2G Electrical short blowing 30A ignition fuse in engine bay after installing gauges

[2G_Spyderic]

I’m working on tracking down an electrical issue causing me to blow the 30A ignition fuse in the engine bay fuse box.

I had no issues with the car previously but just finished installing Glowshift oil pressure and narrowband gauges. Everything worked well at first, I drove the car for about 5 minutes and then everything died due to the blown 30A ignition fuse (first time ever) and I towed the car home. Now the ignition fuse blows within 10 seconds of turning my key to ON.

I have completely removed all the gauge wiring and put everything back to where it was before gauges. I’m working through a long checklist but right now my main question is why would it take 5 minutes and driving to blow the first time, and only seconds before I even start the car now. Does this suggest something is melted, or a relay is burned out or stuck open?

 

[steve]

So after you reverted things to original are you still blowing fuses?

 

[2G_Spyderic]

Yes that is correct, there is no more aftermarket gauge wiring or sensors and still blowing the 30A ignition fuse in the engine bay fuse box

 

[steve]

So something is pinched/shorted or you didn't get everything back to how it was to start with.
Since I don't know exactly what you did while hooking up the gauges and you haven't provided and pictures I can begin to guess what might have gone wrong.

 

[2G_Spyderic]

It's all good, I'm taking a break and back to brainstorming right now. Theoretically, could there have been damage done to a relay or module if something was overloaded during the time the gauges were powered on? Or is that really the job of the fuse to blow before that type of damage could be done.

Or is it much more likely that there is something smaller like a cut/pinch in a single wire?

 

[2G_Spyderic]

While driving my 1998 Spyder GS 2.4L the other day I noticed my speedometer wasn't working. Shortly after that, the car shut off and had blown the 30A ignition fuse.

After investigating the VSS, the wiring and connector is absolutely smoked. The middle pin is broken and gone, black plastic is melted, and about 3 inches up the wiring is about 1/4" of exposed copper (in the last photo).

1. What would cause this?
2. Is the broken middle pin a cause or effect?
3. Would this cause my 30A ignition fuse to blow?
4. Can I get an identical connector from a parts car and use butt connectors on each of the 3 wires for a new sensor?

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[steve]

1. What would cause this?
2. Is the broken middle pin a cause or effect?
3. Would this cause my 30A ignition fuse to blow?
4. Can I get an identical connector from a parts car and use butt connectors on each of the 3 wires for a new sensor?

Pin 1 Black/White is 12v from the ignition switch.
Pin 2 Black is Ground.
Pin 3 Yellow is the signal from the ECU that the VSS pulls to ground to signal.

1. Pin 2 is melted so the most likely cause is something connected pin 1 and pin 2
2. Both cause and effect.
3. Yes.
4. Yes and you should also grab a new VSS in case it's bad and was what shorted out. Is it possible that water got in there?

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[2G_Spyderic]

Pin 1 Black/White is 12v from the ignition switch.
Pin 2 Black is Ground.
Pin 3 Yellow is the signal from the ECU that the VSS pulls to ground to signal.

1. Pin 2 is melted so the most likely cause is something connected pin 1 and pin 2
2. Both cause and effect.
3. Yes.
4. Yes and you should also grab a new VSS in case it's bad and was what shorted out. Is it possible that water got in there?

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Hey Steve, thanks for your reply and for the wiring diagram.

I guess it’s possible some water got in there at some point but I haven’t power washed the engine bay or had the hood open when it rained or anything like that.

I have a replacement sensor and connector to wire in this weekend. There are 2 spots of bare copper wire on the ground wire a few inches up from the connector. Does this sort of short/issue typically travel much further up the harness than that?

I had zip tied a couple other wires for gauges to the plastic sheath for the VSS connector, just to hold them in place. Maybe the ground wire was pulled out from the connector just slightly? Or maybe the pin was slightly pulled out or broken somehow while working in that area

 

[steve]

30A will do a darn good job of turning a copper wire into a toaster before the fuse pops if there's a little resistance involved. Otherwise a dead short should melt the fuse very quickly.

 

[2G_Spyderic]

I think we are in good shape after splicing in a new VSS and connector!

 

[1990TSIAWDTALON]

Good deal. If it was blowing a 30 amp fuse, it was ready to melt something and possibly catch on fire
Do you keep an extinguisher in your car? After a Super Blow of a dipstick MANY years ago, I always have one (but the dipstick doesn't go anywhere now, 2 motors later).
Anyways, good to hear!

 

[2G_Spyderic]

Yes I do! That does wonders for my peace of mind, especially when working through something like this. I think there was a failure with the VSS that resulted in a short, and it did melt quite a bit of the ground wire as it ran up to a branch in the main harness and even a bit further up the wire. That section has been replaced and taped, and now the speedometer works as it should. Thanks for your advice on this!

 

[1990TSIAWDTALON]

Let's add a few more grounds to it. There should be 1 to the firewall, 1 to the starter mounting bolt and 1 to the transmission. There may even be 1 going to the passenger fender. They are VERY important. My son's worked on an old Honda we had and forgot about putting the engine ground wire back onto the valve cover, right up top, and it ended up grounding the motor THRU THE THROTTLE CABLE, seizing it at mid-throttle. I scratched my bald head on that for a bit and then it dawned on me so I PREACH about always check your grounds.
Now, go make sure those are all attached so something like that doesn't happen to you.
Pops

Disclaimer: No kids were hurt during this experience! It was a learning experience, although scary.