Glow plug control problem

[chrisgreenwood1982]

Hi, i have a problem with my glowplug control. I turn the key and the heater light doesnt come on the dash. I have replaced the relay twice with brand new units to no avail. Today i decided to have a poke round with the multimeter.

When the key is in the off position i have 12v to the positive terminal on the relay. When i turn the key to try to heat the plugs that 12v drops off for a few second then when the relay drops out the 12v is restored.

The relay is working at i dont have continuity between the 2 screw terminals when the key is off, but when i switch the key i get continuity for a few seconds until i hear the relay drop out.

Anyone got any idea why im losing that 12v?

[divingscubaboy]

Dont know the Bingo system intimately but sounds to me as though there is a glow plug timer function which is ensures the plugs only heat for as long as is necessary which common in some systems. Dependent on the system arrangement plug operation time is sometimes controlled by the engine coolant temperature. I'll try and have a look at a diagram tomorrow.

[chrisgreenwood1982]

yes i think you are right about it being controlled by the temp sensor but i presumed this was done by switching the relay rather than switching the feed to the relay if you get what i mean. Although i myself am no expert lol

[andy-womble]

yes i think you are right about it being controlled by the temp sensor but i presumed this was done by switching the relay rather than switching the feed to the relay if you get what i mean. Although i myself am no expert lol

Can I ask the question, why are you investigating the heater plug circuit?

Are you having problems starting or vehicle white smoking heavily at initial start up? If non of these symptoms are present then I would presume that the system is working ok.

For your further info, on my old Pug 306 1.9D it used to be a "switch the ignition on and wait for the yellow light to go out" moment but on my Berlingo 2.0HDI things happen a bit differently and you don't even see the cold start lamp illuminate for most of the time. I took my 'lingo through last winter when we had some pretty horrific sub-zero temperatures (-15c ??) but even then the lamp only flashed on for less than a second and away she went no problems....

[Mike]

Mine works the same as Andy's - it came on possibly twice last winter.

[Ol'Jeffers]

I think the primary side of the relay will be switched by the sensor via the timer so once the sensor 'sees' a satisfactory temperature
then the relay cannot be actuated.......possibly. cratch:

[chrisgreenwood1982]

The reason I'm checking it is that when I bought the van a couple of weeks ago the heater light came on for 5seconds or so every time I started it. Now the light doesn't come on at all and the engine wont start. I have bypassed the relay and applied 12v directly to the plugs for 5 seconds before cranking and it then starts first time as normal.

[andy-womble]

Oh right, what engine is it mate? reason I ask is they are all wired differently. Sounds like yours might be one of the old school, which in your favour might be easier to cure. The newer Berlingos have more gismos etc wired in, making the circuitry more complex.

[chrisgreenwood1982]

Yes I think its one of the older engines. Its a 1998 1.8d 600.

[chrisgreenwood1982]

does anyone know what kind of resistance reading i should be getting from the coolant temperature sensor that controls the pre heating?