86 4Runner temp sensor, sensor on tehrmostat housing (1 Viewer)

[flash02]

I have an 86 4Runner that I'm installing an engine harness in, what I've noticed is that the new harness does NOT have the connector for the temp sensor located on the top of the thermostat housing. My question is what is the sensor for, I know the temp gauge sensor is located on the intake manifold water passageways, I seem to remember something about that sensor being used for towing and or 4WD so if the engine starts to run hot the ECU would limit power. As most of you know these harness are becoming harder and more expensive to find, the harness that I'm installed is in real good condition, all I've had to do is replace the injector plugs.

 

[flash02]

Notice the sensor located on the top of the thermostat housing, this is the one I'm speaking of, someone in another post mentioned it may have something to do with A/C. My 4Runner has AC, so now my concern is that my A/C will not work without this sensor providing a signal to the ECU.

Now....if that sensor has a direct link to the ECU I could always find the pin in the ECU plugs and run a direct wire from that sensor to the ECU, I have plenty of beat up ECU harness to canalize ECU pins from.

 

[jynx]

What did the harness come from? There is a temp sensor for the ecu and another sensor for the gauge in the SR5 cluster. Sounds like you may have the non-sr5 harness. Do you have a temp gauge in your cluster? Did the donor? Not sure about the power limiting that you mentioned, maybe someone else can chime in on that.

 

[flash02]

What did the harness come from? There is a temp sensor for the ecu and another sensor for the gauge in the SR5 cluster. Sounds like you may have the non-sr5 harness. Do you have a temp gauge in your cluster? Did the donor? Not sure about the power limiting that you mentioned, maybe someone else can chime in on that.

Funny you ask....
My 4Runner is a DLX but has an SR5 cluster, in most cases the SR5 cluster will connect up to a DLX with no modifications. The original harness had the temp thermostat temp sensor plug. The harness I purchased was sold as an 86 4Runner engine harness, as to weather is was a SR5, DLX or had AC is unknown to me.

 

[jynx]

you are right about the DLX having the expanded cluster. My 1991 pkckup is a regular cab DLX and has the expanded cluster.

Looking at the picture you posted, I don't remember if my pickup has a sensor in the top of the t-stat housing like that, I don't think it does.

 

[flash02]

I think this sensor I'm speaking of has to do with the A/C, if the engine gets to a certain temp, as indicated by the thermostat sensor, it cuts the A/C off. Hopefully it won't prevent the A/C from working if not connected.

 

[KLF]

This diagram might help:

http://www.yankeetoys.org/KLF/EPCDiags/22RE-EFISensors.pdf

This is a scan out of a 1986 "Technician's Handbook" on "EFI and Engine Control Systems". Really cool book, I can't remember where I got it. According to this book, that sensor is used with the VSV on the top/rear of the engine to modify the fuel pressure during hot conditions. It increases the fuel pressure during "Hot Soak Conditions" (coolant temp above 230dF) so "As a result, sufficient fuel delivery is guaranteed for smooth and proper engine speed."

My '87 has the sensor, but the intake from the '89 that I cannibalized for the throttle body upgrade does not. I'm still using my '87 harness, so the sensor is retained.

I can't tell you how important it is, but the fact that they dropped it in later years might indicate it didn't do much.

 

[flash02]

This diagram might help:

http://www.yankeetoys.org/KLF/EPCDiags/22RE-EFISensors.pdf

This is a scan out of a 1986 "Technician's Handbook" on "EFI and Engine Control Systems". Really cool book, I can't remember where I got it. According to this book, that sensor is used with the VSV on the top/rear of the engine to modify the fuel pressure during hot conditions. It increases the fuel pressure during "Hot Soak Conditions" (coolant temp above 230dF) so "As a result, sufficient fuel delivery is guaranteed for smooth and proper engine speed."

My '87 has the sensor, but the intake from the '89 that I cannibalized for the throttle body upgrade does not. I'm still using my '87 harness, so the sensor is retained.

I can't tell you how important it is, but the fact that they dropped it in later years might indicate it didn't do much.

Cool, thanks! My truck no longer has that VSV, it was broken and was removed when I removed the EGR system.

 

[pappy]

The wire to my connector broke many years ago and the wire is taped up out of the way. I'm curious when they stopped using it.

 

[flash02]

New engine harness installed, no CEL, although when I step on the brake with the AC on the engine surges, turn AC off and idles normally....WTF? At normal idle and brake depressed the idle does not drop.

 

[96crooser]

KLF sensor diagram

KLF, I sure could use more info on that, OD Temp Switch (AT vehicles), on that sensor diagram you showed. I have an 85 Delux 22re electronic trans truck, first year for that stuff. I have that OD temp switch on my truck. It's not hooked to anything, My trans od will not shut off, everything else has checked out good I believe this is my problem. I need wire colors and what it should be connected too. I would be indebt to anyone who could help.