86 22re 4wd thermal temp switch........

[emsvitil]

What does it do?   

I have the 86 factory manual, and from that I've determined that it's an on/off temp switch in the thermostat outlet housing that goes to the ECU and only exists in 4WD models. (no determination of only manual transmission (I have manual, so it exist with manual) or both auto and manual)

Other than that, there's no testing procedures for it, and whether the switch is closed hot or cold.

Looks like it tells the ECU that the thermostat has opened up by either turning on or off........ (and only for 4wd models)

What would the ECU use this information for ?


Just curious......

[KDXSR5]

Are you talking about the thing I circled (below)? My truck had the wire snapped for a few months, and when I fixed it I didn't really notice any difference. I think it may have something to do with changing the ECU from open loop to closed loop, but I am not sure.

[emsvitil]

Yep, that one...........

[shmedly]

Some one correct me if I'm wrong....I'm pretty sure what you circled is the temp sending unit. It's for your temp guage. I believe the sensors your talking about are under the temp housing with  green and brown connectors. Those tell the ECU the info it needs..

[emsvitil]

It's not the temp sending unit for the gauge.   The temp sending unit for the gauge is under the manifold on the block

I know about the green and brown connectors...... One's the ECU temp sensor the other's for the cold injector.

[KDXSR5]

The one I circled is not for the gauge If I remember correctly, the one I circled is a single wire gauge. Single wire sensors create a self generating signal that goes back to the ECM. What the ECM does with that self generating signal is a mystery to me. I have only seen it on 85 and 86 trucks, my 88 did not have it and my 90 does not have it.

[emsvitil]

According to the wiring diagram, the one your circled on top is a on/off switch, not really a sensor......   

It either turns on or off once a certain temperature is reached.    But I can't find any specs on what that temperature is or if it's on or off.

[KDXSR5]

I still think it tells the computer when to go from open loop to closed loop. I did notice bad MPG with it unplugged, meaning that maybe my truck was staying in open loop so it would not change the fuel in accordance with the sensors feeding into the sensor.

[sixonthefloor]

Whats circled is the temp sending unit