DMorris Posted July 31, 2015 Share Posted July 31, 2015 Front passenger side light, passenger rear light and number plate light all on one 5 amp circuit/fuse - keeps blowing so can't get it through the MOT - OK when cold, new fuse all works well - take it out for a blast (and the the MOT centre) - fuse blows. Any idea how I begin to track the problem or do I just call an auto electrician?! Cheers Dean Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 31, 2015 Member Share Posted July 31, 2015 Have you got a multimeter and a wiring diagram?(I'm a great advocate of not jumping to electrical conclusions but I'd be looking for an intermittent short to earth in one of the light units.)Jonathan Link to comment Share on other sites More sharing options...
DMorris Posted July 31, 2015 Author Share Posted July 31, 2015 Have found a diagram and have a multitester! Link to comment Share on other sites More sharing options...
tbird Posted July 31, 2015 Share Posted July 31, 2015 Does it blow fuse even when lights not switched on, so when you drive a distance then put lights on has fuse already blown or does it only blow if lights on all the time you are drivingTim Link to comment Share on other sites More sharing options...
DMorris Posted July 31, 2015 Author Share Posted July 31, 2015 Difficult to say for sure Tim, I would have to go out again and see. When you do put a new fuse in after it's been on a run to replace the blown one and turn the side lights on it just blows the fuse instantly. If I stick a new fuse in tomorrow morning when it's cold, it will work fine in isolation or with the engine running. As soos as it goes out for a run - blows. Link to comment Share on other sites More sharing options...
tbird Posted July 31, 2015 Share Posted July 31, 2015 Thats not going to be an easy one, int shorts are a bugger, trying to think how heat could be having any effect, as you say fuse 7 only supplies LH lights and numberplate. I wonder if its heat or something being stretched when driving that slowly eases when stopped, so I guess the place to look could be where cable runs up to the sidelight, could turning the steering be nipping/stretching the wireTim Link to comment Share on other sites More sharing options...
DMorris Posted July 31, 2015 Author Share Posted July 31, 2015 Got it Tim - new fuse - ignition off - all OK. Turn side lights off - start car - all OK side lights work. Turn lights off - start car - all lights OKHoweverTurn lights on and start car - fuse blows ; or if leave lights on working and turn ignition off - fuse blows Link to comment Share on other sites More sharing options...
tbird Posted July 31, 2015 Share Posted July 31, 2015 What CSR and year is it by the way, are you also aware of http://csr.informe.com/forum/ its a dedicated site for CSRs, not as busy as BC but a lot of knowledgeable folk drop in and out, might be worth posting there as well Link to comment Share on other sites More sharing options...
tbird Posted July 31, 2015 Share Posted July 31, 2015 Still going with vibration/stretching/nipping of a cable, somewhere were it runs up to the front side light, trouble is can't see anywhere you can easily split the cct down between front and back :-( guess a physical inspection of visible cables front and back is the first step , I suppose with the igntion and lights off you could connect meter between 12v line at front light and Earth and physicaly cause vibration in light units support bracketTim Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 1, 2015 Member Share Posted August 1, 2015 I can't explain the relation to starting.How much can you isolate various parts of the wiring to the three lights? I think all of them have local connectors. Break all of those and see if the problem persists. If it doesn't add them back one at a time.And what Tim says.JonathanPS: You're going to eat a lot of fuses on this. It might be worth buying a resettable circuit breaker. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 1, 2015 Member Share Posted August 1, 2015 Just checked the diagram for that model. Why are side/tail light RHS fuses 7.5A and LHS fuses 5A?The numberplate light is fed from the RHS, and those fuses don't feed the reversing light or high-intensity rear lamp.Jonathan Link to comment Share on other sites More sharing options...
tbird Posted August 1, 2015 Share Posted August 1, 2015 On my diags the number plate is fed with LHS, fuse 7 , can I upload a PDF to here CSR-SVR Cosworth 2300 - main loom.pdf CSR main loom diag, I also wondered why different fuse ratings Tim Link to comment Share on other sites More sharing options...
tbird Posted August 1, 2015 Share Posted August 1, 2015 Just had another look at Diags, fuse 6 seems to feed a few gauges as well as lights, presumeably that explains higher ratingTim Link to comment Share on other sites More sharing options...
DMorris Posted August 1, 2015 Author Share Posted August 1, 2015 Thanks Gents Have got through 15 or so fuses so far - will keep at it! Give me any problem apart from an electrical one! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 1, 2015 Member Share Posted August 1, 2015 Thanks, Tim. But I do wonder why it's like that when those instrument feeds aren't off the same fuse: it might be a relic of a previous arrangement.JonathanPS: Do you have any more CSR-specific documents that I can add to my store? Link to comment Share on other sites More sharing options...
tbird Posted August 1, 2015 Share Posted August 1, 2015 Steve has created our secret CSR stash Here :-)on my diag fuel gauge , heater fan switch, water temp gauge , oil pressure gauge , wiper sw, tacho and speedo are all have feeds from Fuse 6 Tim Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 1, 2015 Member Share Posted August 1, 2015 Thanks:-)Jonathan Link to comment Share on other sites More sharing options...
tbird Posted August 1, 2015 Share Posted August 1, 2015 dean Hi,the secret to electrical fault finding is splitting the ccts if possible, difficult with that cct,you know that with the lights turned on starting the engine causes the fuse to blow, so , as jk said, can you disconnect all the lights at the bulb holders, then turn the light switch to on and start the engineif fuse doesn't blow then problem would seem to be at a holder, if fuse does blow then its the wiring somewhere, more of a problem to find as its pretty much only physical inspection that will help, its a big step but you could cut wires to split cct and use Multimeter to find shorts, then use in line splice to rejoin wire Tim Link to comment Share on other sites More sharing options...
tbird Posted August 1, 2015 Share Posted August 1, 2015 Just occured to me , I have not had fuse box off but it maybe possible to split back and front ccts on the back of Fuse 7 holder, worth a look to see if there are two or more connectors that could be disconnected. Tim Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 2, 2015 Member Share Posted August 2, 2015 ... can you disconnect all the lights at the bulb holdersSame principle of isolation, but I was thinking of breaking the three circuits where the fly leads from the lampholders connect to the wiring harness rather than at the lampholder.... but it maybe possible to split back and front ccts on the back of Fuse 7 holder, worth a look to see if there are two or more connectors that could be disconnected.Don't know where they separate, but this would help a lot to localise the problem if it does turn out to be in the wiring. Easiest to try the three lamp units first.Jonathan Link to comment Share on other sites More sharing options...
tbird Posted August 2, 2015 Share Posted August 2, 2015 breaking the three circuits where the fly leads from the lampholders connect to the wiring harness - See more at: http://www.lotus7.club/comment/2145613#comment-2145613even better JK, haven't got my car here to see where its possible, didn't realise there were fly leads to the loom, thought loom went straight to lamp holder. Trouble is I am used to mill spec diagrams with every connector defined in the diagram Tim Link to comment Share on other sites More sharing options...
Mark w Posted August 4, 2015 Share Posted August 4, 2015 What happens if you put a slighly large fuse in ? maybe try a 7.5A or ( 10 to start with and work back ?) I had a problem with an ECU fuse continually blowing on my old car and CC advised me to up it one size and it was fine forever after that , seemed the original was just a bit too marginal . Link to comment Share on other sites More sharing options...
DMorris Posted August 5, 2015 Author Share Posted August 5, 2015 Tried that Mark but blows those as well. Lost the will to live with it so an auto electician booked for Friday morning! :) I figure it's horses for courses and he will sniff out the issue in minutes... Link to comment Share on other sites More sharing options...
tbird Posted August 5, 2015 Share Posted August 5, 2015 Hope its simple so it does't cost you too much,but, on the other hand, hope its complicated so we all have some self esteem left :-) Tim Link to comment Share on other sites More sharing options...
DMorris Posted August 7, 2015 Author Share Posted August 7, 2015 Loom passes rear to front over top of gearbox - loom rubbed on one of thr 4 bolts holding gearlever into box - short Voila! Link to comment Share on other sites More sharing options...
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