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when the truck is warming up from dead cold motor with the heater on why does the temperature go over past half way mark close to the red on temperature gage? and when the heater is off the truck warms up to the Proper spot on temperature gage and dies not go past the normal spot on
Temperature gage
its a 1990 22re 2wd
Last edited by shafner30; Nov 29, 2017 at 12:22 PM.
when the heater is off the truck warms up to the Proper spot on temperature gage and dies not go past the normal spot
How about when you suddenly turn the heater on after the truck has warmed up to normal operating temp?
Could be one of those random cases where cold coolant hitting the thermostat keeps it shut, and 2-stage thermostat was the solution.
Closest discussion I've seen is here: http://board.marlincrawler.com/index...opic=102187.30
Last edited by RAD4Runner; Nov 29, 2017 at 06:05 PM.
thia is due to an earthing issue between the gauge and immediate earth (where the instument panel earths to the body)
the coolant gauge gets 12 volts and sends it to 2 places, immediate earth (where all gauges get earthed), and the sensor which earths variably on temp. when the fan turns on, there is curent going to the fans which takes up the capacity of the earth wires and this creates an artificial differemce between the 2 outputs of the gauge.
i had an issue where the coolant sensor would move up amd down with the beat of the indicator haha. this was caused by this same earthing issue. when the bulb would flash on, earth would be taken by the load of the bulb and the gauge would auddenly jump up, the when it turnes off the gauge would go back down to normal.
simple fix would be to just find where the earth is from the dash, and run a new earth wire from it to a good earth.
EDIT: We need come clarification on the original question.
When you mean you turn on the heater and the coolant temperature gauge approaches the red zone, do you mean that you are turning the blower motor on OR that you are moving the HVAC temperature control knob to full hot? I other words, does the temperature gauge react to the blower motor being turned on and off (Blue box) OR from moving the HVAC "cool-hot" slider from full hot to full cool (red box)?
This will help us determine if you have an electrical issue or a mechanical issue.
("Earth" only being actual earth ground is a personal thing, you guys are getting too bent out of shape on this! )
Last edited by old87yota; Dec 1, 2017 at 09:21 AM.
Reason: I was incorrect... I think... You all confuse me!
im not a fool i know how it works.
ok all of ur paragraphs answered.
paragraph one
cmon, earth, ground same thing. the temp sensor is a variable resistor on the ground (earth) side.
pgph 2.
yeah, the blower in the dash. he said "with the heater on" he sees the needle read hotter than mid.
It has a lot to do with the gauge because they share the same earth connection, sorry, ground connection.
bugger this,.. im going back to using correct terminology and calling it earth.
paragraph 3
the two outputs are to the dash earth, (for voltage refference), and to the variable resistor earth (to sense how much voltage can be put out through the coolant temp sender)
prgph 4
i didnt say the problem was the gauge, i said its the dash earth
paragraph 5 and i quote..
"if i understand the original post correctly, the gauge only shows the engine getting hot when the engine is started when it is stone cold ( and allowed to warm up a bit) and the climate control temperature lever is set on FULL HOT and bower motor is running. "
because the car is cold, it should be displaying cold, but its not, its displaying 3 quarters of the way to hot. If the engine was hot, u wouldnt see the anomaly because,... wel... the engine is hot.
i dont need to explain anymore.
im affraid the heater core is in capable of affe ting coolant temp enough to make any difference to the temp sender reading. so this garbage of "temp gauge overshoot" being causes by coolant dynamics is made up by internet armchair experts who havent got a clue.
sorry, no mean to offend anyone, but this is coming from someone with a working brain and plenty of experience.
Last edited by Thommo Thompson; Dec 1, 2017 at 04:46 AM.
In pretty sure he is due to his use of earth and bugger.
however, anyone worth their salt in electrical knows what he meant by using the term earth instead of ground.
the temp gauge over shoot is only an issue when the motor is warm and the heater valve is moved from cold to hot, putting cold coolant on the tstat closing it momentarily. The gauge will rise to 3 /4 for just a moment then drop back down. Mine does this.
if you warm the truck with the heater valve on hot (allowing it to circulate) then it won't do this, I've never had the blower cause the tstat to close.
I ordered the dual-stage t-stat, Toyota part #90916-03070 to try and solve the same problem. From what I understand, the t-stat is allowing the coolant to overheat for a little while each time this happens.
I'll have the part tomorrow so I'll let you know how it goes real soon.
aussie, but we are a brittish colony haha.
bugger is an aussie word guys, not british.
read any electrical diagram, and read the legend, the symbola where a device ia connected to the chassis is called an earth haha
notice they put "ground" in brackets, to make sure the fools can keep up.
aussie, but we are a brittish colony haha.
bugger is an aussie word guys, not british.
read any electrical diagram, and read the legend, the symbola where a device ia connected to the chassis is called an earth haha
notice they put "ground" in brackets, to make sure the fools can keep up.
The use of bugger is actually quite common in the UK as well, also Earth ground is exactly as it sounds. It's a ground physically (and electrically) connected to earth via a conductive material such as copper, aluminum, or an aluminum alloy.
A true earth ground, as defined by the National Electrical Code (NEC), consists of a conductive pipe, or rod, physically driven into the earth to a minimum depth of 8 feet.
gsp4 life, do u really have the same problem, 5hat is, a hot reading when the engine is stone cold? if so, a thermostat change wont fix that.
I must've misread part of the post. No, my problem is that the temp gauge rises to about 3/4 of the way up once the engine has warmed up and only when I switch the heater on. It falls back to 1/4 after ~30 seconds, which is where it usually stays most often.
when the truck is warming up from dead cold motor with the heater on
I see the confusion. Shafner30 uses the words 'dead cold motor', which you could think means just what it says. However he also states that it's 'warming up'.
So the engine's been running a few minutes by the time the gauge is over the halfway line, is this correct Shafner30? Or is your gauge actually reading hot the same moment you start the truck?
The use of bugger is actually quite common in the UK as well, also Earth ground is exactly as it sounds. It's a ground physically (and electrically) connected to earth via a conductive material such as copper, aluminum, or an aluminum alloy.
A true earth ground, as defined by the National Electrical Code (NEC), consists of a conductive pipe, or rod, physically driven into the earth to a minimum depth of 8 feet.
the point of the earth in the system we are talking about is for voltage reference. Its an earth.
Sorry but this is my profession haha.
If it was to shortcircuit or to complete a circuit to make an electrical item work, like a light bulb or an electric motor, then it would be called a ground.
please lets keep calling it what it should be called.
and you can keep your USA (NEC) electrical code.
Not to mention, the NEW is for Electrical stuff, not ELECTRONICS!
So rather than googling stuff in an atempt to prove someone wrong, learn.
Last edited by Thommo Thompson; Dec 2, 2017 at 09:16 PM.
I see the confusion. Shafner30 uses the words 'dead cold motor', which you could think means just what it says. However he also states that it's 'warming up'.
So the engine's been running a few minutes by the time the gauge is over the halfway line, is this correct Shafner30? Or is your gauge actually reading hot the same moment you start the truck?
well if its warming up, and he suspects there is a problem, he would have to be seeing something on the gauge which is an anomaly. (ie, the gauge higher than its usual sitting point)
...does the temperature gauge react to the ONLY blower motor being turned on and off (Blue box) OR from moving ONLY the HVAC "cool-hot" slider from full hot to full cool (red box)?
This will help us determine if you have an electrical issue or a mechanical issue.
RAD4runner: OP didn't clarify this point and neither did I. In my case, the temp gauge spikes are a mechanical problem caused soon after the water control valve is opened at all (when I move the HVAC temp slider anywhere away from the left-most, cold air side).
Curious to see how similar the problem actually is.
Also I have the dual-valve thermostat, just need to find time to throw it in. Now with the garage taken over by my nephew mid-way into his Mazda3 engine-swap, some family staying in our house for the holidays (yep, the entire month! lol) and mother-in-law just began in-home hospice care. For Christmas this year, I just want the garage back.
RAD4runner: OP didn't clarify this point and neither did I. In my case, the temp gauge spikes are a mechanical problem caused soon after the water control valve is opened at all (when I move the HVAC temp slider anywhere away from the left-most, cold air side).
Curious to see how similar the problem actually is.
Also I have the dual-valve thermostat, just need to find time to throw it in. Now with the garage taken over by my nephew mid-way into his Mazda3 engine-swap, some family staying in our house for the holidays (yep, the entire month! lol) and mother-in-law just began in-home hospice care. For Christmas this year, I just want the garage back.
Understood, GPS4life. I hope your family is coping well.
I also got the 2-stage just because I needed to replace my T-stat anyway, and my coolant temp goes higher than normal when I do Tejon Pass, Cajon Pass (both in So Cal) and Towne Pass (Death Valley). Got the Tama one from LCE (supposedly OEM) here:
Nov 29, 2017 | 12:21 PM
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