SAAB 9-3 SE 2.0T, 1999 fuse 29 keep blowing and a complete "meltdown" of wire harness to the tailgate.
Fuse 29 (10A): Tail light right and number plate light.
Why do fuses blow?
Short circuits, overloading, mismatched loads, or device failure are the prime reasons for excessive current. A fuse interrupts excessive current ("blows") so that further damage by overheating or fire is prevented.
In this case a 40A fuse was installed instead of the 10A which should be there. It led to the cables to the tailgate melting together in one solid metal wire.
Not so good.
Never replace a fuse with higher Amp (A) then what is original.
First to the problem causing the fuse blowing:
Remove the tailgate cover. 4 x torx 25 (red circles) and a few clips (green circles). Push the center of the clip and pull it out.
Remove the 2 x 10 mm. nuts (red circles) inside the tailgate and disconnect the cable to the
boot/trunk release, license plate light assembly.
Remove the 2 tail lights. Red circles are 10 mm. nuts and then push at (green circles) to release the lamps from the tailgate.
Remove the 2 x 25 torx bolts (green circle) from the
boot/trunk release, license plate light assembly.
2 x clip holds the
boot/trunk release, license plate light assembly now in place (green circles).
Here you can see the reason for the short-circuit. Water and road salt has come through the hole (green circle). The salted water has corroded the metal wire and destroyed the wire insulation.
I replaced the old wires with new ones. Filled the hole with silicon and "glued" everything together with silicon.
Install in reverse order.
The next problem I had to take care of was to replace the melted wire harness.
I went to the scrapheap to get hold of a wire harness from another Saab. I planned to connect it to the old harness behind the roof lining. 14 wires are in the harness to the tailgate.
Here is the "new" wire harness.
I removed the plastic part on the left of the tailgate window. 3 x clips (red circles) and 1 screw (green circle).
5 x clips (green circles) holds the plastic part at the top of the tailgate.
2 x white clips holds the roof lining in place. Just pull them out and place something in between in roof lining and the roof. It makes it easier to handle the cables.
I then removed the rear speaker cover. 5 x torx 25 (green circles).
Then the white cover around the left rear triangular window. 5 x clips (green circles).
I replaced the old melted wire harness with the "new" one. Pulled it through the 2 plastic holders the plastic tube and underneath the roof lining. Here I soldered it together with the old wire harness. The reason for connecting it here was the fact that the rest of the wire harness seemed to be ok. It was just the green/white cable to the right tail light and number plate light which was melted from here and forward in the car.
I pulled a new red cable as shown on these pictures.
Rear left door:
Front left door:
From here and forward the old green/white cable was ok.
