This is how I improved upon the stock Glow Plug System in my 70 Series Landcruiser.
I was finding the stock glow plug system wasn't warming the glow plugs long enough during cold weather.
First I dismantled a Battery Voltage Readout LCD I bought from Princess Auto (Schumacher Brand) and it replaced my now extinct adjustable suspension button:
Now I can see in real time, all the time what my battery is doing, and I can tell what the glow plugs are doing based on the voltage readout.
Some gents have recommended a light that is in parallel with the glow plugs.
This is also a good way of knowing if your glow plugs are working properly but a voltage readout offers more information on your entire system.
After that I ran a #16 AWG sized wire from No.1 Glow plug relay to one side of my momentary push button ( I actually pushed 5 spare wires through the firewall for future mods)
I use wire loom for all my cabling, it is cheap and offers extra protection against abrasion from vibration:
Cut into the glow plug light and momentary pushbutton:
By wiring it this way, the current Toyota "Superglow" system is intact and it is safer to operate the momentary push button because all the glow plug current doesn't have to go through the switch.
Also, using the existing No.1 relay, the switch can only be operated with the key in the "On" or "Start" position.
You don't want children or curious friends able to energize the glow plugs without the key in the ignition. Kids love to push buttons!
If you will be using this method to override your glow plugs, it's important that the rating of your glow plugs is above 10VDC operation.
You can prematurely burn out your glow plugs if excessively glowing the OEM 6VDC rated glow plugs.
Test for correct operation:
When you first turn your key to "ON", the Toyota Glow timer will energize No.1 Glow Relay which sends 12VDC across the glow plugs.
This provides maximum Wattage (Heat). This will typically be on for about 3 to 4 seconds before the timer disable No.1 Glow Relay.
After No.1 Glow Relay de-energizes, No.2 Glow Relay will energize. No.2 Glow Relay will provide 6VDC across the glow plugs for a much longer amount of time.
6VDC across the glow plugs will generate 1/4 of the Watts (ohms law).
Eventually the timer de-energizes No.2 glow relay and the engine will be running nice and warm.
During this entire process you can use the momentary pushbutton you installed to place 12VDC across the glow plugs longer than the Toyota Timer does.
If it is cold outside and superglow is only activated by the Toyota timer for 3-4 seconds, use your momentary switch to superglow for a bit longer.
It is recommended to superglow in durations of 5 second on-off intervals. Pushbutton for 5 seconds, then off, again for another 5 seconds and attempt starting engine.
If the engine starts, give the momentary button an additional superglow if the engine is sputtering until it runs smooth.
Be conservative with your pushbutton. 15 seconds should be the maximum time under the coldest conditions that you should be pushing it in.
You may drain your battery or prematurely wear out your glow plugs.
Here is a diagram I put together based on my own troubleshooting experience:
Sequence of operation review:
The graphs show what the timer aims for in timing depending on temperatures. It seems Super glowing (12VDC) a few more seconds than the OEM timer improves start up of the vehicle.
So in theory 12VDC on a 11VDC rated glow plug will produce approx. 500 Watts.
When the timer drops to 6VDC (after only 3 seconds) only 1/4 the Wattage will be produced (ohms law).
So say that two glow plugs are dead, you will get only 250 Watts for the first three seconds (Superglow 12VDC), and then a mere 62.5 Watts for the remainder (Afterglow 6VDC).
So I guess a combination of a shortened glowing period and 1 or 2 dead plugs can lead to a pretty cold engine start!
Cheers!
I was finding the stock glow plug system wasn't warming the glow plugs long enough during cold weather.
First I dismantled a Battery Voltage Readout LCD I bought from Princess Auto (Schumacher Brand) and it replaced my now extinct adjustable suspension button:
Now I can see in real time, all the time what my battery is doing, and I can tell what the glow plugs are doing based on the voltage readout.
Some gents have recommended a light that is in parallel with the glow plugs.
This is also a good way of knowing if your glow plugs are working properly but a voltage readout offers more information on your entire system.
After that I ran a #16 AWG sized wire from No.1 Glow plug relay to one side of my momentary push button ( I actually pushed 5 spare wires through the firewall for future mods)
I use wire loom for all my cabling, it is cheap and offers extra protection against abrasion from vibration:
Cut into the glow plug light and momentary pushbutton:
By wiring it this way, the current Toyota "Superglow" system is intact and it is safer to operate the momentary push button because all the glow plug current doesn't have to go through the switch.
Also, using the existing No.1 relay, the switch can only be operated with the key in the "On" or "Start" position.
You don't want children or curious friends able to energize the glow plugs without the key in the ignition. Kids love to push buttons!
If you will be using this method to override your glow plugs, it's important that the rating of your glow plugs is above 10VDC operation.
You can prematurely burn out your glow plugs if excessively glowing the OEM 6VDC rated glow plugs.
Test for correct operation:
When you first turn your key to "ON", the Toyota Glow timer will energize No.1 Glow Relay which sends 12VDC across the glow plugs.
This provides maximum Wattage (Heat). This will typically be on for about 3 to 4 seconds before the timer disable No.1 Glow Relay.
After No.1 Glow Relay de-energizes, No.2 Glow Relay will energize. No.2 Glow Relay will provide 6VDC across the glow plugs for a much longer amount of time.
6VDC across the glow plugs will generate 1/4 of the Watts (ohms law).
Eventually the timer de-energizes No.2 glow relay and the engine will be running nice and warm.
During this entire process you can use the momentary pushbutton you installed to place 12VDC across the glow plugs longer than the Toyota Timer does.
If it is cold outside and superglow is only activated by the Toyota timer for 3-4 seconds, use your momentary switch to superglow for a bit longer.
It is recommended to superglow in durations of 5 second on-off intervals. Pushbutton for 5 seconds, then off, again for another 5 seconds and attempt starting engine.
If the engine starts, give the momentary button an additional superglow if the engine is sputtering until it runs smooth.
Be conservative with your pushbutton. 15 seconds should be the maximum time under the coldest conditions that you should be pushing it in.
You may drain your battery or prematurely wear out your glow plugs.
Here is a diagram I put together based on my own troubleshooting experience:
Sequence of operation review:
- Water Temperature Sensor (thermistor) tells Pre-Heating Timer how long to run No.1 and No.2 glow plugs.
- Key to "ON" : No.1 Relay sends 12VDC to glow plugs giving it initial "Superglow" for a short period. (Around 3-5 seconds)
- Pre-Heating Timer shuts off No.1 Relay and energizes No.2 Relay.
- No.2 relay runs glow plugs at 6VDC to aid in the start up and continue warming up the engine. (Runs for a while depending on Water Temp. Sensor).
- After everything is satisfied the Timer shuts off all Voltage to the glow plugs.
- When you push the momentary switch, you are basically running the "Superglow" No.1 Relay longer than what the Pre-Heating Timer determined.
The graphs show what the timer aims for in timing depending on temperatures. It seems Super glowing (12VDC) a few more seconds than the OEM timer improves start up of the vehicle.
So in theory 12VDC on a 11VDC rated glow plug will produce approx. 500 Watts.
When the timer drops to 6VDC (after only 3 seconds) only 1/4 the Wattage will be produced (ohms law).
So say that two glow plugs are dead, you will get only 250 Watts for the first three seconds (Superglow 12VDC), and then a mere 62.5 Watts for the remainder (Afterglow 6VDC).
So I guess a combination of a shortened glowing period and 1 or 2 dead plugs can lead to a pretty cold engine start!
Cheers!
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