L322 4.4 tdv8 glowplugs not glowing

from what i've read so far, the 4.4 only has one coolant temp sensor, if it was defective the dash display wouldnt work so i can rule that out, plus there is no error code for any sensor
the control boxes are getting power, need to find out what the 4 wires are for that go to each. at a guess, ECT, BARO, injector pulse timing, signal to dash, i presume they go to the ECM
I'm confused, the more i read, while its clever, also seems quite simple, not much to go wrong apart from the controllers or the ECM, which you would think should flag a code

ohferfooooksake!!
i nearly forgot, how stupid of me. its a JLR product
Just been out to the car to double check the coolant temp at the obd port. turned the ignition on and the glow plug light comes on!!!! the freaking car knows i have no intention of going anywhere so it plays ball.

incidentally, ambient temp is about 7c at the moment, ECT says 20c. seems a bit high after sitting overnight? maybe thats the problem after all?

edit: I'll get my IR gauge out over lunch, see what that thinks the engine temp is

Here's some more to confuse you

J

marjon said:

Here's some more to confuse you

J

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thank you that reminds me of the london underground map

kermit_rr said:

..need to find out what the 4 wires are for that go to each....

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sensor ground (ECM)
glow monitor
switched live
glow control

righto, just checked again.
OBD reports engine temp as 19c, so a bit cooler than previous, but still much higher than the 6.8c read by the IR thermometer pointing as deep into the engine as I could get

consensus, i need a new one? it can't hurt and not expensive

If you unplug it it will think its broken and use a default of 0.
Does it run any better on start up?

J

marjon said:

If you unplug it it will think its broken and use a default of 0.
Does it run any better on start up?

J

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Not had chance to do that over lunch, but have ordered a new sensor. At the price its in the 'consumables' bracket to of the old one is ok it can sit on the shelf.
Will unplug later if it's not tipping down.
The fact the light is now showing is big progress. Have to go to office tomorrow, so good chance to check the temp values

Maybe it was just a bad connection and all your "ratching" around has reseated something.
Now the light is showing did you see if it was lumpy on startup?
Cos it maybe you have already fixed it.

Test the new 1 at a know temp so you can compare it with the old 1 when you take it out.

J

marjon said:

Maybe it was just a bad connection and all your "ratching" around has reseated something.
Now the light is showing did you see if it was lumpy on startup?
Cos it maybe you have already fixed it.

Test the new 1 at a know temp so you can compare it with the old 1 when you take it out.

J

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i didnt start up as no time to go anywhere, dont like doing that, battery drain etc
yes will test old vs new, agree yes could have been all the fiddling, or just a sane reading from a temperamental sensor

i wonder if there is an accessible PID to pull through OBD to see when the plugs are actually lit? rather than the idiot gauge "you dont need to know this technical stuff"

kermit_rr said:

Not had chance to do that over lunch, but have ordered a new sensor. At the price its in the 'consumables' bracket to of the old one is ok it can sit on the shelf.
Will unplug later if it's not tipping down.
The fact the light is now showing is big progress. Have to go to office tomorrow, so good chance to check the temp values

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its tipping down and real-feel 3c staying inside

0c overnight and 2c when i got in car to go to work..
OBD stated engine temp was 16c
pretty sure thats not right

kermit_rr said:

0c overnight and 2c when i got in car to go to work..
OBD stated engine temp was 16c
pretty sure thats not right

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FBH pre heating it?

Datatek said:

FBH pre heating it?

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nope its was definitely off. by the time i got to work, rummaged about in parking space etc, OBD reported 90c.. not sure whats normal for a diesesed engine

kermit_rr said:

nope its was definitely off. by the time i got to work, rummaged about in parking space etc, OBD reported 90c.. not sure whats normal for a diesesed engine

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95C on an M51, 105C on an M57 so somewhere around those figures I would expect.

Datatek said:

95C on an M51, 105C on an M57 so somewhere around those figures I would expect.

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cheers, will hopefully receive a new sensor today or tomorrow, hopefully that should sort it
they seem like a press fit with a spring clip to keep in place, maybe i can be quick and swap it out without losing any/much coolant.. i'll get some, just in case

Book says thermo starts open at 88 and fully open at 95.
What would be optimum operating temp? I guess is around the higher number.

J

marjon said:

Book says thermo starts open at 88 and fully open at 95.
What would be optimum operating temp? I guess is around the higher number.

J

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the p38 v8 is similar, starts to open around 82 if i recall, fully open at 96c, drives at 92 then creeps up while stationary

i'll test the old one and the new one in a pan of water, against my IR thermometer, see how they compare.. obviously not at the same time

Just had a look under the bonnet.. can't even see the sensor on the top hose!!! Maybe I'm just being blind. Could have sworn i saw it before, but there's that many bits n bobs