I have an '88 S4 and both drivers and passengers heaters do not work. I wanted to run by you guys what I have found and maybe you can give me some suggestions on where to go from here.


Passenger side:
Checked the red wire at the switch and it is hot. When it is depressed, the green or the yellow wire stays hot. I checked the connector at the relay and the black wire is hot. In my min this tells me the switch and relay are working.
The black wire comes out and goes into a 2-prong connector. The other prong on this connector (where the black wire comes in) there is a white wire which goes into another 2-prong connector right beside it. This white wire is not hot. There are two wires which come out of both connectors (opposite side). The colors are one red and one brown. I an not finding this on the schematic. Can you tell me what to check next? Why are the connectors sliced together with the white wire?

Drivers side:
This side seems to be totally different from the schematic.
At the switch there is a green and brown wire just like the pass. side. But instead of a hot red wire, there is a brown wire which is not hot. The green and yellow wires go to a 15 connector board. #2 is for seat heating. This is where the relay is. There are 3 wires going to this, the green, yellow and a white. When I hit the switch, I do not get a hot wire out of the green or the yellow, but the white wire is hot at the relay. Once it is hot I cannot switch it off using the switch. If I use a hot wire probe and hit the green or yellow connector, the white wire loses its hot and cannot be switched back on. If I hit the other other wire (green or yellow, opposite from the first time) with the probe, the white wire becomes hot again. I am at a loss with this one. Can you explain what is going on and tell me what to check next. Shouldn't the brown wire be hot at the switch?

I hope someone can shed some light on this.

 

Simple thing first. Did you check fuse #8?
Brown is ground in the 928.
Red wire is hot into the switch.
Out of the rely black is hot.
Green connects the two heating elements.
Have you check the continuity of the heater elements with a meter?

 

John,
I checked fuse #8...it is good.

How do you check continuity on the heating elements. What contacts do I use? How do you get to the element? What do you have to remove?

Why does the pass. switch use a red (hot) to the switch and the driver switch uses a brown (ground)?

Thanks