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.
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 else to try. Can someone with wiring knowledge tell me whether or not any of these tests should not have tested the way they did? I need to find this short, and this is my last resort before I go completely insane! I just dropped the motor in, and I want to drive the DSM!!
Can you give some background of this. Did you buy a non running car, or pull a car apart?
From what I see and can understand, that fuse has a lot going on. If I'm reading correctly, when the switch is "on" it sends power to; radiator fan motor relay, condenser fan relay, Then, in the underdash fuse panel (hold the panel so you can read them, #1 starts at the bottom left and goes up)
Fuses; 3, 4, 5, 7, 9, 10
If the fuse does not blow in ACC, try removing the fuses 3 and 7, which get power when the key reaches "on" with those out, see if the fuse blow's. If not plug in 1 at a time.
This is my car. My build link is in my signature. I had this problem after my timing belt broke and I did not touch it for a week. Then one day, the problem went away. This was when I discovered the broken belt and did my build. I put everything back in a couple days ago, but got this problem again before I could start it up.
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, as mentioned previously, 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?
Regarding the underdash fuse panel, does it count up left to right, down to up? or are you saying it's like
3 6 9 ...
2 5 8 ...
1 4 7 ...
^this is what I'm thinking you mean from "...(hold the panel so you can read them, #1 starts at the bottom left and goes up)..."
It is dark outside now, and I pushed the car outside to start it. I'll push it back in the garage tonight and try what you're saying. And yes that fuse has a lot going on, which is why I was dreading these moments when I saw it blow.
If you're holding the fuse cover, 1 is the pop up light, seat belt. 2 is blank, 3 is the heater relay, 4 is radio, 5 cigar, 6 is door locks 7 is (4a/t).
Before when this started, did you add anything to the system? I guess you could have an internal problem with the ignition harness from the key to the first set of connectors. I have seen failures like that on other vehicles, just haven't ran across that with a DSM yet.
I just scrolled back and forth reading what you were doing and that picture, and I'm going to say, my brain is fried. I'm lucky to make it this far in a day. I work on Audi's all day so come this time of night, I can't think anymore. I'll check back tomorrow, lol. All I did today was check engine lights... all day. All waren-freeeeeee.
I get this type of problem near daily @ work.
If you turn the ignition switch on it overloads the circuit, the problem is after the switch.
The Ignition switch powers a few fuses.
They do not overload so you can rule that leg of the circuit out.
If the problem was after a fuse in the fuse box that lower rated fuse would overload.
Obviously not your issue.
I would totally eliminate the turbo timer, may be causing you an issue.
Might be easier to chase without it in place.
Concentrate on the directly powered harnesses & components right off the ignition switch.
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.
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. Thanks!!!!
C59- Control wiring harness and body wiring harness combination.
Why does that blue plug look the same as the ignition harness plug that a TT would go into. Also you did remove all aftermarket wiring correct? Like Wrencher suggested with removing the TT and any gauges?
Yes, I removed all the aftermarket wiring. Wrencher, I've been using those diagrams already. Thanks, though.
Connecting the number 1 (White) wire on C-59 creates the short. The other 5 don't when they are connected. BUT, here's the thing. It only shorts on ON. 1 on the male side is only active when it is on ON. Also, 1 and 5 on the male side are connected on ON. Does this mean my short is on the male side, number 5 (BW) wire?
This seems possible, BUT 5 and 6 already experience a ground on ACC. Why wouldn't something blow then?
I need to find out where 1 (W) on the male side goes to. It's nowhere to be found in the FSM. Since 1 is connected to 5 when on ON, I'm thinking it's on the BW wire. There's just LOTS of wire loom to unravel, and to get to. What if I just buy a long wire, and wire it from the ignition plug to C-54 and C-59. If the short is in this wire, that should fix my problem, right?
Note: Coil pack and transistor both have to be plugged for a short. Not one or the other.
There is no short when C-59 is plugged, and the other two are not. Well, there's a TINY reading, but not as much as the other scenarios.
I connected the plug at C-59 by means of wires and prongs. I disconnected them to make different combinations. Only 1(W) and 5(BW) are involved with my problem. I did find out 1(W) goes from the ignition fuse to the plug, then from the plug to the ignition switch. When the key is ON, 1 connects to 5. 5 is being shorted, thus my problem.
From the plug that goes to the harness (shown in the first picture of post #6), 5 is grounded when both the coil pack and transistor are plugged in.
From the plug to the ignition switch, 5 is grounded with C-54 is plugged in.
After I discovered the above, I went crazy, and said F it. I'm just about at that point to where I've given up. I've wasted my whole break on this stupid electrical problem.
I swear. This car is such a tease. It'll make me hate it, but put out just enough to keep me wanting more. While doing more testing, I was watching the short come and go while plugging in and out the power transistor. All of a sudden, with the transistor disconnected, the short disappeared. I was doing absolutely Nothing. Maybe I have psychic powers or something, but I just stared at the meter, and thee needle dropped down. I kept shaking wires and plugs thinking a loose wire reconnected with gravity or something. The short did not return with all I tried. I was so baffled, I thought "what the heck," and decided to connect the plugs back together.
Upon turning the key, it didn't blow the fuse. My radiator fans just would not come on. The previous owner wired them to come on when the ECU was on. I could not figure out this problem, after countless hours looking at diagrams and the actual wires. I did some wire testing and found that the ground at the radiator plug was not being grounded because I had no thermo sensor at the bottom of the radiator. It still makes no sense as I did not have one prior to this problem, and they still turned on somehow. I gave up and just grounded the wire to complete the circuit.
The fans come on now, but only when the key is on ON, and not when the ECU is on. The difference here is that the fans would have run for the six seconds the ECU remains on after the key is turned off (from ON).
One thing I found is that the turbo timer is bad. I used the meter to find that the timer is connecting an ON wire to the ground. This definitely causes a short on ON. Maybe the turbo timer failing was the cause of all these problems? Still, with it disconnected, I still had the problem until the above-mentioned miracle.
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