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cypermethrin

Member Since: 15 Dec 2010
Location: Berkshire
Posts: 94

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

10th May 2025 11:54am

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17788

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.

10th May 2025 2:02pm

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 750

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..

10th May 2025 2:53pm

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 750

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..👍

10th May 2025 2:56pm

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 750

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..

13th May 2025 10:11am

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