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Two Temp Probes/Sensors around Thermostat - 22RTE

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Old Nov 9, 2017 | 05:20 AM
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Two Temp Probes/Sensors around Thermostat - 22RTE

On my last two ‘87 Turbos (both with A/C) one of these two temp probes/sensors seems to always be unhooked. See pic below - the one closest to the front clip is not being used in my current ‘87. Where do these two go? Is it fine for the one I show to be unhooked? How would I fix it if it needs to be hooked up.

This is one is an automatic and previous one was a manual of that helps.

Thanks.
Attached Thumbnails Two Temp Probes/Sensors around Thermostat - 22RTE-d5a13c5f-fcbb-4cc2-ad92-b955e8908dd8.jpeg  
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Old Nov 9, 2017 | 06:57 AM
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From: nh
a FSM would likely help you answer many of these questions.
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Old Nov 9, 2017 | 10:29 AM
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on my '86 non turbo, i have one (as do any other 22re's). it's for the temp guage..the sending unit. is your temp gauge in the cab working?
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Old Nov 9, 2017 | 12:09 PM
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Originally Posted by thook
on my '86 non turbo, i have one (as do any other 22re's). it's for the temp guage..the sending unit. is your temp gauge in the cab working?
Yes, temp gauge on digital dash works fine. So I'm guessing just having the rear one connected is fine and the front one simply isn't used on my 22RTE?
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Old Nov 9, 2017 | 12:53 PM
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From: nh
Originally Posted by Charles4x4
Yes, temp gauge on digital dash works fine. So I'm guessing just having the rear one connected is fine and the front one simply isn't used on my 22RTE?
clearly you're guessing. why would toyota include an unused temp sender on any production vehicle, instead of a pipe plug?
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Old Nov 9, 2017 | 12:54 PM
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Originally Posted by wallytoo
clearly you're guessing. why would toyota include an unused temp sender on any production vehicle, instead of a pipe plug?
Agreed, but not helpful.
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Old Nov 9, 2017 | 01:27 PM
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Originally Posted by wallytoo
a FSM would likely help you answer many of these questions.
This ^^^

I don't have a turbo so I would not know, either, but Charles4x4, I notice another one of those butt-splices. I strongly recommend you replace them with "parallel" crimp splices. They're called "butt" for good reason; They do not belong on a Toyota.

Last edited by RAD4Runner; Nov 9, 2017 at 01:28 PM.
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Old Nov 9, 2017 | 01:32 PM
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Originally Posted by thook
on my '86 non turbo, i have one (as do any other 22re's). it's for the temp guage..the sending unit. is your temp gauge in the cab working?
This is incorrect I believe..

There are four temp sensors, some are senders (voltage/resistance change depending on coolant temp), some are switches (on/off depending on coolant temperature).

They are easy to identify by the location and plug type.

On the front side of the intake is the cold start time switch, two wires. On the top of the thermostats housing are the EFI TSW (water temp s/w), a​​nd AC cutoff switch. In between the lower intake runners is the gauge sensor/sender

Originally Posted by Co_94_PU
Here is the pictures from the wiring book.



Also the A/C one is not part of the EFI harness, the A/C cowl harness follows along side the EFI harness and goes under the throttle body near the THW sensor wire. The TSW is part of the EFI harness and exits the loom under the plenum near the aft injector wires and gauge temp sender.
These are on the thermostat housing.

Originally Posted by Co_94_PU
Here is one from Terrys87 85 build, don't worry pretty sure thats a 89+ engine from his brothers truck, it has a good angle.
Attachment 168015



Last edited by Co_94_PU; Nov 9, 2017 at 01:42 PM.
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Old Nov 9, 2017 | 02:07 PM
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Originally Posted by wallytoo
a FSM would likely help you answer many of these questions.
Had one, but gave it to the guy who bought my previous ‘87. Need to get another one.
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Old Nov 9, 2017 | 02:33 PM
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Originally Posted by Co_94_PU
On the front side of the intake is the cold start time switch, two wires. On the top of the thermostats housing are the EFI TSW (water temp s/w), a​​nd AC cutoff switch. In between the lower intake runners is the gauge sensor/sender


These are on the thermostat housing.
right. my bad. i recalled incorrectly
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Old Nov 10, 2017 | 01:54 AM
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From: nh
Originally Posted by Charles4x4
Agreed, but not helpful.
it is, in the context of having the FSM, which will probably solve the mystery of what the senders/sensors do.
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