Temp sensor wires? (1 Viewer)

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Remind me as I no longer have me 'ol 2F, were did the temperature sensor wires run into the firewall? where was the connection between the sensor and any wiring harness?

Thanks,
 

Ming89FJ62

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You describing the temp sensor(s) for the coolant or the temp sensor that activates the carb cooling fan?
 
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On my '76 FJ40 the wire runs from the gauge cluster in a bundle of gauge wires into the main wire bundle behind the cluster. It leaves the main bundle and goes through the firewall high and just left of center. There's a spade terminal right there on the engine bay side, then an extension wire to the sensor.
 
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Is it a two-pole connector or single connector? My 1978 has a two pole connector coming high center of the firewall.
 

Ming89FJ62

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My 55 has two coolant temp sensors - one for the gauge the other for the emissions "computer". Both are single spade lug connectors that have a short common wiring harness from the top of the manifold running to the firewall (about the center of the truck). They then run through the firewall and into the gauge cluster and "computer".

Hope this helps.

Harry
 
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I am trying to plug the 3F-E's temp sensor into the 2F harness. I have a 2 pole connector just an inch to the passenger side of high center on the firewall. Any thoughts?
 
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Okay, everyone else has 1 wire with a green connector. Mine is a 12/77 and I have two pole connector. I'll post photos later. Strange...
 

Trollhole

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Two pole one is the carb switched power. Should be constant when the ignition is on.

The other I believe is the temp but I.m not sure. It could be part of the original carb or emissions if it was to the temp I couldn't get it to work so I just ran a new wire to the guage.
Best way to tell is first see if it has power. Second if no power switched or un switched is to ground it. If it's the temp wire it will peg the guage slowly.

at the H of hoses? right?

 
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3fj40 said:
Is it a two-pole connector or single connector? My 1978 has a two pole connector coming high center of the firewall.
You asked me this and I completely ignored you. What a bastid. Sorry.

I have a couple of single pole connectors. I suspect my wiring is the same as Ming89FJ62's - two temp sensors. I ripped the 2F out a long time ago and have only been using the coolant temperature circuit that runs to the gauge (sbc).

I used the wiring diagram and a multimeter to find the right one. The gauge panel has an electrical plug in the back of it. I found the pin on that plug that goes to the coolant temp gauge, then tested continuity from there to each of the connectors in the engine bay. The wiring diagram in Tech Links for a '78 says your wire is Yellow, but that looks more like someone's adaptation of the original. I can look at my Haynes manual for your truck and make a photocopy if you like.

(A one-wire sensor gets current thru the wire and grounds the circuit through the body of the sensor. In a two-wire sensor the current runs in from one wire, through the resistor (sensor), and back to a common ground thru the other wire. If you're trying to use a 2-wire sensor you can ground it wherever you like. Still have to find the right "input" wire though.)

HTH,
theo
 
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theo said:
The wiring diagram in Tech Links for a '78 says your wire is Yellow, but that looks more like someone's adaptation of the original.
In a '76 FJ40 harness, the temperature sensor wire is Yellow w/Red stripe in the main harness under the dash to the gauge however in the engine compartment, its a solid green wire. The wire's color change occurs at a connector under the dash. I looked and looked on this '76 to find the temp sensor wire looking for a Yellow/Red wire in teh engine compartment until I looked under the dash and found the right color and them traced it to the connector where it then turned to a green wire. I am about 99.9% sure this is way the Toyota ran the wiring on this cruiser.
 

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