oil warning light not working

**antvc** · 14th April 2008, 10:03 PM

My oil warning light does not come on when the key is turned, it used to work last week.
300Tdi motor in a 89 Range rover
I checked the wire to the oil switch on the oil filter and there was no 12 volts there.
The wiring diagram shows power coming from the "+ignition load relay" to the warning light then to the oil switch then to earth.
There is a take off to the "voltage transformer"before the switch.

Is there some place to check if the power is coming through the warning light without taking out the instrument panel?

Also , a seperate problem.The low warning light on the dash has never come on and was pointed out to me that it should come on when the ignition is turned on. I checked the 2 wires to the sensor in the header tank and there is 12v to each wire. this doesn't seem right but could be as the wiring circuit shows the wire form the sensor going through the multifunction unit. I think the sensor is broken as it should have a sliding part which would float in the water and it is not there. Is this correct?

Also, i read in the manual that "the brake fluid pressure symbol will also be illuminated while the key is being held over to actuate the starter confirming that the warning circuit is functioning correctly".
The light has never come one when I turn the key. Is this normal as the switch seems to be connected under the bonnet?
Has anyone had experience in this?

thanks.
Anthony

**sclarke** · 15th April 2008, 03:10 AM

Had a similar problem with my last Defender.

It was the multi plug on the firewall, full of mud and crap.

**antvc** · 15th April 2008, 06:50 PM

Thanks ,
Would the rangie have a multiplug?
I can't see a plug on the firewall,but I suppose the wires have to go through the firewall somewhere.
Anthony

**awabbit6** · 15th April 2008, 07:14 PM

You can test the oil pressure warning light circuit by disconnecting the lead on the pressure switch and earthing it while the ignition is on. The light on the dash should come on. If it does, then the pressure switch needs replacing.

**PhilipA** · 15th April 2008, 07:15 PM

Yes there should be sliding sleeve on the water level indicator. There is a reed switch inside the column which opens when the float is fully down, ( i think) Anyway its the opposite of what you expect. And AFAIR, there should only be 12v on one side of the level terminals.
Although I have never heard of one failing, maybe your multifunction unit is crook. It makes a flashing light when the reed switch opens, and maybe it lights up the other two also.
You could try running a magnet across the bottom of the column of the sensor. They are pretty expensive AFAIR.
Regards Philip A

**Bradtot** · 15th April 2008, 09:30 PM

Philip u are correct reed switch and magnet and also resistor 1k from memory in series. What normally happens is the coolant gets inside the sensor and eats away the resistor and or reed switch leads, and renders the unit open cct or dead. I have now repaired 3 of these by replacing the reed switch and resistor and resealing. I am of course reffering to an 89 model rangie but I think it the same or similar for the later ones.
Re the lights on the dash most sensors rely on the sensor to ground or earth to complete the cct so as above pull the wire from the pres switch and earth it and see if the light comes on. You could also check the globes on the the other lights as they do blow sometimes but this does mean stripping the binnicale
Brad

**antvc** · 16th April 2008, 07:55 PM

After poking around the wiring under the bonnet, the oil light worked again so there must be a loose connector somewhere. I checked the oil switch it is working .
There is no plug on the firewall , all the wires just disappear through the wall.
i was dreading having to remove the insturment binnicle, it seems diffucult to do.I might have to do it if the water light doesn't workafter I fit a new water sensor
Thanks for the help.

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