Big Brother Posted August 18, 2001 Share Posted August 18, 2001 Just fitted an FIA battery cut off switch to my 79 Seven and things are not well!!! The switch has been fitted as per Caterham instructions and all new wiring has been TREBLE checked. Tested the operation of the switch as the instructions say, using the lights - all OK. Started the car - runs OK, switched the cut off and the engine died (about 1.5 seconds after turning the switch. "Job done" (so I thought!!!) Restarted the engine, warmed her up and spent a few minutes checking the mixture. When I had finished I decided to use my new switch to "kill" the engine. Switched the switch...nothing, engine carries on running. Started to check the wiring and in the process BURNT my hand with the cut off switches resistor that was VERY HOT! (now have a nice rectangular blister) Switched of the car with the ignition switch - engine dies instantly. I have checked all the new wiring and all seems fine - now totally without a clue! The car recently had an alternator fitted to replace the old dynamo. The wiring was modified as per the Tony Weale book with no problems. ANYBODY GOT ANY IDEAS? All input appreciated! Dazed, Burnt and Confused! Steve cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif Link to comment Share on other sites More sharing options...
Tazio Posted August 18, 2001 Share Posted August 18, 2001 Problem is caused by the alternator providing sufficient output to drive the engine - did it on mine til I also put the ignition circuit through the swith ( but mines on an MBE ECU) Talk to Caterham Alan Link to comment Share on other sites More sharing options...
Andrew Walker Posted August 18, 2001 Share Posted August 18, 2001 It's Saturday night Steve, jack it in now and go have a glass of wine. Come back to it tomorrow morning. But don't forget it's the Grand Prix at 12:30. Enjoy!! Link to comment Share on other sites More sharing options...
Big Brother Posted August 19, 2001 Author Share Posted August 19, 2001 Tazio, I am now thinking along the same lines as you... Obviously, the Caterham "two white wires" approach didn't work due to the cars "modified" wiring. I am now thinking of running the supply for the coil through the master switch's "accessory" terminal instead of the ignition wiring. I think this should kill the engine when the switch is thrown...cant see it running without a spark! Andrew, Taking your advice, however I need to get it sorted by the start of the GP, either that or I wil be listening to radio 5 "live" in the garage! Reassurance still needed... Steve cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif Link to comment Share on other sites More sharing options...
Big Brother Posted August 19, 2001 Author Share Posted August 19, 2001 Still not sortedsad.gif Will the switch still work OK (protect the alternator) if only the supply to the coil is cut, not the entire ignition circuit? ...Ideas anyoneidea.gifquestion.gif Steve cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif Link to comment Share on other sites More sharing options...
R2D2 Posted August 20, 2001 Share Posted August 20, 2001 Will mail you a correct wiring layout when I get home tis evening. I fitted a cut out early this year and it all works fine. Link to comment Share on other sites More sharing options...
Big Brother Posted August 20, 2001 Author Share Posted August 20, 2001 Cheers Chris, The master switch has been fitted "exactly" as the Caterham instructions say, however I think the early (re modified) wiring on my car may be different to the current Caterham spec. Steve cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif Link to comment Share on other sites More sharing options...
Mike Bees Posted August 20, 2001 Share Posted August 20, 2001 Steve, I did the same thing as you (burnt my thumb on the resistor) when I first wired mine up. Found I'd wired up the resistor wrongly. This was 4 years ago so I can't remember what I'd done wrong... Mike Link to comment Share on other sites More sharing options...
Big Brother Posted August 20, 2001 Author Share Posted August 20, 2001 Mike, I bet you connected the resistor to the "battery" side of the master switch and not to the "solenoid" side. I think my problem is the alternator is putting a voltage into the ignition wiring on the "switched off" side of the master switch. This is allowing the engine to run with the battery disconnected. The resistor is getting hot as the "spare" voltage is routed to ground thru it. I think that if I just run the coil supply thru the master switch, not the ignition circuit this should kill the engine OK, but am not sure if this will have and sdverse affects on the ignition circuit. Steve cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif Link to comment Share on other sites More sharing options...
R2D2 Posted August 20, 2001 Share Posted August 20, 2001 Steve, It seems to me that your battery cut out is not disconnecting the ignition circuit as the engine is still running. Blue Book regs require that the "battery master swictch" disconnects the ignition. The reason the resistor get hot is that you are dumping alternator current to earth through the resistor because the engine is still running. You must wire the system up so that the battery master switch cuts the ignition as well as isolating the battery. This means when you operate the switch the engine stops. The resistor stops the alternator from blowing up the rectifier pack by allowing current to flow while the engine stops. If the engine keeps running you must have a complete ignition circuit even with the cut out operated. If the resistor gets hot with the switch in the on position you are still discharging output to ground through the resistor and this is also incorrect. The resitor should only be in the alternator circuit when the switch is off. The normal reistor supplied is only about a 10W wire wound so it won't take full output power for too long. I would suggest you check the ignition circuit with the cut out in the off positon and see whcih side of the ignition switch you have connected. Check to see if the resistor gets hot with the engine running normally with the switch on and if it does this is a second fault. Good Luck. Link to comment Share on other sites More sharing options...
Big Brother Posted August 20, 2001 Author Share Posted August 20, 2001 Chris, I totally agree with what you are saying, however... The MS is wired up so that when operated (switched off) it will do the following 1, disconnect the battery supply 2, route the solenoid supply via the resistor to ground (to protect the alternator) 3, disconnect the following: supply to coil, supply to ignition. Both of "3" are taken from the rear of the ignition switch (2 X white wires) and are joined together. (this links the ignition wiring and the coil supply together) My guess is that when the car was converted to run with an alternator, the wiring was modified to allow the removal of the control box. This is now where the supply from the alternator is fed into the cars wiring. This is also on the "isolated" side of the ignition circuit. When the MS switch is operated, the alternator is still providing a supply, this is reaching the coil and allowing the engine to run on. My solution (I havent tried it, but it looks OK on papersmile.gif) is to take the ignition wiring out of the equation (return it to normal) and use the MS to disable the coil supply. The "ignition" should then die as it will be fed directly from the isolated main supply. What do you think? Will it work? Steve cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif Link to comment Share on other sites More sharing options...
R2D2 Posted August 20, 2001 Share Posted August 20, 2001 Sounds correct to me and thats more or less how my car is wired. Do you have Tony Wheales book? it has all of the relevant circuit diagrams. I have it at home complete with a scanner. Cheers Link to comment Share on other sites More sharing options...
Big Brother Posted August 20, 2001 Author Share Posted August 20, 2001 Chris, Thanks for offer Chris but I have the Tony Wheal book. (Best 7 book ever!) The first circuit diagram in the book, combined with the alternator conversion diagram is basicaly as my car is set out. I will have a play tonight and let you know how I get on. Steve cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif Link to comment Share on other sites More sharing options...
Big Brother Posted August 20, 2001 Author Share Posted August 20, 2001 Thanks to all who posted. I have removed the ignition wiring from the "loop", running only the coil supply thru the cut out switch and it works like a dream, even at high revs. Thanks again Steve cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif Link to comment Share on other sites More sharing options...
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