Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Agemo on 26 March 2012, 14:55:40
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Car has always started fine when cold, and when hot, but sometimes I want the plugs to come on & they don't. A mate of mine had a spare relay, so I fitted it. The car had been stood for an hour, so should have been cold enough to require glow plugs, BUT the light didn't come on. I replaced the relay with the old one, no light again. I discovered the 20 amp fuse under the bonnet had blown, so replaced it thinking that was the problem. No different, the glow plugs still won't fire up. when turning the ignition OFF, the glow plug light blinks. I am now stumped, any ideas?
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Why do you want the plugs to come on when they shouldn't need to?
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Why do you want the plugs to come on when they shouldn't need to?
Sounds like I didn't explain properly. The car has stood for two hours now, and the plugs should come on, this means I can't even start the car.
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glow plugs will only activate when its below a certain air temperature and engine temperature,if its not starting as it should then look at the leak off pipes as they could be letting air in :y
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Ok, forget the light on the dash for the minute, are you getting 12v on top of the GP relay (6 black wires feeding the GP's or pull the top off and measure the pins), if dont have a voltmeter use a 12v bulb to negative. 12v should be there for about 5 sec from ing. on when Engine cold.
The i/p to the Relay is fed directly from the battery positive with a biggish fuse on the side of the relay, looks like a brass strip held in with 2 screws.
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Ok, forget the light on the dash for the minute, are you getting 12v on top of the GP relay (6 black wires feeding the GP's or pull the top off and measure the pins), if dont have a voltmeter use a 12v bulb to negative. 12v should be there for about 5 sec from ing. on when Engine cold.
The i/p to the Relay is fed directly from the battery positive with a biggish fuse on the side of the relay, looks like a brass strip held in with 2 screws.
I will nip out & put a meter on the pins, the brass strip bit is ok.
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Ok, while your there, pull the top of the relay plug off and measure each GP lead to earth, should be 1 to 2 ohms each plug or open circuit if the pugs been cooked.
Wondering if your suffering the arched relay contact problem, any flat battery;s lately?
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OK, I have 3.5 volts at the pins, EVEN WITH IGN OFF! And yes, having flat battery, was going to replace.
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3.5 Volts??, whats the Battery voltage, whats the voltage on the brass fuse, either side of it, if the fuse is 3.5 volts then could be cooked wiring or bad connection to the battery.
If 12v on the fuse then sounds like an arced relay problem, also kills battery quickly (fixable).
Go and have measure.
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Just checking now
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OK. 13 volts everywhere, (IGN off) both sides of the brass strip, and the battery. Terminals were cleaned a couple of weeks ago so good connection.
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Is the 3.5v there with the GP plug on or off, either way sounds like arced relay contacts to me, pull the relay off and take it apart (small blade in at the bottom, probably end up braking the plastic clips dont worry).
Have a look at the 2 relay contact inside.
Got a pic somewhere will dig it out.
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Yep, 3.5 volts there all the time. I have two relays, taking one apart now.
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See the pitted arc on the first contact
(http://i251.photobucket.com/albums/gg299/zirk-photos/Relay1.jpg)
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Still not managed to get it apart yet, may have to go in the vice
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From underneath theres 2 small clips either side holding the cover on, get a small blade / knife in either side and cover should come off.
Do it to relay that you have just been measuring.
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OK, cover off. The contacts are lovely. This is the one that is off the car, I will change it over & look at the other one
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Did you measure each GP resistance to neg, 1 to 2 ohms each.
Sound like its dropping from 12 to 3.2 v through the relay to me, does the relay measure open / short when you press the contacts together.
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OK, I have put the cover back on the relay, and refitted it. It still reads 3.5 volts, IGN on or off. Not measured ohms at GPs yet.
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Readings have been identical with both relays. You will have to talk me through the "does the relay measure open / short when you press the contacts together."
I assume I fit the relay, then test while closing the points at the same time? (Like rubbing head & patting belly) :-\
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We are measuring the right pins here, as you pull the top plug off theres 6 thick pins that are all connected to together?
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OK, I have the relay fitted, meter between earth and the six pins to the GPs, it is reading 3.5 volts. When I close the points, it goes up to 13 volts.
On turning the IGN on, something goes clunk in the triangular box.
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OK, I have the relay fitted, meter between earth and the six pins to the GPs, it is reading 3.5 volts. When I close the points, it goes up to 13 volts.
Its the 3.5 V bit thats throwing me now, been a couple of years since I played with these TD's, in theory from memory it goes battery connects directly to relay (via small red cable and 8mm nut, so 12 volts all the time on one side of the relay contact, which simply switches the GP's on off. not convinced where the 3.5v is coming from on the GP side (assuming the relay contacts are not arced or stuck together.
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Whilst you where doing tests, was the inlet manifold warm or hot?
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Your memory seems spot on. Red wire looks like it feeds 12v, the contacts gives or stops current to the GPs. The contacts are like new. Not sure how I get 3.5 volts either.
This is the original relay, the one I tested & stripped, it worked perfectly this morning.
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Whilst you where doing tests, was the inlet manifold warm or hot?
Cold, engine not been run for seven hours.
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Diss the plug again, measure each GP (+volts) and ground all should be 0v.
Did you manage to measure each GP resistance yet (1 to 2 Ohms).
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Diss the plug again, measure each GP (+volts) and ground all should be 0v.
Didn't quite understand your banter there, sorry, do you mean measure at the six pins?
Did you manage to measure each GP resistance yet (1 to 2 Ohms).
No, not yet, will do it now.
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Diss the plug again, measure each GP (+volts) and ground all should be 0v.
Didn't quite understand your banter there, sorry, do you mean measure at the six pins?
Did you manage to measure each GP resistance yet (1 to 2 Ohms).
No, not yet, will do it now.
No sorry, probably me thinking out loud, measure each lead that connects to each GP, trying to work out if theres any stray voltage floating around somewhere.
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OK mate, just trying to keep up with you. I have checked the lead, at two of the GPs, zero volts. This was with contacts open of course.
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Ok, and each GP restance to neg (plug diconnected).
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checking now . . .
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OK, just making sure I am doing this right. Meter - black lead on Neg of battery - red lead on glow plug, reading zero ohms. I can only reach two plugs without extending wires.
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OK, just making sure I am doing this right. Meter - black lead on Neg of battery - red lead on glow plug, reading zero ohms. I can only reach two plugs without extending wires.
Almost, I meant measure the GP resistance from the top of the relay connecter (6 black wires on the top, that way your measuring the complete circuit of each one after the relay.
Hope we are talking about the same relay here, will try and find a pic (Rob!).
Edit pic added, only pic Ive got is this one shows the GP relay top right, the thicker black wire x 6 are the ones feeding GP's
(http://i251.photobucket.com/albums/gg299/zirk-photos/DSC00419.jpg)
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Thanks Rob. I do appreciate this. :y
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Thanks Rob. I do appreciate this. :y
No Im Chris, Robs the one that should have posted a pic up in less than 10 nano secounds, but failed His task on this occasion. ;) ;D
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Ok Pic posted, go up 3 ^^
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Sorry Chris, Rob you're getting slow! I will have a look for THE BLACK WIRES.
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OK, all six black wires reading zero ohms. Not sure if that is good or bad. :-\
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I am assured the replacement relay was a good one, and to be honest the old one worked this morning. I am thinking I must have disturbed something changing them. :-\
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OK, all six black wores reading zero ohms. Not sure if that is good or bad. :-\
Probably the meter, Digital or Analogue, if Analogue might not read it if not zero'd. so assume GP's are ok, need to log off soon, and still not convinced where this 3.5v on the GP side of relay is coming from, might be worth putting that down as a red herring as it seems to have thrown us off course a bit. or may be someone with a TD could have a measure.
But you get the idea, GP relay straight to battery via fuse relay contact simply supply battery volts to each GP in turn via each off the 6 wires, the relay Timer and Dash Bulb run on a separate circuit, from memory the the GPs are still fed with 12v about 5 seconds after the dash bulb goes out.
So time to start measuring why the 12 volts is not getting to each GP.
Theres nothing to stop you from feeding 12v to the GP's manually or forcing the contacts accross, (no more than 10 seconds at a time) and see if the Car starts.
Chris.
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OK Chris. Thanks anyway, my meter is an old analogue driven by steam, but then it read the 3.5 volts :-\
I like the idea of feeding 12v to the GPs. I will examine every wire in there tomorrow. Thanks again Chris, sorry to take up so much of your time.
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Latest - I have nearly 12 volts at the plugs when I close the points. After ten seconds I tried to start the car, spinning over but won't fire. I found a green wire with a black tracer, which had been kinked, there was bare wire showing, I now suspect this has shorted across something, not sure where to go next. I even think it could have fried the ECU but don't really know a way to test it. I can't paperclip or pedal test mine.
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What happened to the 3.5v is that still there, when you say nearly 12 v what figure should be pretty much battery volts.
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Hi Chris. Yes the 3.5 volts is still there, not sure if it should be. I operated the points (yes they get hot) and there was 12 volts at the plugs, but there was no way the engine was going to start.
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The 3.5v bit cant see that being right, with the relay open, just remind me is it there with the top plug disconnected.
Why did you swop the relay in the first place.
Whats makes you think the ECU screwed.
When you forced 12v to the gp's does the inlet manifold get slightly warm.
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Right, with the relay open, 3.5 volts, closed 12 volts. With the top plug connected the 12v goes to the plugs.
I swapped the relay because the car took a while to start, when warm. i.e. GPs didn't come in, but would have started sooner if they had.
I think the fault seems to be ECU or sensor, because the voltage is getting to the plugs.
Actually not felt for heat at the manifold, good point.
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Ok, without shooting myself in the foot, ECU's are quiet robust but thats not to say its not the ECU.
Think if it was me now would start to concentrate on getting the Engine started and warmed up, nice and warm today, is there plenty of fuel in the tank. pop one of the injector pipes of the top, is it dribbling fuel? etc.
Dont have a TD any more, so cant really do any checks, but if someone can confirm this 3.5v on the GP side of the relay that would be good, cant see why it should be there myself.
Need to shoot back to work, good luck with it.
Chris.
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OK Chris, thanks. I think the manifold was very slightly warmer, hard to say. Half a tank of fuel, car was running fine yesterday. There is something making it refuse to start. I tested the GPs a couple of months ago, "Cherry Red" after 8 seconds.
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Just realised, there is no engine management light. It does give a slight flicker as I turn the IGN off, same with the GP light.