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So, I've been having a temperature problem. I bought a 1985 SR5 4x4 Pickup with a 22RE from a kid in North Carolina a few days ago. He put a Sunpro brand electrical temperature gauge on it. He says that he put it on there just because he likes the look of an aftermarket temp gauge. Its sender is threaded into the port on top of the thermostat housing; the stock temperature sender is removed. He also stated that he replaced the thermostat about a week ago.
On the way back to Atlanta, I started to notice the temperature creeping unreasonably high. A few minutes after hitting interstate speed, I noticed that the temperature gauge was reading 250F. I turned the heater on and slowed down. The temperature decreased to 200F over the course of 30 minutes. I sped back up with the heater still on, and the temp increased back to 260F. I pulled over at a gas station. There was a slight bubbling sound from the overflow reservoir, but nothing to indicate the intense overheating that the gauge was indicating.
While I was sitting at the gas station, I did some smartphone internetting. I found this post related to that gauge: http://www.hotrodders.com/forum/elec...ot-177128.html According to the discussion there, that gauge gives a reading that is too high if there are electrical or ground problems (particularly if Teflon tape was used to install the sender. I finished driving home with the truck running like a top but that gauge having a crazy temperature read out.
That night, after it totally cooled down, I drove it again for a little while, paying close attention to the temperature gauge. The gauge stayed pegged at the lowest reading (100F) until I experienced the 85 22RE "temp overshoot". The gauge rapidly goes from 100F to 250F and then back to around 210F. If I'm puttering around on city streets, it goes down to 195F from there. If I'm traveling 50+mph, the temp rises to 230F over the course of a few minutes.
I noticed that the gauge fluttered a bit when letting the rpm fall on the engine and that it seemed to move a lot. The following day, I confirmed that the temp sender was installed with Teflon tape. I removed the tape and reinstalled the sender. I drove it around and to get the stuff to do a coolant flush. The temperature gauge wasn't fluctuating anymore but was still reading that my truck was pretty much constantly over heating.
I did the coolant flush. The coolant was mud color, and you wouldn't believe how much sand came out of it. It took so many gallons of water to get it to run clear. I filled it up with new coolant and test drove it. The temperature gauge still reads high, but I do not have boiling coolant, even when it says 240F. It seems like the thermostat is opening when the gauge reads about 220F now. This leads me to believe that the truck is running at a reasonable temperature and that this gauge is garbage.
I figured that I'd just hook up the stock gauge and see if it read super hot. I went to Toyota to get a stock sr5 temp sending unit. The part their computer indicates would thread into the port on top of the thermostat housing but has the wrong connector. It has a spade connector, not the corresponding male to the proprietary female connector that is dangling loose under my hood. First, the parts guy said that the correct part is $150, then he told me that it is discontinued. I'm not exactly sure where to go from here because I'm not sure if I'm actually overheating, and I'm not sure what the part I need is.
Here are some pictures of what I have under the hood right now and the dangling connector:
that temp sender is for the dash gauge which is actually behind the thermostat housing, sitting on top of the intake manifold. (sorry no pic) but if you look under the vacuum lines and wiring you'll spot it.
what is on top of the thermostat housing is NOT for the temp gauge cluster but a temp sender for the A/C shutoff. If the temp was too hot, it'll shut off the A/C or something, useful for towing I guess. I broke the housing and found out that it was really rare to even find one of those with the threaded hole on top (mostly 22re turbos or towing packages have them w/ A/C option IIRC) , so what I did was just use one from a regular 22re and soldered the wire into the temp sender behind the thermostat housing, on the intake manifold.
the one you have pictured belongs on the intake manifold for the gauge.
this probably doesn't answer your question though and hope it makes sense lol.
You may find 1 or more temperature senders screwed into the neck of the thermostat housing. What do these dvarious senders do you might ask? Well, it all depends on what sort of setup your truck has.
If you have A/C, there is a thermo-switch in the housing that feeds the A/C Amplifier (behind the glove box). That switch is used to shut of the A/C compressor if the engine coolant temperature rises too high (to prevent overheating).
If you have an automatic transmission, you may have a sender there that feeds the ECT computer. It is used to sense engine temperature and lock out use of overdrive until the engine has reached it's normal operating temperature.
If you have a turbo-charged engine (22-RET), there may be a sender there that feeds into the main EFI ECU that is used to affect the turbo operation in case of engine overheating.
Jackpot! I found the sender and the loose wire. That was an easy fix. Thanks, Vang!
I guess it's the sender that turns off the A/C in four wheel drive that's missing and discontinued from Toyota.
The auxiliary temperature gauge got up to 210F driving in rush hour traffic today. The factory temperature gauge stayed in the 1/3 - 1/2 (always less than 1/2) region the whole time. I wasn't able to get up to cruising speed because of traffic, so I'm not 100% that I don't have a temperature problem. However, my problem seems solved at this point.
Hey cabot what color was the wire/ spade connector and where did you find it dangling? I found my sensor but i have no wire to plug into it!!! Is it just a regular spade connector or does it have some shielding or plastic housing on it. I only have one dangling wire (that im aware of)(other than trying to figure out my oil pressure sensor) and it is grey and small with two contacts on it and I have no idea where it goes... Thanks in advance for the help!
The coolant temp wire on mine is a brown wire insider a larger gray sheething. It comes from under the fuel injection stuff on the left there. Mine was hidden by all the vacuum lines. The PO had tucked it back under the intake area there. Mine has a regular old brass spade connector on it. I'll be able to let you know if this is the correct connector after I replace my wiring harness with all factory parts the weekend of the 17th (a Toyota Tech friend is building it and helping with the install)
I hooked up the wire depicted above with the spade connector female to the correct sender, and the gauge started working properly. I discovered that my engine was actually overheating, but after having my radiator tanked and repaired that stopped.
The connector in the original post hooks up to a sending unit that costs about $150 or something like that from Toyota. All that wire does is turn the air conditioning off if I'm in 4wd and the engine starts to overheat. I just put a brass plug in that hole. I don't have any use for that feature.
I ended up having to work the weekend that I was supposed to replace my harness, and my tech friend and I haven't been able to get out schedules to line up since. That's still pending.
Again, thanks to Vang for pointing out that I had the correct wire and sender already installed for my SR5 cluster temp gauge.
no problem
instead of having a loose wire hanging around your engine bay, you could also just solder it along with the wire for the temp gauge sender that powers to the dash...pretty much does the same thing since they are both temp senders, and haven't had any problems at all...or just forget about it all together lol
what is on top of the thermostat housing is NOT for the temp gauge cluster but a temp sender for the A/C shutoff. If the temp was too hot, it'll shut off the A/C or something, useful for towing I guess. I broke the housing and found out that it was really rare to even find one of those with the threaded hole on top (mostly 22re turbos or towing packages have them w/ A/C option IIRC)
Anyone know at what temperature this sensor is set to activate?
I got an e-fan for my 22re and the thermostat housing with the threaded bung (which is off 85 solid axle EFI pickups) - I want to wire it up to use this temp sensor to activate the fan.
Have you tried replacing the thermostat? Sounds like it is stuck and not circulating the water from the radiator or possibly a water pump. It's a cheap and easy thing to replace (thermostat). Cost maybe 6$ and it's just two bolts on the intake housing.
This sensor goes to the guage/light and has a blue connector and sits between #2 and #3 cylinders.
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From what I have been seeing, and I could be wrong, but my 85 and 86 trucks have them in the thermostat housing and when I have had newer trucks they dont have the sensor in the thermostat housing. I have had a 89 and a 91 truck with AC and they didnt have that sensor so I am still trying to figure that one out.
I have flushed my radiators with the Preston Kits and that helps some, but these radiators are so old, they have alot of build up in them and each one I have pulled and taken to a radiator shop, am completely amazed at how much gunk comes out of them. Would suggest having your radiator professionally flushed. It cost me $25 to have mine done.
How is your fan clutch?
Here is how I burp my system, raise as high as I can and run without radiator cap for about 15 minutes to rid the system of air.
Another thing I tried as found that it apparently helps some but didnt help me any, I tried it on two different trucks about the temp guage. Tighten the screw on the back of temp guage on the cluster assembly and clean the ground wire down by the fuse box. This didnt work for me, but might for you. I will say my screw on the back of the cluster guages were all loose.
This thread is VERY helpful. Being that there are several temp sensors that look similar or exactly the same, some with similar connectors, i've found it to be a bit more involved than expected. Additionally, responses to these inquiries out on the Web are typically uninformed or on some threads, insulting. Tip of the hat to the YotaTech peeps!! Thankfully, my 87 4Runner is getting restored very nicely due to Web community contributions such as everybody's here. Cheers
1987 4Runner, best TEMPERATURE SENDING UNIT sensor thread. (Maybe that'll help other ppl find there way to the proper info)
Okay I know this is an old thread but, the sensor mounted on the thermostat housing has nothing to do with the a/c.
It's part of the EFI and is called a fuel pressure up thermo switch.
It raises the fuel pressure to help with a hot start.....or lower it?
However, its not on all 22REs and I can't even find it in my fsm(?)
Hans
If there is a sensor above the thermostat it will not read until the t-stat opens. There should be a green temp sensor and coresponding connector but not on the t-stat housing, but down beside it this is a sensor for the EFI or rather for the computer. this is part of how the computer set the correct air/fuel mixture. The other guys are right about the sensoe between 2&3 on the intake, it being for the temp guage. Hope this is helpful.
I have no A/C and my ‘86 4Runner has never had A/C nor could it ever have A/C. It’s completely unmolested, but the wire for this sensor broke off so we went ahead and put on a new wire. I’m wondering, if I have no A/C, what is the purpose of this sensor? It’s there for a reason.
I have no A/C and my ‘86 4Runner has never had A/C nor could it ever have A/C. It’s completely unmolested, but the wire for this sensor broke off so we went ahead and put on a new wire. I’m wondering, if I have no A/C, what is the purpose of this sensor? It’s there for a reason.
I’m now told since I have no A/C, it doesn’t affect anything. My problem is I’m dealing with a starting issue and I had to be sure this wasn’t part of it. I will create a separate thread for that. It’s all worth it for this old girl.
07-19-2012, 11:17 AM
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