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Instrument gauges reading high


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Hi All

had another go at the gauges!

Connected a seprate earth!

When i connect the 12v feed to the gauge & test it with my test light! the test light lights up!

But when i connect the test light to the other terminal to check for a feed passing through the gauge! The test light dose'nt light up! But the gauge starts to reads full?

I would have thought the test light would still have lit up as there is a feed passing through it?

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I have a fairly unmolested B reg 110, would it be helpful if I took a picture of the wires in the back of my cluster? I fitted a Discovery 200Tdi a while ago and apart from the temp gauge reading higher because of the Discovery sender all the dials work OK.

Let me know if you want a pic.

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I have a fairly unmolested B reg 110, would it be helpful if I took a picture of the wires in the back of my cluster? I fitted a Discovery 200Tdi a while ago and apart from the temp gauge reading higher because of the Discovery sender all the dials work OK.

Let me know if you want a pic.

A photo would be useful as I still have a suspicion that the feed and sender wires may be reversed but till I pull my dash off this weekend I can't check for Mark.

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Thanks Ralph, having lived and breathed this albeit by remote diagnostic I can only conclude that the instruments are both faulty even though that seems so unlikely in the circumstances.

Anyway a picture would help a bit and I'll take my dash out this weekend.

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Its always hard looking at pictures to decide on what's connected to what but your picture looks like the sender connections are nearest the illumination (dial lamp) holder whereas in Marks picture that looks to be the opposite- it might be my eyes and this small Android screen but worth a check.

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On the discovery gauge on the bench here there is a resistor from one terminal to ground so even though it works both ways round the reading is different depending which way its connected - now I don't know if the defender gauge is the same but if I get ten minutes in daylight tomorrow with a meter might tell us something.

Got a ford 4600 cab to put back on tomorrow and the dash wiring wasn't disconnected when it was lifted off so a bit of wiring to sort.

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So I got round to measuring the temperature gauge on my 90.

So the open circuit voltage to the temp sender is 10.2V - so it is regulated.

Yours measured 12.6V which suggests the regulator in the gauge is not working, either faulty or not wired correctly.

Looking at a scrap discovery temp gauge (which may be similar to a defender) there is a zenner diode stabliser with a 56R series element.

Substituting a resistor to -Ve to simulate the sender getting hot, mid scale (N) needed about 30R and the voltage was 5V Hot was about 10R resulting in 4V - now those measurements were done quite quickly so +/- a bit!

That suggests to me that the reasons your gauges no longer work are:

1 - gauge -Ve connection missing ( you have tested that and the results suggest that it is ok )

2 - possibly gauge input and output have been reversed ( photographs suggest this may be case but its not clear and may not cause the symptoms )

3 - both gauges are stuffed now ( frustrating and unlikely )

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  • 3 months later...

Hi All

Sorry not been in touch for a while regarding this issue! Fuel & temp gauges are still reading high! I know somebody that has got a set of gauges at the back of their garage & has been claiming to dig them out for weeks now! but they cant get to them just now? So i have just been trying to make sure that if i need to use the Landy more than i normally do i stick an extra £10 in & besides i've got other jobs needing to be done that i was spending to much time on them.

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yeah I have a few things to do too, the reason I'm in this mess is because the bulbs in the dash packed up so I was replacing them - now I get to see my gauges just not really any point though!

I'll let you know if I work it out

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