Mo Murphy Posted January 18, 2011 Share Posted January 18, 2011 Looking at the Rave wiring diagram for the glow plug relay, it has main feed in and out, an earth, a warning light wire and a switching wire from the ignition switch. This is a conventional wiring setup for a relay. However, the relay also has a supply from the starter motor relay. What is this for and do I need it ? TIA Mo Quote Link to comment Share on other sites More sharing options...
elbekko Posted January 18, 2011 Share Posted January 18, 2011 Probably that the immobiliser shuts down the start relay, which in turn will stop the glow plugs from working with this setup. Or something like that. Quote Link to comment Share on other sites More sharing options...
DaveSIIA Posted January 19, 2011 Share Posted January 19, 2011 IIRC, the feed from the starter cancels the glow plugs once the engine starts to crank. Quote Link to comment Share on other sites More sharing options...
Eightpot Posted January 19, 2011 Share Posted January 19, 2011 I don't know for certain, but does the wire from the ignition switch not just suppy the trigger for the relay, and the main feed to the relay>plugs come from the pole on the starter motor? Thats how I have mine set up, but I have a diesel conversion and put the relay on myself, so not factory, however the wiring loom that came with it (from 200tdi disco)seemed to support my theory. On my old 2.5NA, the ignition switch fed the glow plugs directly, taking it's feed from the starter motor pole - necessary as there was no timer relay, and you just hold the key over for as long as you need before firing up - but it seemed a poor design to me, and in fact caused a massive dash fire when the switch came a little loose once and the glow plug terminal grounded out on the steering column Quote Link to comment Share on other sites More sharing options...
Buzza Posted January 19, 2011 Share Posted January 19, 2011 Description of glowplug operation from Defender 300tdi manual: Glowplugs are fitted to the TDi engine to assist starting. A constant battery feed is supplied by fusible link 3 (C907-3) to the glow plug timer (C189-5) on a brown wire. When the ignition switch is turned to position "II", a second feed is supplied to the glow plug timer (C189-3). This triggers a feed (C189-6) to the glow plugs. With the ignition switch in position "II", the glow plug warning lamp (C230-4) is provided a feed via fuse 17 (C580-33) of the passenger compartment fuse box on a white wire. The warning lamp (C233-10) is connected to the glow plug timer (C189-2) by a yellow/black wire. When the glow plug timer provides a feed for the glow plugs (C189-6), it simultaneously provides an earth path (C189-4) for the warning lamp. After a set period, feed to the glow plugs, and the earth path for the warning lamp are cut; extinguishing the warning lamp. Hope that helps. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted January 19, 2011 Author Share Posted January 19, 2011 Thanks for your replies Gents Since I always wait for the glow plug dash warning light to go out before cranking, and that the relay itself is a timer unit, I would imagine then that this supply is superfluous and could be left off. Anyone else care to confirm that I could leave the red/white supply from the starter relay off the relay ? Mo Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted January 19, 2011 Share Posted January 19, 2011 The 300tdi keeps the glow plugs on for a short time after the engine has started to reduce the cold start emissions. That's why it has a relay and does not just rely on the manual operation of the glow plug position on the ignition switch like the 2.5TD did. I guess the link to the starter solenoid is to provide a signal which starts the timer running for the glow plugs for the period which they stay on after the engine has started. Nick. Quote Link to comment Share on other sites More sharing options...
fozsug Posted January 19, 2011 Share Posted January 19, 2011 When i riped out EDC from my Disco, i ended up rewiring and did not reconnect the red/white wire to the Glow Plug relay. I do get a puff off smoke from the exhaust on start up, but not much more than before. Quote Link to comment Share on other sites More sharing options...
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