TEMPRETURE GAUGE Fault diagnostics
 

hi all i am trying to find out how to find the fault with my non working temperature gauge i have swopped the gauge and the faults still there . heres my problem sometimes i turn on the ignition and the gauge never moves sometimes i turn on the ignition and the gauge goes straight to 11 o clock when cold all advice most welcome !

My mate simply replaced the whole sensor and gauge using a £6 universal kit off ebay. Slightly longer than the original sensor. There was a bit of limescale to clear out to fit it. He mounted the new gauge in a spare hole on the dash.

I did see a supposedly original sensor on ebay too for about £6 I think

What year is your car? It may be from the range that used the infamous Bosch "biodegradable" wiring. In that case, the wiring would be highly suspect. A good troubleshooting method would be to temporarily use a good length of wire between the sensor and the gauge.

hi ngoma what terminals woud i need to wire on the clock as there are 5 on the back of the clock and just 2 from the señsor auction block near front of the engine regards jim

its a 1995 year of manufacture

1995 would be new enough that it should not have the problematic wiring insulation I believe, although that doesn't mean it couldn't have a bad connection or chafed wire anyway.

Let's try to be systematic about how we troubleshoot this. I suggest starting from the front and going through the system piece by piece until we find the issue. First thing to check will be the sensor itself.

The sensor (sometimes also called a sender or sending unit) should be located near the front of the cylinder head, close to the glow plug for the #1 cylinder. I think you have seen it there before. Here are the first two questions:

1) Once you have found the location of the sensor, can you confirm if the sensor has ONE wire on it? Or does it have the later style sensor with a TWO wire connector?

2) Do you have access to a volt/ohm meter?

Depending on which style sensor and connector your car has, the first diagnostic step will be to look up the correct resistance values for the sensor on a cold and warm engine. Then you can test your sensor's actual resistance readings using an ohmmeter and see if your measurements are close enough to the required values.

thank you v8volvo
my sensor has 2 wires i have just purchased a basic multi meter to test battery and alternator and it works ok so take it the next thing is give you the readings but from which wire just looked 1 is white and orange1 is black and yellow hopefully regards jim

sorry v8volvo i have a back probe and a red probe from multi meter s where do i put the probes for each test im a carpenter by trade so excuse my questions please

OK sounds good.

The sensor is a thermistor which works by changing its resistance with different temperature. Low temperature should show high resistance across the two terminals, and then as the sensor warms up the resistance should decrease at a steady rate. Typically the service literature will give a specification for the correct resistance for a cold sensor and at regular engine operating temperature, to allow the sensor to be tested for correct operation.

With the multimeter set to measure resistance (ohms), disconnect the electrical connector from the sensor and then touch the two multimeter probes to the two sensor terminals. One probe goes on each terminal. For measuring resistance it doesn't matter which probe you use in which position, the measurement is the same.

Depending on what type of multimeter you have, you may need to choose the correct range to get a valid reading for the resistance of the sensor.

Take the measurement with the engine cold (sitting overnight) and again after driving when the engine is fully warm and let us know what the resistance readings you measure are.

In the meantime I will try to find a source of information on what the correct values are to compare your readings to. Here in the US we only had the early model diesel cars which came with a different sensor that uses only one wire so US D24 service information doesn't have the info you need. However, the later US gas cars had a 2-wire sensor like the one on your car. I'm trying to confirm whether the late diesel sensor and gas engine sensor are the same part with the same specs. If not, we may need to get a forum member from outside the US to test a known good sensor on a different car.

thanks for your valued input V8volvo i did disconnect the connections under the bonnet on each side .the connectors are on on the wing on each side but got no readings on either sensor but on the power side with ignition on i got 4.65 on each side does that make any sense ? regards jim