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Solved - Strange parking sensor problem

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bladeowner
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Solved - Strange parking sensor problem

Post by bladeowner » Mon Aug 13, 2012 4:48 pm

Hi, My parking sensors have stopped working properly when the engine is running. Although sometimes the gong squawks a little like it's trying to beep. When I just turn on the ignition but not start the car they work fine. Each sensor is 'ticking' whether the engine is running or not and works perfectly with an obstacle - if I don't start the car. I have tried another gong and it's just the same. Any ideas anybody? I'm baffled. :?
Last edited by bladeowner on Thu Nov 09, 2017 2:50 pm, edited 1 time in total.
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Stuart Truman
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Strange parking sensor problem

Post by Stuart Truman » Mon Aug 13, 2012 6:16 pm

Weird. If you think about the difference, the only thing is that the alternator is running. Do you get interference on the radio? I'm wondering if a suppressor is failing and you're getting interference on the 12v line.

The battery heading towards end of life can cause all manner of strange things, but this doesn't sound like that type of symptom
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bladeowner
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Re: Strange parking sensor problem

Post by bladeowner » Mon Aug 13, 2012 7:29 pm

Hi, No there doesn't appear to be any interference on the radio. I have an oscilloscope but no probe at the moment and so I could check when I get one. I am thinking that maybe the PDC controller also gets a signal to say the engine is running?? - and this is a bad connection. As I mentioned, it seems like it tries to work. The reversing light comes on in both scenarios. Is the same switch used for PDC and the reversing light? Thanks.
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Strange parking sensor problem

Post by Stuart Truman » Mon Aug 13, 2012 7:52 pm

bladeowner wrote:Hi, No there doesn't appear to be any interference on the radio. I have an oscilloscope but no probe at the moment and so I could check when I get one. I am thinking that maybe the PDC controller also gets a signal to say the engine is running?? - and this is a bad connection. As I mentioned, it seems like it tries to work. The reversing light comes on in both scenarios. Is the same switch used for PDC and the reversing light? Thanks.
That I don't know, but I'd suggest a dirty switch would give you the same symptom whether or not the engine is running.

I'd probably test the battery (as that's a simple thing to do if you have a meter) and then check the 12v line. You could also check for noise on the earth when the engine is running as that would also bugger up the voltages.

After that it's probably worth plugging into diagnostics for any errors. If you've got iffy voltages flying around there's a good chance something else will get upset.

Another giveaway is the rev counter "bouncing" randomly (the needle randomly skips up and immediately back to a correct reading with no change in revs)

You have an oscilloscope! Good man :thumbsup:
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Re: Strange parking sensor problem

Post by bladeowner » Mon Aug 13, 2012 10:17 pm

Thanks, will check the 12V out.
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Re: Strange parking sensor problem

Post by bladeowner » Thu Aug 16, 2012 6:19 pm

I checked the 12v to the gong and the voltage is pulsing when the engine is running. Other 12 V lines are fine as far as I can tell. I left the scope on it and started pulling fuses to see if another unit was causing it. When I pulled fuse 23 the pulsing stopped. F23 is a 5A fuse for various lighting circuits. The PDC worked ok then for a few seconds but the dashboard warning lights don't work with the fuse pulled and so this stopped it.
Obviously the gong doesn't like this pulsed DC and so for the interim I've soldered a 220uf capacitor inside the gong across the supply rail to smooth the dc- all now working.
So I still need to find out why this rail is pulsing. Anybody know a link for decent wiring drawings of the car?
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Strange parking sensor problem

Post by Stuart Truman » Thu Aug 16, 2012 7:14 pm

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Re: Strange parking sensor problem

Post by bladeowner » Thu Aug 16, 2012 7:23 pm

Cheers :)
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Strange parking sensor problem

Post by Ducklakeview » Wed Sep 20, 2017 2:39 pm

bladeowner wrote: Thu Aug 16, 2012 6:19 pm I checked the 12v to the gong and the voltage is pulsing when the engine is running. Other 12 V lines are fine as far as I can tell. I left the scope on it and started pulling fuses to see if another unit was causing it. When I pulled fuse 23 the pulsing stopped. F23 is a 5A fuse for various lighting circuits. The PDC worked ok then for a few seconds but the dashboard warning lights don't work with the fuse pulled and so this stopped it.
Obviously the gong doesn't like this pulsed DC and so for the interim I've soldered a 220uf capacitor inside the gong across the supply rail to smooth the dc- all now working.
So I still need to find out why this rail is pulsing. Anybody know a link for decent wiring drawings of the car?
Have you replaced any bulbs with LED's?

Mike

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Strange parking sensor problem

Post by ph001 » Wed Sep 20, 2017 3:03 pm

I wonder if he still cares 5 yrs on!
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Strange parking sensor problem

Post by Ducklakeview » Wed Sep 20, 2017 3:05 pm

ph001 wrote: Wed Sep 20, 2017 3:03 pm I wonder if he still cares 5 yrs on!
Probably, as he's just pm'd me regarding it :)

Mike

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Strange parking sensor problem

Post by ph001 » Wed Sep 20, 2017 3:11 pm

Wow!! LOL
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Strange parking sensor problem

Post by bladeowner » Wed Sep 20, 2017 3:16 pm

ph001 wrote: Wed Sep 20, 2017 3:11 pmWow!! LOL
:rofl:
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Strange parking sensor problem

Post by bladeowner » Wed Sep 20, 2017 3:22 pm

Ducklakeview wrote: Wed Sep 20, 2017 2:39 pm
bladeowner wrote: Thu Aug 16, 2012 6:19 pm I checked the 12v to the gong and the voltage is pulsing when the engine is running. Other 12 V lines are fine as far as I can tell. I left the scope on it and started pulling fuses to see if another unit was causing it. When I pulled fuse 23 the pulsing stopped. F23 is a 5A fuse for various lighting circuits. The PDC worked ok then for a few seconds but the dashboard warning lights don't work with the fuse pulled and so this stopped it.
Obviously the gong doesn't like this pulsed DC and so for the interim I've soldered a 220uf capacitor inside the gong across the supply rail to smooth the dc- all now working.
So I still need to find out why this rail is pulsing. Anybody know a link for decent wiring drawings of the car?
Have you replaced any bulbs with LED's?

Mike
I did wonder about that myself but only fitted a few leds after the problem started. Anyway, the only leds that are lit are the sidelights as drl and they are on when the ignition is on but engine not running as well and it doesn't cause an issue then.
I ran the engine with alternator disconnected and the problem stopped and so it does appear to be the alternator.
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Strange parking sensor problem

Post by Ducklakeview » Wed Sep 20, 2017 3:24 pm

bladeowner wrote: Wed Sep 20, 2017 3:22 pm
Ducklakeview wrote: Wed Sep 20, 2017 2:39 pm
bladeowner wrote: Thu Aug 16, 2012 6:19 pm I checked the 12v to the gong and the voltage is pulsing when the engine is running. Other 12 V lines are fine as far as I can tell. I left the scope on it and started pulling fuses to see if another unit was causing it. When I pulled fuse 23 the pulsing stopped. F23 is a 5A fuse for various lighting circuits. The PDC worked ok then for a few seconds but the dashboard warning lights don't work with the fuse pulled and so this stopped it.
Obviously the gong doesn't like this pulsed DC and so for the interim I've soldered a 220uf capacitor inside the gong across the supply rail to smooth the dc- all now working.
So I still need to find out why this rail is pulsing. Anybody know a link for decent wiring drawings of the car?
Have you replaced any bulbs with LED's?

Mike
I did wonder about that myself but only fitted a few leds after the problem started. Anyway, the only leds that are lit are the sidelights as drl and they are on when the ignition is on but engine not running as well and it doesn't cause an issue then.
I ran the engine with alternator disconnected and the problem stopped and so it does appear to be the alternator.
Ok - I'll let you know when I've changed the rectifier and post before and after scope traces.

Mike

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