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Topic: Failure to start. (Read 3179 times) |
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Snoopy
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Re: Failure to start.
« Reply #20 on: Dec 14th, 2015, 8:23am » |
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Don't you just love the easy fixes!!!!!!!!!
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Simmo
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Re: Failure to start.
« Reply #21 on: Dec 16th, 2015, 9:49pm » |
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Spoke too soon!!  
I used the car today and did well over a hundred miles. Stopped several times for a variety of periods including going to the pub !. No issues. Came home for dinner,parked up outside as normal. No issues.
A short while ago I realised I had left my glasses in the car. Going from the house in to the garage I could hear an unusual noise. Opening the garage door I find that the cooling fans are roaring away!!  The only way to stop them was to pull fuse 44. All parts are bone dry the wiring is sound. I suspect the relay but it seems the only way to check is to swap it over with a known good one? I thought that once the power was removed things might clear BUT replacing the fuse immediately brought the fans back on.
Anyone got any ideas and does anyone have a relay?. Large green one fitted behing the offside headlight. Watch this space!.
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Glyn
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Now an OAP ! 95 cossie and another !and a 12v
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Re: Failure to start.
« Reply #22 on: Dec 16th, 2015, 11:42pm » |
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If the relay was stuck wouldn't you have noticed the fans going ballistic when you parked the car ?
Was it both fans going full belt?
Fuse 39 supplies permanently 12v to fan 1. If on slow speed the fans are connected in series and fan 2 gets it's feed from fan 1 hence fuse. 39
When the relay operates for high speed it switches fan 1 to ground and supplies fan 2 with 12v from fuse44
Pulling fuse44 should only stop fan 2 in high speed
I had a problem with fan 1 rather like yours and it turned out to be the fan wiring close to the fan where it had rubbed against the fan guard and rubbed through the negative thus grounding the fan and operating it at full speed.
It was intermittent
Glyn
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TiberiuS
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Ex. 1996 2.3 Ultima - RIP P789 KHJ
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Re: Failure to start.
« Reply #23 on: Dec 17th, 2015, 2:43am » |
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Mike,
As I was just reading page 1 of the thread, I was thinking 'it's going to be more than a tired battery'.
My gut feeling would be an earth fault, but from what Glyn says it sounds that fan 2 is permanently connected to ground anyhow (fans in series for low speed, in parallel for high speed with F44 supplying power to the lower fan, which makes sense).
The relay could be faulty, but in my experience relays tend to fail open circuit (i.e. just don't switch on, or don't conduct well), which would cause the opposite fault to what you're experiencing. That said, a fan motor is a difficult load to drive and if the relay is old and worn the contacts could possibly be welding (sticking when it switches the motor on), you can try to test it but probably the movement from taking it out will temporarily free it up so it might test OK on a multimeter yet be faulty in reality.
What you can do if the fans are still running when you put the fuse back in, is find out which terminals power the relay coil, pull the relay and if you get 12V across those, then it's whatever drives the relay which is at fault.
IF it's the relay and you can't get hold of one this side of the holiday, you should be able to substitute a different power relay as long as the contacts can handle the current - when I had problems last on our old Mondeo I managed to connect another relay using male spade terminals on jumper leads which were attached to the terminals on the new relay...not ideal but it worked OK.
Hope this helps - I'm too rusty when it comes to these cars to be much help, but I am an electronics guy so hopefully that's some use 
Bruce.
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Bruce - '07 Jaguar XKR coupe, '95 Jaguar XJ Sport 4.0, '82 Ford Capri 2.0 Ghia, '15 Honda Civic (sloooooww..)
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Simmo
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Re: Failure to start.
« Reply #24 on: Dec 17th, 2015, 6:40am » |
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Glyn/Bruce. Thank you both for your thoughts.
Glynn. I take your point BUT there has been no sign to date of the fans running when the car has been locked up until last night!. I can't be sure if it was BOTH fans but I hope to check later today in daylight if my mate can come and give me a hand. Certainly the noise would indicate that both were going at full belt. I will check the wiring out but at first glance all seems sound.
Bruce. I'm glad the system makes sense to you! The one thing I deduced from the diagram and indeed the whole saga is that somehow the fans are getting a feed outside the ignition circuit. The diagram indicates that there is a permanent live feed to fan 1 via fuse 39 and there is a link to the relay so my simple mind says that might be a possible route of the power supply. It is an aspect I will look at today. Last night in the rain all I wanted to do was stop the fans and keep things dry and pulling F44 did that. Only after checking the site did I see that F39 and indeed F37 are also involved in the fan circuit. F37 is only live with the ignition ON. Typing this I seem to recall that at one point yesterday when I switched the ignition ON I did hear the fans start up?. Might this again point to the relay as it is the common denominator?
The relay, as far as I know is original and thus 19 years old! As for testing it I have no idea how to do that in much the same way as I have no idea how to find out which terminals power the coil! You will by now have gathered that I am not an electronics guy!  As for jury rigging another relay although I understand what you mean I suspect, with my lack of knowledge,the likely result would be catastrophic! I have trawled e-bay etc and Google but I can find no sign of a correct relay so I guess they are no longer available.
Will carry on today and report back. Thanks again for your feedback.  I have also had a word with Tompion who is similarly 'on the case'.
Mike
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Scorpio_Mike
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Jeep Grand Cherokee 3.0 V6 & 2.8 Sierra XR4i 4x4
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Re: Failure to start.
« Reply #25 on: Dec 17th, 2015, 7:42am » |
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Probably got a spare relay in my stash...
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Simmo
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Re: Failure to start.
« Reply #26 on: Dec 17th, 2015, 7:48am » |
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I had a feeling you might have Mike!!
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Tompion
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1997 2.3 Ultima estate.
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Re: Failure to start.
« Reply #27 on: Dec 17th, 2015, 9:44am » |
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Disregarding the chance of major loom damage (crumbling wires) or the need for a fusebox rebuild. For the big green relay to turn on both fans at high speed without the ignition on would require 2 faults:
BK/WH from the PCM to be earthed
VT from fuse 37 to be live
There is earth & power from other wires within the relay but not having looked inside one I wouldn’t know if internal failure allowing this to happen is likely.
As far as I can make out from the diagrams unlike the earth fault Glynn had the fan from fuse 44 is already earthed & assuming the contacts haven’t somehow closed within the relay would require a short between OG/BU (fuse 44) & the fan OG/GN.
If it helps there’s a loom shown on the first link in this thread:
http://www.fordscorpio.co.uk/cgi-bin/yabb/YaBB.pl?board=Advice;action=di splay;num=1280261377;start=1
I assume power from fuse 44 is coming down the battery side wing along the front & to the relay. Presumably the fan wire OG/GN only runs from connector 8 or 9 back to the relay with a possible loop back where the wire bundles meet the main loom.
I'll have a play later to see if another relay could cause this but I think it's unlikely as the fans initially go off.
Dave
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Andycan
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Re: Failure to start.
« Reply #28 on: Dec 17th, 2015, 11:13am » |
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I had this problem on my scorpio years ago. I can only remember that it was something simple like a earth to one of the fan plugs.
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Simmo
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Re: Failure to start.
« Reply #29 on: Dec 17th, 2015, 11:50am » |
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Replaced F44 this morning. All quiet. Just checked the fan wiring and connectors and all seems sound.Relay is now loose and I will tie it up so I can access it readily for the time being. Will check the earth connection which is near the relay while I'm down there. More to follow! 
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