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Hi all - Welcome back for the second time this month!

I apologize for the inconvenience of the site being offline. The site was down for technical reasons, but it didn't help that I was of offline for two weeks (camping and travel). Once I got back, it took a while to get things sorted out. That's resolved, and the site is now back up. Huzzah!

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Author Topic: Temperature Senders  (Read 21392 times)
lbhsbz
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« on: November 01, 2007, 03:41:49 AM »

My engines has 5 of them...and after searching through AllData, the FSM, and a couple more manuals (& bulletins) I've finally figured out what they all do...though it might be helpful to someone, because nobody I talked to had a clue about the 2 on the T-stat housing.

The brown switch on the front of the intake manifold is the Thermo-time switch to run the cold-start injector

The green switch on the front of the intake is the EFI temp sensor.

the single terminal switch on top of the T-Stat housing with the round connector is a "fuel pressure up" switch...toyota calls it "temp switch #2.  There is a bulletin on this switch. 

The single spade terminal switch on the T-Stat housing is only on "Tow Package Equipped" trucks WITH A/C...and disengages the A/C compressor clutch if coolant temperature gets too hot (213)

The single spade terminal switch on the intake manifold between the #2 and #3 injectors is the Guage sender unit.


Here's my attempt at the bulletin:



MODIFICATION INFORMATION











YEAR/MODEL APPLICATION:






PART NUMBER INFORMATION




PRODUCTION CHANGE INFORMATION:

CONDITION 1:           Temperature Switch No. 2 specification (same as

                       field fix) changed at beginning of 1988 model year.

CONDITION 2:           ECU modification at beginning of 1988 model year to
                       activate cold start injector at higher temperature (22R-E only).

REPAIR PROCEDURE:

1. Replace cold start injector time switch with the new part.





2. On vehicles equipped with a pressure-up system, (see application chart on page 1) also replace Temperature Switch No. 2 with the modified one.



3. For vehicles equipped with Air Conditioning, the ACV terminal must be disconnected from the ECU when installing the modified Temperature Switch No. 2 (Condition 1). This is necessary to prevent the Engine Idle-Up from working continuously after warmup.
HOW TO REMOVE THE WIRE TERMINAL


« Last Edit: November 01, 2007, 06:24:45 AM by lbhsbz » Logged
dcg9381
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« Reply #1 on: November 01, 2007, 05:50:41 PM »

Further info the curve of the ECU temp sender - This should be of particular interest to people doing aftermarket EFI using the stock sender:

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BB
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« Reply #2 on: November 02, 2007, 02:18:19 AM »

This is cool. Thank you.

"Fuel pressure up" so does that mean that the computer increases fuel pressure with a temperature contolled switch? How does it accomplish that?
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lbhsbz
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« Reply #3 on: November 02, 2007, 04:08:02 AM »

I think so, dunno how it works though, still studying.
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boostnut
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« Reply #4 on: November 12, 2007, 01:00:01 AM »

One thing I found that's interesting is when I replaced the stock temp sender to the dash gage with a auto meter sender, and gage set.  The stock sender (evan tho not connected or plugged in) still continues to send a signal to the dash temp gage.  Sometimes it shows 1/2 way right after the engine is started.  and goes up and sporadically.

weird huh?   
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88 pickup 99k miles, stock ct20 with 2.5" exhaust, modified AFM from a supra and air intake.
other mods in progress.=)
dcg9381
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« Reply #5 on: November 12, 2007, 06:14:36 PM »


Just to make sure - you replaced the sensor that is in the middle of the lower manifold, near the center of the head.  It's typically a spade connector.

I believe the stock temp gauge setup is electrically "dampened" - that is it's setup to read "normal" across a wide range of temps.  The idea behind it is that this prevents some Toyota service calls.
I haven't confirmed this personally, but I've seen write ups on removing the circuits that provide the dampening.  I do notice that my gauge tends to sit down in the low temp range and then suddenly jump to normal.  It has some range of motion, but doesn't really seem to correspond to reality until it starts getting hot (over 215 degrees).

I wouldn't think that it should be dampened enough to read normal without being connected, but if the cold resistance is in megahohms, that could indeed be the case...
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redevil
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« Reply #6 on: November 08, 2008, 11:32:58 AM »

My truck was having a hard time starting up when cold.  I noticed today that the brown plug was barely unplugged b/c I'm missing the little metal clip.  I fixed it and now it fires up quickly.
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jimep
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« Reply #7 on: February 15, 2009, 04:07:39 PM »

Good stuff but I have another question. I found 2 more temp sensors. Whats the one above the green and brown plug on the intake manifold that has 2 vacuum lines running to it. There is no electrical connector on this one. one of the nipples for the vacuum line broke off on my truck and I need a new one. I have one off an 85 RE But they look different. The RE has some type of plastic cap on the top of it. Also whats the sensor for in the block between the oil and fuel filter? so it actualy looks like 7 temp sensors on my 86.
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01 lexus IS 300, 00 Tundra limited 4.7, Mostly 86 turbo yota truck xtra cab on reg cab frame, SAS, 38's, dual cases, CT 26 swap, intercooled.    05 Honda Rancher 4x4, 06 Triumph Daytona 675. $500 reward for my stolen 2000 RM 250 Carlisle PA
86turboyota
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« Reply #8 on: March 06, 2009, 07:22:45 AM »

the first you described operates the cold/high idle. it has like a slide plate inside that raises/lowers with the coolant temp and thus controls the amount of air to the throttle body. does that make sence? please correct me if i described it wrong. as for the second one on the block, i think you are reffering to the knock sensor.
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mica
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« Reply #9 on: April 24, 2009, 07:55:57 PM »

on automatic trans. vehicals there is also a active coolant temp sending unit right behind the oil filter under the fuel filter that controls weather or not the O/D engages

I think that the "temp sensor" discribed above is a thermal vacuum switch that keeps the EGR from opening when the engine is cold. as NOx are produced at high temps there is no need for the egr to be open. I think it is a thermo wax pellet that operates similar to a thermostat, as the wax heats up it allows vacuum to flow through it
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swerks
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« Reply #10 on: May 30, 2009, 05:36:05 AM »

any one have a part # for switch #2 I can not find any replacement info any where
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86 Turbo 4Runner
RobWS
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« Reply #11 on: September 16, 2009, 04:11:38 AM »

Thank you GOD!
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88 X-Cab 4WD 22RTE 198,000
Riverrat Cargel
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« Reply #12 on: June 23, 2012, 12:24:36 AM »

Went to Toyota today looking the Cold Start temp sensor and the Fuel Pressure Up Temp Sensor. Could not find the fuel pressure one, found the cold start one. Toyota wants $188 for the cold start and aftermarket was $460!! WTF?!

The guy was nice thou and sent me home with this, it has some part numbers.
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'85 SDR MKII 6M-GE 5-Speed
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79spitfire
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« Reply #13 on: August 31, 2013, 06:30:13 PM »

Some of the pictures are MIA, is there anyway to re-post them?
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mosk
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« Reply #14 on: August 31, 2013, 07:11:37 PM »

Probably not, as they were hosted externally. I'll see what, if anything, I can do.

Jeff
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Ugly, but probably worth reading: Jeff's 22R-TE Page
Just sayin': If Ronmar and I both post on the same topic, listen to Ronmar! His answers are typically better and more accurate than mine. Cheesy
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