no glow plug light

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dannyvbrowne
Glow Plug
Posts: 8
Joined: Sun Oct 30, 2011 10:55 am

no glow plug light

Post by dannyvbrowne »

howdy all ,,,
i'm slowly working through a 1.9td conversion, many prodlems but no real mountains yet, she's been running, but as of today there's no life in the glowplug light on the dash and she wont start, i fitted new bosch plugs during the build, could it be that the old relay from the 1.6td has died?could it be alternator related,it looks fine,if it is the larger of the 2 relays located in the engine bay? anyway i just read here i the forum that it's the same as the horn relay so i'll swap and see today....
anyone got any thoughts,on what,other than the relay might be the problem??

thanks Danny
IRELAND

1990 leisuredrive hightop
1.6jx turbo manifolds and sump
1y block with turbo pistons
n/a caddy head
coke

Re: no glow plug light

Post by coke »

The glow plug light is no indication whatsoever of the actual glow plugs functioning at all. Its just a light run by a timer based on input from the temperature sender to tell the light how long to stay on to give you an idea of when to start the car.

My advice to you would be to disconnect the glow plug temperature sender. This will cause the glow plugs to stay on indefinitely until you start the car, then they will go out a short amount of time after that (usually 3-5 seconds unless it is fitted with an afterglow relay)

The light not coming on at all seems to tell me that the sender is not sending the signal to the relay, or the relay is fried, or the light is burnt out. You can use a 12v test light and connect it to ground and touch the buss bar terminal and have a helper turn the key on (or run really fast) and see if the test light lights up. If it lights, the plugs are getting power. If it doesn't light, they are not getting power.

The light not coming on at all seems to tell me the sending unit for the temperature reading may be bad and telling the relay no glow is needed (which is what it does when the engine is warm)
dannyvbrowne
Glow Plug
Posts: 8
Joined: Sun Oct 30, 2011 10:55 am

Re: no glow plug light

Post by dannyvbrowne »

great stuff man thanks for the knowlage... up date for today... i put power directly to the plugs from the battery, held it there for about 15sec,then nipped up front turned the key and she fired up like usual! i think i need a new relay :?:, i could hunt one at the local scrappy if i knew what to look for :? ...is it the big one with the fairly heavy red wires runing to and from(i know it sounds obvious) :).. also i have no idea where the tempature sender is, is it the one that threads into the no-pulley end of the head, similar to the one on the top of the oil cooler......
thanks again
danny

it just as well i love my van :mrgreen:
coke

Re: no glow plug light

Post by coke »

The temperature sender for the glow plugs are either screwed in (metal flange only) or clipped in (plastic coolant flanges) It should be easy to find out if its malfunctioning. Unplug both senders, and see if your glow plug light comes on. If it doesn't, I would suspect the relay. If it does come on, I would suspect the sender.
rsxsr

Re: no glow plug light

Post by rsxsr »

The relay if stock is quite large in comparison to a regular relay and yes has very large gauge wires going to it. A more common failure is the fuse. It is in a flat black plastic housing screwed to the firewall next to the relay. It is a metal strip held by two philips screws. Find it and pick at it. They can fail and you don't see it burnt out. If it has failed, I recommend one from an audi 5000 diesel from the early 80's it is rated for slightly higher amps. The initial amp draw of your glow plugs could be as high as 100 amps, which the fuse can't take for extended time. The audi fuse is about 75 amps. You will need a glow plug relay, not just an ordinary relay. There is also a quick glow relay that uses different glow plugs, you should match the plugs to the relay. Regards
dannyvbrowne
Glow Plug
Posts: 8
Joined: Sun Oct 30, 2011 10:55 am

Re: no glow plug light

Post by dannyvbrowne »

great stuff lads, thanks for the knowlage,i shall put it all to use over the next few days (once the glorious irish weather gives me the chance :mrgreen:)
thanks again
danny
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