P38A Rear Heated Screen ticking behind dash...

As above really. The recent cold snap has necessitated use of the PROG function in the mornings.

I've noticed whilst sitting there waiting for the screen to clear a quiet but distinct ticking sound from behind the steering wheel/binacle area. If I switch off the rear screen it goes away, so I think it's connected. Sounds a bit like a relay switching on and off randomly and quickly. A bit like morse code.

There's no connection with engine speed, but once the car is well warmed up switching the rear heated screen on again doesn't have the tick any more.

I can't understand it, according to RAVE the rear heat relay is in the BECM under the seat and it really doesn't sound like it's coming from there, unless the sound id bouncing off the windscreen or something!

I'm suspecting a bad earth (as usual), or maybe the screens switching in and out due to low volts after a cold start... but has anyone else had anything similar ever? I've noticed getting radio interference whilst the rear heat is on recently, could that be connected??? I'm sure it never used to do that.

Rear screen relay is in BECM as you say, but front has two relays in engine fusebox. I would suspect connection issue from HEVAC output to the BECM. Maybe bung an inline fuse thingy in place of F12 & see if the current changes with the ticking ?

The ticking may sound like it's from under the dash but actually be coming from under the seat, pin pointing a noise source like that can be difficult.

Datatek said:

The ticking may sound like it's from under the dash but actually be coming from under the seat, pin pointing a noise source like that can be difficult.

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Good shout. I assume the BECM will switch it off if there isn't the voltage there to power front and rear screen at the same time....?

If my rear screen element is breaking down, it's possible it's drawing too much current too right?

MrGorsky said:

Good shout. I assume the BECM will switch it off if there isn't the voltage there to power front and rear screen at the same time....?

If my rear screen element is breaking down, it's possible it's drawing too much current too right?

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I don't know the answer to your questions as I have never experienced the problem. Personally I would be looking for bad connections in the power line from the under bonnet fuse box and bad earths.

Datatek said:

I don't know the answer to your questions as I have never experienced the problem. Personally I would be looking for bad connections in the power line from the under bonnet fuse box and bad earths.

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DVM out then

MrGorsky said:

Good shout. I assume the BECM will switch it off if there isn't the voltage there to power front and rear screen at the same time....?

If my rear screen element is breaking down, it's possible it's drawing too much current too right?

Click to expand...

I would imagine less power if elements are failing as they won't be in the circuit anymore.

Some of the lines across mine have failed. I need one of those pens with conducting fluid to join them back up again.