Our new (to us) 2009 MG TF 135 has recently developed a problem where shortly after starting a journey the battery charge light on the dash comes on and stays on for the rest of the journey. To be clear, the light extinguishes once the engine is started and stays off for the first mile or so before coming on and staying on.
Thinking it might be a slack or worn alternator belt, I purchased a new one from B&G together with one of their rose jointed adjusters. However, when I jacked up the car and examined the belt, it appeared to be sufficiently tight and there is no sign of the alternator being seized or overheating.
Any ideas?
Battery charge light on while driving?
Moderator: Committee Members
Forum rules
Not many rules really, this board being aimed at technical issues, it shouldn't fall foul (hopefully) of some of the more personal issues that can affect forums.
Rule 1 - Is that you need to think very carefully before posting anything technical or asking anything technical relating to the security system of the car - See 'Security Issues' sticky for more info.
Rule 2 - We (MGF Register) do not support copyright infringement and therefore references to CD ROM, PDF versions or paper copies of the workshop manual (for instance) should not be posted on the forum. We don't want to get into trouble and we'd rather sell you a genuine hard copy through our Regalia shop anyway!
Because advice is honestly and freely given in this technical section, much of it will be amateur experienced based, so any information is given in good faith and is not guaranteed as correct.
Not many rules really, this board being aimed at technical issues, it shouldn't fall foul (hopefully) of some of the more personal issues that can affect forums.
Rule 1 - Is that you need to think very carefully before posting anything technical or asking anything technical relating to the security system of the car - See 'Security Issues' sticky for more info.
Rule 2 - We (MGF Register) do not support copyright infringement and therefore references to CD ROM, PDF versions or paper copies of the workshop manual (for instance) should not be posted on the forum. We don't want to get into trouble and we'd rather sell you a genuine hard copy through our Regalia shop anyway!
Because advice is honestly and freely given in this technical section, much of it will be amateur experienced based, so any information is given in good faith and is not guaranteed as correct.
-
GJO
- Posts: 117
- Joined: Sat Oct 20, 2012 10:45 pm
- MGF Register Region: South Midlands
- Model of Car: MG TF 135
- Contact:
Battery charge light on while driving?
Graham
2009 MG TF 135, Radiant Red
2009 MG TF 135, Radiant Red
Re: Battery charge light on while driving?
Alternator brushes sticking?
Diode pack breaking down when warm?
Diode pack breaking down when warm?
-
Charless
- Posts: 2364
- Joined: Tue Oct 09, 2007 1:52 pm
- MGF Register Region: South Coast
- Model of Car: 96 Mpi, 99 VVC
- Location: Chilbolton
Re: Battery charge light on while driving?
What voltage are you getting at the battery with engine off, engine on without light on and on with light on?
-
GJO
- Posts: 117
- Joined: Sat Oct 20, 2012 10:45 pm
- MGF Register Region: South Midlands
- Model of Car: MG TF 135
- Contact:
Re: Battery charge light on while driving?
Without the engine running I am getting 12.47 volts - the battery is less than six months old.
With the engine at idle speed (about 800 rpm) I am getting 14.0 volts across the battery terminals and I get the same at 2000 and 3000 rpm.
Strangely, I have not been able to replicate the original problem with the car at a stand so I probably need to invest in a cigar lighter adapter so that I can test the voltage on the move.
Graham
2009 MG TF 135, Radiant Red
2009 MG TF 135, Radiant Red
Re: Battery charge light on while driving?
Engine earth?
-
Chris Tideswell
- Posts: 828
- Joined: Mon Oct 08, 2007 5:58 pm
- MGF Register Region: Midlands
- Model of Car: TF 135
- Location: Shepshed Leicestershire
- Contact:
Re: Battery charge light on while driving?
Assuming a 09 TF is the same as the MGR F/TF, if the issue was with the alternator electronics the battery warning light wouldn’t aluminate at all when the ignition is on but before the engine is started.
-
GJO
- Posts: 117
- Joined: Sat Oct 20, 2012 10:45 pm
- MGF Register Region: South Midlands
- Model of Car: MG TF 135
- Contact:
Re: Battery charge light on while driving?
This is weird - I took the car out for a fairly long run and couldn't replicate the problem.
I did tighten the earth clamp on the battery and I also replaced the bolt that connects the battery earth to the body (it was rusty) the replacement is stainless. That must have done the trick!
I did tighten the earth clamp on the battery and I also replaced the bolt that connects the battery earth to the body (it was rusty) the replacement is stainless. That must have done the trick!
Graham
2009 MG TF 135, Radiant Red
2009 MG TF 135, Radiant Red
-
Charless
- Posts: 2364
- Joined: Tue Oct 09, 2007 1:52 pm
- MGF Register Region: South Coast
- Model of Car: 96 Mpi, 99 VVC
- Location: Chilbolton
Re: Battery charge light on while driving?
I found they didn't remove the paint when fitting the earth strap on all of mine, so the contact point to the body was only the thickness of the metal in the bolt hole or spot welds on the captive nut (the threads vulnerable to corrosion over time). Removing the paint under a new crinkle washer is a good plan on all Fs (and probably TFs).