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| pannawonica Member Since: 21 Nov 2010 Location: Clackline Western Australia Posts: 568  
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Unusual electrical issues make me suspicious of a bad earth somewhere!
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7th Jan 2018 4:46am |
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| Screbble Member Since: 26 Apr 2015 Location: Lancashire Posts: 2024  
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I haven't got cruise control so can only offer a general comment.
I agree that it is probably likely to be a high resistance or faulty earth connection somewhere. It might be worth taking a look (if possible) at the earth connections you have made for both installations. Are any of them common (if you pardon the pun)? I know the wiring diagram you refer to so I'd have a closer look around the relay you've installed for the driving lamps as I recall the dash switch makes/breaks the earth to the coil. With the two circuits being entirely separate, and the feed for the lights coming straight from the alternator, I can't think of anything else obvious. Sometimes it's worth getting someone rise to look over the installation as they will see things you don't if you know what I mean. Easier said than done I know. Hope you get it sorted |
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7th Jan 2018 10:03am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16858 
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It may be a noise or inductance related 'feature'.
Ever since I rewired my headlights via relays I get a half-powered flicker from both indicator tell-tales on the Ipac and the trailer indicator tell-tale whenever I go from main to dip. I suspect that somewhere there's a 'switching transient' causing this, but I've never been concerned enough to do anything about it. It could be a similar phenomenon witb your CC. |
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7th Jan 2018 10:09am |
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| Bluest Member Since: 23 Apr 2016 Location: Lancashire Posts: 3996 
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Panawonica, Screbble - I will check the earths. The spots are earthed to a bolt on the ac compressor, but I can’t recall where the earth for the cruise control went to. It’s possible the earth for that is shared with the driving light dash switch illumination/tell tale, which coincidentally failed recently....
Black wolf. I too get the momentary flash of the indicator tell tales when coming off high beam. It irritates me but am not smart enough to understand the cause! 2007 110 TDCi Station Wagon XS |
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7th Jan 2018 10:37am |
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| rallysteve Member Since: 10 Feb 2014 Location: Cumbria Posts: 2196 
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Both,
Using relays with a resistor built in (believe the yellow LR ones have this) should help with this. It is probably caused by back emf when the relay coil de energises. You could also use a relay with a diode built in but you have to be careful that the relay coil is wired correctly or you will have a short circuit. I believe diode relays are wired differently to the DIN standard 85/86 terminal designations. Try swapping your headlight relays (assuming you have used 4 pin ones) for a couple of yellow ones in the fuse box and see if it goes away. Steve 02' 110 TD5 Double Cab Rebuild Thread 84' 90 3.9 V8 Caged Pickup Build Thread - Now For Sale Mobile Diesel Heater Build Thread |
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7th Jan 2018 11:53am |
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| MadTom Member Since: 10 Sep 2013 Location: Olomouc Posts: 572  
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Or you can add diodes to the current relay coils. For the diode something like 1N5408 is more than enough, and cost nearly nothing. Diodes must be placed just next to the relay, with short wires connecting them. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo
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7th Jan 2018 1:09pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16858
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Steve, many thanks. I replaced the standard relays I had for dip and main with genuine yellow LR ones at the weekend and the flicker phenomenon has gone. It doesn't matter if the relays used are the Tyco or the Siemens type (both yellow and both genuine - I tried both types as I have a number of each), the fact that they have the on-board resistor appears to stop the flicker. Another interesting feature which I hadn't noticed until fiddling around with relays at the weekend is that with the old, non-resistor-fitted relays, the flicker only happened if the engine was actually running. If the ignition was on but the engine wasn't running there was no flicker. Although I still don't quite understand the exact mechanism by which the ficker was occurring, the better relays have cured it. |
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15th Jan 2018 12:21pm |
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| rallysteve Member Since: 10 Feb 2014 Location: Cumbria Posts: 2196
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Excellent
Always nice when a theory works, cheers for confirming. Steve 02' 110 TD5 Double Cab Rebuild Thread 84' 90 3.9 V8 Caged Pickup Build Thread - Now For Sale Mobile Diesel Heater Build Thread |
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15th Jan 2018 12:28pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16858
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Hmm, it seems I posted too soon.
It was daylight when I swapped the relays around, and it was dark when I drove home from work. There is actually still a flicker from the three indictor warning lights after all, I just couldn't see it in daylight. It may be dimmer than before (it is hard to tell) but it's still there. It is not a problem, but it is a puzzle. |
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15th Jan 2018 7:50pm |
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