screen is 24v on a 24v system.
The 12v screens are much smaller and not very effective in really cold climate.

Does each post go directly to each screen then the screen are grounded in the intake?
Yes, one end of each screen is crounded to the manifold or screen frame.

 

[lostmarbles]

But then I really know nothing about these things..

I suppose you've seen these threads ....

https://forum.ih8mud.com/diesel-tech-24-volts-systems/199401-12ht-please-help-identify-parts.html

https://forum.ih8mud.com/diesel-tech-24-volts-systems/267396-12ht-glow-wiring.html

http://www.4wdaction.com.au/forum/viewtopic.php?f=68&t=130624

But after studying them I'm still left in a confused state...

Good luck..

 

[lostmarbles]

...On the factory installed automatic system, when you first turn on the key you are acticating both screens until the glow light turns off. Then when you start the engine, the system continues running one screen for a few minutes until the right temperature is reached. This is called "afterglow"

Looking at your first photo, you can see a red wire and a black wire.
Don't remember without looking inside but when you apply 24v to one wire you are heating both screens. If you apply 24v to the other wire you are only heating one screen.
On the front side of the heater you can see that the red wire connects to both screens thru a jumper strap.
If you remove that jumper strap you can control the screens individually, that's what I did on mine.

Each screen is 24v on a 24v system.
The 12v screens are much smaller and not very effective in really cold climate.

one end of each screen is crounded to the manifold or screen frame.

Wow. Great info Amauri.

I'm sorry for butting into your thread Crimson (and contributing nothing other than confusion). But I often can't control myself when I see an interesting topic being raised again that left me in confusion when it had been discussed previously.

Up until your post here Amauri, I had been assuming the same intake heater was used in both 12V and 24V cruisers (but just got wired differently for each application).

And the epc confirms what you're saying (ie. that the 12V and 24V intake heaters are two very different items) as shown here with the 12V version being the ARL (Australian) one in the inset:



But what are you calling a "jumper strap"?

If it is the thing I have circled in red, then Toyota call that "INSULATOR, INTAKE HEATER TERMINAL" which is an odd description for a JUMPER. (And if it was indeed a "jumper"you would never be able to control each element separately anyway. But then the other side of the coin is "If it isn't a jumper then why is it joined and not two separate insulators?")

And am I reading this correctly that both elements of Crimson's intake heater are earthed/grounded (to the manifold) internally and the black wire goes to the other end of one element with the red wire going to the other end of the other lement and that both elements are equivalent in heating power?


I feel I'm really getting somewhere in understanding these 12HT intake heaters now ...

 

[Lasse]

If it is the thing I have circled in red, then Toyota call that "INSULATOR, INTAKE HEATER TERMINAL" which is an odd description for a JUMPER. (And if it was indeed a "jumper"you would never be able to control each element separately anyway. But then the other side of the coin is "If it isn't a jumper then why is it joined and not two separate insulators?")

If it contains a diode it could just as well be named an insulator. It insulate the current in one direction and let it flow freely in the other. This way you can either run one glow screen or both depending on which cable you are applying current to.

Using a diode will lower the voltage on one of the glow screens by ~0.7v if it is made out of silicium.

 

[lostmarbles]

If it contains a diode it could just as well be named an insulator. It insulate the current in one direction and let it flow freely in the other. This way you can either run one glow screen or both depending on which cable you are applying current to.

Using a diode will lower the voltage on one of the glow screens by ~0.7v if it is made out of silicium.

Thanks Lasse. Pity I don't have an HJ61 to run some tests on.

(I never thought of that.)

 

[maat]

if you were to remove this pre heat element in a warmer climate would it let the engine perform better? rathrr than restricting the intake?

 

[amauri]

The diagram from the 12H-T manual maybe a little confusing but it is correct, and that's why I always need to touch and feel things before I can figure it out.
Attached is a photo of a spare intake heater I just happen to have in my parts shed.

There are no diodes and removing the heater will not result in any performance gains.

 

[bj40green]

Diodes come in many forms and shapes and are sometimes not recognizable as a diode.
A simple ohm test performed on the strap will tell if it's a "strap" or a "diode".

Rudi

 

[amauri]

In my post #6 above, I incorrectly stated that "one end of each screen is grounded to the manifold or screen frame"
That is not completely correct as you can see from my photo on post #12.

When 24v is applied to the black wire, both screens glow red hot, think of it as two big resistors connected in series.
When 24v is applied to the red wire, only one screen will glow as there is no ground to the second screen.

I know what a diode looks like and I also know how to use my VOM.
Let me say it again "there are no diodes"

 

[Crimson Cruiser]

That's awesome, thank you!

This leads me to believe that Red wire activates both screens for "cold start up" and the Black wire is just for one screen for the "Afterglow"


I ended up ditching the Hella Relay and tapping into and using the Stock HJ60 24V Glow Plug Relay. This relay is weather proof and has a high current rating that the Hella... and the engine bay retains it's stock apperance.

I'll post up pictures and a diagram for others to see.

 

[amauri]

This leads me to believe that Red wire activates both screens for "cold start up" and the Black wire is just for one screen for the "Afterglow"

Sorry if I didn't explain it very well, but it is the other way around.

Black wire turns on both screens.
Red wire turns on only one screen.

Reading section EM-13 in the 12H-t manual, you can see that the automatic system turns on solenoid #1 for 14-seconds during pre-start heating and up to 70-seconds with solenoid #2 for afterglow once the engine is running.

 

[bj40green]

Hi Amauri,

Just to get my documentation straight...
Can you check both pictures for correctness? please?




If the 2 pics above are correct than this should be the 12V version based on the ARL picture from Tom .


Rudi

 

[amauri]

Rudi,

I can't say for sure because I've not seen a 12v heater, but I think your modified drawings looks correct.
Thanks for the drawing, that makes it easier to understand.

 

[Dieseler]

Has anyone compared the wiring diagram to a 13BT diagram since they both use a screen and are 24V system.
I still can't get my head around how 24V is being reduced to 12V for each side of the screen what would be the purpose why would it not just use the full 24V like a 24V GP system.

 

[amauri]

I still can't get my head around how 24V is being reduced to 12V for each side of the screen what would be the purpose why would it not just use the full 24V like a 24V GP system.

I don't think they are being reduced to 12v for each screen.
They are both running at 24v.

The 12v version of the heater uses a single and smaller size screen compared to the 24v screens.