Technical Help: Multipla II rear parking sensors not working

[multijet]

Hi. I have a 2005 Multipla II. Unfortunately the rear parking sensors have stopped working. When reversing, the beeper does not sound. According to the instruction manual, the beeper should also sound in case of malfunction when engaging the reverse gear (it doesn't). The reverse light is ok.

I have checked fuses in all thinkable and unthinkable locations (spent 3-4 hours), but none of the fuses have blown. :bang:

I've also checked at the left and right side of the luggage compartment (near the rear lights) and found a Valeo box at the right side marked 51753804 with two cables connected (several pins). Not sure what it does though? Seems like there is some kind of CPU and two capacitors++ on the circuit board inside (the capacitors look fine). Could this be related? :idea:

Any clues? Where is the Multipla parking sensor ECU and beeper located?

Regards,
T.Lodberg

 

[multijet]

Conclusion: beeper!

 

[DiamondDave]

Is the conclusion that you solved the problem?
Was it the beeper?
Were you able to get another one and replace.

Our multipla has the sensors on the back but nothing happens when I go into reverse.

Do you have any pointers as to where to start when trying to solve this?
The fuse for the cigarette lighter was blown, but when I replaced it the reverse sensors still didn't work. Even from the manual, I couldn't find out where the fuse for the sensor is. Do you know?

Thanks

 

[DiamondDave]

Conclusion: beeper!

Quote

 

[widemouthfrog]

It looks as though multijet last visited the forum in July. It might be worth sending him a PM if you want to know more about his fix - that way, he'll be sent an email notification from you.

 

[multijet]

Yes it was the beeper. If there is a problem with the reversing sensor, a warning signal should sound when engaging the reverse gear. So, if there is no warning signal (and the reversing light works), there is probably a problem with the beeper. The beeper is located in the baggage compartment at the right side under the window (for LHD, probably the same for RHD).

 

[DiamondDave]

Just wanted to add some other info you sent in a reply mail

---------------
No it's not the box that was pictured, it looks more like a small loudspeaker.
---------------

Thanks, that info should be helpful.

 

[sirias]

Hi, my sensors just make a continuous beep ? But I think in summer when things dry out it works normally ? Could it be water

 

[DiamondDave]

I think with a continuous beep that one of the sensors on the bumper is faulty. Of if it works in dry weather then it could be a connection.

On this subject, I eventually found that little speaker and took it out. It is supposed to be 50-Ohm. So I measured it expecting it to be open circuit and got 49-Ohm. Not sure where to go from here.

 

[sirias]

Thanks for the reply, how do the sensors come out to check them ?

 

[DiamondDave]

Thanks for the reply, how do the sensors come out to check them ?

Don't know and hoping I'll never have to find out!
Probably from behind the bumper push in a lug or something.

 

[sirias]

I'll have a look sunday reverse up my ramps, thanks I'll post on here if water can get in from the back

 

[widemouthfrog]

Don't forget that when tracking faults with individual sensors, you can hear the ones that are working if you get your ear right next to them. The 'good' ones will be emitting a very high pitched clicking sound. Something as simple as giving their faces a good clean can sort the problem; if they're dirty, the film of muck can be enough to reflect the ultrasound, giving a bogus reading.

 

[DiamondDave]

So, after eventually finding the little speaker and thinking it surely should be shot - then measuring it with a meter and finding out that it is fine, I put it back this evening assuming it must have been a bad connection.
No, still not working.
Then it struck me, are my reversing lights working????????
No! they fe!k!ng aren't!
I presume this is cause? Anyone know if the reversing sensors are powered by the reversing lights? Which would kinda be logical.
If the non-working lights are the culprit, is there a single fuse for them or does the the gearbox switch give trouble?

 

[widemouthfrog]

Check the gearbox switch. I think I've seen threads on here or the Yahoo user group about duff switches.

The reversing sensors are wired through the switch - I've seen that much stated elsewhere. You'll need to get that sorted for the MOT (or your equivalent) anyway.

 

[DiamondDave]

Update.
Yes the reversing switch is faulty. I crossed the connector with a wire to put on the reversing light and the reversing beep came on and then off again - indicating a fault.
I put my ear to the four sensors and two are "clicking", two are not.
Anyone know if the connectors on the sensors cause a fault or is it just that the sensors themselves go faulty?
I had a look underneath and it looks like it could be easier to take off the rear bumper to get at the sensors - particularly the higher ones on the corners.
Anyone have experience taking off the rear bumper??

 

[sirias]

I had a listen and my near side top corner is at fault I can reach up to it but can't get the connector off.


Sent from my iPhone using FIAT Forum

 

[DiamondDave]

I copied this from another thread as I think it is most suitable here.
As I couldn't get one locally I bought the Vauxhall switch from ebay http://www.ebay.co.uk/itm/Genuine-Va...item56617d6725
and went about fitting it myself today.
Got a bit of wood to fit inside the plastic trim and cut a slot for the Vauxhall switch. Glued this in with chemical metal type stuff. Added a couple of screws to hold the timber in place. Joined the cables to the old cable off the original switch and hey presto a working tailgate opening system!!
I took some images but can't upload them for some reason. Anyway it looks as bad and home done as you are imagining it would, but you have to be on your knees looking up to see it. One for the tight ass who couldn't pay £100 for a $5 switch!

 

[sirias]

Did you remove the dud sensor ? If so do you have to turn them clockwise/ anti-clockwise to release them thanks


Sent from my iPhone using FIAT Forum

 

[DiamondDave]

Did you remove the dud sensor ? If so do you have to turn them clockwise/ anti-clockwise to release them thanks

Haven't gotten that far yet.
If the rear bumper is easy to get off I recken that could cut out a lot of hassle in the long run.
I've been warned not to spend any more time on it this long weekend, but I'm sure I could sneak in a couple of hours and find out.