Glow plug power

Hi Folks
I need your help please on my Defender 90 with 300tdi conversion done by previous owner. Engine starts up without any issue but exhaust emit lots of smoke on start up only.

I thought to check up the glow plugs power. When I switch on the ignition, glow plugs light doesn’t illuminate on the dash board. I have also checked with a multimeter there is no voltage on the glow plugs (Yellow/black) wire with ignition switch on.

But when I start the engine then glows plugs light illuminates for a fraction of a second. There is no Glow plug relay under the bonnet and I can’t find Glow plug relay anywhere. When it try to trace the wiring backwards, Glow plug wire (Yellow/black) wire has connected with a Brown/red wire and that Brown/Red wire is coming from the main harness which goes straight into the fuse box. But from the fuse box it is going up somewhere into the dash board and not visible.

I am just wondering if that is how it normally sets up on a conversation? How do I supposed to know if glow plugs are getting the power when it requires?

Have you got the spring resistance 'position ' on the ignition switch?
I put my relay, 200tdi conversion, behind the metal fusebox mounting.
Edit...later models didn't have the resistance position so glows were timer relay controlled.

Flossie said:

Have you got the spring resistance 'position ' on the ignition switch?
I put my relay, 200tdi conversion, behind the metal fusebox mounting.
Edit...later models didn't have the resistance position so glows were timer relay controlled.

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Hi I did switched on the ignition and Battery’s red light illuminate on the dashboard. Sorry I don’t know what does mean by spring resistance. But Glow plugs ligh doesn’t come on. Does that mean it didn’t had any glow plugs replay at first place?

Is your truck a pre tdi model that has had a 300 conversion?
If so the previous models had no relay.
Glow plugs are ignited in the spring position on the key. It go's, turn key on and dash lights come on. Turn a bit more and feel the pressure of the spring, in this position glow plugs and the indicator lamp in dash light. Turn a bit further starter engages.
Power to plugs is direct from the ignition switch. This type of switch has some large thick wires on it and is rated for the job.

Hi yes it’s pre Tdi model. It only has one position to switch on the ignition then on the further turn it starts the engine. Please advise what would the best way forward

Was the car a petrol before the conversion?

You may have hit the nail there @Flossy, just no glow plugs connected.

Flossie said:

Was the car a petrol before the conversion?

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Hi I think it was the 2.5td diesel engine

Singr07 said:

Hi I think it was the 2.5td diesel engine

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Sounds like you have a petrol ignition switch, fits to the rear of the ignition barrel, buy a diesel one, not expensive and fit that.
That's the easiest cheapest way or you could fit a stand alone glow plug circuit, a switch, cable and relay.

Flossie said:

Sounds like you have a petrol ignition switch, fits to the rear of the ignition barrel, buy a diesel one, not expensive and fit that.
That's the easiest cheapest way or you could fit a stand alone glow plug circuit, a switch, cable and relay.

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To add...are you sure there is no spring type resistance just before the engine crank position?

Flossie said:

To add...are you sure there is no spring type resistance just before the engine crank position?

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Hi Flossie, I’m being so dumb as I didn’t realise that yes there is a spring on that ignition switch and finally I have leaned it now how to use it. It does allow me to twist the key to spring and glow plug light come on. Thanks for your help you are a star