BJ70 '85 Thermo Switch (1 Viewer)

[LostinDartmouth]

Hey 70's.
Figuring out the Thermo Switch on the BJ70. It was unplugged since I bought the truck. Orange arrows show two-pronged plug and socket. Located right beside the Water Temp sensor - Yellow Arrow. Curious if someone could help me understand its role in heat management of the engine?
Also, the previous owner had a separate switch installed on the dash to activate the heater relay, apparently to resolve cabin-low-heat issues in winter. Would you know if the ThermoSwitch is somehow linked to the heater relay? Thanks for the insight.

 

[jblueridge]

I think the orange arrows are pointing at the temp sensor wires that trigger glow plug action.
Maybe the dash switch you mentioned is a glow plug on demand switch and the factory’s sensor has been disabled.

 

[LostinDartmouth]

Hello jblueridge. I think you nailed it. In addition to the Heater Relay switch, yes, there is an additional aftermarket switch on the dash to manually activate the glow plugs. Thanks. Will leave it unplugged for now.

 

[jblueridge]

I recognized the green connector on the right. Mine fragmented when I disconnected it from the sensor.

 

[ToyotaMatt]

Hey 70's.
Figuring out the Thermo Switch on the BJ70. It was unplugged since I bought the truck. Orange arrows show two-pronged plug and socket. Located right beside the Water Temp sensor - Yellow Arrow. Curious if someone could help me understand its role in heat management of the engine?
Also, the previous owner had a separate switch installed on the dash to activate the heater relay, apparently to resolve cabin-low-heat issues in winter. Would you know if the ThermoSwitch is somehow linked to the heater relay? Thanks for the insight.
View attachment 2895951

I think the orange arrows are pointing at the temp sensor wires that trigger glow plug action.
Maybe the dash switch you mentioned is a glow plug on demand switch and the factory’s sensor has been disabled.

i have this Repair KIT now

includes the GREEN plug Sender sensor and the harness side connector and a new crush ring too

OEM GENUINE NipponDenso / DENSO 3FE PLUG and PLAY Repair KIT Sensor, Sender Water Temperature (For E.F.I.) Comes With Repair Connector Seals & Extra Terminals Fits 85 - 7/88 FJ62 USA & Canada Spec. & 3B, 3FE 3B, 3FE; BJ70LV-MNK BJ70LV - Vintag

- OEM Genuine NipponDenso / DENSO - DOES come with OEM Copper crush ring gasket - DOES Comes with OEM Repair...

vintageteqparts.com

 

[LostinDartmouth]

Thanks Matt. However, I wasn't looking to replace the sensor, but to understand its function related to heating relay and/or glow plugs.

 

[ToyotaMatt]

Thanks Matt. However, I wasn't looking to replace the sensor, but to understand its function related to heating relay and/or glow plugs.

do u simply need a period correct FSM EWD diagram ?

 

[LostinDartmouth]

Not familiar with FSM EWD. Stands for....

 

[ToyotaMatt]

Not familiar with FSM EWD. Stands for....

FSM - Field Service Manual / Field Shop Manual

EWD - Electrical Wiring Diagram



I think …......

This is the correct EWD or at least a generalized version that may assist you in helping to understand its function related to heating relay and/or glow plugs.

 

[LostinDartmouth]

Very much appreciated. I do have both of these already and they are incredible resources. Thanks for reaching out.

 

[ToyotaMatt]

Very much appreciated. I do have both of these already and they are incredible resources. Thanks for reaching out.

your welcome ,

if you need a base line reading for example , of that green plug sensor , u have unplugged ?

please don;t hesitate to ask , i will be happy to assist you with that

using one of my NOS ones i have

kindly matt

 

[Irish11]

Anyone have a source for the other end of the connector? I have the sensor in place, but someone cut off the connecting plug on mine unfortunately. I traced the wires back last night and found them. Wondering if this might be a partial cause for my white smoke on startup.

 

[jblueridge]

I bought one maybe 2 years ago. I can't recall where online.
I do remember that it was used on many Toyota car models in the 80's.
Sometimes it is named Oil Temperature Sensor.
Maybe there's a junkyard near you with Corollas going back to 1985?

 

[Irish11]

Found one. "Coolant Temperature Sensor Connector Repair Pigtail Fits Toyota" Thanks!
Amazon product ASIN B01EENEJ8M

 

[jblueridge]

Be careful. Might not be right. Check your sensor.
The notch or slot at the bottom of the plastic housing is off-center on my plug.
My replacement is red if that helps at all.

 

[Irish11]

It is showing two different photos which is strange. One symmetrical and one asymmetrical. The left one should be correct:

 

[jblueridge]

That’s a different shape than mine. But then mine’s 1988.