SLROC Forum

My tank on a 1990 200tdi diesel is reading full permanently it's driving me nuts. what color I have black green and white.

Please help thanks Bill

Hi Bill, just came across your post when looking for something else, did you get things fixed or still need help, I've got a 200tdi and could check mine.
Jock

The only progress i have made is it now reads empty permenantly 

Hi Bill, took the dash off and looked at the wire colours for the fuel gauge, reading from let to right viewed from the rear of the gauge,
 
1 Green/Black,(left) 2 Black to Earth onto the nurled nut, 3 Green (right) (12v fused supply)
 
on the fuel tank on my Defender there were only 2 wires used, looking at it from top to bottom,
1 spare/blank, 2 Black (middle) 3 Green/Black (bottom)


Hope this helps
Jock

I will give it a try but I'm running out of hair to pull out.

Hi Bill I sympathise with you I've none left either !

Hi guys Kieron mentioned a voltage regulator or reducer for the gauges going from 12 volt to 10 can't find it does anyone know what it's called

Thanks Bill

Hi guys Kieron mentioned a voltage regulator or reducer for the gauges going from 12 volt to 10 can't find it does anyone know what it's called

Thanks Bill

If I'm right if you trace the wires through the bulkhead and viewing the engine bay from straight on just right if the strewing wheel a black box will have the wires running to it and from it your wires to the tank should be there also Hth 

Bill

Found this article on another forum and I think this might help you solve your problem, in the end it was the voltage stabiliser that was the issue, I have no idea where this stabiliser  is so maybe someone else on the forum could help locate it or a quick phone call to a local Land Rover specialist might be beneficial, the previous post from Lurch is I think pointing you towards a voltage regulator for a dynamo driven system and if I am correct yours will be an alternator which has the regulator located inside

Full credit  to Paul  fhttp://forum.landrovernet.com/member.php/62643-gw8izr the author.

PHP Code:
+12v-------A-----O/O-----B-----{REG}---C-------(TEMP)-----/\/\/\/\/\/\/\/\------------GND
                Fuse                   \                     Temp sender
                                        \                                         
                                         \----(FUEL)------/\/\/\/\/\/\/\/------------GND
                                                              Tank sender 

Its a very simple circuit, the supply (12V) is fused then regulated to a reduced voltage to supply the meter circuit. The meters both rely on the regulator supplying power to the dials and the sender units provide the return current path, The resistance of the sender units varies from a high resistance to a low resistance depending on temperature or fuel level.

A quick test is to disconnect the temperature gauge sender unit wire and connect it to a good GND or earth and the gauge should read full scale.

For BOTH instruments to fail at the same time the problem is most likely to be BETWEEN points A and C in the above drawing. Note that a wiring short circuit to GND or EARTH at point C will stop both instruments working, If that is the case it should blow the fuse assuming its not been replaced with a larger fuse or piece of silver foil which could then potentially damage the regulator.

To test:

1 - Connect the black lead of a multimeter to a known GND or Earth connection.. such as the end of the gear lever where the paint has rubbed off ;-)

2 - Verify that your meter is working by turning it on to a DC voltage measuring range then connecting its red lead to a known good working 12V line, it should read about 12V.If that wasn't successful find out why before you proceed.

3 - Connect the red meter lead to the feed to the fuse (point A) it should read about 12V If that wasn't successful find out why before you proceed.

4 - Connect the red meter lead to the wire on the output or load side of the fuse (point B) it should read about 12V If that wasn't successful find out why before you proceed.

Likely causes of this step being unsuccessful is the fuse being blown, the connections being corroded or simply vibrated off.

5 - make sure the 12v feed from the fuse is now reaching the instrument regulator. Without disconnecting anything press the red lead of the meter onto the spade connector on the input of the instrument regulator (point C) it should read about 12V If that wasn't successful find out why before you proceed.


6 - Measure the output of the voltage regulator to see if its working. Disconnect the output wire and then connect the red meter lead to the terminal or spade connector on the regulator, it should read between +7V and +12V depending on the type. If it reads zero its faulty.If that wasn't successful find out why before you proceed.

Some regulators are electronic, some are very simple bimetalic strips but whatever type - if there is no load or connection to the output there should be an output voltage.


7 - Re connect the output of the regulator to the circuit. Confirm that the wires connected to the regulator output are secure, not corroded or fallen off. confirm that the output of the regulator is still there by connecting the red lead of the multimeter to the output terminal.


A stable voltage of about 7V confirms its OK, also 12V and 0V rhythmically switching on and off is OK, but 0V all the time suggests a faulty regulator or a shorted wire to one of the senders.

If there is a wiring short or trapped wire after the output it can connect this voltage to earth which can damage the regulator or blow the input fuse.


If you have got this far and it still isn't working and you still havent found the fault first go to the tank sender unit and disconnect all of the wires. Then go to the temperature gauge sender unit and pull the wire off the terminal. Measure by connecting the red lead of the multimeter to the disconnected wire, (not the gauge terminal) and the voltage should read almost identical to measurement in step 6 - if not find out why before you proceed.

Assuming the voltage reading is now the same connect that wire to GND or EARTH - the temperature gauge should now read full scale or HOT. If it does the sender unit is faulty.

Repeat for the tank sender.

Hi Bill
I've found out where the voltage regulator is, it's apparently on the back of the alternator, mine packed in today and when i was at the garage picking up a replacement I asked the electrician where it was, hope  your getting your problem sorted.
Jock