Help needed understanding the different HZJ75 Glow Plug Systems (1 Viewer)

lelandEOD

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I have a 1HZ pulled from a 12V Canadian mine truck I plan to use in my FJ40. Oneof the challenges I have to solve is that the wiring harness in the donor truck was completely swapped out with a custom-made job when and when it was converted for mine use. As such, I need to retrofit an entire 1HZ engine wiring harness and install a glow plug system that would've been found on the HZJ75. I have found a dismantler in Australia who can supply me with a used HZJ75 wiring harness as well as the glow plug relay and timer assemblies.
Before I get too far into this, I wanted to reach out to you guys to get a better understanding of how the glow plug system on these trucks was designed to work. From what I've been able to decipher from the factory manual, it appears there were two separate glow plug systems offered to the Australian market: a fixed delay timer system and a super glow timer system.


The factory schematics indicates that the super glow system utilized two separate relays, a temp switch, and a glow plug resister that work with the glow plug timer module, whereas the fixed delay timer system only uses one relay. Am I on the right track so far? I don't want to order the wrong stuff since shipping from Australia is not an inexpensive affair.

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The HZJ75 harness I am getting appears to have the super glow system as I can see that the timer module has 8-9 wire leads and I think he can supply the two relays as well. I just want the glow plug system to be as close to stock as possible.



Last question: Why did Toyota offer two different glow plug systems for the same market? I'm guessing the super glow system controls the amount of glow under different environmental and engine temp conditions - and presumably results in marginally longer glow plug life?
 

mudgudgeon

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My guess is the top one was superseded, or intended for mine spec vehicles. Top one shows a basic start switch vs a more typical ignition switch for the second.

second system will alter glow time depending on coolant temp
 

lelandEOD

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Thanks for the replies guys! I looked at the Bogaard system a couple weeks ago but ultimately decided to retrofit everything back to a factory configuration. I understand that a lot of aftermarket systems are probably superior to the 20+y/o factory equipment but I’m just that hardheaded and everything I’ve done to this truck has put emphasis on configuring it in a to way Toyota would’ve done it from the factory.

I went ahead and bought the HZJ75 harness and glow timer/relays so hopefully I’ll have it in a week or two.
 
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Superglow is superior in cold climates. You'll be good to go as long as the relays are healthy and the temp sensor is the right one. on mine the actual wiring connectors needed some cleaning to rid some extra resistance and it works really well. Like half a second of cranking at 20F well.
Just make sure you use the correct plugs for a 12v Superglow system.
 

lelandEOD

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Superglow is superior in cold climates. You'll be good to go as long as the relays are healthy and the temp sensor is the right one. on mine the actual wiring connectors needed some cleaning to rid some extra resistance and it works really well. Like half a second of cranking at 20F well.
Just make sure you use the correct plugs for a 12v Superglow system.
It’s quite cold here in Northern Nevada so I think it’s the best bet. Since the truck already has a 12V system, shouldn’t the glow plugs I have work fine?
 
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You should check the plugs. Factory 12V superglow uses 6v plugs to get hot faster then slow glow at 12v for a duration depending on how warm the coolant is. If they are 8.5 it was setup with a standard glow controller. 10v was for fixed delay. If it's a really early 1HZ it can come with 11v plugs for fixed delay.
 

lelandEOD

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Awesome info, thanks. Are they marked somehow to identify them? Plugs aren't super expensive so definitely not a deal breaker. Where do I find a part number for the correct 6v plugs, if I need them?
 
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All the 7* and 80 series in Australia use this part number for the 1HZ glow plug 19850-64031 12v - 11v from 90-99.
The Coasters were all 24v
After 99 there doesn't seem to be a 78/79 listed for Australia, maybe they were all GEN
These were using ( I don't know why they call them a boost ventilator)
19850-17020 BOOST VENTILATOR-GV=12V-11V

The cold climate markets all seem to be using 24v in the 7* series.
 

BreckenridgeCruiser

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You might save some case and just put in a wilson switch. I have an HZ in my BJ44 that came from a superglow HZJ75. My BJ44 was also superglow, but I didn't want to try to make the systems try to play nicely together. I instead used one of my glow relays to be excited by a manual switch in the cab, and swapped out the super glow rated plugs for the correct ones for getting 24v to them.

Let me know if you want to see pictures or discuss the setup. If not the super glow is nice, but not superior to standard glow. it just super heats the plugs for a few seconds and lets you start the truck sooner. The secondary glow is to smooth out the idle as the cylinders warm up....

I liked my superglow, but I had a healthy system. It is a bit complex if something goes wrong as you have the computer reading resistance and such to know when to stop the primary and kick in the secondary...
 

Mr Cimarron

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Looking at the photos of the interior of the truck it has the sticker that states “Glow Plugs. Push and hold max 7 seconds”. That makes me think it had some sort of Wilson switch type wiring installed.
 

lelandEOD

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I'm sure they used something akin to the Wilson switch as there are two starter solenoids on the DS fender that fire the glows. I'd like to have it as closely wired as possible to the factory to ease future troubleshooting.

I hope to have the engine out soon. Then the hulk is off to it's new home in Texas. I sure hope I can find a way to manipulate the steering once the engine is out...:eek:
 
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I'd like to have it as closely wired as possible to the factory to ease future troubleshooting.

It would be much easier to wire in an aftermarket timer.
The factory systems were designed for owners who knew little about diesels. They were trying to make the cold start procedure as simple as a petrol engine car.
I've been looking at the factory glow system for a decade and still don't fully understand it. But that Bogaard timer is a lazy afternoons work. And you can program it to suit local temperatures from season to season and fit the timer where its easily accessible.
That's what Ill be getting if my OEM glow system dies.
 

Mr Cimarron

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I’ve never tried it but if you disconnect the steering linkage to the axle/wheels you may be able to turn the wheels by hand?
 

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