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Odd glow plug timer behavior


cjmt
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Hi All,

My glow plug timer behaves a bit oddly. It seems (if the glow plug light isnt lying) to energise the glow plugs in inverse proportion to the outside temperature - the colder it is the less time the light stays on. I haven't a starting problem, its quite sluggish to start when below freezing but always goes after 20 seconds or so. I'm intrigued as to the cause though.

The starting wiring has been messed about quite a bit in the past by a former owner, starting is by turning the key to II and then a starter button. I havent investigated much further as I'm scared of the magic smoke and dont want to let it out. Does it sound like the timer relay is connected back to front or does that just prove I know nothing and should continue to fear the magic smoke..

Charlie

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If this is a Tdi, the glow plug light ALWAYS lies. When it goes out the plugs are still energised. Eventually the relay will disengage (if I can use that word) with a 'clonk'. This is often quite a few seconds after the light has gone out and depends on the ambient temperature.

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Without meaning to hijack this, I changed my glow plugs this week with a hope to improve the cold starting. No difference whatsoever! The old plugs were either sooty or oily and didn't glow when attached directly to a battery. However, neither did the new ones :blink:

Anyway, I then checked for what I assume would be +12V at the plug thread vs. GND on the block itself and I see nothing. So, I'm assuming the timing module is knackered. Am I going in the right direction? I do hear the relays click away, but of course I also assume there's more than one thing starting up when I switch the ignition, so that could be a red-herring.

Thanks,

Scott

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The old plugs were either sooty or oily and didn't glow when attached directly to a battery. However, neither did the new ones :blink:

Scott

In that case you should throw the 'new' ones away and buy some decent ones. I have found that only oem BERU glow plugs are any use, all the others are rubbish.

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Lesson #1 - start from the battery and work towards the plugs!

Turned out the problem was a burnt out cable between the battery and the relay. Replaced with something more heavy duty and all is well, just in time for the next cold spell! :)

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If this is a Tdi, the glow plug light ALWAYS lies. When it goes out the plugs are still energised. Eventually the relay will disengage (if I can use that word) with a 'clonk'. This is often quite a few seconds after the light has gone out and depends on the ambient temperature.

This is true to the maveric, the light goes out after 5 secs the relay clunks after ten, it's the difference of winding if over cold for 5 secs or a split second when warmed

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That wire is probably a fuseable link and needs to have a BIG fuse fitted in it's place. I'll bet it was a silvery metal inside the cable, perhaps slightly brittle and crumbly? bit of blue tape over a soldered joint part way along the wire?

Urrr, yes, that's right! Was that thin wire actually the fuse?

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