Hey guys

Have a grande punto 1.4 tjet 2009. Have an unsual one, which when trying to search for it on the forum was proving too specific / odd, but ill try to explain.

Whilst im driving i can hear a slight constant humming. This seems to be eletrical related becuase when i interact with say my rear demisiter buttpn turning it on and off, the hum will change in pitch. The same will happen when i close my windows but press the buttons to close them (even though they are closed). This all seems to have a bearing on my headlights as they dim in perfect rhythm to me pressing buttons / closing windows.

Ive done a video to help explain but it is alittle unsual. Any ideas appreciated.

[ame]https://youtu.be/z64hVU7uUPY[/ame]

Could be a ground but I'd imagine its something having a higher current pull, could also be something to do with the battery in the car. Anything out of the ordinary there? Have you modified anything?

Teirminator said:

Could be a ground but I'd imagine its something having a higher current pull, could also be something to do with the battery in the car. Anything out of the ordinary there? Have you modified anything?

Click to expand...

Hey thanks for response. No i dont have any modifications as i always worried about it causing electrical issues ironically. The battery looks fine and when i test with a multimeter things all check out.

Definitely have a voltage drop because of a resistive connection in the circuit !

With volmeter to DC 20V scale, measure between the negative POST of the battery (the lead part) and a good earthing point: you shouldn't read ANY voltage (or only a few mV). If you read a significant voltage drop, you've got a resisting point (battery clamp, earth lug/cable).
Do the same with the positive POST and the main positive at the fuse box: you shouldn't read ANY voltage either, if you do the resisting point is in the positive line ...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Definitely have a voltage drop because of a resistive connection in the circuit !

With volmeter to DC 20V scale, measure between the negative POST of the battery (the lead part) and a good earthing point: you shouldn't read ANY voltage (or only a few mV). If you read a significant voltage drop, you've got a resisting point (battery clamp, earth lug/cable).
Do the same with the positive POST and the main positive at the fuse box: you shouldn't read ANY voltage either, if you do the resisting point is in the positive line ...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Bernievarian said:

Definitely have a voltage drop because of a resistive connection in the circuit !

With volmeter to DC 20V scale, measure between the negative POST of the battery (the lead part) and a good earthing point: you shouldn't read ANY voltage (or only a few mV). If you read a significant voltage drop, you've got a resisting point (battery clamp, earth lug/cable).
Do the same with the positive POST and the main positive at the fuse box: you shouldn't read ANY voltage either, if you do the resisting point is in the positive line ...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Click to expand...

Ill definitely have a look at this. Electrical is def8nately my weak point in car understanding, that and wiring diagrams. Not for the lack of trying (believe me) but ill watch some videos to do the test of battery / alternator / drop test etc and post my results back. Hopefully up my skillset further.

Be sure to take the BATTERY POSTs (the lead part) and NOT the clamp as measuring point !!

everson38 said:

Hey guys

Have a grande punto 1.4 tjet 2009. Have an unsual one, which when trying to search for it on the forum was proving too specific / odd, but ill try to explain.

Whilst im driving i can hear a slight constant humming. This seems to be eletrical related becuase when i interact with say my rear demisiter buttpn turning it on and off, the hum will change in pitch. The same will happen when i close my windows but press the buttons to close them (even though they are closed). This all seems to have a bearing on my headlights as they dim in perfect rhythm to me pressing buttons / closing windows.

Ive done a video to help explain but it is alittle unsual. Any ideas appreciated.

Click to expand...

When you try to close your already closed electrical window I see a little voltage drop due to a current drain to the window motor.
This shows as a lower intensity of our headlights.
You can try two things first:
Put a voltmeter on your battery and measure before and also when you press the window close button.
You will see a slightly drop in voltage e.g. 12,3 > 11,8V
If you can measure the voltage also at your headlight and it almost shows the same values, then nothing seems wrong.
Otherwise I suspect voltage drops in the fusebox or indeed a bad earth connection.

Nothing else wrong with the car itself and the electrics?
Also listen to your alternator, increase in load might also give the humming sound.

Thanls for this i will g8ve this all a check also.

damted said:

If you can measure the voltage also at your headlight and it almost shows the same values, then nothing seems wrong.

Click to expand...

Let's assume there is a voltage drop (because of resistive point) between one battery post and its clamp (or the "ground" of the
car): it will result in a different voltage reading EVERYWHERE on the car ! This is why the headlights fade... A dying battery would do exactly this due to internal higher resistance.

Ohm's law says U=R*I, therefore if either I or R increases, so will the U drop...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Bernie,
I agree on that.
If battery is bad the drop of voltage will be there also (measured directly on the terminators)

Ohm's law is always true. but when everything is ok you will not notice.

The problem is find the big resistance in the wiring and solve it.
TS could measure first with the engine off, possibly there is no humming sound to hear

Bernievarian said:

Let's assume there is a voltage drop (because of resistive point) between one battery post and its clamp (or the "ground" of the
car): it will result in a different voltage reading EVERYWHERE on the car ! This is why the headlights fade... A dying battery would do exactly this due to internal higher resistance.

Ohm's law says U=R*I, therefore if either I or R increases, so will the U drop...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Click to expand...

Well alittle background. In an average week my car gets driven about once a weekwhuch is about 30 mins of motorway driving. So i know this lack of driving can cause a weaker battery and when i check my battery voltage from time to time is is about 11.69 volts which i again know 12.4 and above is what you want. I always attribute the lower voltage down to my cars usage style. My question is how do i know if the battery is out right bad or just needs a charge? As i have charged my battery and get it to where it should (12.6v) be but then after a few days of not driving it i know it will be lower again. So is that a bad battery or just the circumstances my car is put in due to lack of driving?

You could do a battery test at a local workshop.
They measure directly on the battery and that will show the condition of your battery.
As long as your car starts without issues battery seems fine for the moment.
Did you measure already the battery voltage when you trigger the window close switch?
Best done with engine not running!
Try to measure Voltage difference between these 2 conditions.

You can have your battery and charging circuit (free) checked in numerous places. An healthy battery wouldn't loose that much voltage over a few days, go to the next shop and get it checked !!

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Bernievarian damted

Ok guys, so from your suggestions and so i have plan / steps of action to begin with. This is what im deducing i should do first to get to the bottom of this issue.

(This week some point, currently away)

1) Im going to take a voltage reading of what my battery currently is to give me bench mark.

2) Check window volt drop: Do a battery check as i press the window button to see if there is a drop in voltage. (Note down readings)

3) Take my car to Halford to get one of those battery / load checks done. BUT should i just head over there as is, or should i charge the battery / drive the car awhile for a more accurate test?

Full charge it over night or run it 1/2h going to Halford for testing, the battery should then be "as it should". The test under load will tell if it's still healthy, and the charging circuit test will tell about the alternator.
I bet on the battery ....

On a side note, can anyone answer this since im in battery check mode. I havd noticed these wobbly bolts on my terminals? (See video below)

Now 1) Are the missing some type of securing nut

2) Could i use these points with crocodile clips on my multimeter to take readings, as i need away to be in the car and see readings at same time

[ame]https://youtu.be/BYsAbH-JHHY[/ame]

I guess you meant "loose" bolts ? I believe they're there for (optional) power connections, they, being wobbling, are NOT a good reference for measuring. You really need to connect to the battery POST (lead part); you can drill a 2mm hole in its center an fit a self-taping screwin it with a round lug to your testing cable ...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Bernievarian damted danted Hey Guys, so I have managed to get out with my car today and do some checks. The car has not been driven for about 2 weeks now and my battery is a Halfords 400cca 45ah HB012. Results/ Test:

ENGINE OFF / NO ELECTRICS / BATTERY CURRENTLY AS IS: PART 1:
1) Multi-meter directly on terminal posts - Battery Voltage: 11.57v
2) Multi-meter connected via crocodile clips on battery clamp bolts (I just wanted to test how accurate this was) - Battery Voltage: 11.55v.
3) Volt drop test from Positive post to positive clamp: 0.00v (no drop).
4) Volt drop test from negative post to negative clamp: 0.00v (no drop).
5 Battery Surface drain test : the battery had surface drain all over ranging from: 0.02 volts - 6 volts.

ENGINE OFF / CAR IN RUN POSITION aka Electrics on PART2:
1) Multi-meter directly on terminal posts - Battery Voltage: 11.14v (a drop).
2) Multi-meter connected via crocodile clips on battery clamp bolts: 11.15v (a drop).
3) Volt drop test from Positive post to positive clamp: 0.00v (no drop).
4) Volt drop test from negative post to negative clamp: 0.00v (no drop).
5) Closing the window (when window is closed) reads at 11.08v and drops to about 10.64v when pulling up the window for a split second
6) Putting Headlights on only: Battery reads 11.08 > 10.64v and stays that way.
7) Putting on a load: head lights, main beam, blower on max , rear demister: Battery plummeted and kept falling. 11.08v > 7v. Then my car beeped and said air bag failure and ESP on my dash.

CURRENTLY:
I have cleaned up my battery with baking soda and water to get rid of surface drain, cleaned the positive connection to the fuse box. This got the battery back to 11.68v and it is currently being charged overnight. Whilst it was on charge for about an hour, it read 12.24 volts, but i checked again about 2 minutes later and dropped down to 12.15v. Tomorrow I plan to load test with engine running to load test the alternator. Thanks again

Hi Emerson,

this sounds like a dead battery ! One cell should be 2,1v when charged, this is 12,6v when 6 of them are in serie. Your reading is below that, meaning the battery pack is not charged. After one hour or so of charging, the tension reaches a "normal" level, but it's not true: as soon as you will drain some current out of it the tension will collapse. The "no drop" you noticed between post and connector is because you're not draining any current (contact off), that doesn't mean the connection is good: you should measure the drop whilst draining huge current !

Anyway, looking forward for your tomorrow's update ...

edit: battery voltage is not EXACTLY reflecting its charge status: when discharging it stays almost at 2,0v (per cell) untill it gets quite low in capacity when the potential (voltage) will drop severely ...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)