keastygtir
Well-Known Member
Havent read the whole lot but are you sure you ahve a good battery ground? When putting mine back together the temp and centre gauges were reading high which was done to the battery earth.
Water temp sensor fault
- Thread starter Danroyd
- Start date
Im getting 8.9volts from the sinal wire and if i ground it the gauge gos to max, ill try to get hold of a lazer heat thermometer to see how hot it is but i dont think its overheating because wouldnt it boil and pop the radiator?
Ive just taken the earth on the chasis off and redone it just to make shore but its still doing it ☹
I would say your regulated gauge voltage is high, should be 8V
The water gauge sensor reduces resistance as heats up which allows greater current flow to earth which increases needle movement.
The water gauge sensor is not linear and sensitivity and accuracy worse at lower resistance ranges (hot) so running over standard regulated gauge voltage would show high always but in greater amounts as water gauge thermistor getting hotter .
The water gauge sensor reduces resistance as heats up which allows greater current flow to earth which increases needle movement.
The water gauge sensor is not linear and sensitivity and accuracy worse at lower resistance ranges (hot) so running over standard regulated gauge voltage would show high always but in greater amounts as water gauge thermistor getting hotter .
Ok cool, can you think of a reason why the regulated gauge voltage would be high? Thats the wire coming from the tm teminal on the gauge to the sensor right?
You going need look at the service manual 2 EL section, look at wiring diagram for clocks and pull clock assembly and test voltage feed for clocks and 3 middle dash clocks too as would think they same base voltage spec. I can't recall if voltage regulator built into clock printed board but visual, multimeter and wiring diagram should conclude . Don't recall much spec on gauges in the service manual. other quick test you could try is adding a resistor to pull voltage down by 1V for the water meter and see if that makes gauge work in expected range and helps conclude on right track with diagnosis.
When you replaced water gauge was it just part of clock cluster or did you get a whole cluster ?
When you replaced water gauge was it just part of clock cluster or did you get a whole cluster ?
I got a whole cluster but swaped it in to mine do you think i should try it in that cluster?
Ok i will try that, thanks for all your help this thi gs doing my head in lol
Ok i tried changing the water temp gauge over to another dash cluster and its still doing the same thing . So theres 4 terminals on the gauge - ground - power and the tm wire that goes to the sensor. Do you know if there is a resistor or regulator on the tm wire somehere? Or does it just go staight from the gauge to the sensor?
Would say rules out voltage reg as pretty sure that in the clock board assembly.
I done voltage reg on earlier 80's nissans and they been 8V, is possible later nissans 9V which would make your 8.9V reading good, need collect some readings on good cars see what is standard.
Sensor wire goes straight to sensor from cluster
Not making any easy progress unfortunately, If 9V is standard reg voltage then you looking at some other earth path for the sensor wire to make gauge read high. could try a temp wire from cluster to sensor to see if reads normal as would pin down a harness issue.
I done voltage reg on earlier 80's nissans and they been 8V, is possible later nissans 9V which would make your 8.9V reading good, need collect some readings on good cars see what is standard.
Sensor wire goes straight to sensor from cluster
Not making any easy progress unfortunately, If 9V is standard reg voltage then you looking at some other earth path for the sensor wire to make gauge read high. could try a temp wire from cluster to sensor to see if reads normal as would pin down a harness issue.
Rewired tm to sensor and still the same issue , im thinking the only thing it could be is maby theres a external regulator somwhere on the wiring loom thats supposed to bring the voltage down , i found a 2 wire black box on the wiring loom that plugs into the back of the dash cluster do you know what this could be?
