How to test a Temp Gauge
#1
How to test a Temp Gauge
I have a 1990 GXL with a LS1 swap. All of my dash gauges were working for over a year and now my temp gauge stopped working. I have a second cluster so I swapped the gauges and the temp gauge still doesn't work. My question is, What type signal does the sensor send to the gauge?
There are three screws. I assume one is power, one is ground and one is a signal from the sensor.
When I put my test light on the three screws, I get:
screw 1 - a bright light I am guessing power 12V
screw 2 - no light I am guessing ground
screw 3 - a dim light I am guessing the signal or a short. What type signal does the sensor send to the gauge?
There are three screws. I assume one is power, one is ground and one is a signal from the sensor.
When I put my test light on the three screws, I get:
screw 1 - a bright light I am guessing power 12V
screw 2 - no light I am guessing ground
screw 3 - a dim light I am guessing the signal or a short. What type signal does the sensor send to the gauge?
#2
Rotary Enthusiast
From the 89-91 FSM, grounding the sending unit wire through a 13 ohm resistor gauge should display 130C (266F) and through a 154 ohm resistor gauge should display 50C (122F). I am assuming that 50C and 130C are respectively the bottom and top of the operating region or hatch marked portion of gauge. Sending unit acts as a variable ground dependent on coolant temperature. Sending unit should have a resistance of 57.7-49.3 ohms at 80C (176F). Here is reference: https://www.rotaryheads.com/PDF/2nd_...cal_system.pdf
Last edited by Hot_Dog; 11-19-20 at 07:58 PM.
#4
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,949
Received 2,680 Likes
on
1,896 Posts
From the 89-91 FSM, grounding the sending unit wire through a 13 ohm resistor gauge should display 130C (266F) and through a 154 ohm resistor gauge should display 50C (122F). I am assuming that 50C and 130C are respectively the bottom and top of the operating region or hatch marked portion of gauge. Sending unit acts as a variable ground dependent on coolant temperature. Sending unit should have a resistance of 57.7-49.3 ohms at 80C (176F). Here is reference: https://www.rotaryheads.com/PDF/2nd_...cal_system.pdf
you could do it with a switch and resistors too, i just used what i had laying around
#5
Rotary Enthusiast
i put a potentiometer on something (i think its in an enclosure?), and put a **** on it. then i measured the resistances, and marked the **** position. then you can put one side to ground, one side to the car and turn the ****, and the gauge moves accordingly. the S5 one is weird!
you could do it with a switch and resistors too, i just used what i had laying around
you could do it with a switch and resistors too, i just used what i had laying around
#6
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,949
Received 2,680 Likes
on
1,896 Posts
Thread
Thread Starter
Forum
Replies
Last Post
wickedrx7
Interior / Exterior / Audio
1
02-19-07 11:06 PM
darth fc3s
2nd Generation Specific (1986-1992)
4
12-07-05 01:57 PM