Rear Demister Terminals

March 18, 2009

Hi you all,

I have a 02 2.0 Avensis sedan, were the rear demister hasn't worked for quite som time. I've decided to fix this and need some help.

First, I have found out that the fuse is ok and the relay is working, the light comes on and so on.

What I'd like to know is what panels I need to dismantle to find the terminals on the rear screen, and how to do it.

Thankful for any hints! :-)

March 18, 2009

Hi you all,
I have a 02 2.0 Avensis sedan, were the rear demister hasn't worked for quite som time. I've decided to fix this and need some help.
First, I have found out that the fuse is ok and the relay is working, the light comes on and so on.
What I'd like to know is what panels I need to dismantle to find the terminals on the rear screen, and how to do it.
Thankful for any hints! :-)

Not sure exactly but would have thought they are under the side trims as the wires go accross the screen. They may be like the hatchback and come in from the bottom. If you have a look you should be able to see where the heavier strips go down the side of the screen (the cross wires run between these) , the connections are on those heavy strips somewhere and you should be able to see where the soldered on connections are if you look under the trim edges.

Hopefully someone might know exactly where they are on the sedan, I can only be certain on the hatch. The heavy strips on the hatch run around the bottom of the screen and the terminals are under the tailgate trim.

March 19, 2009

I removed the side trimmings and found one terminal on each side of the screen. I could measure through the heating strips from plus terminal to ground, which means this end works ok. I have checked the fuse again and its not broken, I can hear the relay switching and seen the button light go on. I suppose next step is to find the relay and confirm the function of it. Anybody nows were it is situated? Suppose it could be different on my left hand side steering car? Seems the sound is coming from near the floor by the drivers outer foot.

Any comments or hints?

March 20, 2009

I removed the side trimmings and found one terminal on each side of the screen. I could measure through the heating strips from plus terminal to ground, which means this end works ok. I have checked the fuse again and its not broken, I can hear the relay switching and seen the button light go on. I suppose next step is to find the relay and confirm the function of it. Anybody nows were it is situated? Suppose it could be different on my left hand side steering car? Seems the sound is coming from near the floor by the drivers outer foot.
Any comments or hints?

Try with a voltmeter on the positive terminal, see if there is voltage reaching the screen.

Check that the other terminal has a good connection to earth (ground).

If no feed voltage getting there, as you say, next step is to see if any is coming out of the relay.

Sorry don't know where it is.

March 22, 2009

Success!

I found the relay after some searching, it was situated at the upper end of the clutch pedal by the return spring in a fairly tight corner. I got the relay out of the socket and ohm measured the contact when switched on. It was way over 200 ohms, which means it wasn't working at all. I opened it but could not really see the problem. While I was thinking of what to do next I switched the relay with another one mounted close by. Now I had power all the way to the rear screen. I decided to use my pliers and cut the bad relay to pieces. Now I could see that the switching tongue of the relay had got soft by the heat generated by the high current. Instead of being hard and springy it had a leadlike constitution. The colour was rather blueish, but the contact surface was not very burned. I knew I had a really good Potter&Brumfield power relay at work so I decided to use the remains of the old relay as a connector. I soldered two 4mm2 Leads to the relay for the switch terminals and two thinner wires for the coil. I put fibre glass tubing over all solderings and strapped the relay to some wires near the socket. Now it works fine again and I'm convinced this will last forever which may not have been the case if I just had replaced the relay with another of the same type. It was clearly to weak for this current.

PS I'm not so used to writing technical english, hope you understand.