L322 4.4 tdv8 glowplugs not glowing

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kermit_rr said:
ok, the relays have 2 plugs each, one goes to a bank of glow plugs, the other is power, plus 4 other.. signal? wires?
engine is cold, the relays should be coming on and I've confirmed they aren't, none of the 8 are getting any power. they should be used when engine is below 50c so something isn't right. All 3 big fuses are OK, so its a signal issue/bad connection somewhere. I can't imagine both controllers have gone bad at exactly the same time
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Anything is possible because everything is interlinked on the CAN BUS.
 
Datatek said:
Anything is possible because everything is interlinked on the CAN BUS.
Click to expand...
agree, but with no error codes generated, i'm guessing it must be pretty close to the glow plugs.. with 5 wires plus power going to the relays/controllers, doesnt that mean they are not CAN connected? otherwise would be one wire plus power?
 
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Item 8 is the ECT - Again this is for the 3.6 but could be similar on the 4.4
 
Thanks, there is a sensor in the top coolant hose, not sure what is used for though.
Worth unplugging then turning the ignition on? See what happens?
 
Hmm. If the signal or sensor were faulty, it reads as though the cooling fans should be in operation? That sounds like a noisy experience i wouldn't miss
 
kermit_rr said:
Hmm. If the signal or sensor were faulty, it reads as though the cooling fans should be in operation? That sounds like a noisy experience i wouldn't miss
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I am sure you would notice them running!!

Try unplugging it - the ECM should default to 80degC - the fans should run....if they don't run, then either the fans are kaput or power thereto is non-existant.

BUT will this prove or disprove the ECT as an issue???....as if the fans are an unknown you could be chasing false positives or false negatives...

Plugged in, ECT Faulty = Fans should run
Unplugged, ECM thinks ECT is faulty = Fans should run
Unplugged, ECM thinks ECT is faulty BUT fans DON'T run = Faulty Fans or circuit
Plugged in, ECT Faulty BUT fans DON'T run = Faulty Fans or circuit

I would do the test just to see - but I would take the results with a pinch of salt UNLESS the fans DO start running - this will then prove the ECT and the control logic are sound...and the fault is not the ECT

If you have access to live data, you could unplug and the sensor and see if the values of the coolant temp change to suit.

Also, although it is not written in the control logic document we both seem to have read about the glow circuit operation - will they also only function if outside temp is below 5degC?? or is that just the A/C Compressor?

Reading the doc - it is all based on engine temp not OAT.
 
I'll try that tomorrow.
I've got SDD which should do live data but complains of the engine is off, complains if it's on etc, probably need something more usable
 
From what iv found,
The glowplug light will only show if theres going to be a delay from you pressing the start button to it actually turning over if it needs a glow pre start,
The ceramic glowplugs heat much faster then older ones,
After burn will be on till it gets upto too a certain temp,
modern things won't need a pre start,

Also since the Glowplugs are part of the emissions equipment like the dpf regen any non or failed operation or activation will log a fault and an engine management light,

You'd get faults for short or open circuit for each relay power too and from,
and for each glowplug itself,

If you really want to see it work pre start you'll need a pre start coolant temp of around -10
 
I also note in you say its got a tick is it only lumpy with the tick? If so it could be down to an injector or the copper sealing washer
 
stustrong said:
From what iv found,
The glowplug light will only show if theres going to be a delay from you pressing the start button to it actually turning over if it needs a glow pre start,
The ceramic glowplugs heat much faster then older ones,
After burn will be on till it gets upto too a certain temp,
modern things won't need a pre start,

Also since the Glowplugs are part of the emissions equipment like the dpf regen any non or failed operation or activation will log a fault and an engine management light,

You'd get faults for short or open circuit for each relay power too and from,
and for each glowplug itself,

If you really want to see it work pre start you'll need a pre start coolant temp of around -10
Click to expand...
When i first got the car, the glow light would always come on even if the car was cool (not cold) for maybe half a second or so and there was a start delay. I'm certain there should be a glow delay when it's been left over night and cold outside.
As you say there are used for emissions and to prevent diesel rattle on a cold engine so not just about starting
Also used during regen to ignite the diesel injected during the exhaust stroke, from what I've read. If that's not happening then I'll be in trouble soon enough
 
Mabye a daft thought but i found a temp sensor online for 7.50, could order that and put a cup of anti freeze in the freezer overnight and see if it dose a glow plug start,
 
thinking about it, dont know if its normal behaviour or not, but if i stop the engine for a couple of hours, turn the ignition on and the coolant temp gauge shows the wrong temp until the engine is started, then it drops to where it should be ie. 'cold'
 
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