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Resolved 2G 30 amp ignition fuse blowing, short to ground...Power Probe???

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KMJDSM

Proven Member
61
0
Aug 9, 2018
Riverside, California
Hi all,

I just bought a 97 GSX as a project car and have detailed the car in the newbie forum and profile page. The car is currently blowing the 30amp ignition fuse as soon as the key is turned to the “ON” position. :banghead:

I have searched and read many different forums on this and the test light article and it looks like a short to ground. Only problem is this fuse looks to connect to nearly all systems! If anyone has any tips to narrow down the hunt please let me know. I am going to dive into this on the weekend. The previous owner said he removed the radio (no after market alarm) and then gave up. The car does have a few after market gauges that look to be tapped into the driver headlight wiring and electric fans that look to be wired aftermarket also.

I found this wiring diagram online but it looks to be for a 1996 GST/2wd. Is it safe to assume the circuit diagrams should be the same for my car? Or if anyone has the correct wiring diagram for a 1997 GSX would you mind emailing it to me or posting a link? My Haynes book doesn’t look to have the circuit diagrams and only the broader wiring diagrams.

Lastly, is a power probe w/ short detection like this one worth it? here . I would be willing to spend a couple hundread dollars to have a useful tool in my garage that would help me solve this in a weekend!

I am going to get started on this project this weekend I am hoping I can solve this problem without towing the car to a shop! That would be a big confidence booster for me!

Thanks,
Kyle
 
Thank you for the reply!

No I purchased the car not running because of this issue. The previous owner said that the speedometer stopped working shortly before the fuse issue started so I am going to check there. I am also going to pull the fuses in the interior kick panel one by one with a test light on as the short/battery drain article suggests. From there though I am not sure what else to do if that doesn't work.

9 times out of 10 the fuse blows as soon as the car is switched to "on." One time though the car successfully switched to "on" and then I tried to start the car and the fuse immediately blew. I am going to check around the starter also I suppose as well.
 
First thing you do is DISCONNECT COMPLETELY all aftermarket stuff (and suspect stuff) to see if the 12v light you replaced the 30A fuse with goes out (remember anything that normally draws current, like floor lights due to a door open, may keep the light partially on so disconnect them - eg. like both door open switches). If light then goes out, start reconnecting the stuff one at a time until it goes on to find the culprit.

Remember however when you turn the ignition switch to ON, it powers all kinds of stuff that it's supposed to. So the light being on would be normal - although it should not be normal brightness due to all that stuff now being in series with the light. So you are going to have to unplug all the "normal" stuff that the switch powers for the light to be meaningful. If the light is on full brightness however, that indicates a short somewhere, even with all the "normal" stuff connected. If the smaller amp fuses are not blowing (only the 30A fuse blows), than the short must be before all those smaller amp fuses. Like in the main power harness of the alt, starter, cable to fusebox, or usually in the aftermarket wiring/devices that bypassed the smaller fuses, etc.

I assume you've found my finding a short article: http://www.dsmtuners.com/threads/finding-a-short-partial-short-or-battery-drain.179481/#post-1496998

The 96 wiring is slightly different than the 97. If you pm me your email address I can send you the 97 wiring diagrams.
 
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Thank you! I did read your article and plan to use it this weekend. The only fuse boxes on the car that I can see in the diagrams are the one under the hood next to the battery and the one under the driver side kick panel correct?

Thank you for the help.
 
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You can download the 97 electrical manual HERE
 
Thank you all for the replies and tips. I don't think my 97 GSX has the noise capacitor thing but I will look.

Luv2Ralleye - Is it safe to assume then if no fuses are blown in the interior kick panel fuse box or no others blown in the engine by then the issue must be before the fuse block (direct connect to starter, alternator, etc. as you mentioned). Also, I am a bit confused on how the test light will help me if it isn't going to turn off? I was assuming it would turn off when I isolate the short. It seems like rather than off I should be looking for it to dim considerably?

Going to dive into this head first tomorrow morning!
 
I just re-looked at the diagrams and told you wrong.

The battery + goes to the 30A fuse. From there it goes to the ignition switch and the sunroof. From the ignition switch it goes to all kinds of things through individual fuses mostly in the interior fuse box but a couple in the engine fuse box. I would replace the 30A fuse with an incandescent light bulb and notice the intensity when ignition switch on. If there's a short to ground after that point, the light will be bright. If bright, then I'd pull every fuse I can find with a helper watching the light. If the light goes out that's the circuit with the short (after that individual fuse you just pulled).

Chances are however, the short will be between the 30A fuse and any individual fuse since you say individual fuses are not blowing (unless someone put in too big a fuse in a circuit which has the short). Someone may have added a wire after the 30A but before any individual fuses (so it may be in either fuse box) to power some after market thing which may have the short. Another possibility is under the engine fuse box a couple wires shorted together (this happened to me when an overload happened causing two wires to melt together under the fuse box). You may want to disconnect the battery and unbolt the engine fuse box and look underneath at the birds nest of wires there to be sure.

If the light is always dim, a circuit is drawing power (since the light in series with the device in that circuit path will split the voltage making the light dim). Unplugging all fuses everywhere should make the light go out.

I just noticed the file I sent you doesn't show the ignition switch wiring. Download the "97-99Electrical.pdf" file here: https://www.mediafire.com/folder/5k14qlaulb9s1/dsm_mitsubishi#mxxoud953d09r (look on pages 98 and 102).
 
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Okay so I have disassembled the interior, unplugged all aftermarket parts, removed the radio, etc. I wired up a test light and it is full brightness the second the ignition switch is turned on. I pulled every fuse in both fuse boxes (after taking pictures to be sure where everything goes) and disconnected every connector I could find under the hood and with all fuses removed the light is still full brightness when the ignition switch is turned on.

I did unmount the engine fuse box to look under and talk about an intimidating bunch of wires! I do not see any melted wires though but I am concerned about the quality of wires feeding the fuse box (Photo #2 below). Through my inspections and tests today I did notice four areas of concern. I have attached photos to get your guys opinions and I am hoping one of these is my problem (crossing my fingers it is #3!).

Pic 1) I found an loose connector by the driver headlights. The plastic is broken but no melted wires so I am assuming maybe a rock or something broke the connector. Not sure what this goes to.

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Pic 2) There are two white wires that run directly from the positive battery terminal to the engine fuse box. These wires don't appear to be touching metal and the wires under the fuse box seem to be okay but the connections at the B+ terminal do not look very good. Could this be causing the short? Should I shrink wrap around the exposed wires or do these need to be replaced.

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Pic 3 & 4 (THIS IS PROMISING I HOPE!!!) I noticed there is another unused connector up on the driver's side of the intake manifold. I am not sure what this goes to and I am hoping someone might be able to help me with what this is. There is no unused connection points from what I can see so maybe this was something that was bypassed in some way. The connector looks to trace back to part of the main harness that is mounted on the firewall. Anyways, the wires going into the connector and the plastic connector itself look to be MELTED!!!! See pic 4 attached. Even though this connector is not in use do you think this can cause my short? If so, should I cut the connector off, separate the red and black wires and cap them to see if this fixes the issue?

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Pic 5 . The auto meter boost gauge looks to have a vacuum line, white, and blue wires. The blue wire is disconnected. Is this a ground? I imagine the white is the power wire?

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Thank you again to all that have responded, especially @Luv2Ralleye
 
- I assume your test incandescent (NOT LED) light literally replaces the 30A fuse, correct? [One lead to one fuse socket side and one to the other - NOT one side to ground. The light literally replaces the fuse - connects to each side the fuse did].

- Pic 1 should not be a problem.

- Pic 2 is not the short but it is the main power to the fuse box and the poor connections will be a problem eventually (strands will break with vibration or melt with high current draw, or corrosion causing problems). They need to be replaced or have the 4 white wires soldered to copper terminals that then bolt onto the B+ terminal (onto the bolt that holds the B+ terminal onto the battery post). They are actually 2 sets of white wire pairs that go to different buses in the fuse box (one set goes to the alternator for charging through a 120A metal strip fuse). The large cable in the plastic protector loom goes to the starter positive and that is the cable you should buy with a molded B+ terminal (molded prevents corrosion and vibration breakage) on one end and starter terminal on the other. Otherwise the high resistance you have at that poor connection will give you starter problems (due to a voltage drop there).

- Pic 3 looks to be the connector for the EGR Solenoid Valve (which is missing on your firewall). Someone probably did an emissions delete (and removed this solenoid) but tryed to plug some resistor (or something) into that connector plug to prevent a check engine light and that eventually melted it. Yes cut that connector off (maybe leave some harness wires there in case you have to install a new solenoid and connector there some time in your future).

- Pic 5 someone else will have to tell you although read below.

- Note that if you want to check if any connector pin is ground (or shorted to ground), you can disconnect the battery and do a continuity test to ground with a multimeter (one lead to ground, other lead to pin, setting to lowest resistance). Don't do with battery connected. Of course you have to understand that some pins are supposed to go to ground (so you should read less than 2 ohms). Other pins go to a device the other side of which goes to ground and so you'll get some resistance reading (usually less than 100 ohms) since you're measuring the resistance of the device. Other pins may read infinite since they never go to ground, or they go to a switch which is off, or they go to a fuse that you removed.

{You can also do the reverse: check if they connect to the battery positive terminal (keep battery not connected) with one probe on the B+ cable terminal (NOT post, battery terminal should not be connected for this test) and other probe on the pin. Of course you may not have continuity on many pins with the fuses out and switches off. But if you suspect a short to B+ on a pin, you could check it this way and ignition key on.}
 
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If the autometer gauge is just a mechanical gauge. Those two wires will be power and ground for the lighting that's it. Can't see it being a stepper because all of those are three wire gauges atleast IIRC.

You have verified nothing has been wired in to the ignition switch wiring? That is the number one issue I commonly come across with Ignition Switch fuse blowing. Usually aftermarket radios, alarms, gauges, lighting, etc. Just don't want you going down the rabbit hole after something small.
 
Thank you for the info on the auto meter gauge. Fixing the melted EGR solenoid connector and wires did not fix the problem. I am stumped! I am going to jack up the car with the tires off and anything else I can removed to try and get an eye on the alternator and starter wires. Could the ignition switch itself be bad?

Here is my test light. It is a headlamp I had lying around that I wired up. It has metal tabs on the end of the wires that I make touch the fuse terminals.
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It looks like the only splice coming out of the ignition wires is red, blue, and green which go to the Apexi turbo timer. I unplugged the wires from turbo timer module and I think I am still shorting out because the test light is still on full brightness.
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I cut out the melted EGR connector and capped the wires. Still no fix. I thought the light originally seemed to be dimmer but upon putting in a 30a fuse it popped right away. Here is my temporary "fix" for this but I am going to redo properly once I can get the car started.

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Upon looking in the engine bay again I found another problem area. It looks to be with connectors that go into the down pipe and perhaps this has something to do with the AEM wide band install. This set of wires is between the upper intercooler piping and engine near the radiator cap. After removing the wire sheath I found several frayed wires and one that looks to have no cover on it at all. I am assuming it some kind of ground since it is not copper? I separated all of the wires and covered frayed spots with electrical tape. Still no luck though - the test light is still on bright.

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I also removed the ECU and I see one of the white wires coming out of the connector looks to be frayed as well. What the heck did I buy! LOL

Anyone have any guesstimates on what it would cost to have the car professionally re-wired hahaha. I am guessing thousands!!!!!

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Clarifying again, the fuse blows when you turn the ignition switch to "ON" correct? The fuse does not blow in "ACC" or "Start" necessarily. I do know you said one time it didn't blow until you started the car but the most common time for the fuse to blow was when you switched the vehicle to "ON"?
 
Lastly, I am not sure if this helps the diagnosis but the test light came on even with the ECU completely unplugged.
 
Correct, ACC the fuse doesn't blow. headlights and radio work on ACC. The fuse also blows with every other fuse removed from the car. As soon as it goes to "ON" it blows. I don't know about "START" since it blow on "ON" before start.

The more I am working with this the more I have a feeling it is something wrong with the direct wires to the starter or alternator. I am going to check these next.
 
Ignition switch only feeds starter at "Crank" and alternator is not fed directly from ignition switch. Alternator is fed from fuse 5 and the 100 amp fuse for b+. If you have pulled all interior and exterior fuses and it's still blowing the ignition switch, I would imagine its on the feed side. So between the ignition switch and any fuses. I have to imagine there is something added on to the wires that is causing a problem. The biggest issue is people find some of the most creative ways to tap in to power wires.
 
I like your test light - perfect for this. Yes disconnect both the alt and starter and anything else you can. Disconnecting things is the fastest way to find shorts. Leave the ECU unplugged during all this testing to prevent electrical spike/glitching damage. Yes a shorting ignition switch is also a rare possiblitity - unplug it to see if the light stays on (which means the short is before the switch).

As a last result when you're totally out of ideas there's another technique but it's VERY time consuming (so try everything else first). With the test light on, place a needle compass along wires to find which one has the shorting current flowing. Start at the 30A fuse and go from there. The magnetism will deflect the needle until you go past the point of the short (or another wire which the current is going down). Here's a writeup about it (last couple paragraphs): http://www.inliners.org/tech/tech6.html
 
This set of wires connects directly into the back of the ignition switch. With this set of wires unplugged the headlight still turn on when the key is put to "ACC." When turned to "ON" with this unplugged the test light does NOT turn on and nothing powers on (I believe because I have disconnected the "feed"?). When this connector is plugged into the back of the ignition switch and it it turned "ON" the test light comes on right away.
I think maybe I am getting close!
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I am trying to figure out where the fat white wire goes using the wiring diagram but reading this thing is a second language for sure
 
The fat white wire is the actual power feeding in to the ignition switch. We don't care about that wire as of right now. We care about the outputs. Blue/Black is the output when the key is turned to the "Run" position. Do you have any tools or feel comfortable de-pinning that connector?
 
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No I am not comfortable de-pinning just yet but my test light is a 55w headlight so it should be pushing about 4-5 amps of current through the system and a do have a clamp style multimeter. I will see if I can get a AC voltage reading. By "Run" I assume you mean the key to the "On" position?

The more I think about this the headlights will work whether the key is on ACC or not. The radio does turn on at ACC but I wonder if the fuse box in the kick panel is getting power on ACC or ON. I am going to test this right now.
 
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