Bandog Posted January 26, 2017 Share Posted January 26, 2017 Please could anybody tell me, when the relay fails , does it just stop working all together, or does it offer less voltage to the plugs? I get a current drop down to around 10 v pluss a bit when the plugs are engaged. thank you Quote Link to comment Share on other sites More sharing options...
Bandog Posted January 31, 2017 Author Share Posted January 31, 2017 Yes, seems like the question that nobody can answer Quote Link to comment Share on other sites More sharing options...
simonb Posted January 31, 2017 Share Posted January 31, 2017 (edited) The only way it can drop the voltage is if the internal contacts are badly burned - in which case its scrap anyway. I assume you have checked that there isn't a burnt/melted contact in the connector plug? If all is well there, then I would suggest a new relay. Bit confused by your wording " I get a current drop down to around 10 v plus a bit" Current is measured in amps, not volts. 10v sounds a bit low when the plugs are on - it sounds like a high resistance somewhere - internal contacts/connector to relay/fuse contacts - in aux fuse box next to heater box. Edited January 31, 2017 by simonb Quote Link to comment Share on other sites More sharing options...
western Posted January 31, 2017 Share Posted January 31, 2017 when my 200tdi glowplug relay gave up the warning would only be on for approx 2 second & glowed dim once engine was running, a new relay cured the problem. Quote Link to comment Share on other sites More sharing options...
Bandog Posted February 1, 2017 Author Share Posted February 1, 2017 OK. It's wired into a genuine disco relay, and comes on for around 10 seconds when activated. The light goes out OK. I can hear it clicking on and off, and the light in the dash correlates to this. The voltage goes from 10 and slowly creeps up to 11.6 before timing out. (as they are getting hotter, I guess that it takes less juice?) The warning light has to come directly off number 4 glow plug, because the discovery glow plug wire on the relay plug, only supplies around point 6 of a volt. Assuming the disco glow plug warning light is a low voltage resistor or led maybe? It's a common complaint about this set up in the series land rover. Incidentally, I have two relays, both do exactly the same. 12 v goes into the relay, and 10 comes out? Thanks for the help Quote Link to comment Share on other sites More sharing options...
Bandog Posted February 1, 2017 Author Share Posted February 1, 2017 No visible issues on the connections simonb Quote Link to comment Share on other sites More sharing options...
Ex Member Posted February 1, 2017 Share Posted February 1, 2017 Who knows. I'm not sure why anyone would ever check this. Why are you concerned? Quote Link to comment Share on other sites More sharing options...
Bandog Posted February 2, 2017 Author Share Posted February 2, 2017 (edited) Because I want it to work if the weather gets cold. I have a separate switch. I have heard 200s in very cold weather, no glow plugs, trying to fuse 450 amp cable whilst cranking. It's a myth that the 200 doesn't need them. They do. No disrespect at all, but why do all UK specification 200tdis have them fitted in the factory. Millions of pounds of research and development and then Fred in the shed cuts the wires because "y don't need um" Its a little bit like a layman (normal motorists) saying, "why do you need a winch, you have a 4x4!" Yes most of the year they are redundant. But when you really want them, and don't have the option, it is the difference between stop or go. Besides overloading the starter motor. Not trying to be annoying, it's just me personally like things to be right. Edited February 2, 2017 by Bandog Needed additional information Quote Link to comment Share on other sites More sharing options...
Ex Member Posted February 2, 2017 Share Posted February 2, 2017 I'm sure you will be fine. If I get bored and remember, I can check mine. It get to -40 in my neck of the woods and there is no problems starting. 1 Quote Link to comment Share on other sites More sharing options...
honitonhobbit Posted February 3, 2017 Share Posted February 3, 2017 My 100" never had the relay fitted - never got round to it. Still started in -16 with no issues Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted February 3, 2017 Share Posted February 3, 2017 The voltage drop you are seeing is the consequence of the high current being taken by the glow plugs (around 70A if they are working properly) and the contact resistance in the glow plug relay. The resistance of the wiring and the connectors on the relay won't help either. As the plugs get hot, the current reduces (down to less than 40A after around 10 seconds) which is why the voltage goes up. Sounds like your relay is working fine, although it's to be expected that a used relay will have higher contact resistance than a new one. You really need to measure the current, not the voltage, to determine if the plugs are working OK. They fail by going high resistance. 1 Quote Link to comment Share on other sites More sharing options...
Bandog Posted February 4, 2017 Author Share Posted February 4, 2017 Excellent. This is what I was wanting to hear. Very articulate indeed. This is the best forum I have ever been on. Thanks lots Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.