Kev Rayner Posted August 28, 2001 Share Posted August 28, 2001 Hi, Can somebody point me the right direction? I am having trouble with the ignition warning light on the dash. My problem is, once I have started my car the ignition light goes out, when the car is idling, but if I rev the engine the light comes back on and glows brighter with the more rev applied. I have a 1991 Ford x/flow engine it's not given me any trouble before and has just passed its MOT for this Year with out a hitch. Has anybody had a similar problem if so what was the fix. Thanks for you help Kevin Link to comment Share on other sites More sharing options...
ashaughnessy Posted August 28, 2001 Share Posted August 28, 2001 I reckon your alternator's packed in. I've had this several times before and each time I had to get a new alternator. If you get a cheap alternator, it won't last long. The one that Caterham supply (or used to) has a metal cover for the fragile control circuits (compared to black plastic for the cheaper ones) which keeps the heat off better. The cheaper ones don't keep the heat from the exhaust off properly and fail quickly. Anthony Link to comment Share on other sites More sharing options...
Dave H Posted August 28, 2001 Share Posted August 28, 2001 Kevin, I had a similar problem a while ago, check the connections to the alternator, mine were corroded and once cleaned up all was OK. Note - disconnect the battery before you start. Dave H Link to comment Share on other sites More sharing options...
oilyhands Posted August 28, 2001 Share Posted August 28, 2001 As Dave H suggests check the connections they can easily corrode/erode and cause a real problem, if the brushes are worn then the brush spring tension is correspondingly less and the brushes can 'bounce' at higher RPM causing the alternator to stop charging, check these too. A decent auto electrics place should be able to check the output and diagnose the problem. Oily Link to comment Share on other sites More sharing options...
Kev Rayner Posted August 28, 2001 Author Share Posted August 28, 2001 Thank you all for the help and advice. I take a look at the alternator and clean the connection, if that dosen't fix it, I'll get a new alternator. Kevin Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted August 28, 2001 Share Posted August 28, 2001 The ignition light has 2 connections. A permanant live from the battery and the other connects directly to the alternator. When the engine is off, the alternator acts as an earth as it is not generating any current. When the engine turns, the alternator produces current and the light has two +ve supplies and doesn't light up. From what you're describing, I'd be suspicious that the fault could be on either the alternator or battery side. Get to both sides of the light and check them with a voltmeter. The alternator side should read 0 volts against earth with the engine off and 12v+ with the engine running. The battery side should read 12v whether the engine is running or not. This should help work out whether it's a short on the battery side or a problem on the alternator side. Alex Link to comment Share on other sites More sharing options...
Super_Rich_Bernie Posted August 28, 2001 Share Posted August 28, 2001 Kevin Don't be in too much of a hurry parting with cash for a new alternator. They usually come to pieces quite easily. Brushes are a matter of pennies to replace, and it will either be those or the bearing which has failed by the sounds of things. Jonathan Link to comment Share on other sites More sharing options...
Samkingdon Posted July 24, 2020 Share Posted July 24, 2020 Hi there, I am having a similar problem with my Caterham 150 SV. The ignition light is illuminated at lower revs but flickers out at higher revs. I have checked the charge of the battery prior to start 12.4v, start the engine, i get about 11.3v, if i then rev to 1500rpm i get 14.4v (so it is charging the battery again) however the light remains on. It seems the alternator is working but the ignition light remains on!? having spoken to a garage and explained the problem, they have suggested it is a diode within the alternator that may have failed, resulting in a new alternator being required.Any help would be much appreciated. Sam Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 24, 2020 Member Share Posted July 24, 2020 Private Message sent.Jonathan Link to comment Share on other sites More sharing options...
SM25T Posted July 24, 2020 Share Posted July 24, 2020 Take your alternator off the car and take it to an auto electrical place that tests and repairs alternators and starters. Quick and easy fix and you know it fits your car. Link to comment Share on other sites More sharing options...
Samkingdon Posted August 15, 2020 Share Posted August 15, 2020 Sadly this problem is still ongoing. I have replaced the alternator, problem is still there. Looking closer the 2pin single wire connector was corroded. So i replaced this. Problem still persists. Had a look at the wiring going into the tacho and it all looks fine. Have you guys got any suggestions? Any help would be much appreciated. Link to comment Share on other sites More sharing options...
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