Glow Plug Light?

[pgra0909]

I will try and keep this short Guys... in need of Help?
Just got my T25 Diesel back from having the head rebuilt Drove back from garage perfectly.. parked up and tried it an hour later and the glow plug light on the dash isn't working so it wouldn't start. I've been looking through threads on here doing all sorts of tests. I've hit a brick wall.

First I noticed a wire which was attached to the Water Temperature sensor was broke (this is the one that fits in the back of the head) spade was snapped so bought a new on from Heritage.. fitted that and still no light. cleaned all the terminals on the relay and tested power was getting to it. The 50amp fuse I've replaced. power to it. checked there is power to the glow plugs (thick red wire) which is fine. A thread on here said jumper pin L on the relay to earth and make sure the glow light on the dash works...which I done and yes it worked.. so I'm now at a loose end.

If I unplug Pin L on the relay the light on the dash works...
I've replaced most of the spade connectors and any wiring which looked corroded

Getting really sick now... I just seem to be handing money out none stop. I just want to get on the road.... please help me... grrrrr

Thanks Paul.

[clone123]

I had the same problem and mine after changing the engine mine was a bad earth the ones on the body work on the left hand side of the engine bay just take it off and clean them it will take hurt to try

[RogerT]

I note in your first para you say...
glow plug light on the dash isn't working so it wouldn't start.

Could you give a bit more detail of what kind of not starting you have? Is it cranking over, coughing and spluttering, chucking out lots of smoke, etc etc? Or something else maybe?

I guess it is possible that your absence of a glow plug light is incidental to not starting, but I hope not..

[Mr Bean]

To be truthful I have never fiddled with a diesel engine but for what it is worth:
There are some simple harmless tests which can often give an indication of where the problem lays. These high current circuits require really good electrical connectivity.
A quick check can be undertaken by observing the battery voltage dip slightly when the glow plugs are energized then dip a bit more when the starter is engaged . If the voltage at the plugs dips drastically the problem will likely be between the battery and the plugs. It can even be a failing battery. No dip then no significant current is flowing. However an open circuit earth fault will show as a voltage reading between say the engine block and the battery negative when the glow plugs or starter is engaged.
Hope this helps
CS

[Smcknighty]

Jump lead to the glow plug bar, wait 30-45 seconds, then turn it over. If it starts (probably will) then you have narrowed things down. Then it's a case of figuring the circuit stuff


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[Smcknighty]

Actually that might be a bit long....


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[pgra0909]

Thanks for all the quick replies guys... When I say not starting.. I should have said it's turning over fine.. it's like there was no fuel... however there defo is.. and I'm sure it's electrical??

I did read on here to switch on the interior light and watch it dim when you turn on the ignition... try this and it didn't dim. When I have the ignition on I have tested the 50 amp fuse and there is voltage getting to it fine. I've also checked the live feed to the fuel pump and you can here it click.

I'm just thinking it could possibly be a relay fault? TBH the fues box where all these wires are located are/were a mess.. however I have gone through the wiring and cleaned it all including connectors and replaced any that looked damaged. The thought did cross my mind that the garage might have connected the wrong wires to the wrong sensors so I have noted what's connected to what at present.

Yellow - connected to Water temperature sensor (on the head)
Yellow/Red - Water Temperature sensor (on the rubber pipe)
Green/Black - Water Temperature sensor (on the rubber pipe opposite side to above)
Blue/Black - Oil Pressure Sensor
Brown/Red - Oil pressure sensor
Black - Fuel pump

I'm no mechanic as you've probably already guessed...lol don't mind giving anything ago tho
Smcknighty when you say "Jump lead to the glow plug bar, wait 30-45 seconds" do you mean live feed from the +12v directly to the glow plug terminal that is located just next to the rocker cover and held on with a 10mm nut?? (sorry if I sould thick)

Again I'll do some of the checks above... ie the earths etc.. keep any advice coming I really aprecate any suggestions.. I'm just itching to get him running... - Thanks guys.

[Smcknighty]

Yeah jump lead from the positive 12v to the top of one of the glow plugs. Be very sure you don't touch anything else. I'm not sure what the glow plug time period is - 30 seconds is probably way too much. Maybe start with 10. If the plugs aren't getting power then mine will turn over for ever. With warm plugs it fires up first turn. If you do this and it doesn't help you at least know it's not the plugs not getting power. Seems likely it is as you don't get a glow light.


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[pgra0909]

Cool... I'll try it this afternoon. If it starts after doing this procedure any ideas where the issue is? Thanks again for your help mate. [WHITE SMILING FACE]

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[pgra0909]

An update - I have jumper ed a wire from 12v on Battery directly to the glow plugs as suggested above and yes it started... and run perfect. So I have been out and bought a new relay... swapped it out but still no joy.. now I have a spare..lol.
I have been testing the feeds to the relay and got the following -
(PIN L from the glow plug indicator light) = NO POWER
(PIN 85 Ground) = Works fine
(PIN 30 Battery) = 12 Volts Worked fine
(PIN T Engin Temp Sensor) = 12 Volts Worked fine
(PIN 86 When Key is ON) = Worked fine
(PIN 50 When Cranking) = Can't check as I'm on my own
(PIN 87 Power to the Glow Plugs) = Nothing.. NO POWER
So I guess this is where the issue is?? any Ideas why it's not feeding the glow plugs??
Or anything else I can check/test
Thanks guys

[pgra0909]

Just done another quick test... Jumper ed a wire from PIN 87 on the relay directly to the fuse... counted to 10 started first turn of the key. Had to remove the wire straight away as it was getting hot.. This has to be something really daft...? - Cheers

[MGP]

Have you tried unplugging the glow plug relay temperature sensor? That should make the relay do a full duration heat cycle, if there is a fault in the temperature sensor or wiring making the relay think the engine is hot you won't get any pre heat.

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[pgra0909]

Unreal.... I have been reading all sorts on here and other places... I have it SORTED... yipeeeee

Well... the 2 temp sensors which are on either side of the pipe... one which tells you when it's too hot the other when it's cold...turned out that these were the wrong way round...? I switch them over just as a test... an bobs ya uncle the glow plug light come on and I have live feed to the glow plugs... This is how it was returned to me after the garage had the head off and sent away for a rebuild. I just presumed they either didn't touch them or if they did they put them back the right way... can't believe this has caused so much hassle.

Least I'm sorted... Thanks to everyone who replied, Really appreciate all your help.
Top forum!

[Smcknighty]

Nice


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