pre-heat light not on

[calsbeek]

Mornings are getting colder.
My light has never come on, but I'm wondering if the bulb is just bad or if this means the glow plugs aren't functional either?

I assume the lamp should always come on as the ignition key passes through the first click. Is that right?

 

[JimmyPrado]

Yup

 

[calsbeek]

so I changed out the bulb with one I know to work (it works in another socket) and the light still doesn't come on with the key in the "on" position. Do the glow plugs only work when the temperature dips below some threshold or am I screwed with winter coming?

Or might they be working and the light just doesn't work?

argghhhh

 

[Dprio34]

If you have a super glow system, I'm pretty sure everything is timed.

 

[JimmyPrado]

I'm no expert, but, mine always comes on regardless of outside temp. It is possible that they are working but the message isn't getting to the bulb due to a wiring issue. I think you can check the glow plugs with a meter, they should read 11 volts I believe, but, you will need to have someone else turn the key. One with more knowledge should confirm this.

 

[Dprio34]

Heck, I by-passed my Super-Glow System with a Wilson Switch, and my light still comes on when it is 117 degrees F outside.
Go figure.

 

[calsbeek]

forgive me. I don't know what "super-glow system" means
I have a 1986 BJ74 with a 13BT

 

[Dprio34]

Super Glow is a timed system that sends voltage to your glow plugs prior to start up and after. (not temperature based). I'm pretty sure whatever glow plug voltage controller you have, is time based. Just trying to help with your question. There is no outside air temperature threshold input that I am aware of.

 

[Dprio34]

Calsbeek,

lostmarbles, posted a great article on glow plugs a while back in 2011, you may want to read. "Which plugs should I be running". It talks about the different GP controllers and the various GPs that each engine should be running based on what system you have.

Apr 2, 2011

 

[Mookies]

Super Glow works with input from the water temp sensor and measures current draw of the plugs during the timed cycle.. If the temp sender or alternator wiring are faulty the system will not work correctly. There is a good thread explaining the system here....Super Glow - explained There are two solenoids controlled by the sending unit. If it's warm the controller still gives the few seconds of fast initial glow but hardly any after glow. My system is working normally and my dash light only ever registers the quick initial glow. Check the bus bar connecting the glow plugs for current. You should hear an audible clunk from the solenoids under the hood. A wilson switch is a good way to eliminate the expensive parts but the system is pretty robust and easy to diagnose with a FSM. The dash light can be somewhat misleading but make sure current is getting to the plugs first.

 

[Dprio34]

Mookies, just to confirm. Regardless of outside temp, Super Glow will send the same voltage to the plugs on start up, and it will vary the voltage sent to the GPs during the warm up period based on coolant temp?

 

[Mookies]

Thats my understanding. it also keeps the voltage regulated over a long afterglow so as not to draw the batteries down. Pretty ingenious system actually. If all the parts are healthy it means a quick bump of the starter fires up my 1PZ cold. If any of the components are faulty, specifically the solenoids themselves, the current won't reach the plugs. You can also manually control the initial glow relay if you tap into the #5 wire out of the back of the controller.

 

[Dprio34]

Thanks for that! Yeah, hats off to the guys that came up with it.

 

[calsbeek]

I've read the "what plugs should I be running" thread and also this one:
13BT cold start procedure
The second thread suggests that my BJ74 with a 13BT engine doesn't have the same glow setup and may not glow at all if it isn't cold out?
I'll have to check the current to the bus bar as Mookies suggested.

 

[coldtaco]

I've read the "what plugs should I be running" thread and also this one:
13BT cold start procedure
The second thread suggests that my BJ74 with a 13BT engine doesn't have the same glow setup and may not glow at all if it isn't cold out?
I'll have to check the current to the bus bar as Mookies suggested.

You know the 13bt doesn’t have glow plugs,right? Don’t know how the screen works.

 

[Mookies]

Forgot about the screen! Although the screen timer works via a temp sensor as well. The screen is basically a huge "glowplug". Easy to test for current from the timer to the solenoid and then the screen.

 

[calsbeek]

OH boy , the plot thickens.
No glow plugs? BUt I still have a pre-heat light and I have what look like 2 relays under the hood near the battery (part #
28610-58040) which toyota lists as "28610 RELAY ASSY, GLOW PLUG"

???

 

[JimmyPrado]

And, the one with more knowledge has arrived. . LOL

 

[coldtaco]

OH boy , the plot thickens.
No glow plugs? BUt I still have a pre-heat light and I have what look like 2 relays under the hood near the battery (part #
28610-58040) which toyota lists as "28610 RELAY ASSY, GLOW PLUG"

???

Yeah no glow plugs for the 13bt, glow screen. The 1HD-FT has screen also.

 

[calsbeek]

am I correct to assume then, that I may be entirely premature in thinking my glow-screen (?) isn't working if it, in fact, only activates at tempertuares below some threshold (looks like 35 deg. F)?