Heated front screen earth location?

[Countax]

Can anyone pls advise the location of the common earth connection for a P38a heated front screen. My screen is measuring 25 ohms to earth which means its pumping out a whopping 5.7 watts of heat per side !

I have a similar problem with both door mirrors. One heater is at 9.4k ohms so is producing 15 milliwatts, the other is 8 milliwatts!.....is it a common problem for door mirror heaters to fail high resistance?

Nigel

[David Sparkes]

The Screen Earth is E199, and it's location is described as centre rear of engine compartment.

More literally, if you look at the windscreen wiper pivot that is nearest the centre of the car, the earth connection is between that and the rubber seal at the rear of the engine bay. Yes, you have to remove that plastic moulding, so now is the time to change the plenum foam if it's looking manky.

I've never had to look for this, so that information is just 'by the book'.

Before going that far, I suggest checking the relays.

Relay 5 operates, to an earth from the HEVAC panel (which is also the HEVAC ECU). This powers the LH half of the screen, and relay 4. Relay 4 powers the RH side of the screen. The engine needs to be running as each half should take about 25A.

Door mirrors not heating, hmmm, I suspect a lot of people don't notice. The wiring connectors hidden in the A pillars between the windscreen and the floor have a bad press for getting wet and corroded.

There is also an outstation mounted on each door through which current passes, so that's another check point.

You'll be after a RAVE CD about now. The Tech Archive on this site has a link to a site.

Cheers.

[Countax]

The Screen Earth is E199, and it's location is described as centre rear of engine compartment.

More literally, if you look at the windscreen wiper pivot that is nearest the centre of the car, the earth connection is between that and the rubber seal at the rear of the engine bay. Yes, you have to remove that plastic moulding, so now is the time to change the plenum foam if it's looking manky.

I've never had to look for this, so that information is just 'by the book'.

Before going that far, I suggest checking the relays.

Relay 5 operates, to an earth from the HEVAC panel (which is also the HEVAC ECU). This powers the LH half of the screen, and relay 4. Relay 4 powers the RH side of the screen. The engine needs to be running as each half should take about 25A.

Door mirrors not heating, hmmm, I suspect a lot of people don't notice. The wiring connectors hidden in the A pillars between the windscreen and the floor have a bad press for getting wet and corroded.

There is also an outstation mounted on each door through which current passes, so that's another check point.

You'll be after a RAVE CD about now. The Tech Archive on this site has a link to a site.

Cheers.

Dave,

Many thx. Your right, its underneath the plastic cover and the earth bolt is close to the wiper wheel box. I found the earth wires were badly oxidised and prevented the current flowing. I cut back the original earths to find some fresh copper and made up a short jumper lead with new lugs and soldered the joints. Hopefully its closer to 17A than 25A as thats the only wire i had. It said suitable for heated rear windows so i hope it does what its says on the label.

Now the screen is now working well and you can hear the engine change note as the alternator starts to deliver the amps.

The mirrors can wait until Sodbury in a few weeks.

I already have the Rave CD, absolutely invaluable, on mine it did not give a location for the earth, but after i posted the question i found it in the windscreen repair section.

Nigel