darve Posted March 1, 2015 Share Posted March 1, 2015 That's what I suggested Q but Mike's leccy knowledge is far superior to mine Seems a simple option though so you haven't got to change much wiring 1 Quote Link to comment Share on other sites More sharing options...
Quinten Posted March 1, 2015 Author Share Posted March 1, 2015 Beer tokens to everyone who helped out Tested the backfeed theory by pulling the 12V to the Bright6 once it stayed running without ignition and sure enough, the engine died straight away. Soldered a diode in between and now it's working as it should Then went one step further and tried to get the start button led to mimic the battery light, but then I got the same backfeed issue again, so will have to re-think that situation. It's for another day though, it just started to rain and I haven't even been able to start on my steering wheel button plate Quote Link to comment Share on other sites More sharing options...
TableLeg Posted March 1, 2015 Share Posted March 1, 2015 Excellent, glad you got it sorted. Well done to both Darve and R7WSC. I learnt something new today. 1 Quote Link to comment Share on other sites More sharing options...
corsechris Posted March 3, 2015 Share Posted March 3, 2015 Bit late now, you've sorted it, sorry ...but, had a very similar issue after fitting an ECU to a previously clockwork car. There was enough current coming out of the alternator warning light feed/bootstrap terminal to hold the main ignition switched relay on...whcih then maintained power to the ECU etc. Like yourself, just fitted a simple blocking diode in the warning light feed. 1 Quote Link to comment Share on other sites More sharing options...
Kingster Posted March 11, 2015 Share Posted March 11, 2015 Just got my engine started for the first time (properly anyway) and it too would not turn off. The alternator warning light stays on even though the ignition is off - thus I suspect it is as above - so what exactly do you do with a diode to fix it? Chris Quote Link to comment Share on other sites More sharing options...
Quinten Posted March 11, 2015 Author Share Posted March 11, 2015 Well the diode acts like a one-way street for current. It can flow in one direction, but not the other. Your alternator light (I'm going to assume a normal bulb, i.e. not led?) has two wires into it: 1) from the alternator, and 2) from your ignition switch. With the ignition switch on, 12V will flow from ignition to the bulb as the alternator will act as the ground. When the engine is running, the alternator will also output 12V (or sometimes a little bit more) and send it to the bulb. But because 12V is 'pushing' on the other side too (from the ignition), there is effectively no difference, and hence the light goes off. To cut a long story short, the diode should be on the ignition 'leg' and should only allow 12V to go to the bulb, not from the bulb (the diode has a ring indicating the 'blocking side' printed on it). 1 Quote Link to comment Share on other sites More sharing options...
darve Posted March 11, 2015 Share Posted March 11, 2015 Good description Q 1 Quote Link to comment Share on other sites More sharing options...
Kingster Posted March 11, 2015 Share Posted March 11, 2015 Indeed, can you guide me to the correct diode to use, there are many to choose from! Quote Link to comment Share on other sites More sharing options...
Quinten Posted March 11, 2015 Author Share Posted March 11, 2015 Can't take credit for this (think it was Mr Eastwood who pointed them out), but I have bought these: http://www.ebay.co.uk/itm/271685459209 Quote Link to comment Share on other sites More sharing options...
Kingster Posted March 11, 2015 Share Posted March 11, 2015 Crickey they sure are pricey 1 Quote Link to comment Share on other sites More sharing options...
Lyonspride Posted March 13, 2015 Share Posted March 13, 2015 No and yes. When I had the engine running for a short time, I was able to switch it off again using the key as normal. It stopped the fuel pump just as expected. When the engine was running for a bit longer, the key no longer switched the engine off Was the rad fan running? Since changing my radiator, if the engine is warm enough for the rad fan to be running, when I turn off it takes about 5s for the engine to stop, as the fan spins down it feeds voltage into the ignition, which then keeps the engine running.. Quote Link to comment Share on other sites More sharing options...
Quinten Posted March 13, 2015 Author Share Posted March 13, 2015 Was the rad fan running? Since changing my radiator, if the engine is warm enough for the rad fan to be running, when I turn off it takes about 5s for the engine to stop, as the fan spins down it feeds voltage into the ignition, which then keeps the engine running.. In my case, no. But it is a valid point. You should fit a diode as well to block current going back into the ignition circuit... Quote Link to comment Share on other sites More sharing options...
Kingster Posted March 13, 2015 Share Posted March 13, 2015 Earlier I tried starting to dee what would happen. Even cold it would run ignition off. Pull the ignition light off thr loom and it stopped. So diode between light and loom to be added soon! Quote Link to comment Share on other sites More sharing options...
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