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RESOLVED - 30 amp ignition fuse blowing, short to ground...Power Probe???

Posted by KMJDSM, Aug 14, 2018

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  1. KMJDSM

    KMJDSM Proven Member

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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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    1997 Mitsubishi Eclipse GSX
    297 whp · 284 lb/ft · 2G DSM
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  2. asexton6969

    asexton6969 Proven Member

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    Have you pulled any relays yet? I know you pulled all the fuses but what about relays?
     

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  3. KMJDSM

    KMJDSM Proven Member

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    Okay so I know that power on ACC is getting to the interior fuse box. All things that should be powered by ACC show current like the heater, defogger, door locks, etc. The items I believe to be powered by the "ON" position like the sunroof, back up lights, and turn signals have no power. I believe this is all as expected. I am thinking myself in circles though. I don't know what new information this gives me.

    I was not able to get any voltage readings using my clamp multimeter either.:banghead: . I am going to watch some video's on "de-pinning."

    So the fat white wire comes from the 30a ignition fuse or from the batter directly? Then it leaves on the blue and blue/black wires and goes where? It looks like those two wires do feed the interior fuse box as well.

    If the test light is turning on does that mean the short is between the fuse and the ignition switch on the white wire or does that mean the short must be on the blue and/or blue/black wires?


    Thank you all for your help again!
     

    Street Build 329  1

    1997 Mitsubishi Eclipse GSX
    297 whp · 284 lb/ft · 2G DSM
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  4. KMJDSM

    KMJDSM Proven Member

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    Okay short is definitely AFTER the ignition switch since the light turns off when the switch is unplugged. So this narrows it to the blue and blue/black wires?
     

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    1997 Mitsubishi Eclipse GSX
    297 whp · 284 lb/ft · 2G DSM
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  5. asexton6969

    asexton6969 Proven Member

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    correct, the test light is turning on once you plug the connector in or with the connector in and the ignition turned to "RUN"?
     

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  6. KMJDSM

    KMJDSM Proven Member

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    I have not pulled any relays. I will try this but to be honest I am not sure where or what relays look like?
     

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    297 whp · 284 lb/ft · 2G DSM
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  7. KMJDSM

    KMJDSM Proven Member

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    Thank you so this narrows it down a bit further I think.
     

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    297 whp · 284 lb/ft · 2G DSM
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  8. asexton6969

    asexton6969 Proven Member

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    The picture you posted with the head light attached to the fuse box. All the black rectangles are relay's. For sh**s and giggles will you pull all the fan relays first. Then pull all of them.
     

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  9. luv2rallye

    luv2rallye DSM Wiseman

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    Yes the large white is the power input and comes from the 30A fuse (now your test light). When in "On" position it gets connected to the black/white, the blue/black, and the all blue. When in "Acc" position it only gets connected to the all blue.

    You said "With this set of wires unplugged the headlight (I assume you mean test light) still turn on when the key is put to ACC.". REALLY? Without this connected to the ignition switch that's not even possible. I think you worded this wrong.

    What I would now do is with the ignition switch connector unplugged, try connecting a test wire from the white wire pin to each of the other pins one at a time to see which one lights the test light.

    And yes I agree pull all the fan relays out while watching the test light.
     

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  10. KMJDSM

    KMJDSM Proven Member

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    Sorry, I was referring to the actual car headlights but that is irrelevant.
     

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    297 whp · 284 lb/ft · 2G DSM
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  11. KMJDSM

    KMJDSM Proven Member

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    Thank you, I will try and pull these next.
     

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  12. KMJDSM

    KMJDSM Proven Member

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    Here is something interesting:

    With the car on ACC when I run the windshield wipers the test light replacing the 30A ignition fuse does light up but dim. Is this normal? Does this indicate a short in the wipers some where that might be causing my problem?

    When the ignition is switched to ON the wipers turn off automatically and the test light goes immediately bright.
     

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    297 whp · 284 lb/ft · 2G DSM
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  13. KMJDSM

    KMJDSM Proven Member

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    I just pulled all 10 relays under the hood and the two in the interior fuse panel and no luck. Test light still full brightness.
     

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    297 whp · 284 lb/ft · 2G DSM
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  14. KMJDSM

    KMJDSM Proven Member

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    Okay!!!!!! Narrowing down this further!!! I did the test wire procedure linking the main white power wire to the four outgoing wires one at a time and two of the four wires are causing my test light to turn on bright. These two wires are the red with black stripe and the back and white stripe. I am going to try and figure out where these go with the diagrams.

    Side note, the blue with black stripe looks to power something in the interior fuse panel because when i connect the white wire I can hear a clicking sound from that area.
    30.jpg
     

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    297 whp · 284 lb/ft · 2G DSM
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  15. KMJDSM

    KMJDSM Proven Member

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    Based on what you say here I should only have three outgoing wires (black/white, blue/black, and all blue).

    I also have a red/black....

    I wonder if this is supposed to be connected to the ignition switch? However, both the black/white and red/black cause the test light to come on when connected to the white incoming power wire.


    I tell ya I very much appreciate your help. I am also an avid home brewer and I will send you some beer when this is all said and done!!!
     

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    297 whp · 284 lb/ft · 2G DSM
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  16. luv2rallye

    luv2rallye DSM Wiseman

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    The red/black goes to the starter and should be connected to the white when in "Start" position along with the black/white.

    One thing. When the test light is on, would you measure the voltage (to ground) on the test light lead that goes to the devices (not the battery +12v side) for the two jumpering cases?
     

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  17. asexton6969

    asexton6969 Proven Member

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    There is actually four wires as outputs from the ignition switch. Your black/red is power for the starter relay behind the center of the dash. Wiring at the starter SHOULDN'T be an issue as the relay shouldn't apply power until you turn the ignition switch to "CRANK" I would verify that no one has tapped in to power on this wire for the radio or some other nonsense. I am seeing something in the wiring diagram that I find extremely weird and I am gonna check more than one manual to verify. When looking at the red/black going to the starter relay I noticed a connection with a black/white wire that trails off and says "No Connection" I just find it weird that we have red/black and black/white that both light your test light....
     

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  18. KMJDSM

    KMJDSM Proven Member

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    shoot okay so the fact that the red/black triggers the test light to come on doesn't help much since I was simulating "Start." It seems the white/black triggering the test light is also no help. If both of those are dedicated to "Start" I wonder why none of the blue wires made the light come on indicating that there would be a short on those?

    Admittedly I am not the best with my multimeter. I just bought it a month ago to diagnose some electrical issues in my house. I set the multimeter to record the "Max AC Voltage" (I am not sure if this is the right setting) and I tested from the white incoming ignition wire inside the car to ground and also tested both sides to the ignition fuse terminal to ground all with the test light on. Here are the readings and below is photos. Shouldn't this be much closer to 12V or am I doing something wrong??? Not sure if it matters but my headlight test light is a 55V bulb.

    Measurement from inside the car - white wire to ground.
    IMG_7820.jpg IMG_7821.jpg


    Then I tested from the ignition fuse terminals I got readings of 41.8V and 39.2V.

    IMG_7824.jpg
    IMG_7822.jpg IMG_7825.jpg
     

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    1997 Mitsubishi Eclipse GSX
    297 whp · 284 lb/ft · 2G DSM
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  19. KMJDSM

    KMJDSM Proven Member

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    Thank you for your input! I traced both the red/black and the white/black as far back up under the dash as I could (until it goes into the OEM wire sheath and eventually through the firewall. I did not see any splicing or indication that the wires have been tampered with.
     

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    1997 Mitsubishi Eclipse GSX
    297 whp · 284 lb/ft · 2G DSM
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  20. asexton6969

    asexton6969 Proven Member

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    Your multi meter is set to Volts AC needs to be Volts DC - squiggly line is AC (think Alternating Current) the flat line with straight dashes underneath is Volts DC (think Direct Current - Direct Line - Straight Line)

    Also NEVER jam the test leads in to a connector. You will damage the terminals or pins.
     

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  21. KMJDSM

    KMJDSM Proven Member

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    Oh shoot :ohdamn:. I though cars were AC and houses were DC? Cars have an alternator so I though "alternating current?" This shows how absolutely green I am with electrical. I will re-test tomorrow. I ran out of day light.
     
    Last edited: Aug 18, 2018

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  22. asexton6969

    asexton6969 Proven Member

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    Other way around, homes are AC and cars are DC. You are kind of correct on the alternator. The alternator creates AC but there is a rectifier inside that converts the energy to DC.
     

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  23. KMJDSM

    KMJDSM Proven Member

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    Okay couldn't wait - went and tested with a flashlight. :)

    The B+ side fuse terminal and battery itself measured just over 12V like it should. With the test light on the outgoing fuse terminal (going towards the ignition switch) measured just 0.50V (I assume because the test light itself is pulling all the power). With the test light connected and the incoming ignition wires disconnected from the ignition switch inside the car the white wire coming into the ignition measures 12V. I was very careful just to touch the connector rather than jam it in.
     

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    297 whp · 284 lb/ft · 2G DSM
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  24. asexton6969

    asexton6969 Proven Member

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    Disconnect the connector at the alternator, pull the coil pack, pull the power transistor, check the capacitor (noise filter) disconnecthe fuel pump relay or disconnect the fuel pump.
     

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    450 whp · 368 lb/ft · 2G DSM
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  25. KMJDSM

    KMJDSM Proven Member

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    I did disconnect all relays under the hood in the engine fuse box. I will check tomorrow to be sure one of those is the fuel pump relay. I will do the other suggestions too but I looked on the left side of the intake manifold and I don't think my car has the noise filter thing.
     

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    1997 Mitsubishi Eclipse GSX
    297 whp · 284 lb/ft · 2G DSM
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