If the temp sensor near the thermostat reads bad, would that potentially cause a high idle? I had a problem with the connection when I changed my Thermostat - the wire basically fell out of the thing, so I soldered it and then put some JB Weld around it to hold it all in place. When I drove it on Sat it was idling about 1200 RPM after being warmed up.

Recently had a new radiator and new thermostat after a minor overheating issue.

 

Well, there's 3 sensors close to around the t-stat. The single wire one facing up is for the guage; that one won't effect the running of the truck. Looking at the intake from the front of the truck, the one to the left is for the cold start valve; might make the truck hard to start, but otherwise should run fine. Now if the one to the right of that is broken, then yes, it will cause some problems. That's the one that sends the temp info to the ECU and controls fuel delivery, and timing if I'm not mistaken.

What do you mean reads bad, like with a mulitimeter? If it's physically broken, replace it regardless.

 

There are four for your year and earlier. Three of which iam' has named, however maybe incorrect on the location of one.....the sending unit....if I understand what is said correctly.

Anyway, are you talking about the sensor "on top" of the thermo housing?

This one?



The sending unit for the temp guage is between the upper manifold and the head.....mounted in the middle and on the lower manifold, of course. It would affect nothing, as iam' said.

Sending unit...



But, the one on top of the thermo housing I "believe" controls the auxiliary air valve on/off. The dealership calls it the "EFI temperature switch" (as opposed to "sensor"....being that is single wired and not two). However, no one I've asked has been able to verify it's real function. So, if I'm correct in that it controls the air valve, the air valve may not be shutting off when the coolant reaches temp and therefore give you an unusually high idle.

Try this..
When the motor warms, pinch off the large vac hose that runs from the TB to the air valve and see if that curbs the idle.

AAV hose....

 

Awesome - it's the one on top that had the problem. The gauge reads fine from cold to mid while warming up, so it seems to be working.

I guess the Idle is being caused by something else then.

 

ah, yes, I have a 91 22re, so that's right, my fault. mine does not have the one on the t-stat housing itself, just the one mounted close to the head

 

Well, try running the little test with the auxiliary air valve. Or, have you?

If it's the temp switch you had problems with, then the ECU wouldn't know whether the engine would be hot or cold and would therefore keep the valve operational.

Here's an excellent overview of the air induction system on yours and many Toyota vehicles..
http://www.autoshop101.com/

Iam'....
This autoshop article applies to your vehicle, also. Yours has the thermo wax type valve.....non electrical and not dependant on a sensor or switch. Just for future info, if you like.

 

Thanks dude. Haven't tried yet - I'm at work and my 4Runner isn't my daily driver, will give it a try this evening tho for sure.

 

Other than the idle air valve, three other things to cause high idle are the VSV for the air condition, pressure regulator and the cold start injector staying on.


as for the temp sensor on the t-stat housing, the FSM is a little vague on that. It only mentions it in the ac section as a thermo switch for towing package and it refers to it in the auto tranny section for the switch for OD. And it refers to a 22R in the pics and the temp sensor is just behind the t-stat housing. My 86 and two of my friends 86's have the temp sensor in the same place. The water temp sensor in green above is for the ecu, not the dash.

 

Well hell, that's more than I could get out of the dealership.

What manual did you get this info out of? I just recently got my hands on an '85 manual. I've yet to find the temp switch in there, though. If it's for the A/C, mine is not working anyway. I think my vehicle did have the tow package since it had a towing bumper when I bought it. And, yeah, it was the factory bumper. But, my 4rnr is a DLX model. I wonder if that would make any difference?

 

I have an 86 FSM. This is the pic when it refers to a sensor near the t-stat housing, but it's not like my 86. Mine looks like the one thook posted above. The wiring diagram for the tranny shows a single wire temp sensor for overdrive to engage, but it doesn't mention where it is.

 

Well, my 4rnr is a 5spd. Is yours?

I just tested mine tonight a got the ol' infinite ohms.....which, according to that test, means it's bad. BUT! I don't know what hell it's for exactly. Ungh..I'm going to do some calling around tomorrow.

 

Has anyone found out what this switch does?

 

NOOOOOOOO!!!!!! WAAAAAAHHHHH!!!!

 

I just received a TSB on this nebulous switch. I'll see if I can get it from my email to the board.

 

judging by the wiring diagrams and such...
does the truck with the nebulous switch have electric fan(s)?
umm... strike that... back to the thinking board.

 

No. It sits on top of the thermo housing and is on the same circuit as the fuel pressure up VSV.

Shizzle sticks....the TSB is in my email as a PDF. How do I get it posted to here?

 

if you want to email me the pdf, i'll put it on my server and give you the link to it.

 

Courtesy of abecedarian....

http://headhunter.h1x.com/portals/0/ten01189.pdf

The switch is related to fuel pressure up, though I'm totally clear on it, yet. I haven't studied the TSB in depth to extrapolate the functioning. Later....along with some images, hopefully.

Props to the Kirkmeister....

 

I hope this is not a thread jack. On my truck(87 22rec) the sensor that is in the t-stat housing does not have the right connector on it. here is a pic of the wire harenss that goes to it. if this not the right connector can anyone tell me what it goes to. And no it is not the original engine and i do not know what it came out of.

thanks

 

That plug goes here, which should be bolted to your valve cover.