Repaired The Rear Window Heater

drjeckle · February 16, 2009

Since I purchased my 92 SC400 the rear window heater has not worked. Searching the archives found many questions, but no repair suggestions. Checking the under hood relays proved they were all good and working properly.

Recently the Nak amp died and I chose to install a modern sound system rather than to repair or replace the amp. That meant tearing the interior behind the seats out of the car to run wires and replace the rear speakers.

Looking for problems with the rear window heater was high on the to-do list while I had things apart for the sound system installation. What I found was that someone had been there before, and they did not know what they were doing. Both with the electrical connections, and reassembling the car when they were done.

There are three 1/4" wire connectors on the left side of the rear window. The connectors for all three connections had lost their spring tension from heat and were not making real contact with the window connectors. I cut the connectors off of each wire and installed new 1/4" female connectors. The fit to the window connection very tight, and now I have a good rear window heater.

Only two of these connectors are used for the window. The bottom connector is ground, the center is power for the heater wires, and the connector at the top of the window is the antenna for your keyless entry receiver. When I reconnected the antenna the range moved from right next to the car to about 6-10'. Much better.