MUDGUTS Posted March 10, 2012 Share Posted March 10, 2012 Hi, looking for a little help with this: Recently the readings went far too low, even earlier today it read 4 when it must be much warmer than that. I have located the sensor and disconnected it but now the reading is -30 and even after pluggging the sensor back in it reads the same, shorting the connections changes nothing. My questions are: Will this affect anything else on the car? Does the system need re-setting? Is a reading of -30 an open circuit or short? Thanks in advance Quote Link to comment Share on other sites More sharing options...
jaswood Posted March 10, 2012 Share Posted March 10, 2012 Hi, looking for a little help with this: Recently the readings went far too low, even earlier today it read 4 when it must be much warmer than that. I have located the sensor and disconnected it but now the reading is -30 and even after pluggging the sensor back in it reads the same, shorting the connections changes nothing. My questions are: Will this affect anything else on the car? Does the system need re-setting? Is a reading of -30 an open circuit or short? Thanks in advance Sensor/wiring/connector is open. DSP, Digital Signal Processing, prevents the OAT indication from changing faster that mother nature makes possible. Possibly doesn't even react to an out-of-range, zero ohms, sensor resistance. Try 2800 ohm resistor. Thermistor has negative temperature coefficient, resistance increases with lower temperatures. A/C compressor is disabled when the OAT is below freezing and climate control acts, reacts, as if lots of HEAT is needed. Quote Link to comment Share on other sites More sharing options...
1990LS400 Posted March 10, 2012 Share Posted March 10, 2012 I think the "cooler thermistor, ambient" on my 2000 LS400 only shows the outside temperature on the LCD. It does not seem to affect the way the HVAC system operates but I am not certain. Assuming you are in the U.K., the parts number website I use - www.toyodiy.com - shows the same sensor (part number 88625-14110) being used on both the LHD U.S. spec 1997 LS400 and the RHD 1997 U.K. speci LS400. Here in the U.S., the sensor is quite inexpensive - $21.80 at http://lexus.sewellparts.com with a car forum discount. The outside temperature on my 00 LS400 often reads low for a few minutes after I wash my car at a manual wand-type car wash. Just yesterday I noticed it was reading about 15 degrees Farenheit lower than the actual temperature just after I washed the car. The display slowly returns to the accurate outside temperature as I drive away from the car wash. Maybe the sensor on my car is starting to fail. Quote Link to comment Share on other sites More sharing options...
MUDGUTS Posted March 10, 2012 Author Share Posted March 10, 2012 Thanks Guys! I must have triggered this open circuit when I removed it and unplugged it to give the contacts a clean. Since then I tried shorting the connections and found this made no difference. I now have re-connected it all and re-fitted it under the bumper. During a short drive it changed to -29, then -28. I read somewhere on the internet a few mins ago that an open circuit causes a -22 F reading (this is -30 C) and you have to pull the fuse for the A/C to re-set it. Whereabouts is the A/C fuse? I can't find it anywhere, I did read that the Cigar Lighter fuse is for that system and pulled that: The clock and temp display disappeared but when I fitted it the -30 reading was still there. Quote Link to comment Share on other sites More sharing options...
1990LS400 Posted March 10, 2012 Share Posted March 10, 2012 Do you have an owners manual? U.S. specification models may not be the same but the owners manual for a U.S. 1996 LS400 at http://drivers.lexus.com/t3Portal/document/om/OM50487U/pdf/lexomsou/96lexom/96lsom/sect6/640.pdf shows four fuses for the air conditioning system. The Lexus website does not have manuals for the 1997 U.S. LS400 but the 95-97 are essentially the same. Quote Link to comment Share on other sites More sharing options...
MUDGUTS Posted March 10, 2012 Author Share Posted March 10, 2012 Thanks for this, I have just tried pulling fuse No. 6 but no change, I'll try all 4 tomorrow. Will post back with the results. Quote Link to comment Share on other sites More sharing options...
MUDGUTS Posted March 11, 2012 Author Share Posted March 11, 2012 Update: I pulled fuses for: HEATER FUEL OPN FR CIG PANEL This seemed to work, as the temp indicated was now more realistic, One thing that did happen though was the 'Front' LED on the climate control panel was flashing when I switched the Ignition back on. After I pressed a few buttons on the panel it all came to life. I then tidied up the insulation on the sensor etc., looked again and the temp was -3, so I had to go through the whole re-set again. Now it seems to be working OK but I guess the sensor is on its way out. Thanks for your help guys. In order for folk to find this fix in the future I'll post this reply on both UK and USA / Canada forums and link to each. http://www.lexusowne...showtopic=76602 Quote Link to comment Share on other sites More sharing options...
95LexusAl Posted August 30, 2016 Share Posted August 30, 2016 (edited) Looks like it's been awhile since there has been any discussions on this topic.So I'll start by saying BIG PROBLEM for me.I hope someone will respond afterward.I recently had my '95 LS400 repainted.Somehow my ambient temp. sensor plug that's in front of the radiator and mounted to the bumper got unplugged and just hung just below the front bumper.I was going to get it plugged back in.But before I could,the body man apparently cut the plug off from the wiring and wrapped the harness wire around something to keep it from hanging. He made a $2,152.00 mistake just like that.I called Butler Lexus in Macon,Ga. and that's the price for a new one with the harness.Question is,is the plug that's wired to the harness a Female plug?I have a new bumper mounting plug with the two terminals(part# 5S5837)(bar code 80044 80762)from RockAuto.com and it snaps onto a medal brace that has a small hole in it to mount it to.It seems to me that the sensor plug that is wired to the harness would have to be female.But I want to make sure.No way I'd go to the dealership for this part.I'll probably wind up trying to find one at a junk yard.BTW,my outside temp reading next to the clock shows -22.Not good as the temp control unit on the dash will not work properly nor will the A/C because of that plug being cut off.Thanks in advance for any help.Al Edited August 30, 2016 by 95LexusAl additional info needed to be added. Quote Link to comment Share on other sites More sharing options...
Exhaustgases Posted August 31, 2016 Share Posted August 31, 2016 To bad in needed a repaint. Maybe ebay has one, I don't see many that year in wrecking yards. Quote Link to comment Share on other sites More sharing options...
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