TD27 Glow plug system

[cowman]

So I have just bought a 1992 terrano, 2.7td.

Runs pretty sweet, but has become just about impossible to start when cold.

So with my limited knowledge and the help of google I started looking at the glow plug system for problems.

Pulled all of the glow plugs out and tested them - all glowed orange straight away.

Used a test light on the lead that powers the glow plugs while flicking the ignition on and off, it appears no power is getting there. (glow plug light on dash flicks on then off as normal).

I think I have located the glow plug relay, i can hear it clicking when I turn the ignition on, and so I opened it up thinking something might be obviously wrong with it... looks fine now ive got to seal it up somehow .

After I had flattened a battery trying to get it going and then did all of the above, i recharged the battery and disconected the glow plug rail and conecected it straight to the battery for a couple of seconds and it started straight away without hardly even turning over.

So what to check now? there must be a reason that the glow plugs are not getting power, what is it that tells them to turn on/off? Is there a controller and timer somewhere?

What other components are there in a glow plug system?

Any help appreciated, seems like the best place to come to

[mud_slinger]

should be a timer somewhere unsure where tho

[cowman]

so when you flick the key, the timer tells the relay to turn on/off as needed.

are there any other bits in the system?

[sibainmud]

Hey there, there are two relays close to each other, one does the glow plugs and, I think the other is the after-glow. The main power to the relay runs through the manifold heater. There are two wires from the intake manifold heater. Unplug it at the firewall and bridge it out. Test for power at the glow plugs. If there still isn't any power there it will be one of the fusible links onto the battery. (they look like wire but are fuses)

P.S, the relays are the same so the plugs can be swapped around to tell if it is the relay or not.

Cheers,

[cowman]

Sounds like a good bit of information ill have to go and get my head around - I had a feeling the two relays connected, they are on the same bracket and look exactly the same right? on the right hand side between the battery and the cab?

[sibainmud]

Sounds like a good bit of information ill have to go and get my head around - I had a feeling the two relays connected, they are on the same bracket and look exactly the same right? on the right hand side between the battery and the cab?

Yip, that's them. The large white wires are the power to and from. You could just test them there too.

Cheers,

[slide]

yea thats them.
Also check at connector plugs on inlet manifold.

Best way to know for sure is if you get someone to operate key (keep switching on/ glowing it), and you probe along wiring with testlight you'll find where power is lost.
As mentioned, check fuseable links. Be wary that they can be blown but look ok visually. Test light is your friend in this matter
Nath

[cowman]

alright by limited knowledge i meant pretty limited where abouts are the connections for the manifold heater and what does it look like.

how far away would the fuseable links be from the battery? I can see a bunch of plugs and then it all joins up and is covered

[slide]

where abouts are the connections for the manifold heater and what does it look like.

Theres a plug on inlet manifold just behind boost pop-off valve. 1 is for glows, other is for manifold heater. Manifold heater sits lower in intake, you can only see where the wires go in from memory.

how far away would the fuseable links be from the battery? I can see a bunch of plugs and then it all joins up and is covered

Fuseable links are very close to battery positive. Look just like wires with plug at battery + end, then another plug 5cm or so further along.
Thats probably them you've found.

If you trace the wires back from glow plugs it should be reasonably easy to follow the circuit.

[cowman]

so what is it that makes the glow plugs turn on and off?

its a bit of a mess in there to follow, birds nest of insulation tape and what not.

i think ive found the manifold heater plug, its taped up to the glow plug plug, and the wires disapear below the manifold. not quite sure how to test it though will switching the plugs over tell me anything?

[sibainmud]

I have done a little research on the subject. It is not a manifold heater but a resistor that uses the air in manifold to cool it
Here are some snaps from the manual






Cheers,

[cowman]

Any reason why I cant ditch the automatic system and have a momentery on manual switch ?

[monstr]

Nope thats how my Safari is wired up ,I have a push button switch ,did that after the relays and timer packed up .was the easiest temporary fix at the time .Still like it 3years later .I push button count to 5 and it starts first pop every time ..

[sibainmud]

Thanks Steve,
saved me the typing
Manual ok in our "sub-tropical climate"
Kind of get the feeling he asking because can't get head around the system and the wiring diagrams above.
The cause of the system failure may be simple.

Cheers,

[cowman]

Cheers for your help so far, those diagrams look good but are too small too see clearly.

See if this makes sense to anyone

Disconected the power to the glow plug rail and conected it to a voltmeter, flick the ignition and I get 10.56v (at the lead which should connect to the glow plug rail).

Connected a glow plug to that and earthed it (as it would be in the engine) and flicked the ignition... nothing.

Connect a glow plug straight to the battery with jumper leads and it smokes and glows orange straight away.

All I can think is that 10v is to low? shouldnt it work if theres power getting that far?

[sibainmud]

Pm me your e-mail and I can send them to you in their full glory. Volt meters can be misleading, voltage can be there but no load capability, (poor connection). Still sounds like fusible links or relay.
With the wiring diagrams you can at least know which relay is which by the colour codes on the large wires. After identifying the right relay, unplug the large white wire from relay (input) and hook your magic bit of wire to the relay terminal and get someone to turn the key to see what happens.
It is so easy when you're there but hard to explain. I
My thoughts are, it is still an easy fix

Cheers,

[sibainmud]

Fusible links.


Cheers,

[Pinelli]

Hi, sorry to bring up an old thread, but it's been a good help for me.

Can any of you give me a hint as to how to identify the glow plug controller? I've got a dismembered loom from a 92 Terrano, and there seem to be 3 controllers - EGR, Auto and Glow. Which one is which???

Cheers