Glow Plug Problem

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marzco

New Member
Posts
7
I've got a 1996 300tdi Discovery, the glow plugs won't work (No power) when the yellow/ black cable from the timer is connected. If i disconnect the lead from number 4 glow plug and test it with a meter there is power when the ignition is switched on until the timer switches itself off. I'm thinking it could be an earthing problem from the engine to the chassis, how many earth points are on the engine? And has anyone had the same problem. Cheers Mark
 
you should'nt really need glow plugs mate ... dont get cold enough fer that .... if ya gotta use umm ya got summat wrong .....
 
There's 1 earth engine to chassis, located kinda underneath the turbo/exhaust manifold area, remove air intake pipes and you can see it clearly a braided hose/wire, nuts arnt easy to get to so just bolt on another anywhere i think it should have two anyway retrofit a nice bit of wire around it and tighten onto the suspension mounting above it.:eek:
 
tis more like one of the plugs is a dead short - test them one by one

Agree with Sean, even if there is a load of current flowing if one or all of the plugs are 0R (no resistance/dead short) then you won't read any voltage accross them when they are on.
 
Cheers for the info, all the glow plugs are brand new just fitted! I will still have a look at them though, let you know how i get on.
 
Well it looks like all the plugs are faulty as they are all showing dead shorts, i'm off to supplier tomorrow to see what they say!
 
Well it looks like all the plugs are faulty as they are all showing dead shorts, i'm off to supplier tomorrow to see what they say!

how did you test them ?

the only way is to put a high curreent 12 volt supply across them and if they get hot they work

if you measure the resistance it will look like they are all shorted (unless you have a very good tester that can measure low resistance accurately)
 
Well i learnt something new being more of a petrolhead than a diesel genius and have come away with a diagram for the glow plug circuit, so i'm gonna dive in for a swim tomorrow!
 
glowplugtimerwiring.jpg
 
Well weekend came and went, ran another white cable but still no joy, think it could be a component problem i've got the dealership workshop manuals now with all the schematics, keep u updated. But i think the welding of new sills is gonna take 1st place!!
 
Well got to the problem of the glow plugs, found the brown lead from the battery which goes to a fusable link then to the glow plug timer as a brown and orange had been bypassed for some reason? The cable was joined together using an 8amp rated cable which in turn due to the load on the timer 70amp rated caused the 8amp cable to melt!! Which was'nt detected until i unbolted the fuse box in the engine compartment and found the offending cable tucked underneath PHEWW Upshot I've managed to put right the wrong and works perfectly. Thanks for all you suggestions and help.
 
I had a starting problem with my 300 TDi during the recent really cold weather. I fitted new glow plugs and it made no difference, so I took a multi-meter to the timer relay. There is 12 v input from the big brown cab,e, but no output.
Fitting a new relay has made no difference.
Now being fed up with it i am ordering a 100 A relay, a push button starter switch and a small warning light. These will arrive next week than I shall re-wire it with manual control of the glow plugs, thus removing and simplifying the glow-plug system. The push button switch will be close to the key position and the relay will be in the same place as the existing relay.
 
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