Do I have a dodgy ground?

Ste.Sales · 27th February 2019, 18:03

My wife bought a diesel last year. Been fine until a month ago ish.
Started by saying the headlights were dimming at idle, then when revving they got noticeably brighter. Same when changing gear, the drop in revs would dim the headlights.
Next symptom, about a week later, started to hear a whine through the radio/stereo that increased and decreased with the revs.
Made me think that alternator was on its way out.
Anyhow, now I've got dimming lights, whine through stereo AND a very annoying loud ticking through the stereo on top of the whine that increases frequency with revs.
I have a friend who told me he had whine and ticking due to a faulty ground at his amplifier. I don't have an amplifier. So could I have a corroded ground somewhere? Any ideas / suggestions?
Thanks

gadget1960 · 27th February 2019, 19:39

Quote:

Originally Posted by Ste.Sales

My wife bought a diesel last year. Been fine until a month ago ish.
Started by saying the headlights were dimming at idle, then when revving they got noticeably brighter. Same when changing gear, the drop in revs would dim the headlights.
Next symptom, about a week later, started to hear a whine through the radio/stereo that increased and decreased with the revs.
Made me think that alternator was on its way out.
Anyhow, now I've got dimming lights, whine through stereo AND a very annoying loud ticking through the stereo on top of the whine that increases frequency with revs.
I have a friend who told me he had whine and ticking due to a faulty ground at his amplifier. I don't have an amplifier. So could I have a corroded ground somewhere? Any ideas / suggestions?
Thanks

I'm not a guru on these matters by any means but years ago I had a couple of new wings put on an old mini of mine and a few days later I was driving home at night and the lights began to dim quite noticeably along with the 'tape deck' slowing and making the speakers pop and crackle! it eventually died and I had to get a mate to tow me home, I eventually traced it to a very loose earthing point on the inner wing (which the body shop failed to tighten!), tightened it up, charged battery and all was good.
Not sure if this will help your situation but the symptoms you describe sound similar, won't hurt to check major earthing points I suppose.
I'm sure someone will be along to diagnose your problem far more accurately than I can though, good luck with sorting it.

trikey · 27th February 2019, 21:26

Check the voltage at your battery when running, it will be either a failing battery, or the alternator on its way out.

slovcan · 28th February 2019, 02:05

I think your alternator is toast (probably needs brushes).

BoroRover · 28th February 2019, 07:21

Classical duff alternator symptoms.

Ste.Sales · 3rd March 2019, 10:38

Hi,
I have managed to get out to the car this morning and would like to report my findings. I have measured the voltage across my battery from cold. It was 12.31v. During cranking, it dropped to 9.8v. At idle it reads 14.51v.
Now when I rev the engine, at around 1500rpm the voltage increases to 15.1 and stays there at higher revs. But when letting off the gas, when the revs drop below 1500rpm, the voltage drops to 12.3v until the engine reaches idle. Then when idling, voltage slowly increases back to 14.51v.
Would one conclude the alternator is definitely duff?

Lee T · 3rd March 2019, 20:48

12.3v is on the low side for the battery, 15.1v is rather high suggesting a duff regulator, worn brushes/slip rings or both, Mabey even failing diodes. Is it the original alternator? And what mileage has the car done?

27th February 2019, 18:03	#1
Ste.Sales Avid contributor Rover 75 Saloon Join Date: Jan 2015 Location: Preston Posts: 233 Thanks: 9 Thanked 37 Times in 35 Posts	Do I have a dodgy ground? My wife bought a diesel last year. Been fine until a month ago ish. Started by saying the headlights were dimming at idle, then when revving they got noticeably brighter. Same when changing gear, the drop in revs would dim the headlights. Next symptom, about a week later, started to hear a whine through the radio/stereo that increased and decreased with the revs. Made me think that alternator was on its way out. Anyhow, now I've got dimming lights, whine through stereo AND a very annoying loud ticking through the stereo on top of the whine that increases frequency with revs. I have a friend who told me he had whine and ticking due to a faulty ground at his amplifier. I don't have an amplifier. So could I have a corroded ground somewhere? Any ideas / suggestions? Thanks

27th February 2019, 21:26	#3
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,763 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	Check the voltage at your battery when running, it will be either a failing battery, or the alternator on its way out. __________________ Lest we forget..

28th February 2019, 02:05	#4
slovcan Gets stuck in 75 Tourer CDT MK2 manual in Glorious Grey Join Date: Jan 2018 Location: Slovakia Posts: 987 Thanks: 926 Thanked 346 Times in 252 Posts	I think your alternator is toast (probably needs brushes). __________________ Southern Slovakia Anything can happen in Formula 1 and usually does - Murray Walker 1999 Triumph Trophy 900, Saddlesore 1600, Iron Butt Riders Association #63720 2005 Rover 75 CDT Tourer MK2

3rd March 2019, 20:48	#7
Lee T Gets stuck in MG ZT Join Date: Jul 2014 Location: Liverpool Posts: 850 Thanks: 180 Thanked 248 Times in 189 Posts	12.3v is on the low side for the battery, 15.1v is rather high suggesting a duff regulator, worn brushes/slip rings or both, Mabey even failing diodes. Is it the original alternator? And what mileage has the car done? __________________ [SIGPIC][/SIGPIC]

28th February 2019, 07:21	#5
BoroRover Posted a thing or two Rover 75 Join Date: Sep 2016 Location: Middlesbrough Posts: 1,518 Thanks: 1,861 Thanked 723 Times in 471 Posts	Classical duff alternator symptoms.

3rd March 2019, 10:38	#6
Ste.Sales Avid contributor Rover 75 Saloon Join Date: Jan 2015 Location: Preston Posts: 233 Thanks: 9 Thanked 37 Times in 35 Posts	Hi, I have managed to get out to the car this morning and would like to report my findings. I have measured the voltage across my battery from cold. It was 12.31v. During cranking, it dropped to 9.8v. At idle it reads 14.51v. Now when I rev the engine, at around 1500rpm the voltage increases to 15.1 and stays there at higher revs. But when letting off the gas, when the revs drop below 1500rpm, the voltage drops to 12.3v until the engine reaches idle. Then when idling, voltage slowly increases back to 14.51v. Would one conclude the alternator is definitely duff?