Not The Usual PDC Problem!

[skylined_gtr]

Hi all 

Have just bought a 2004 X3 3.0i Sport Auto, great car, very happy with it bar one or two things.  The thing that's bugging me at the moment is the PDC/Parking Distance Sensor system.

When I bought the car, it wasn't working at all.  One long beep and PDC light flashing. Found the faulty sensor (P/S rear corner), bought a new one and replaced.  This time it works but a different problem. 

Switch ignition on, press the PDC button, it's on and silent, place your hand in front of a sensor, it starts beeping, take it closer, it goes to a solid beep.  Each sensor behaves that way, all good. 

THE PROBLEM starts when the engine starts or is running.  press the PDC button, it's on but this time beeping away from the rear, detecting lots of phantom objects!  I have tried to isolate if it's a particular sensor but I'm having trouble seeing which one it is.  I could go to BMW and get them to connect up but I am sad and enjoy the manual troubleshooting way  >:D

I have now replaced all rear sensors, cleaned all the electrical contacts on the plugs going into the sensors and the plugs going into the PDC control unit. Does anyone have any other ideas what to do before replacing the PDC unit?

Cheers all!

[Sanj]

Firstly when you start to get used to the forum you'll know that I'm the one that likes pictures!

So when can I see pics of the Skyline please!  ;D

Have you still got the old sensors? I would get into the boot and disconnect the PDC module, clean it, test and then disconnect just the rears (one of the plugs to the module). See if the fronts work, then vice versa, see if you can isolate the problem to front or rear or module.

THEN with some of the rears you replaced you might find you can use em for the fronts (if they're at fault). Fronts are same as back only for the corner ones though, not nearest the number plate (from a poor memory).

Keep us posted and best of luck. Oh and no more help from me if I don't get any pics!

[X5Sport]

What he means is.......

  O:-)

[skylined_gtr]

lol! Sorry chaps, I should have posted some pictures of the ol' beast up.  It was the R32 GTR, I don't have the car any more (Skyline) but she was a beast!  Got lots of pictures somewhere, I'll have to dig them out.




Thanks for the hints Sanj, they sound like a logical place to start.  I'll give that a shot and post back the results.  Just find it really weird that it only happens when the engine is running. 

[Sanj]

Yum yum and thank you for being such a sport! 

[hibbs]

Hi

I was wondering whether you ever managed to solve this problem.  Our E83 has been detecting phantom objects at the from of the car.  Having replaced the suspected faulty sensor, it is still doing it.

Was it the PDC unit in the end?

Thanks for the help!

[skylined_gtr]

Hey!

We're still diagnosing. The suggestion to unplug the PDC sensors to see if it's the PDC ECU didn't work as the PDC ECU goes into fault if you unplug any of the sensors.

I have ordered a s/hand PDC ECU which should be here any day now. Will post the results once I've fitted it.

[skylined_gtr]

**UPDATE** the replacement PDC unit/module arrived today, plugged it in but it appears the same problem is happening.  Having said that, the car was parked closer to some objects so it's possible they were picking up on those.  I'll be using the car tomorrow so I'll test it out then and report back. 

If it is still occurring, it has to be a wiring fault.  The weird thing is this:

• IGNITION ON - MANUALLY ACTIVATE PDC - PDC BEHAVES CORRECTLY (NO FALSE ALARMS)
• ENGINE ON - MANUALLY ACTIVATE PDC - PDC BEHAVES INCORRECTLY (FALSE ALARMS)

I think the next step would be to recreate the harness from the rear PDC's to the PDC unti/module.  If anyone has any better ideas please let me know!

[hibbs]

Are you sure it's not a faulty sensor?  We had issues a couple of years ago with the sensors. Turns out they had been switched around in the bumper so there was a faulty sensor, just not where the error said it was.

I've tried swapping our sensors too, but I have a nagging suspicion it's one of them

[skylined_gtr]

I guess it's a possibility even though I have replaced all of the rears for new ones but I noticed something else yesterday...

If there is a load on the engine while the PDC is active, the beep comes from the rear (alone).  For example, engine idling, car is in park, switch the PDC on and then press the brake pedal, it starts beeping more!!  Release the brake pedal and the beeping either slows down or stops!!!!  This same behaviour happens if I put the headlights on. 

I am starting to think more and more that this is an electrical problem.  I might start by bypassing the power to the PDC ecu and wiring it direct to the battery just to test if the same thing occurs. 

If anyone has any better ideas, let me know?

[mikesmith2939]

If you have front and rear sensors I think the fronts only work whilst pressing the brake pedal.

This would be why the sound stops when you release the brake pedal.

[skylined_gtr]

It's the rears that are reacting to the engine load, the front seem to be perfectly fine and work as they should do. 

Such a very odd problem!

[mikesmith2939]

I would suggest you find someone with INPA or buy and install it a Windows XP laptop.

This software and lead will give you a much better idea of where the problem is.

[skylined_gtr]

I think that sounds like a better idea, I'll download and install. Have never used it before but hopefully should be straightforward enough to read the errors.

I've got autoenginuity which I use to diagnose engine faults, not sure if the OBD connector for that will be recognised by INPA or if INPA will specifically be looking for a serial port.

I guess we'll find out soon enough!

[mikesmith2939]

The OBD lead should come with a USB connector for the laptop.

INPA is easy to use for diagnosing faults