90 TSI FWD
15+ Year Contributor
- 264
- 11
- Oct 26, 2004
-
Columbus,
Mississippi
Whenever I turn the ignition switch to ON, the ignition fuse on the positive battery terminal (30A) blows. I printed out this wiring diagram, and started to disconnect things that could be grounded, but the fuse kept blowing. I went through about 10 fuses I had laying around before I realized how stupid I was for wasting them.
Things I disconnected, yet still had the fuse blow:
Starter
Radiator fans
Alternator
Coil pack/other plug underneath it (forgot what it's called)
Radio
MPI/Other fuse on the positive battery terminal
Fuel pump
Other things I've checked:
Took the fuel pump out the check wiring
Changed pump rewire relay
Tested Starter
Cigarette lighter wiring
Then I got around to pulling the dash apart and borrowed a meter to test continuity. I placed one end on the prong for the ignition fuse at the positive battery terminal, and I placed the other on the ground. The system was definitely being grounded only when the key was turned ON. I left it on there while I kept disconnecting things to see if the resistance would go up (ground contact would decrease - good thing). When I unplugged the turbo timer, the ohm reading went up a little. I don't know what that meant, but still, the system was being grounded with it removed.
Here's the plug that goes to the ignition switch (Connector A). This is as if you unplugged it from the rest of the car and are looking at the prongs (I believe) that go to the switch:
(Taken from the Haynes manual)
Colors:
1 - No wire
2 - Blue/Black stripe (LB)
3 - Blue (L)
4 - Black/White stripe (BW)
5 - Black/Yellow stripe (BY)
6 - White (W)
I did a check for continuity using the bottom image in the above picture to test the switch is working properly. It passed. I also checked what wires from the plug-to-harness were continued. 4-2 and 4-5 had continuity (thus 2-4-5).
Edit:
Also, with the meter connected again to the ignition fuse on the positive terminal and a ground, I disconnected the ignition switch plug to the harness.  I then used a wire to make connections on the plug-to-harness.  The meter found that the system was being grounded when 6-2 OR 6-4. You can see above that when the ignition is turned ON, 2 and 4 is added to the circuit.   Also, from the above paragraph, you can see that 4-2 has continuity, so this does make sense. BUT, is 4-5 supposed to have continuity?  This is telling me that when the key is ON, I'd have 6-3-4-2-5 instead of 6-3-4-2 as shown in the manual, correct?
The following wires were tested for continuity at a ground with the key turned ON. These listed are grounded at some point in their wiring.
Plug to switch
2
3
4
6
Plug to wiring harness
2 - highest ohm reading compared to the other two (weakest ground, but still present)
4
5
I don't know what to do now. Can someone with wiring knowledge tell me whether or not any of these tests should not have tested the way they did?
Today's update
Okay. So I've been studying the electrical diagrams all night, and pulled some plugs again today.
The ignition switch connects two wires in the ON position: 2 and 4 as seen in this diagram. I decided to follow 4 first. You could see that 4 (BW wire) connects to two main plugs: C-54 and C-59.
I unplugged C-54 at the junction block (J/B) to eliminate the possibility of a short from there. The J/B is where all this misc fuses go near the driver's side kick panel. I turned the key to ON, and saw that I was still getting a short.
Next, I unplugged C-59. You can see what C-59 is from the following photos taken from projectzerog.com (source). C-59 is the blue plug in the second photo.
Colors:
1 - White
2 - Black/Red
3 - Blue/Red (thinner wire)
4 - Yellow (thinner wire
5 - Black/White (thicker wire)
6 - Black/White (thinner wire)
After unplugging C-59, I no longer had a short. My problem lies within the circuit of this plug. I checked to see which wires of the plug experienced a ground. On the male side (plug to ignition), 4, 5, and 6 were grounded on ACC. 1, 4, 5, and 6 grounded on ON.
On the female side (plug to harness in first picture), 2, 3, and 5 were grounded. Now I need help to determine whether or not the aforementioned is supposed to be this way or not.
For those willing to help who have a FSM, please let me know what wires to check, or what I should do next. I could email you a copy of the manual if you'd like. It's about 15 MB. Thanks!!!!
Things I disconnected, yet still had the fuse blow:
Starter
Radiator fans
Alternator
Coil pack/other plug underneath it (forgot what it's called)
Radio
MPI/Other fuse on the positive battery terminal
Fuel pump
Other things I've checked:
Took the fuel pump out the check wiring
Changed pump rewire relay
Tested Starter
Cigarette lighter wiring
Then I got around to pulling the dash apart and borrowed a meter to test continuity. I placed one end on the prong for the ignition fuse at the positive battery terminal, and I placed the other on the ground. The system was definitely being grounded only when the key was turned ON. I left it on there while I kept disconnecting things to see if the resistance would go up (ground contact would decrease - good thing). When I unplugged the turbo timer, the ohm reading went up a little. I don't know what that meant, but still, the system was being grounded with it removed.
Here's the plug that goes to the ignition switch (Connector A). This is as if you unplugged it from the rest of the car and are looking at the prongs (I believe) that go to the switch:
(Taken from the Haynes manual)
You must be logged in to view this image or video.
Colors:
1 - No wire
2 - Blue/Black stripe (LB)
3 - Blue (L)
4 - Black/White stripe (BW)
5 - Black/Yellow stripe (BY)
6 - White (W)
I did a check for continuity using the bottom image in the above picture to test the switch is working properly. It passed. I also checked what wires from the plug-to-harness were continued. 4-2 and 4-5 had continuity (thus 2-4-5).
Edit:
Also, with the meter connected again to the ignition fuse on the positive terminal and a ground, I disconnected the ignition switch plug to the harness.  I then used a wire to make connections on the plug-to-harness.  The meter found that the system was being grounded when 6-2 OR 6-4. You can see above that when the ignition is turned ON, 2 and 4 is added to the circuit.   Also, from the above paragraph, you can see that 4-2 has continuity, so this does make sense. BUT, is 4-5 supposed to have continuity?  This is telling me that when the key is ON, I'd have 6-3-4-2-5 instead of 6-3-4-2 as shown in the manual, correct?
The following wires were tested for continuity at a ground with the key turned ON. These listed are grounded at some point in their wiring.
Plug to switch
2
3
4
6
Plug to wiring harness
2 - highest ohm reading compared to the other two (weakest ground, but still present)
4
5
I don't know what to do now. Can someone with wiring knowledge tell me whether or not any of these tests should not have tested the way they did?
Today's update
Okay. So I've been studying the electrical diagrams all night, and pulled some plugs again today.
The ignition switch connects two wires in the ON position: 2 and 4 as seen in this diagram. I decided to follow 4 first. You could see that 4 (BW wire) connects to two main plugs: C-54 and C-59.
I unplugged C-54 at the junction block (J/B) to eliminate the possibility of a short from there. The J/B is where all this misc fuses go near the driver's side kick panel. I turned the key to ON, and saw that I was still getting a short.
Next, I unplugged C-59. You can see what C-59 is from the following photos taken from projectzerog.com (source). C-59 is the blue plug in the second photo.
You must be logged in to view this image or video.
You must be logged in to view this image or video.
Colors:
1 - White
2 - Black/Red
3 - Blue/Red (thinner wire)
4 - Yellow (thinner wire
5 - Black/White (thicker wire)
6 - Black/White (thinner wire)
After unplugging C-59, I no longer had a short. My problem lies within the circuit of this plug. I checked to see which wires of the plug experienced a ground. On the male side (plug to ignition), 4, 5, and 6 were grounded on ACC. 1, 4, 5, and 6 grounded on ON.
On the female side (plug to harness in first picture), 2, 3, and 5 were grounded. Now I need help to determine whether or not the aforementioned is supposed to be this way or not.
For those willing to help who have a FSM, please let me know what wires to check, or what I should do next. I could email you a copy of the manual if you'd like. It's about 15 MB. Thanks!!!!
Last edited: