Rx400h Front Parking Sensors Playing Up!

[DEB811E]

Has anyone got any information for fault finding on these aftermarket parts which were fitted by the dealer prior to delivery of my car in August 09.

These darn things are fine one moment and then are not the next :tsktsk:

Dealer has had the vehicle once and low and behold they were working that day......so did nothing to investigate the fault!!

I see from other posts that others have experienced similar problems, I would be grateful for any guidance on this.

[The Editor]

Has a pressure washer been used on them (the bumper) regularly? - Is so they are probably knackered!

Don't put a pressure washer anywhere near them.

[ihpj]

Has a pressure washer been used on them (the bumper) regularly? - Is so they are probably knackered! Don't put a pressure washer anywhere near them.

+1 Good advice - but not always possible not to ;)

[DEB811E]

Has a pressure washer been used on them (the bumper) regularly? - Is so they are probably knackered!

Don't put a pressure washer anywhere near them.

Haven't used one on the car, so don't think it is the cause

Initially thought it may be due to the cold/snowy weather......

No problems with the factory fitted rear sensors......yet!

[Parthiban]

I think it could be the snow, our Merc was covered in snow for about 2-3 weeks while we were away and now it's also having parking sensor problems. Need to get it checked out by Mercedes but I think the snow has somehow penetrated the sensor - I'm guessing one or two of the sensors might need replacing and it could be a similar problem for you.

[DEB811E]

I think it could be the snow, our Merc was covered in snow for about 2-3 weeks while we were away and now it's also having parking sensor problems. Need to get it checked out by Mercedes but I think the snow has somehow penetrated the sensor - I'm guessing one or two of the sensors might need replacing and it could be a similar problem for you.

Many thanks, I had the same thought, but am wondering why it is only the front sensors that are playing up?

And one journey it is working OK, then after stopping, they are then not working when the car is restarted??

Am very pleased with all other aspects of the car, but this is a little annoying!!!!!

[Parthiban]

Many thanks, I had the same thought, but am wondering why it is only the front sensors that are playing up?

And one journey it is working OK, then after stopping, they are then not working when the car is restarted??

Amvery pleased with all other aspects of the car, but this is a little annoying!!!!!

I'm not sure to be honest, it's the front sensors on the Merc as well that are causing trouble but not sure whether that's relevant or not! And it's exactly the same, sometimes they work fine, and sometimes they start shouting that they don't want to do anything so it's clearly a similar problem.

Probably easier to explain on your car though, if your front sensors are aftermarket, maybe they're not the same quality as the ones on the rear? Although in some ways that's better as aftermarket sensors should be quite cheap to replace........

Sorry I can't be more help, but you're not alone as there's quite a few people on the merc forums speaking of the same problems......

[rhosneigr]

The same thing happened to the sensors on my car. They were fitted by the dealer so one assumes they would be approved. They kept on bleeping all the time. Luckily there is a switch to turn them off. I've had them sorted by the dealer today(I bought the car second hand so they knew about it then) but the daft thing is now that they are working they are on a direct feed from somwhere so even with the car turned off they still work so they have to be manually swithed off. I would have thought that they would only be activated in drive. Are other Lexus cars wired similarily?

[DEB811E]

The same thing happened to the sensors on my car. They were fitted by the dealer so one assumes they would be approved. They kept on bleeping all the time. Luckily there is a switch to turn them off. I've had them sorted by the dealer today(I bought the car second hand so they knew about it then) but the daft thing is now that they are working they are on a direct feed from somwhere so even with the car turned off they still work so they have to be manually swithed off. I would have thought that they would only be activated in drive. Are other Lexus cars wired similarily?

Glad to hear your sensors are now working - my car is with the dealer at present - awaiting news!

Don't think they should be wired on all the time.....the buzzer will be on continually if you park near an object, os someone parks close to you!

[rhosneigr]

I've been on to the dealer about the wiring up of the sensors. Awaiting a reply.

[Parthiban]

It's only the aftermarket sensors that need to be switched, the OEM ones of course only switch on under 10mph or so.

[rhosneigr]

Even ones fitted by a lexus dealership? I've had rear ones fitted by the dealer (not keen on the camera) and they have been wired up to come "live" when reverse is selected, surely the same could be done to the front sensors that they come "live" when drive is selected.

[Parthiban]

Even ones fitted by a lexus dealership? I've had rear ones fitted by the dealer (not keen on the camera) and they have been wired up to come "live" when reverse is selected, surely the same could be done to the front sensors that they come "live" when drive is selected.

The rears are generally wired up to the reverse lights, so quite simple to do. The fronts could really be on all the time, on most cars with OEM sensors the fronts are always on as when you're reverse parking you still want to be aware what's going on at the front.

However the problem is that you don't want them on and bleeping as you drive past cars at 70mph on the motorway - OEM sensors will switch off over 10mph, but aftermarkets will stay on.

I've only come across one set of aftermarket sensors that would work pretty well, can't remember what the brand was but the way they worked was to be activated when you press the brake pedal and then they'd stay on for a 10 second time delay or something, so they're not on all the time but remove the need for a switch.

[DEB811E]

Car back from Dealer and sensors now working

It would seem that when they were originally fitted, the control "card" was fitted near the Battery in the engine compartment (this was obscured by one of the plastic engine covers) - this was affected by damp/wet through the winter causing intermittent problem with the sensors, until three of the sensors failed!

Dealer has returned the car after fitting four new sensors, and relocating the control "card" to within the driver cabin.

All now working :) Watch this space!!

Many thanks to all who took the time to post on this thread :D

[Parthiban]

Glad you got it all sorted :)

[rhosneigr]

Good to hear that all is OK now. How are yours wired up? Do you have to manually switch them on and off?

[DEB811E]

Good to hear that all is OK now. How are yours wired up? Do you have to manually switch them on and off?

When the ignition is on they are active - they are sometimes triggered at speed by rain/snow or the like, and there is a seperate switch which can be used to turn them off if required - all as fitted by the dealership.

The factory sensors are deactivated above 10MPH as already stated in this thread which is obviously a better arrangement.

[rhosneigr]

Thanks for the reply. As mentioned before my sensors are active even though the ignition is switched off so I have to manually switch them off after turning off the ignition. But if they are only activated occasionaly whilst driving I think I will get the dealer to wire them from the auxilliary circuit leaving the switch in situ so there is a choice between on or off.

[Parthiban]

Depending on whether power consumption would be ok, could it not be wired up to something like the cigarette lighter socket, that way it would switch on and off with the car? They've clearly hooked it up to a permanent live which is a bit of a silly thing for a dealer to do.

[rhosneigr]

Depending on whether power consumption would be ok, could it not be wired up to something like the cigarette lighter socket, that way it would switch on and off with the car? They've clearly hooked it up to a permanent live which is a bit of a silly thing for a dealer to do.

Not sure what you mean about the power consumption. I thought the cigarette lighter was powered from the auxuliary circuit.

[Parthiban]

Nothing really, I just don't know a lot about electrics, so don't know whether it would be safe to hook the sensors up to the lighter socket - while theoretically it should be fine, I have no idea whether it works in practice :)

[rhosneigr]

I think they should be able to hook up to anything that comes on when the ignition is turned to aux providing the fuse is large enough. I understand your comment though.