larsianer

when i was driving today, i noticed that my head lights got dim,when the esp engaged, i also have a kind of weak light in the speedometer,and the headlights is also weak.
i have mounted a new ground from the engine to the chassie.could it be the alternator that is starting to get bad,when i use the volt menu in the dash/speedometer,it says 13.8v-14.1v,its mostly 13.8 when the car is cold, and when its warm,its allmost 14.1v hole the time.

What you thing??

LarsTheCodman

mersum1es

Sounds like voltage/grounding problem, but hard to say where. Your Charging voltage is good, try measure from battery poles too to ensure all battery leads are tight and sound. See there is no flood in under aux battery and front/rear SAM, pre fuse box leads in passenger footwell not corroded.

larsianer

thank you for reply, i dont have aux battery,cause i dont have sbc brakes,but where is the front and rear sam??

mersum1es

Ah, I didn't see your car details...

SAMs are 'fuse boxes'

larsianer

Thank you, do you know of any places in the sam,where they have had problems?

Lars

mersum1es

Just normal signs of moisture, corrosion... I once saw nice pictures of ML rear sam circuit board where large part of board back was under white corrosion... You should also see if your charge current is altering just when ESP triggers on, it may have been stabilized later when you put your display on. You mentioned you renewed your earth strap between engine block, double check that now.

f4i 954

sounds like a poor connection, check batt terminals to see if they are loose or corroded

larsianer

i have measured the volt output at the headlights, they are 11.7 volt,when the battery was 12.4v-12.5v.i have also checked the front&rear sam,both looked good.i have checked and cleaned the ground under the hood, and the one near the rear sam.the battery terminals looks good.where are the other grounds?,and what more should i check??

kajtek1

Some voltage drop at big consumer like headlight is normal, but you have 0.7v and that is not normal.
Check your connectors. Also confirm the voltage on battery terminals or at least on jumping peg under the hood.
Cluster usually shows 0.5v lower than actual charging voltage, so 14.1v there might be overcharge.
How old are alternator brushes?

larsianer

i will try to go check the jumping peg for voltage, how much should it be there??
i dont have any history on the alternator,but its covered with mud and oil, cause the previous owner did not have the skid plates, i have mounted a new one,should i also remove the alternator and clean it?? the car has now 428,000km

Thanks for reply

Regards from:Lars

kajtek1

At that kilometerage you will have pretty good bet for new brushes aka voltage regulator.
Charging voltage should be close to 14V after start and 13.5-13.7V maintaining.

larsianer

i have mounted new brushes,and voltage regulator,and its still i 11.7volt at the headlight, the strange thing is that when i turn the key to "on" position,and measure the volt output at the headlights, its 12.6,but when i start the car,the voltage drops to 11.7...do anybody have an idea what i shal check next?

kajtek1

That is a tricky one.
You need the track where the drop is. I would make long ground wire directly to the battery and probe the voltage along the wire.
Headlight/fuse/switch.