Question about temp guage
05-30-2018, 02:28 PM
#1
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Question about temp guage
Hey guys, my temp gauge is starting to act a little weird, and I'm not sure where to start. When the truck is warming up occasionally the temp gauge will jump to the middle for a while and then fall back down to cold. The gauge does work and reads the correct temp, just jumps sometimes when still cold.
The temp sensor is new OEM, and all other gauges work properly as well. Thanks for any tips!
87 4x4 manual.
The temp sensor is new OEM, and all other gauges work properly as well. Thanks for any tips!
87 4x4 manual.
05-30-2018, 03:46 PM
#2
Hey guys, my temp gauge is starting to act a little weird, and I'm not sure where to start. When the truck is warming up occasionally the temp gauge will jump to the middle for a while and then fall back down to cold. The gauge does work and reads the correct temp, just jumps sometimes when still cold.
The temp sensor is new OEM, and all other gauges work properly as well. Thanks for any tips!
87 4x4 manual.
The temp sensor is new OEM, and all other gauges work properly as well. Thanks for any tips!
87 4x4 manual.
If you are absolutely positively sure and swear by good connections and condition of the gage and circuit.
Search dual-stage or two-stage thermostat.
Last edited by RAD4Runner; 05-30-2018 at 03:47 PM.
05-30-2018, 04:03 PM
#3
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Just so you realize, as your engine heats up the thermostat is closed, when the coolant in the engine gets hot enough to open the t-stat the coolant in the radiator is still cool/cold. So when the t-stat pops open you get a rush of cool/cold liquid into the engine which closes the t-stat. this will cycle a few times until all of the liquid gets up to normal temperatures.
05-30-2018, 04:13 PM
#4
05-30-2018, 04:20 PM
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Thanks guys. Maybe I didn't explain very well unless I'm misunderstanding how this system works.
My gauge works properly. The problem I'm trying to solve is first thing in the morning when the coolant is still cold occasionally the gauge will go to the middle, stay there for a second, then fall back to cold. This only happens very occasionally, and never happens once the coolant starts warming up.
I was thinking there was some kind of short or something, possibly in the gauge itself?
My gauge works properly. The problem I'm trying to solve is first thing in the morning when the coolant is still cold occasionally the gauge will go to the middle, stay there for a second, then fall back to cold. This only happens very occasionally, and never happens once the coolant starts warming up.
I was thinking there was some kind of short or something, possibly in the gauge itself?
05-30-2018, 04:20 PM
#6
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Yes. The two-stage t-stat^^^ is what many have successfully used to fix this.
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05-30-2018, 04:47 PM
#8
see the sticky thread about temp gauge repair. one or more connections within the gauge have broken, so the gauge acts as you see. mine did that for five years. now, it jumps to the middle, then pegs to overheat and stays there. i need to solder the wires in the gauge, which are tiny.
05-30-2018, 04:51 PM
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05-30-2018, 04:55 PM
#10
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I need a little more information here.
How long has this been happening an how long have you owned the truck.
Do you have a "Base / Deluxe" truck with only a speedometer, coolant temperature gauge, and fuel level gauge, OR do you have the "SR5" truck with speedometer, tachometer, oil pressure gauge, coolant temperature gauge, volt meter, and fuel level gauge?
How quick does the gauge jump to the middle after you start it? Can it happen even before you start the truck when the key is in the "ON" position?
What I am trying to find out is if you are observing actual temperature changes (warm to cool, back to warm) as the engine warms up (which I have actually never witnessed on my truck), or if you have an intermittent electrical issue with your temperature gauge circuit.
How long has this been happening an how long have you owned the truck.
Do you have a "Base / Deluxe" truck with only a speedometer, coolant temperature gauge, and fuel level gauge, OR do you have the "SR5" truck with speedometer, tachometer, oil pressure gauge, coolant temperature gauge, volt meter, and fuel level gauge?
How quick does the gauge jump to the middle after you start it? Can it happen even before you start the truck when the key is in the "ON" position?
What I am trying to find out is if you are observing actual temperature changes (warm to cool, back to warm) as the engine warms up (which I have actually never witnessed on my truck), or if you have an intermittent electrical issue with your temperature gauge circuit.
05-30-2018, 04:55 PM
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It happens immediately. It's an instant jump from cold to middle and an instant jump back to cold.
I've gone through the repair steps in the temp gauge sticky and there are no broken wires in the gauge. I've inspected the gauge twice now.
I've had the truck about a year but I bought it non running and rebuilt the engine. I've noticed this going on for a couple weeks now. It doesn't happen before the engine is started, but can happen immediately after is started. My cluster does have oil pressure, temp, speed, voltage, etc.
I've gone through the repair steps in the temp gauge sticky and there are no broken wires in the gauge. I've inspected the gauge twice now.
I've had the truck about a year but I bought it non running and rebuilt the engine. I've noticed this going on for a couple weeks now. It doesn't happen before the engine is started, but can happen immediately after is started. My cluster does have oil pressure, temp, speed, voltage, etc.
Last edited by heifetz17; 05-30-2018 at 04:59 PM.
05-30-2018, 04:59 PM
#13
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I have a few broken SR5 clusters that did the same thing as your coolant temperature gauge and I could not find any broken wires either, however, I must admit I have not really investigated where the problem(s) lie beyond looking for broken wires.
05-30-2018, 05:02 PM
#14
fwiw, my sr5 cluster temp gauge behaved exactly like yours. -15* overnight, start engine, gauge immediately jumps to middle, then after minute or so, drops to cold, then gradually rises to normal.
05-30-2018, 05:02 PM
#15
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I need a little more information here.
How long has this been happening an how long have you owned the truck.
Do you have a "Base / Deluxe" truck with only a speedometer, coolant temperature gauge, and fuel level gauge, OR do you have the "SR5" truck with speedometer, tachometer, oil pressure gauge, coolant temperature gauge, volt meter, and fuel level gauge?
How quick does the gauge jump to the middle after you start it? Can it happen even before you start the truck when the key is in the "ON" position?
What I am trying to find out is if you are observing actual temperature changes (warm to cool, back to warm) as the engine warms up (which I have actually never witnessed on my truck), or if you have an intermittent electrical issue with your temperature gauge circuit.
How long has this been happening an how long have you owned the truck.
Do you have a "Base / Deluxe" truck with only a speedometer, coolant temperature gauge, and fuel level gauge, OR do you have the "SR5" truck with speedometer, tachometer, oil pressure gauge, coolant temperature gauge, volt meter, and fuel level gauge?
How quick does the gauge jump to the middle after you start it? Can it happen even before you start the truck when the key is in the "ON" position?
What I am trying to find out is if you are observing actual temperature changes (warm to cool, back to warm) as the engine warms up (which I have actually never witnessed on my truck), or if you have an intermittent electrical issue with your temperature gauge circuit.
06-07-2018, 03:45 PM
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I haven't had much time to dig into this yet, but I was able to get a short video of it happening. I plan to pull the cluster and check the gauge again, and possibly replace it.
This is immediately after starting the engine cold. Hadn't even put my seatbelt on and released the park brake yet.
This is immediately after starting the engine cold. Hadn't even put my seatbelt on and released the park brake yet.
06-10-2018, 10:30 PM
#17
07-20-2018, 07:18 AM
#20
bringing this back up for the OP.
based on my recent experience, i do not believe the issue is with the gauge. it is either a wiring issue (broken/cracked/corroded) or a bad ground (sender or harness). i swapped the temp and oil pressure unit from my '87 (with the improperly functioning temp gauge) with the unit from my '88. both are sr5 units, and the units are identical, even though one is from a 4-cyl and the other is from a 6-cyl.
the problem stayed with my '87. both temp gauges work properly with the '88; both function improperly in the '87. therefore, i have confirmred that both gauges work correctly, and the issue is in my '87.
based on my recent experience, i do not believe the issue is with the gauge. it is either a wiring issue (broken/cracked/corroded) or a bad ground (sender or harness). i swapped the temp and oil pressure unit from my '87 (with the improperly functioning temp gauge) with the unit from my '88. both are sr5 units, and the units are identical, even though one is from a 4-cyl and the other is from a 6-cyl.
the problem stayed with my '87. both temp gauges work properly with the '88; both function improperly in the '87. therefore, i have confirmred that both gauges work correctly, and the issue is in my '87.
