Rear Parking Sensor Possible Wiring Fault

[jordanmac]

Hi again,

 

I am looking for some guidance.  The rear parking sensors on my 04 Galaxy stopped working a few months ago and i have decided to try and fix them.  After the usual tests of listening for ticks,  the rear drivers side sensor was dead.  I got a new sensor and after a wee wiggle i noticed it started working. It only worked on and off for a few minutes so a had a wiggle at the main connector that comes out from under the car.  This stopped it working again completely and i can only hear 2/4 sensors clicking now.  I am now sure that there is a broken wire but i am not sure where.

 

I am going to take the rear loom out completely and do a continuity test on all wires coming from the rear connector to all sensors (12 wires but some are shared).  If that works then it has to be the wiring under the car.

 

I want to split the connector and check that there are no shorts in the plug that joins to the rear loom but i cant figure out how to do that?  I have a feeling that if its not a wire in the rear loom then i might have to re-run new wiring from the main unit to the rear sensors and that might be beyond me.  Am I doing the right things? or am i missing an easy check?

 

Cheers

 

Jordan

 

 

[insanitybeard]

If it's a wiring fault, it's far more likely to be either corrosion at the multiplug where the body wiring loom meets the external wiring loom for the rear parking sensors or broken/ shorted wires, I think there is possibly a bit of tension (i.e, not enough slack in the cable where it emerges from the body in the vicinity of the spare wheel) which could make the external loom susceptible to broken wires also.

[jordanmac]

Thats what i am thinking but the plug looks really clean with no rust visible.  Some one has been in there before though as the wiring at that pug has been cut a lot shorter and its really right with a lot of black tape about.  Is there a way to split that plug to check? or should i cut the plug off and just join the wires together first? that would be slightly quicker than taking the entire rear loom out and test each wire.

[insanitybeard]

You wouldn't be able to see the state of the actual brass contact pins in the multiplug until you actually separate it. They can be a fiddle to get apart, what is meant to happen is that you push in the raised lug on one side of the mutiplug and pull the two halves apart, but with a bit of dirt from the road and the resistance from the dry sealing rings they can be very tight. It's very hard to explain in words, a picture would show better but the site won't let me upload one. If you need me to send a picture you'll need to message me your email.

 

If you can see evidence of previous tampering and the cable is a bit too taught then that's where I'd start looking.

[jordanmac]

I have separated the plug i.e unplugged the rear wiring loom from the car side, and the contact pins inside look nice and shiny.  I can't see a way of looking inside each half of the plug if that makes sense, as i dont think its meant to be split.  I might remove the rear loom from the car completely and see if i can find a wire that is not showing a resistance from the connection block to each of the three sensor pins.  That might indicate a break.  Also i can do it in the garage as its freezing out there.

 

If this all tests OK, i might then cut that joining plug off both the car side and the other half on the rear loom side and hard wire it back together.  If that still doesn't work (assuming as i had ticking from the sensors before fiddling with the wires) i can only assume its the wiring that goes in to the chassis.  This is where i might have to stop and maybe get it re-wired from the control unit bypassing this. Does this make sense?  I will take pictures and post them later before i snip anything off though.