WATER TEMP SWITCH female side of harness connector (upper thermostat housing) (1 Viewer)

[88Retired62]

The thin wire pulled out of sealed female side of the connector. Of course the connector is NLA for the FJ62. This has to be a common problem for us FJ62 owners. Just a few questions for those of us who have experienced this problem.

1. Describe the purpose of the WATER TEMP SWITCH? What does it control?

2. What happens if the vehicle is operated without the switch connected?

3. Is there an aftermarket switch (female housing) that can be substituted for the NLA part?

 

[OSS]

Someone more familiar with the 3F-E will likely set your questions straight, but I believe the water temp switch is used by the ECU as an input to control engine functions. A/F ratio for one. When the ECU knows the engine is cold, it can adjust "stuff" to help it run better. The other water temperature sender is used for the gauge.
I'm sure Toyota designed in a fail safe mode for a broken connector to the water temp sender, possibly with the only downside being that the engine doesn't run as efficiently when cold.

 

[89BIGBLUE]

You might be able to remove the pin from the plastic of the female side, and repair or rig up a another female connector, that may or may not fit back in the plastic.
When my sensor went out, it was finicky to start and it gave me the check engine light. OSS is onto it.
I think it tells the ECU info to control fuel/air for startup and running.

 

[Prairie Swamp]

I just had to take apart my housings due to a bad sensor on the lower housing. I believe there are 4 or maybe 5 sensors in total - someone posted a labeled picture on here somewhere. Which sensor specifically has the issue?

Thinking out loud - there are: Coolant temp input to the ECU (lower housing), cold start injector timer switch, sensor for the in dash gage, and....

 

[Prairie Swamp]

No the diagram I was looking for but here's some pics:

Thermostat housing questions?

The other one is a BVSV for EGR maybe - obviously not an electrical sensor.

 

[Prairie Swamp]

It was our very own @OSS that posted the excellent pic I was looking for.

FJ62 Temperature Sensor Question

 

[88Retired62]

I believe you’re spot-on, OSS & BIGBLUE. The already low gas mileage has headed even further south since the wire break. Just one of the myriad of switches born on the eve of the EFI revolution

 

[88Retired62]

View media item 59078

 

[Prairie Swamp]

I know the green one on the right is a variable resistor that feeds coolant temp to the ECU. This is what failed on mine went open circuit making the ECU think it was -40 degrees outside.

The single wire sensor on the upper left is a on-off switch at some set temp. Not sure what the ECU uses it for maybe EGR. Being in the upper this will only see coolant flow when the t-stat is open. Hopefully you can find a replacement connector or get it wired up somehow.

 

[88Retired62]

Sorry ‘bout the photos gentlemen. I haven’t the slightest idea as to how that happened?

 

[89BIGBLUE]

Sorry ‘bout the photos gentlemen. I haven’t the slightest idea as to how that happened?

I thought it meant that you had fixed the problem, and the rig was on the road=cabinet and driveway empty!