VAG Glow Plugs operate on door opening. Fact or Fiction

MugMugs

Overheard this old geezer getting spun what I thought could be a line the other day in a VW Garage.

Customer was asking why his Glow Plugs had failed and the Employee came back with this.(couldnt see what your man was driving on the forecourt)

"VW Glow plugs operate the minute you open the door so you're not left waiting. That's why even on cold mornings, the Glow Plugs dont stay on too long when you turn the key. (my 03 TDI did !) "

Was he spinning your man a yarn or is he telling the truth and if he is, is there not a potential for battery drain if you were to open the door and leave it open for some reason ?

Anan1

That sounds familiar to me. AFAIK they're timed anyway, so they wouldn't stay on if the door was left open.

langdang

Some manufacturers use this, integrated with keyless entry. EG if someone puts their hand on the door handle (and is wearing or holding the correct RF fob) then the car unlocks the door and pre-primes various bits.

Dunno if it would wear out the battery or the plugs tho, I presumed they have factored this into the design!

colm_mcm

Can't see how that would make them wear out

dharn

in the life of a car, it could be unlocked many times without being driven away so they would be heating unnecessarily

dell1211

langdang wrote: »

Some manufacturers use this, integrated with keyless entry. EG if someone puts their hand on the door handle (and is wearing or holding the correct RF fob) then the car unlocks the door and pre-primes various bits.

Dunno if it would wear out the battery or the plugs tho, I presumed they have factored this into the design!

Keyless entry has nothing to do with it, its the door opening that activates the plugs

lifer_sean

On the petrol Golfs and Boras (98 onwards), you can hear the fuel pump in the tank running after you open the door, presumably to build pressure in the fuel line.

langdang

dell1211 wrote: »

Keyless entry has nothing to do with it, its the door opening that activates the plugs

You're right. 100% right. For all systems.





Except for the systems where it's working before you touch the door at all.

cadaliac

lifer_sean wrote: »

On the petrol Golfs and Boras (98 onwards), you can hear the fuel pump in the tank running after you open the door, presumably to build pressure in the fuel line.

yes, you can hear it in my old merc too, but not with the door, its the first stage when you insert the key in to the ignition.

langdang

cadaliac wrote: »

yes, you can hear it in my old merc too, but not with the door, its the first stage when you insert the key in to the ignition.

Ya, that was the old way. More audible in some cars than others. Having had a fuel pump fail on me in the past I relax a bit when I can hear one priming

Many of the new diesels pre-prime, warm the glow plugs etc if you brush off the handle (with the right key/card/fob on your person) or opened the door or even got within a certain radius of the car - depending on the system.

hanloj1

When i purchased my 03 audi remote on keyfob didn't work. everytime i got into car i had to heat plugs for short while. I don't need to heat them anymore since I've keyfob. Not sure what actually triggers the whole process but the new keyfob is involved.

MugMugs

Presumably the remote?