Radio and brakes!

[King Kenny]

Hi, can anyone shed some light on my little problem? The act of braking interferes with the radio. It's like a static noise drowning out any broadcast material. Any help will be much appreciated.
Kenny.

[CovKid]

Sounds like weak contacts on brake light switch causing minor arcing. If its persistent (ie after switch changed), your radio may just be a little sensitive and switch may need a suppresor across it.

[King Kenny]

Many thanks for that. I will change the switch next opportunity.

[ghost123uk]

2 things to add :-

Check your pads and shoes still have plenty of meat on them. (metal to metal contact can cause static)

Also, a less than good signal from the aerial can cause this. Normally the radio signal coming in is strong enough to mask any localised interference, but if the aerial is not working properly.... Check the aerial cable with your meter and check the case of the radio is well earthed to the bodywork behind the dash.

[ghost123uk]

I just thought,

Many thanks for that. I will change the switch next opportunity.

Does it do it when you apply the brakes when stationary? If it does, then yes, it could be the switch, but if it only does it when on the move, it is less likely to be the switch.

[slowcoach]

2 things to add :-

Check your pads and shoes still have plenty of meat on them. (metal to metal contact can cause static)

Also, a less than good signal from the aerial can cause this. Normally the radio signal coming in is strong enough to mask any localised interference, but if the aerial is not working properly.... Check the aerial cable with your meter and check the case of the radio is well earthed to the bodywork behind the dash.

Sorry,just to jump in on this - is there a way to 'test' an aerial to find out if that's why reception is bad?

Mine having snapped in half probably won't help, but I'm still surprised how bad it is...
Cheers!

[ghost123uk]

Also, a less than good signal from the aerial can cause this. Normally the radio signal coming in is strong enough to mask any localised interference, but if the aerial is not working properly.... Check the aerial cable with your meter and check the case of the radio is well earthed to the bodywork behind the dash.

Sorry,just to jump in on this - is there a way to 'test' an aerial to find out if that's why reception is bad?
Mine having snapped in half probably won't help, but I'm still surprised how bad it is...

Snapped in half is not going to help - Radio aerials are supposed to be a specific length to work properly. Even those "bee sting" ones are actually a coil of wire wrapped around a centre core, to get the right length (usually what is known as a 1/4 wave).

Assuming you are not using a fancy "active" aerial with an amplifier built into it, to test it you simply use your multimeter to test for 2 things, both of them using the lowest Ohm setting it has got (or continuity buzzer setting if it has one).

Remove the aerial plug from the back of the radio.

1) = Touch one probe onto the centre tip of the plug at the radio end, and the other probe onto a metal part of the actual aerial rod. It should read virtually zero Ohms, i.e. the same as if you just touched the two probes together. Or if you're using the continuity buzzer setting, the buzzer should sound clearly, (again, the same as if you touch the probes together). A reading of more than say 10 Ohms (or no buzzer or weak sounding buzzer) means a poor connection somewhere in the plug, the wire, or the base of the aerial.

2) = Touch one probe onto the centre tip of the plug at the radio end and the other to a clean bit of metal bodywork ("earth"). Here the reading should be very high (or better still, give no reading) and if using the buzzer, it shouldn't sound.

[a1winchester]

I recently replaced a broken aerial and it has made an incredible difference to reception.

[King Kenny]

Thanks every one. New pads and shoes fitted last year, problem persists. And yes, it happens when stationary. It could be the areal as I fitted a new one when I first got the van. I suspected the brake switch as this seemed the most obvious even if I didn't understand why. I have to do some work for the French MOT before February. It's every 2 years here. I will take the opportunity to strip out the console to find out what combination of switches and wires I have. I will check out the areal as well.
Kenny.

[slowcoach]

Snapped in half is not going to help - Radio aerials are supposed to be a specific length to work properly.

Remove the aerial plug from the back of the radio.

1) = Touch one probe onto the centre tip of the plug.

Thanks for the info! I'll check it out

[California Dreamin]

It will be the radio waves produced from the electrical arcing inside the brake light switch.....Resolution:

New switch: the clean contacts will make and brake more precisely and so arcing/radio interference will be reduced.
Routeing of the aerial lead: Re-route aerial cable away from the brake master cylinder (brake light switches)
Not done this myself but I don't see why you couldn't 'SHIELD' the switches with some bacofoil (being careful not to short anything out of course)

Martin

[King Kenny]

Many thanks Martin. I think you are correct and come the better weather I will check those ideas out, especially the re-routing of the cable. The van has just passed its CT ( French MOT) and I had a couple of advisories, nothing serious. The radio interference is getting on our nerves. I had thought of changing the brake switch but I am not shure if I have one or two, so the idea of re-routing the cable or even sheilding the switch if very attractive.
Kenny.

[Mocki]

The only way to remove interference is at its source, anything else is just masking it
It's a darn site easier to swap a brake light switch than reroute an antenna lead or shield the switch