Seat Heater Repair 80/90/CQ (LONG)

[Andrew Lundy]

This is the procedure that I used to repair the seat heaters on my 80Q.
This procedure will be able to be used on the 80/90/CQ.  This procedure will
also work on the 4000/5000/100/200's but the wire colors may differ.

Tools needed:

Circuit tester
Multimeter
10 mm socket (possibly)
Ratchet w/ small extension (possibly)


The connectors:

Locate the green six point connector located under the seat.  You should be
able to gain enough access to this connector by simply sliding the seat all
the way back.  Pull the connector apart.

Here is a (very) rough picture of the connectors---label as shown as if
looking into connector:

Connector A:

-------------------------------
:   X(1)  *  X(2)     X(3)    :
:   X(4)  *  X(5)     X(6)    :
-------------------------------
(This connector goes under the carpet and leads to the auxiliary relay
panel)
X - Denotes a metal (female type) electrical connector
* - Denotes empty (void) space---helps better relate orientation

(Wires colored as follows)
     Drivers Side           Passenger Side
(1) -Brown                       Brown
(2) - Black/White             Green/Black
(3) - Black/Yellow             Black/Red
(4) - Brown/Blue (Jumper to 5) Brown/Blue
(5) - Brown/Blue               Brown/Blue
(6) - Brown/Black             Brown White




Connector B:
--------------------------------
:    ---(1)  * ---(2)  ---(3)  :
:    ---(4)  * ---(5)  ---(6)  :
--------------------------------
(This connector goes into the seat)
--- - Denotes a metal (male type) electrical connector
* - Denotes empty (void) space---helps better relate orientation

(Wires colored as follows)
Drivers Side/Passenger Side(both are the same)
(1) - Brown/Blue
(2) - Brown/Blue
(3) - Brown/Black
(4) - Brown
(5) - Black/White
(6) - Black/Yellow



Testing procedure:

1) Turn the ignition to the on position---warning lights on
2) Flip on the seat heater switch
(Leave this for the entire testing procedure)

Step one:
The first step is to be sure that there is power going to the seat. Find a
good known ground in the car, I like to use the top of the cigarette lighter
(the metal at the very top), hook one side of the circuit tester to the
ground and the other side into Connector A (3).  If you have power (light)
skip to step three.

Step two:
If you don't have power then remove the panel under the steering wheel and
locate the auxiliary relay panel (Ratchet and Socket needed).  Locate the
appropriate relay, #13 & #14 (pre-'91) or #14 and #18 (`91+).  Remove the
relay and look at the bottom of the relay, near the prongs there will be an
"h" on one and another will have a "15" by it (along with markings for all
the other prongs).  Locate where the prongs of the "h" and "15" plug-in to
the relay panel.  Test the "h slot" (in the relay panel) with the circuit
tester to be sure it has power.  If there is no power, check the fuse, if
fuse is okay locate the break in the wiring between the fuse and relay
panel.

If "h slot" has power then test the continuity of the wire between the relay
and the seat.  To do this put the multimeter in the lowest
resistance() range, put one end into the "15 slot" and place the
other end in Connector A (3).  You should get a very small resistance
between the two, if you get no reaction from the multimeter, trace the wire
and repair the break.  If you obtain a resistance test the function of the
switch.  To do this, use the circuit tester and connect it to ground and the
"86 slot" in the relay panel.  Also check the "P slot" for power......this
should barely light only in the first two positions and then it shouldn't
light.  If power is not attained at both slots then repair/replace the
switch or wiring between.  If power is attained at both slots then swap the
relay with the other one and return to step one (or see if the seat gets hot
with the new relay in).

Step three:
This step requires checking the continuity of the heating elements.  To do
this use Connector B.  Use the resistance setting on the multimeter and
connect (6) and (2).  Again, you should end up with a very small resistance;
if not, then the "butt" heating element has a break in it.  To fix this
check here:
http://members.aol.com/c1j1miller/body.html#Seat%20Heater%20element%20fix

If you obtain a small resistance then, on Connector B, use the multimeter
and connect (1) and (4).  If you obtain a small resistance then go to step
four.  If no resistance is returned then there is a break in the "backrest"
heating element.  There are two methods that can be used to fix this.

 Method one:  Follows similar to the following link except your in the
backrest:
http://members.aol.com/c1j1miller/body.html#Seat%20Heater%20element%20fix

 Method two:  You can simply splice wires on Connector A and bypass the
"backrest" heater.  If you choose to do this, on Connector A, cut the jumper
wire, then splice the wire from (5) into wire (1).  You can leave the loose
wire at (4) disconnected.


Step four:
Connect circuit tester to a known voltage source and to Connector A (1).  If
there is no power then trace wire and repair break.  If you get power you
made a mistake somewhere, go back to step one and follow the procedure again
(or your seat heater works)!!!


I thought this would be good information to have in the AudiFan archives.

Good Luck....HTH!!!
---
Andrew Lundy
fast928 at prodigy.net
90 80Q
91 90
95 90Q