AM radio interference when braking
Submitted: Tuesday, Oct 30, 2007 at 13:09
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murray murray
Hi folks. This not a 4x4 question but one related to a 1999 Mitsubishi Magna Altera with a standard auto 4 speed gearbox. When braking interference is heard on the radio when tuned to AM only.
When at lights and put the auto in neutral the noise stops. Put it in drive and it immediately returns. So the source is the gearbox. The same goes when using the handbrake instead of the foot brake.
The car has 136,000k and was had its full 100,000k service by Mitsubishi 14 months ago, including adjusting the gearbox. The noise has only started in the last two weeks. So my question is: is this a simple replacement of a capacitor or a forewarning that gearbox trouble is in the near future?
Of course, I could just listen to FM and pretend I don't have a problem.
Thanks in advance
Paul
Reply By: Andrew from Vivid Adventures - Tuesday, Oct 30, 2007 at 13:53
Tuesday, Oct 30, 2007 at 13:53
could be the computer... I had strange transmission behaviour from a 1997 Verada that ended up with the computer being replaced. Negotiated my way out of the $2300 paper bag by getting noisy with Mr. Bishi who agreed that the computer shouldn't fail that quickly, and admitting that by then (I guess 2002) they had a revised computer from the next model they would install.
You might want to check all your connections and try doing what was suggested to me recently (I've not done it) and put the controller in a wrapping of alfoil.
Cheers
Andrew.
AnswerID:
269115
Reply By: Member - Doug T (Qld) - Tuesday, Oct 30, 2007 at 14:05
Tuesday, Oct 30, 2007 at 14:05
You get no electrical noises on FM , I reackon the Alternator is on the way out,
Why and how could the foot brake lights be connected to Gearbox , I don't this could be, it has to be in the electrical circuit . maybe a loose bulb in the brake lights .
On numerous occasions In a truck I have had excesive AM interferance , about 2 or 3 months later the Alternator packs it in ,
I;m not saying this is your problem, just another avenue to check
AnswerID:
269117
Follow Up By: traveller2 - Tuesday, Oct 30, 2007 at 15:23
Tuesday, Oct 30, 2007 at 15:23
Doug
Most electronically controlled auto's have sensors connected to throttle, brakes, trans mission selector, engine cpu etc, everything talks to everything else these days ;-))
FollowupID:
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Reply By: Member - Sam (NSW) - Tuesday, Oct 30, 2007 at 15:02
Tuesday, Oct 30, 2007 at 15:02
sounds more like an earth issue between the transmission selector and the brake circuit.
does the vehicle have an indicator light on the dash that tells you what gear you are in? if so, chances are the indicator light circuit and brake circuit have something amiss and this is causing an earthing problem (possibly through the accessories circuit) which is causing your interference on the radio.
AnswerID:
269121
Follow Up By: murray murray - Tuesday, Oct 30, 2007 at 18:22
Tuesday, Oct 30, 2007 at 18:22
Sam,
yes it does have a dash light showing the gears. Hmmm...sounds as if it could be more than a 10 minute job and then maybe an auto elec.
Thanks
Paul
FollowupID:
531983
Follow Up By: Member - Sam (NSW) - Wednesday, Oct 31, 2007 at 07:24
Wednesday, Oct 31, 2007 at 07:24
let us know how you get on Paul. would love to know the outcome.
FollowupID:
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Follow Up By: murray murray - Friday, Nov 02, 2007 at 19:41
Friday, Nov 02, 2007 at 19:41
Sam,
I booked the car into an auto electrician and guess what? The interference has stopped! I hit a speed bump the night before and I can only think this moved the lose connection. I'll have to wait until it returns.
Paul
FollowupID:
532627
Follow Up By: Member - Sam (NSW) - Friday, Nov 02, 2007 at 19:58
Friday, Nov 02, 2007 at 19:58
hahah, always the way.
definately sounds like a poor connection.
well good luck! Keep us informed.
FollowupID:
532634
Reply By: Zebra400 - Tuesday, Oct 30, 2007 at 15:32
Tuesday, Oct 30, 2007 at 15:32
Paul
I have a similar problem with my HF. When transmitting a selcall on 8Mhz, my brakelights come on. Also you can hear the car alarm ringing very very quietly in the background. We have had it checked out. It only happens on 8Mhz.
Oh almost forgot, transmitting under my garage roller door on 8Mhz made my door motor go crazy and it tried to roll up the door even though it was already open. This broke some gears in the roller door motor.
Although we have had it checked out, we still don't know what causes it.
Does it happen on all frequencies on your AM?
Laurie
AnswerID:
269125
Follow Up By: murray murray - Tuesday, Oct 30, 2007 at 18:28
Tuesday, Oct 30, 2007 at 18:28
Sad to hear about the garage door, but its a good story. I only use two AM channels and it does it on both. (6.12 and 6.93) I don't know enough to say if these are close channels. Today the interference was intermittent. I was in traffic and had plenty of time to test a variety of variations. The handbrake didn't cause interference today. I think Sam, in the previous post, could be on the ball. Maybe a lose connection or bad earth through the dash lights.
Thanks for your input
Paul
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