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No Battery Light, Alternator e.t.c

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4K views 7 replies 5 participants last post by  sanane  
#1 ·
Hi all,

Need some pointers here please !

So on Tuesday morning driving to work my SRS light came on. I pulled over and the battery was flat, After waiting 15 mins or so I tried cranking again and there was just enough energy in the battery to start it. (SRS light now gone by the way - random!?)

From here I managed to drive the car back home, during which the rev counter/speedo needles were bouncing up and down on/off, to then no avail at all. No radio, very dim lights, wipers barely managing to move.

Having gotten the car home I have replaced the battery and tested new battery at a healthy 12.6 volts. upon starting the car, the voltage does not rise.

ALTERNATOR.

However, I have also noticed that upon turning the ignition on, the battery light does not illuminate as it should. - to which I am having side thoughts that perhaps its not the alternator, but a connection/earth?

I am much more mechanically minded than electronically, so I'm not entirely sure how to check things properly with a voltmeter.

Can anyone guide me how to check/ what to check here before replacing the alternator?


Thank you in advance !

James
 
M
#2 ·
I would start by checking the wiring and connectors - check the battery earth leads - one attaches to the front slam panel, and one to the inner wing below the engine bay fuse box. The attachment points often corrode and lose contact - the result can account for similar symptoms to those you are experiencing.

Also check that the wiring to the satrter motor is in good condition and the connecors are secure. Ditto the connectors to the alternator.
 
#3 ·
Your alternator is knackered.

I had similar symptoms a couple of years ago, SRS & ABS lights coming on and no battery light at all when turning on the ignition.

The battery light is earthed through the alternator, when the alternator breaks down the earth connection to the battery light bulb is lost.
 
#4 ·
Defo sounds like alternator. Pin 1 of alternator multi plug goes into pin 8 of the black multi plug in top of engine bay fuse box and is a switched live/ground to turn the warning lamp on and off all tho even with alternator plug off you still get just over 13volts so if you have no increase at all must be the unit its self at fault
 
S
#8 · (Edited)
While your engine is not running, take your voltmeter and connect it across your battery and take note of the voltage. Then start up your engine and connect your voltmeter across the battery again. It should read higher than when your engine is not running. If it is not, try stepping a bit on your accelerator. If there is no voltage rise, then its the alternator. You can either replace it or get it recoiled.

electronic assembly
 
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