glow plugs dash light

How long should it take to heat glow plugs my dash light goes out in a few seconds is this normal??

The glow plug light is there to inform you to wait until it goes out. Once out the plugs should be hot enough to allow the engine to start fine. The plugs themselves will stay on for much longer, as they are controlled by the ECM as a running improvement and emissions reduction strategy. Sometimes the glow light doesn't show at all, but the plugs will still be used for the above reasons, they're just not needed to start the engine.

Nodge68 said:

The glow plug light is there to inform you to wait until it goes out. Once out the plugs should be hot enough to allow the engine to start fine. The plugs themselves will stay on for much longer, as they are controlled by the ECM as a running improvement and emissions reduction strategy. Sometimes the glow light doesn't show at all, but the plugs will still be used for the above reasons, they're just not needed to start the engine.

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Thankyou nodge

Nodge68 said:

The glow plug light is there to inform you to wait until it goes out. Once out the plugs should be hot enough to allow the engine to start fine. The plugs themselves will stay on for much longer, as they are controlled by the ECM as a running improvement and emissions reduction strategy. Sometimes the glow light doesn't show at all, but the plugs will still be used for the above reasons, they're just not needed to start the engine.

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I find also weird that my glow light never show, even in winter. I lit it only with diagnose software, so it works, but otherwise never. And it starts perfect in an instant.

The Pilgrim said:

I find also weird that my glow light never show, even in winter. I lit it only with diagnose software, so it works, but otherwise never. And it starts perfect in an instant.

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From memory, if the glow light doesn't show when it should (normally starting below about 10°C), the it may be an indication of a fault in the system.

I know it's a different car, but mine didn't light up when there was a sensor unplugged.
It started fine but lumpy and smoky when freezing cold

I repeat, it starts instantly, no hesitation. I just do not see the glowlight.

The Pilgrim said:

I repeat, it starts instantly, no hesitation. I just do not see the glowlight.

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It means the engine is in good condition. A good condition M47 doesn't need the glow plugs to start, it's just slightly cleaner with them when it's above freezing, and slightly faster starting below freezing.

Ok, and since no error is recorded, how should I fix this almost problem?
I'll check the presence of 12V on glow plugs at start. On a good working Td4, are they on at least a second even in summer, in order to be verified?
Thank you Nodge.

If the TD4 is like my early car, then when you put the key in the ignition and turn it on (not start the engine), all lights on the dash light up for a short time then they go out.

On my early Wabco car the ABS light will stay lit until I am travelling at (something like) 5mph, and the glow plug light will stay lit for a few seconds - however, if your car doesn't need them, then presumably it won't - but presumably will come on with the other lights that go out after the initial test.

No, the glow plug light does not apear even at contact's first position, disregarding the weather. Only when checked with test software.

Are the glow plugs actually coming on? Can measure with an amp clamp.
You might find it starts perfectly fine without them while it's warm outside

This is to be done soon. Starts perfect in winter also.

Don't know if this helps!?!? I had a 2003 TD4 that did the same thing. All plugs good, power to plugs when needed, plugs powered after starting sometimes correctly.

Never showed a dash glow light. Glow light tested ok with diagnostic tester.

The light is lit from the ecu. Maybe a software error. Never solved it !!!

Thank you Andy, then why scratch when it doesn't itch?
I'll check the power on plugs though.

Can all be checked at the glow plug relay in the L shaped box. 4 wires to glow.
Can also disconnect the plug and check continuity of plugs. Saves taking the inlet manifold off.

Thank you, I will.