No Voltage on my glow plugs

Hi,
I am having trouble starting my 110 Defender diesel and it looks like I am getting no Voltage to the plugs. Is it just a straight run from the Ignition switch to the plugs ? It's an 86 2.5 Diesel so I don't know if a timer relay is fitted.
Also what does the 24V battery symbol mean on the dash and I have no glow plug indicator there either, is this right or is this the wrong dash put in ?
Cheers

Danny

you know you have to hold the key 1/2 way between ignition and start to preheat?

i didnt know this for months when i first got my 90, boy was i pleased when i found out i could start her without having to turn it over for 30 seconds!

They've all got the 24V symbol, the glow plug light is the choke symbol. You probly won't have a timer unless someone has fitted one. Have you had a look at the connector from the dash harness to the engine harness, and are you sure your getting 12V at the ignition end going into or out of the switch.

the ignition switch has a seperate (electricaly seperate) switch just for the plugs, the Tdi has a relay timer in line but the TD and before is just fed from the switch - it's the contacts right at the end of the ignition, ignore the others - best to disconnect the wires and test that it's open/closed when its supposed to in line with wot chris mack says - your probably looking at a new ignition switch as i dont think you can but the bits seperatly

chris_mack said:

you know you have to hold the key 1/2 way between ignition and start to preheat?

i didnt know this for months when i first got my 90, boy was i pleased when i found out i could start her without having to turn it over for 30 seconds!

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i did exactly the same thing! for 12 months! still not much better though, i reckon ive burnt out the new plugs i put in

schoolboy error

Cheers for the help/advice guys. I'll maybe try and check the voltage when the glow plug (or choke ?!) lamp is lit to see if I am getting anything then.
Thanks again everyone.

Danny

you will need 2 people for that as you have to hold the key to keep power to the plugs.

G

The best idea is to source a 70 - 100 amp relay (for example for Ford Sierra glow plugs) and wire a push-button on the dash to heat the plugs as you decide.

It's an easy and cheap solution, and if you hide the push-button only you will know how to start it up.

CharlesY

I am going to wire a new cable from the battery, via a 30amp fuse, to a heavy duty starter/horn push botton switch then to the glow plugs. I have done a few tests and this works fine.
It looks like the ignition barrel gets either corroded or worn to the extent that the glow plugs only get about 9v instead of the full 12v accross them, thus 45 second warm up time for them.

Patman1200 said:

I am going to wire a new cable from the battery, via a 30amp fuse, to a heavy duty starter/horn push botton switch then to the glow plugs. I have done a few tests and this works fine.
It looks like the ignition barrel gets either corroded or worn to the extent that the glow plugs only get about 9v instead of the full 12v accross them, thus 45 second warm up time for them.

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The drop of voltage CAN NOT be blamed on resistance in the switch as the IGN switch doesn't carry the huge current the glow plugs draw. The IGN switch only energises the glowplug relay.

Whatever switching system you use MUST be capable of handling 100 amps at 12 volts or it will probably melt or go up in smoke and flames..

CharlesY

CharlesY said:

The drop of voltage CAN NOT be blamed on resistance in the switch as the IGN switch doesn't carry the huge current the glow plugs draw. The IGN switch only energises the glowplug relay.

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on my old TD there wasnt a relay so the switch attached to the ignition was taking the full load

Sean said:

on my old TD there wasnt a relay so the switch attached to the ignition was taking the full load

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I am going to be very surprised about that, but not arguing.
A 100 amp turn ON at 12 volts DC needs a HEFTY and FAST set of plated contacts. Once the plugs are red hot the current drops a bit but 70 amps steady is likely with 4 good plugs.

CharlesY

deffo didnt have one, as just before the TDi went in it the contacts failed which required a complete ignition switch replacement and i've sorta known the vehicle since new and i'm positive it's not been altered

Must have had some tough IGN switch then, but saves the complications and cost of a relay I suppose.

Mine dunt have a relay either 1989 2.5 turbo. Was going to fit a timer relay when I put the dash back in but don't know if I'll get round to it. As I said before the connector plug that joins the dash harness to the engine harness can get crudded up an when I cleaned mine it made a big difference in the starting department.

GRUNT said:

Mine dunt have a relay either 1989 2.5 turbo. Was going to fit a timer relay when I put the dash back in but don't know if I'll get round to it. As I said before the connector plug that joins the dash harness to the engine harness can get crudded up an when I cleaned mine it made a big difference in the starting department.

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Is there a great big fat wire both to and from the IGN switch that leads direct to the plugs?

I suppose if it goes through a connector block twice (once in once out) dirty connectors could make a very big difference due to resistance in the line.

I would use the IGN wiring to switch a bloody big relay if it was mine. I fitted a Sierra relay when I made Discomania's 90 into a Diesel.

CharlesY

Three big fat uns plug into the switch at least two must go through the connector block. http://www.landyzone.co.uk/photopost/showphoto.php?photo=7158&size=big&cat=

The 2.5 NA and 2.5 TD use only the ignition switch to heat the glow plugs. This is a 1960's engine after all and I don't think anyone thought that a relay would be needed for likkle glow plugs back then.
A relay would be ideal but I can't be arsed and I'm too cheap.

Just priced a delay type relay at a local auto electricians, they wanted 25 friggin quid fer one!!