Disco 300tdi auto. Am I right to assume that's the light for glow plugs?

Scenario:
Drove home Sunday past with the light remained on the whole journey. Battery flat this morning while trying to start her up. Put the battery on charger for next 2 hours, and started straight away. Went out for a round trip of approx 3 miles, with the light remained on the whole journey.

Switched off engine. Turned key from off to on (just before start), check engine, TC lights etc all came on then went off after a few seconds except the "coil" light which remained on.

Removed -ve on battery and put a multimeter between -ve lead and -ve on battery, had a reading of 0.001 (20m setting on "A"). So assume no abnormal battery drain. Re-attached -ve terminal onto battery. Turned key from off to on (just before start), the "coil" light doesn't even come on while check engine, TC lights etc came on and went off in a few seconds.

Set multimeter between glow plugs leads to -ve on battery, no reading. Maybe should have tested the glow plug lead to -ve on battery 'before' removing -ve lead for test.

Can anyone shed some lights here??

I'd guess its the glow plug relay sticking on???

davek0974 said:

I'd guess its the glow plug relay sticking on???

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I sustain that but in the wiring diagram it's named glow plug timer relay........ are we talking about the same thing?......

yeah thats the one. The mini fuse box under your bonnet. Its the big black one attached to it at the back iirc

sierrafery said:

I sustain that but in the wiring diagram it's named glow plug timer relay........ are we talking about the same thing?......

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Sorry yes thats the one, you may need some glowplugs if they were kept on for a long period as they are only meant to be on for a few seconds at a time, might be worth testing them.

thanks guys.......am feeling sheepish for missing that myself...!!!!!

took the relay out, bench tested it:
12+ to terminal 30 (orig from battery +ve)
12+ to terminal 50 (orig from starter solenoid)
12- to terminal 86 (orig to ground)

0.75v output from L (orig to dash glow plug bulb)
1.15v output from 85 (orig to EGR)

0.00v out put from 87 (orig to glow plugs)

So, it appears that the timer relay is truly ****ed....will try and run it a few days without glow plug and see how it goes........as it costs 20 odd quid for a new one...

for record sake.....

disco won't start this morning while the relay is disconnected....but started straight away once re-fitted........had a look on wiring diagram and it did show a connection from #85 to EGR as well as fuel stop solenoid..........

spoken to a friend who has disconnected the glow plugs and taken off the relay on his 300tdi without EDC........and his worked alright....

so conclusion is...if yours a 300tdi auto with EDC....a relay must be fitted to 'disengage' the fuel stop solenoid........(maybe a good point for a secret immobiliser)......so, best carry a spare if you bother....!!!