Noticed couple of days ago car misfiring, especially at low speed after just starting off. Once going much less in evidence, just the odd stutter. So out comes the old code reader. Most of the usual rubbish codes in evidence but one P0380 will not clear and as you know that is the glowplug circuit.
So checked F1 which is fine. Now F4 how do I get to it as is covered by a plastic shroud and want to avoid damaging it? And the glowp[lug relay is the same as couple of others is it safe to just swap it around.? All this as a starting point before you tell me the fault is the plugs themselves.
And am I cracking up but I thought, and am sure I have seen, the glowplug light on the dash light up everytime I press the start button. Does it , as it does not now, or am I cracking up?

I only ever saw the glow plug light in the depths of a very cold winter. But, I’m reliably informed that the glowplugs are in use at every start and operate for minutes after the engine has started to help with fulfilling emissions requirements.

I find strange they are used everytime I though only when a bit parky.

From a post by Alex Pescaru,
There are two phases: pre-glow and post-glow.

Pre-glow is before starting the engine, for a period of time depending on the outside temp.
This period occur no matter if you start or not the engine. After expiring, the glow plugs are disconnected.
In order to repeat the process, you need to switch off the ignition and then switch it back on.
The engine cranking command is generally given before the pre-glow period to expire.

After the engine was started, the glow plugs are energized again, in order to help combustion and lower the emissions. Again, for a period of time, until water temp is over a certain value (about 20 degrees).

Thing is that the glow plugs themselves doesn't warm up (or pre-heat, as you said) the engine... They are too small for that big hunk of metal the engine is...
The glow plugs are for igniting the injected fuel and the pre-glow period is for allowing them to reach incandescence in order to ignite the fuel easier.

Well there you are simple is it not? No as it is a FL2

Do you know how to access fuse 4 ?

Have since measure the output of the relay to groundand is reading 4k ohms. Some what high for 4 supposed 1 ohm resistors in papallel!

Bogart wrote:

I find strange they are used everytime I though only when a bit parky.

We have spent many an hour on this forum discussing the Glow Plug operation and the general starting procedure.
https://www.freel2.com/forum/topic37673.html?highlight=glow+plugs FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

jules wrote:

Bogart wrote:

I find strange they are used everytime I though only when a bit parky.

THere is a good explanation of the glow plug function in the JLR manual (free) from this forum.

Use of the glow plugs cuts down emissions in a cold engine, not just to aid starting in winter.

IanMetro wrote:

We have spent many an hour on this forum discussing the Glow Plug operation and the general starting procedure.
https://www.freel2.com/forum/topic37673.html?highlight=glow+plugs

Ah yes but I am more interested in why I have this error and is it the glowplugs I should be pointing the finger at? What with the 4kohm reading.

Have all four glow plugs failed ?




Is it possible to test the glowplugs in situ without taking the manifold off ? Jules

There are different glow plug relays according to VIN

https://parts.jaguarlandroverclassic.com/p...and-rover/ Jules

There are different glowplugs too

https://www.advancedfactors.co.uk/dw12-fue...1220-c.asp Jules

Been having a good look at circuits etc.This relay looks a confusing item as putting in the LR number pictures show something completely different nothing like what is in the vehicle. Vin is AH181447 so falls into the 11v plug category. Attached is a photo of the actual relay with part number which can be got for about £7 not the £70 or£80 being quoted for the LR part LR 001206

Have measured volatges and there is 12v present across the relay coil with igniton on as expected.
There is also 12v on pin 3 the feed from the 60A fuse hence proving that is good. So fault in my mind is either relay or the plugs more prone to think plugs but will order plugs and a relay anyway.
Might add that I did a short run with the relay removed same results but the P0308 could be cleared but superceeded by a glowplug circuit error, not surprising with no replay present.

Click image to enlarge

Click image to enlarge

Yes - its amazing what JLR were prepared to charge for a common, all garden FoMoCo part.

Hopefully its the relay at fault and not the glowplugs - they arent easy to get at. Jules