Sorry parking sensors again!

[johnnyroper]

I have checked wiring from control unit to rear sensors previously which was good but led me to believe rear sensors were all knackered as vcds showed faults. I have changed them all for genuine ones but still I have faults that won't clear,it has also thrown up all front fault codes.
Would I be right in thinking the control unit is knackered? There is no sign of water damage to it.

[bony6777]

I have checked wiring from control unit to rear sensors previously which was good but led me to believe rear sensors were all knackered as vcds showed faults. I have changed them all for genuine ones but still I have faults that won't clear,it has also thrown up all front fault codes.
Would I be right in thinking the control unit is knackered? There is no sign of water damage to it.

Which codes vcds does show.On my Galaxy vcds was showing what one of the sensors are faulty and was showing which one exactly. I think if control unit at fault,vcds would tell that.more concerned about wiring loom from unit. Did you tried to check wiring from unit up to sensors for damages with a multimeter?

[johnnyroper]

It shows faults for all 8 sensors,I have checked wiring from control unit multi plugs down to sensor plugs all 3 wires on all the sensors check out ok at 0.4ohms.

[bony6777]

It shows faults for all 8 sensors,I have checked wiring from control unit multi plugs down to sensor plugs all 3 wires on all the sensors check out ok at 0.4ohms.

If wiring is ok,I would try to fit second hand unit or would try to borrow unit from someone for test.looks like you tested resistance,I would test continuity for every wire separately. By description of your problem and thinking logically,ecu receiving signals from sensors and to read sensors data need to be connected to ecu.you have communication with ecu and ecu telling you what sensor faulty.If you near London we can meet and swap ecu for test. From yours to mine and mine to yours.

[johnnyroper]

That's what I have done checked each wire individually out of control unit to sensors,as well as continuity I checked control unit puts 12v to sensor and checked the ground everything checks out fine.
Thanks for the offer but I am in Wiltshire.

[bony6777]

That's what I have done checked each wire individually out of control unit to sensors,as well as continuity I checked control unit puts 12v to sensor and checked the ground everything checks out fine.
Thanks for the offer but I am in Wiltshire.

Have you tried to fix just 1 brand new sensor?what readings are you getting in vcds measuring blocks?when I tested my one,on a faulty sensor measument was 255.

[steveo59]

Hi,,
I'm coming in here not having seen your previous thread about your sensors but have you checked each sensor by listening for the faint clicking noise. I'ts usually the ones not clicking that that have a problem either with the sensor or the wiring. If they are clicking I would guess you do have continuity.

[johnnyroper]

I checked wiring a few weeks back and found all ok back then it was just showing fault with rears,I did listen for the clicking but there wasn't anything. I have replaced all the tears with brand new OE ones but still it does not work and now shows fault with all 8 of them.

[johnnyroper]

This parking sensor situation is getting stupid now,I have resurrected them so they work and show no faults when static with engine off.
As soon as using with it running 3 tears are showing between 21 and 50cm on measuring blocks the other shows 255 with no obstructions behind vehicle.
The sensors are all brand new oe ones,I can't see they are faulty as that would show all the time I would think? Anyone got any other suggestions before I just disconnect the system?

[Mirez]

Does the system actually work when the engine is off or just show no errors?

The sensors have a common supply and a common ground so for the issue to effect all 4 would indicate an issue here, have you measured the supply voltage at the sensors themselves? You'll have to pull one from the circuit but then with the system on you'll be able to see supply voltage and also measure out the resistance in the ground.

If the system IS working when the engine is off then I would start by looking at the alternator, what voltage its putting out when running and if the values measured by the sensors are effected by the revs. It could be that its generating electrical noise so you could also run the car with the aux belt removed to eliminate an alternator issue.

Where abouts in Wilts are you? I can lend you a control module

[johnnyroper]

Yes it works when engine is off as I can walk in front of sensors and get them to operate,as soon as starting it then plays up.

The alternator is kicking out about 13.9 on idle well it was when I checked other week.
I checked all wiring couple of weeks back before buying some sensors,ground good to all and supply was battery voltage. The signal wires continuity checked back to control unit and that was all ok.
Think I will try with alternator disconnected and see if that makes any difference.
I am in Westbury

[Chrispb]

  your not neighbours are you

[insanitybeard]

My only other thought would be a wiring short or fault which only occurs when the engine is running and particular circuit/s are energised. I'd try a substitute control module next though.

[johnnyroper]

Thought about it and might also try taking boost heat fuse out as when that's running on the interior lights flicker so maybe that's affecting signal or something?

[bony6777]

Thought about it and might also try taking boost heat fuse out as when that's running on the interior lights flicker so maybe that's affecting signal or something?

Just as option. What about to take  power supply directly from battery to avoid fuse box.

[johnnyroper]

For the boost heat or parking sensor control unit?

[bony6777]

For the boost heat or parking sensor control unit?

For parking ecu.

[johnnyroper]

Took main cable off alternator and ran engine parking sensors work normally as soon as charging again they play up so looks like alternator causing interference.

[johnnyroper]

Changed alternator today and fault still same with parking sensors,so my thoughts are either faulty sensors or control unit playing up?

Mirez any chance I can take you up on your kind offer to try a different control unit please?

[Mirez]

Yes I'm breaking a 2.3 down at the moment with fully working sensors so I'll get the lads to remove it tomorrow and then we can meet up whenever suits

[johnnyroper]

That will be brilliant thank you. Can I be cheeky and ask to borrow sensors to test also just In case my new ones are iffy as the one you are breaking is fully functional?

[Mirez]

Yeah no worries, I've got a pot of them somewhere

[johnnyroper]

Excellent thank you👍