Re: Rear Defroster on 200TQW

[four_rings@juno.com (Igor Kessel)]

On Wed, 19 Nov 1997 23:32:45 -0500 Karleen Oosterwal <karleen@jannon.com>
writes:
>Listers,
>
>A few weeks ago a lister posted the identical problem I have with my
>1990 200TQW.  I apologize if I somehow missed the answer, but I was
>unable to find it anywhere.  He asked about the connection/relationship
>between the antenna booster and the rear window defogger.  My fuses 
>test all OK, the switch to the rear defogger works, 

How do you know the switch is OK if nothing works? 
The light in the switch belongs to a completely different circuit.

>but nothing works (i.e.
>poor radio reception, no defrosting on side mirrors nor rear window).

Sure, all of them are in the same circuit.

The defogger, side mirrors and antenna amp have a common power supply
but 3 different ground connections.
The fact that the side mirrors don't work indicates that the circuit does

not get the supply voltage, although the ground is probably OK. 

1. Turn the ignition ON.
2. Measure voltage on BOTH sides of the fuse 16 (30a). If 12v =>
3. Pry the defogger switch out of the dashboard. 
4. Measure voltage on terminal 5/75h of the switch (WHT/YEL wire). If  0v
=>
-repair the brake in WHT/YEL wire between the fuse box and the switch.
4a. If 12v =>
5. Turn the defogger switch on.
6. Measure voltage on terminal 6/HS of the switch (WHT wire). If 0v=>
-replace the switch
6a. If 12v =>
7. Pull the LH D-pillar cover off. Inside you'll find the rear antenna
amplifier.
It has two wires connected to it's bottom and two - to the top.
8. Pull the THICKER wire off the bottom of the amplifier.
9. Measure voltage between this wire and the KNOWN ground. If 0v =>
-repair the break in the WHT wire between the switch and the amplifier.
9a. If 12v =>
10. Reconnect the THICK wire back to the amplifier and pull the 
THINNER wire off the lower defogger connector on the LH side. 
Careful! Don't peel the connector off the glass.
8. Measure voltage between this wire and the KNOWN ground. If 0v =>
-replace the rear antenna amplifier.
8a. If 12v =>
-Beats me :) 

Just kidding! You should be OK.

>Could a shorted out rear lighter have anything to do with this?

No. Two completely different circuits.


Igor Kessel
'89 200TQ - 18psi (TAP)
'98 A4TQ - coming soon