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cypermethrin



Member Since: 15 Dec 2010
Location: Berkshire
Posts: 95
United Kingdom 2008 Defender 110 Puma 2.4 SW Bronze Green
Diagnostic help - glow plugs always receiving voltage
Hoping the collective can provide some direction here

2010 2.4 puma

It’s had a laboured cold start for a while (used to be instantaneous)

Shows fault P037D glow plug sense circuit signal invalid under Forscan

I have checked all the fuses including the 60A in the drivers seat and the 10A 37

Disconnected glow plug loom at terminal in engine bay

Voltage is shown and the relay can be heard energising and switching itself off

But the voltage remains well afterwards when engine is running for 6 mins !! (I gave up at that point)

Presume the culprit is fault glow plug relay ?


TIA
Post #1067435 10th May 2025 11:54am
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17802
United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
The glow plugs do stay on for a while after engine start on the Puma but I can't remember for how long.
Post #1067441 10th May 2025 2:02pm
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andy63



Member Since: 30 Jun 2023
Location: north east
Posts: 763
United Kingdom 
I have the 2.2 and I believe the glow plug operation is different on the 2.4, but i can vaguely remember the pre heat phase ..ie while you see the dash board light lasts only for 2 to 3 seconds max when it's cold.. after that it's on a so called after glow ..the plugs will continue to be heated by a pulsed voltage to each plug ..that continues for a set period of time or dependant also on intake air temp coolant temp or driver demand..
It used to be a direct injection engine didn't even need glow plugs, but they now apppear to be more reliant on them..for starting and complying with emissions regs..
As I said I'm not sure the 2.4 works like I've described..
Post #1067443 10th May 2025 2:53pm
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andy63



Member Since: 30 Jun 2023
Location: north east
Posts: 763
United Kingdom 
A quick check of the plugs individually for their resistance would be a good place to start.. 1 ohms or less for a good plug I'd imagine..👍
Post #1067444 10th May 2025 2:56pm
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andy63



Member Since: 30 Jun 2023
Location: north east
Posts: 763
United Kingdom 
Re: Diagnostic help - glow plugs always receiving voltage
cypermethrin wrote:
Hoping the collective can provide some direction here

2010 2.4 puma

It’s had a laboured cold start for a while (used to be instantaneous)

Shows fault P037D glow plug sense circuit signal invalid under Forscan

I have checked all the fuses including the 60A in the drivers seat and the 10A 37

Disconnected glow plug loom at terminal in engine bay

Voltage is shown and the relay can be heard energising and switching itself off

But the voltage remains well afterwards when engine is running for 6 mins !! (I gave up at that point)

Presume the culprit is fault glow plug relay ?


TIA

Any joy with this.?
I found a mention of the afterglow period of operation lasting up to 500 seconds.. so it would be possible to detect a voltage to the plugs for a while after start up if it wasn't been driven to cause the temp to rise sufficiently..
Post #1067588 13th May 2025 10:11am
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cypermethrin



Member Since: 15 Dec 2010
Location: Berkshire
Posts: 95
United Kingdom 2008 Defender 110 Puma 2.4 SW Bronze Green
So just to complete this ….. got round to replacing all the glow plugs. All of them were dead.

Also changed the injector washers and seals (as you can see from the photos they needed cleaning etc) and its now like a new truck and starts on the button.

Need to change oil and filter and fuel filter and should be all good.

Click image to enlarge
Post #1069457 10th Jun 2025 10:16pm
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