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Dan
Dan, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 1694
Experience:  Auto Technician
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My brake light fuse keeps blowing (Mitsubishi Eclipse GT

Customer Question

My brake light fuse keeps blowing (Mitsubishi Eclipse GT 2007) when I step on brake pedal, but not every-time. I checked wiring with ohm-meter and it show no short from back harness, when other brake light disconnected, 825 Ohms when they are connected ( I assume it is resistance of the bulb). wires look OK with no visible wear. Any suggestion?
Submitted: 10 months ago.
Category: Mitsubishi
Expert:  Peter Bagley replied 10 months ago.

Hello and welcome to just answer. My name is ***** ***** here to help. I value your input to my questions so I may help you. Are you good at checking automotive electrical systems?

Customer: replied 10 months ago.
it depends what I need to do... do you have any suggestions what might be a problem?
Expert:  Peter Bagley replied 10 months ago.

Ok does this happen every time you step on the brake pedal, or intermittent?

Expert:  Peter Bagley replied 10 months ago.

What I would suggest first is to remove all brake lights and try that as brake light bulbs have two filaments and I have seen them short out. Also they should be replaced any way at that age .

Customer: replied 9 months ago.
It is intermittent, more often when engine is running , but some times even without it. I checked resistance: both brake lights show 830 ohm. And I don't think bulbs are replaceable: I think I need to change whole cluster. Have you ever seen it on Eclipse?? Is there any relay which can cause it? I understand it can be intermittent "short" , but wires look ok, tightly bundled and wrapped and I never saw "short" with ohm-meter.
Expert:  Peter Bagley replied 9 months ago.

Just checking with an ohm meter is only checking for resistance not a short, what you need is a short detector. you put the circiut breaker in place of the fuse that blows and walk the meter along the suspected wiring area, as you get closer to the short the needle on the meter vibrates faster and when you pass the short it stops. What you could do is disconnect the tail lights one side at a time to isolate that area and see if that's it if either one doesn't blow the fuse it has to me in the wiring up to the fuse.I ;ll give you a pic of one of those short finders, saved my bacon many times fast and easy to use. For that price is an invaluable tool. the one on the link is the better one as it does more then one job.Remember a good tech finds the problems not just replacing parts. I can't recommend this tool enough because it will save time and money not only on this job but any similar ones . If your handy using and ohm meter this is a piece of cake. https://www.aliexpress.com/store/product/Universal-Automotive-Short-Open-circuit-Finder-checker-Auto-Circuits-wire-Tracer-Detector-ADD330N-Car-Repair-diagnostic/620726_1800945660.html

Customer: replied 9 months ago.
Thank you, ***** ***** might be useful to exactly locate the "short". My problem however is that I don't see the "short". Since a "short" by definition is a pass with low resistance between hot "wire" and a ground then it should be detectable with ohm-meter: but I only see high resistance between stop light wire and a ground. As a Mitsubishi mechanic do you know if there is the relay for the stop light or it is a "straight wire" from brake pedal sensor to the light?
Expert:  Peter Bagley replied 9 months ago.

You don't need to physically see the short with that tool all you do is pass it over the arear of the wiring from power source to what it's supposed to run amd it will find it for you as soon as you pass it the meter stops vibrating and you just back it up to where it starts again and that's where the short is.With your ohm meter you would have to pull out the whole wiring to look for it.

Expert:  Peter Bagley replied 9 months ago.

Behind the center of the dash is a flasher unit that the power branches off from the brake light switch. One branch continues to the 3rd brake light that works, and the two "combination" lights are powered off the second branch that goes through the flasher unit. Based on this I would be most suspicious of the flasher unit, but you can test for power to prove it or try the flasher. Question? did you try as I mentioned about disconnecting the tail light connectors one at a time to see if that stops the fuse from blowing, also don't forget the high mount brake light as well.

Customer: replied 9 months ago.
I disconnected third light sometime ago, because it temporary helped (could be just coincidence), so it is currently off. If taillight and third light are on different branches, is it still the same circuit?? ..short in either branch will be ground either branch? And how exactly this flasher looks like? Have not had a chance to check taillights yet
Expert:  Peter Bagley replied 9 months ago.

Yes same circuit till the branch off so it is possible the third brake light can cause the short.

Expert:  Peter Bagley replied 9 months ago.

have you solved the problem or need more help?

Expert:  Dan replied 9 months ago.

I am contacting you because the post has not been closed or rated.

This question is coming up on 7 days which means it will time out and close.

You have already paid to get this question answered, but you have not rated.

Let me help some more. Is there anything else I can help you with?

Customer: replied 9 months ago.
I solved the problem , but unfortunately without much help from this website. There is a break in a wire where it goes from hatch into the body. This wire constantly bends when you are closing the hatch and I assume has to be a common problem in those cars. I would think one who is an expert in Mitsubishi should know it.
Expert:  Dan replied 9 months ago.

Yes this is a common problem. This also happens in the doors. I am glad you were able to correct the problem. Sorry I could not help you sooner with this.