glow plug light

[suveer]

Hi there.

my glow plug light which comes on just before you start the disco has not been coming on in the dash for the last few days. Is it the globe in the dash or the glow plugs itself that is stuffed. Advice as to where to start looking will be appreciated.

thx

[BogMonster]

poss the bulb, poss the timer unit (can you hear it click on and then off?)

[orangemach5]

Have someone hold a multimeter on the top of one of the glowplugs when you turn the ignition on, if you have noo 12v feed to the glowplugs then its probably a relay problem.

[suveer]

poss the bulb, poss the timer unit (can you hear it click on and then off?)

thanks for some pointers. Is the timer unit that Bogmonster spoke about, the samething that Orangemac mentions also. Where is this located? It sems that i cannot here any click when i turn the key on.

thx guys

[BogMonster]

Yes it is. There is a combination timer/relay unit, a black box about 2 inches square with a multiplug in the bottom of it. IIRC on a 300Tdi Discovery it is in front of the driver near the RH front shock turret somewhere, though it is a while since I looked at one. Normal operation is when you switch the ignition on it clicks on (with the bonnet open you should clearly hear it), after a few seconds the heat light on the dash goes off and then a few seconds later the relay clicks off. It is a really big meaty click (glow plugs draw 100 amps or so, so it is a big relay) not some crappy little spotlight relay click - you can hear it in the cabin if you have the radio and heater off, and you should also be able to feel it with your hand on the relay casing.

It also drives the feed to the light on the dash I think, so it may be the cause of the problem. It ain't cheap though!

[orangemach5]

The relay is either located where bogmonster says, or its behind the screenwash bottle on the bulkhead.

[suveer]

The relay is either located where bogmonster says, or its behind the screenwash bottle on the bulkhead.

thanks a million guys. will start checking there. i'll keep you posted.

cheers

[suveer]

thanks a million guys. will start checking there. i'll keep you posted.

cheers

hi guys

i found the relay/timer as you pinpointed. When i turn the key on i can hear and feel the click in the relay. But yet the glow light does not come on. Anyway, i changed the relay with another and it is now perfect. The light glows on the dash just before starting. But just a thought, if the relay is clicking, why is it not activating.

Thanks a million Bogmonster and Orange5mach. Much apreciated

[Pete Attryde]

Mine does this occasionally, (it did it last night). The light is controlled by one set of contacts within the relay and the power to the plug goes through a different set. On mine the plugs work fine regardless of the light operation, to fix the light I just pull the connector off and then re-connect it which cleans the corrosion on the connection and the light starts working again. When I first got mine the relay didn't work at all and when I investigated I found that all the connections had gone green and loose with corrosion, so I cleaned them all up and squashed the crimps a little to make them tighter and since then the plugs have worked every time, just sometimes the light doesn't.

Pete.

[turbomangler]

Mine does this occasionally, (it did it last night). The light is controlled by one set of contacts within the relay and the power to the plug goes through a different set. On mine the plugs work fine regardless of the light operation, to fix the light I just pull the connector off and then re-connect it which cleans the corrosion on the connection and the light starts working again. When I first got mine the relay didn't work at all and when I investigated I found that all the connections had gone green and loose with corrosion, so I cleaned them all up and squashed the crimps a little to make them tighter and since then the plugs have worked every time, just sometimes the light doesn't.

Pete.

in case it helps anyone the white/ brown wire to the timer /relay is the earth from the dash warning light . if u suspect the bulb has gone , with the ignition turned on and this wire earthed out the bulb should be lit . this is easier than taking out the instrument panel to find out if the bulb has blown ! but if it has then its to come out anyway.

just converted my v8 to tdi when i wired in the heater relay the warning light wouldn,t light . this is because the v8 loom doesn,t have a wire from the warning light to the heater relay . as i had a spare loom to butcher i removed a connecter from the instrument multi plug and put it into my v8 multi plug (i think it was terminal 5 on the plug , this gave me the wire i needed to make the warning light come on ) connect this to the white /brown wire on the relay. connect the relay white wire to ignition live i used the original coil feed wire which i have also used for the fuel shut off. connect the relay white/ red wire to the white /red on the starter motor . i had 2 white/reds in a connecter of there own when i traced them thru the harness they both join together and go to the starter , i split them and used one of these . u could run a wire direct to the starter but my way looks a lot neater. the black wire from the relay just needs to go to an earth point . the thick brown to battery positive and the thick black/yellow to the heater plugs . it all now works as it should and the warning light comes on when the key is turned stays on for around 5 seconds then goes out the relay is still on for around another 10 seconds before switching off. hope this helps someone out . of corse u can make the heaters work without the warning lamp but i wanted mine to work and be a tidy job when finished. no ugly wiring under the bonnet . nothing to give it away that its not a factory fitted tdi . steve.