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Idle increases when lights go off
Posted: Tue Mar 19, 2013 5:47 pm
by Blueberry
Hopefully someone can help here:
When at idle (750~) and I turn off the headlights (no DRL) the idle increases to ~950 or so. This just started a few days ago.
Any suggestions? A symptom of...?
Thanks,
Graeme
Re: Idle increases when lights go off
Posted: Wed Mar 20, 2013 9:44 pm
by Rattlenbang
Sounds like something to do with your battery. Having the lights on is loading up your alternator, which of course does supply juice for them, but having fully changed battery acts as a bit of a buffer. Make sure you battery is good, connections clean etc.
Re: Idle increases when lights go off
Posted: Wed Mar 20, 2013 10:07 pm
by nxski
Mine's been doing that for 2.5 years, I never thought anything of it.
Re: Idle increases when lights go off
Posted: Thu Mar 21, 2013 8:50 am
by Rattlenbang
It is typical for lights to slow down the engine at idle, but if he's noticed a change, always a good idea to go snooping.
Re: Idle increases when lights go off
Posted: Thu Mar 21, 2013 5:48 pm
by Big-Bird
First thing you should do is clean your battery posts, cable clamps and then make sure the battery connections post are secure when you reconnect everything
Next is to check for proper tension on the alternator belt. A loose belt will also prevent the alternator from operating at peak output of around 14volts.
Finally: Go to Partsource and aks for a charging system test. Its free and their device will either point to your battery or batteries if you got 2, or the alternator.
Cheers!