edmason Posted August 29, 2011 Share Posted August 29, 2011 I can’t get the temperature gauge to work properly on my Land Rover. My Series IIA has the 2.5l petrol defender engine. On the block there are 3 sensor terminals: 1. On the filter casing there’s a terminal, connected to the oil pressure warning light, which works. 2. On the n/s/f of the block, at the top, just behind the thermostat housing, is a terminal in a flat topped sensor, held in by 3 bolts, which is connected to the temperature gauge. When the engine is cold the gauge shows cold, and a test light to the terminal doesn’t light. As soon as the thermostat opens the gauge goes straight to hot, and the test light lights. 3. On the o/s/f of the block, at the side, near No 1 plug, is a brass hex with a terminal, not connected to anything. Test light = nothing, engine hot or cold. So, have I got a faulty gauge, a faulty sensor, or is something wired up wrong? Is one of these sensors for an oil pressure gauge? I’m trying to sort out a thermostatic fan. I’ve got a rad (from the Defender I assume) with a sensor/switch just below the top hose entry, which has 3 wires, black, red & white. I assume that red should be a +ve supply, black earth, and white should switch the fan (I’ve used a relay), but I can’t get it to work, and without the temp gauge working it’s hard to know what’s going on. Can someone help please? Quote Link to comment Share on other sites More sharing options...
secondjeremy Posted August 29, 2011 Share Posted August 29, 2011 The sensor held in by 3 bolts is the 'Otter' switch which is part of the choke warning light system. Land Rover use a sophisticated choke warning light system with a switch on the control itself or the cable (depending on model) and the temperature switch (otter switch' in the cylinder head. The warning light therefore only comes on when the 'Otter' switch operates at about 50 degrees. So try the cable on the other sensor (which should be somewhere round the thermostat) and see what happens. Quote Link to comment Share on other sites More sharing options...
Mr Bean Posted September 3, 2011 Share Posted September 3, 2011 The sensor at the front near the thermostat is the choke warning switch. It just switches on when the engine is up to temp to bring on a light on the dash.The switch nearer the spark plugs is the correct one. This may have failed and needs replacing.Trev Quote Link to comment Share on other sites More sharing options...
Jon White Posted September 5, 2011 Share Posted September 5, 2011 You also need to bear in mind that a defender sensor will not work with a seruies gauge correctly. You need to change the sensor for a series one then the gauge will work correctly, as they are totally different resistance ranges. I would also add that no defender came with a factory mounted thermostatic switch or electric fan, s the rad you've got is probably not from a defender. The series rad will keep the 2.5 petrol cool without any problems at all, so i would just use the standard series fan and cowling and you'll have no problems. I ran my series like this for many years. I've since found electric fans and thermo switches to be nothing but trouble so would avoid them at all costs. However as I'm now running a disco 200tdi its not possible to run an engine driven fan on one (otherwise I would!) Jon Quote Link to comment Share on other sites More sharing options...
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