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Electrical Issues/Interference.


MildSeven

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I had this issue before rebuilding the car but hadn't thought about it during the project...

 

There's some type of electrical interference in my '02. Originally I thought it was just the radio or amp because I had more important things to think of but now I think it's something else.

 

Symptoms/observations:

 

On acceleration...

- Crackling distortion noise when radio is powered (regardless of source or volume. -  I re-grounded the stereo and the amp, during the winter.

 

- The fasten seat belt light, slightly lights up along at the same time as the crackling distortion. If I turn stereo off, it will still continue.

 

- I also noticed yesterday that my a/f gauge messes up reads like 25.5 or something when this is happening. I have a digital LED read out a/f.

 

- If i have the aux fan on and some other items, lights, fan, the crackling noise will be way less apparent, maybe even gone.

 

- On a few occasions, I don't believe I had any issue.

 

Does anyone have any idea what this might be? pointers

 

I've been reading around on the net, and I was thinking of re-grounding my coil as well as my alternator, to see what happens.

 

Thanks for your help,

Anthony

 

EDIT: I'll try to film a video of what happens next time I'm driving.

 

Edited by MildSeven

picked up what i thought was a sound Verona Red '76

 

The Refresh Blog: http://www.bmw2002faq.com/blog/155-76-verona-red-refresh/

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That’s weird. Crackling rather than whining would imply ignition related noise rather than alternator. What’s the situation with plug leads, cap etc.  The induced voltage into the wiring is strange. Any LED bulbs on the car?

rtheriaque wrote:

Carbs: They're necessary and barely controlled fuel leaks that sometimes match the air passing through them.

My build blog:http://www.bmw2002faq.com/blog/163-simeons-blog/

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Presume your car is a US version, with the seat belt warning light and connections in the seat belts themselves that (once upon a time) triggered a buzzer if you didn't fasten your seat belts.  That whole wiring mess is attached to fuse 11 (at least on '72 and 73 cars, possibly on squarelights)--and it's not shown in the wiring diagram.  I kept blowing fuse 11 (instruments) and couldn't find the cause until I pulled the fusebox and discovered an extra wire attached to fuse 11.  It led to the sensor in the seat that triggered the seat belt buzzer, and the sensor had shorted out to the seat frame.  

 

Try pulling your fuse box and carefully examine the wires leading from fuse 11; if you see two green/white strioe wires,one goes to the instruments, the other to the seat belt warning circuit.  They're identical so you'll have to guess which is which.  But if your instruments don't work after clipping the one wire, then it's the other.  Clip it, tape the cut end and see if that stops the interference.  At least you won't have to put up with the fasten seatbelt sign any more--after all it's a 2002, not a Boeing 737!

 

cheers

mike

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'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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Hi,

 

Does this happen only during acceleration?

 

What mods, if any, are on this car?  Electronic ignition, upgraded alternator with internal regulator, etc.

 

How are the radio and amp wired, that is, where exactly do they get their "always hot" power?  Where is the connection point for ignition switched power?

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Thanks a lot guys.. it was raining last night, so no drive/video.

 

16 hours ago, Simeon said:

That’s weird. Crackling rather than whining would imply ignition related noise rather than alternator. What’s the situation with plug leads, cap etc.  The induced voltage into the wiring is strange. Any LED bulbs on the car?

 

So, I had the issue before and the issue remains, after the restoration.

 

Before: Crane XR700, After: 123Tune (new cap) + new wires.

 

Before: I didn't have LED bulbs, After: I have LED bulbs in my tail light (brakes).

 

15 hours ago, mike said:

Presume your car is a US version, with the seat belt warning light and connections in the seat belts themselves that (once upon a time) triggered a buzzer if you didn't fasten your seat belts.  That whole wiring mess is attached to fuse 11 (at least on '72 and 73 cars, possibly on squarelights)--and it's not shown in the wiring diagram.  I kept blowing fuse 11 (instruments) and couldn't find the cause until I pulled the fusebox and discovered an extra wire attached to fuse 11.  It led to the sensor in the seat that triggered the seat belt buzzer, and the sensor had shorted out to the seat frame.  

 

Try pulling your fuse box and carefully examine the wires leading from fuse 11; if you see two green/white strioe wires,one goes to the instruments, the other to the seat belt warning circuit.  They're identical so you'll have to guess which is which.  But if your instruments don't work after clipping the one wire, then it's the other.  Clip it, tape the cut end and see if that stops the interference.  At least you won't have to put up with the fasten seatbelt sign any more--after all it's a 2002, not a Boeing 737!

 

cheers

mike

 

 

I would have to look at it, I did take a lot of photos of the wiring behind the fuse box when I was disassembling the car. I haven't ever heard a buzzer for the seat. I do have a buzzer for the key in though.

In this photo I believe the bottom left would be 12 & 11.

 

19392425668_ce8b799f9c.jpg

 

15 hours ago, Healey3000 said:

Hi,

 

Does this happen only during acceleration?

 

What mods, if any, are on this car?  Electronic ignition, upgraded alternator with internal regulator, etc.

 

How are the radio and amp wired, that is, where exactly do they get their "always hot" power?  Where is the connection point for ignition switched power?

 

I have the 123Tune alternator, used to have a Crane Hot Spark, XR700. I'm not sure about my alternator, will have to look at it.

 

The amp has a + wire direct to the battery (with fuse), the negative was grounded to the chassis (behind rocker, under rear seat) next to the amp... but a couple of weeks ago, I brought a wire from the (-) to the same point on the chassis.

 

If I'm not mistaken, the switched power, is controlled by the stereo, and the stereo ign. on, is tapped behind the key.

 

 

thanks again for the replies... appreciate it!

 

 

picked up what i thought was a sound Verona Red '76

 

The Refresh Blog: http://www.bmw2002faq.com/blog/155-76-verona-red-refresh/

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The reason I ask about LEDs is that I found asfter putting cheap LED bulbs in my side lights (city lights within the headlights) that they would flicker when switched off. This is due to interference in the wiring and the difference in electrical characteristics between an incandescent bulb and an LED. Have you got LED in your Fasten Seatbelt sign?

rtheriaque wrote:

Carbs: They're necessary and barely controlled fuel leaks that sometimes match the air passing through them.

My build blog:http://www.bmw2002faq.com/blog/163-simeons-blog/

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The reason I ask about LEDs is that I found asfter putting cheap LED bulbs in my side lights (city lights within the headlights) that they would flicker when switched off. This is due to interference in the wiring and the difference in electrical characteristics between an incandescent bulb and an LED. Have you got LED in your Fasten Seatbelt sign?
No LED in fasten seat belt.

I finally filmed a short video. I didnt mount the camera and the crackling is hard to hear.

You'll see, the fasten seat belt flickers and the wideband flashes quickly at 25.5 when the crackling is heard.



Thanks guys.


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picked up what i thought was a sound Verona Red '76

 

The Refresh Blog: http://www.bmw2002faq.com/blog/155-76-verona-red-refresh/

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  • 4 weeks later...

I haven't had some solid time to look at this but have been searching the net.

 

One suggestion is that the engine/ignition ground should be isolated from the body (not grounded to the body).

 

Anyone else have ideas for me?

picked up what i thought was a sound Verona Red '76

 

The Refresh Blog: http://www.bmw2002faq.com/blog/155-76-verona-red-refresh/

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Well if you have the BMW ground cable with the large strap to the block and the small strap to the body  or the equivalent you'll have the grounds as separate as possible, I mean it will all have to end up at the negative terminal of the battery anyway. Make sure both wires are good and have a clean sound connection at both ends and it should be good. 

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If everybody in the room is thinking the same thing, then someone is not thinking.

 

George S Patton 

Planning the Normandy Break out 1944

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My car came from the factory with a ground strap from the engine head directly to the coil.  The only reason I can think of for the strap is that sparkplugs need a ground route back to the coil case to complete the high tension circuit.  Maybe try adding one if it isn't on the car. Later cars don't seem to have (or it was removed) and the HT ground travels thru the big strap, back to the fender thru the small battery strap and maybe dances thru some other circuits in the route home to the coil.

 

Edit note:  If I have the only ground head to coil ground, it may also have been added because the radio was a factory install.  I also have noise suppression capacitors on the coil low tension side and on the alternator and another ground strap from the hood to the body at the hinge.

Edited by jimk
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A radiator shop is a good place to take a leak.

 

I have no idea what I'm doing but I know I'm really good at it.

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I would take a good look at your ground wires and connections from and to the alternator and battery. I have seen many times the wires and connections have corrosion, even hidden under the wire insulation. The alternator must have its own thick ground wire to the engine. On the earlier alternators with internal regulators, some had a noise suppression capacitor. Just my $.02 worth.

Matt



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My battery was relocated to the trunk. I have a wire from the battery connected to (i believe) the stock ground wire. They're connected on top of the driver shock. [i'll get a photo].

 

Other notes.

The battery also grounds to the chassis in 2 locations: in the trunk + under the rear seat on inner rocker (with amp).

 

While trying to eliminate issue during the winter...

- The amp was originally grounded to the chassis on the inner rocker but then I ran a wire directly from the battery.

- I re-grounded the stereo as well.

 

 

 

Edit, photos:

fd5b1f174fff165560302ab159186dc1.jpg

9f07b447ffb4fa4e08057fc024b7f34d.jpg

750d2f191afe1fb82fe0f8caeceb370e.jpg

Edited by MildSeven

picked up what i thought was a sound Verona Red '76

 

The Refresh Blog: http://www.bmw2002faq.com/blog/155-76-verona-red-refresh/

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Hi,

 

Grounding the battery at a single point on the chassis should be sufficient (and is recommended).  The chassis is a much better conductor than a cable running from the battery to the front of the car.

 

Multiple grounds can sometimes cause ground loops, leading to strange behavior.  Search for "single point grounding techniques" to see if perhaps it sheds light on your particular issues.

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1 hour ago, Healey3000 said:

Hi,

 

Grounding the battery at a single point on the chassis should be sufficient (and is recommended).  The chassis is a much better conductor than a cable running from the battery to the front of the car.

 

Multiple grounds can sometimes cause ground loops, leading to strange behavior.  Search for "single point grounding techniques" to see if perhaps it sheds light on your particular issues.

This

 

If you have an aftermarket stereo and amo setup then this is definitely something to look at. Ground loops can be frustrating to track down if you don't know you are looking for them.

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