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I've been lazy to get under the dash, so I just started with the wires up on top and easy to get to. I checked the (-) wire from battery to chassis and did not get a tone. So I sanded down all the connections and used dielectric grease where ever it connected and I got a tone. But it took me several hours over a Friday evening to diagnose that problem. I work 7 days a week at two jobs, so time is something I have a short supply of. I'm gonna test the wiring at the stoplight switch this Friday. I'm hoping that the chassis ground was the problem ( it never works so easy for me).
Just for shieeets and giggles a DIY test. Unplug the harness going to one of the 2 tail light brake light bulbs. Replace your fuse and see what happens. If no fuse blown the disconnect that light , reconnect the other side and repeat the test.
It may also be a good idea to completely disconnect the middle or third light as you stated has not worked in some time.
I need to repeat this is purely a DIY test not really in the service manuals. Lol
I guess the chassis ground was the problem. I changed the fuse and stoplight switch and got a tone at every connection, I did not place a bulb in the middle stoplight position. Let's hope that does the job. I'll pop back in here in a week to let everyone know if that solved it or not.
A poor earth will not cause a fuse to blow. It creates a high resistance which will give you dim lights but not blow a fuse. OHMS Law. Fuses blow from excess current flow and there are a few causes for that. Anyway good luck with it.
Well, it's been a week with no blown fuses. So next oil change, I will disconnect battery and really try to trace wire from middle brake light back to its source. That's the only one that had no continuity.
I was doing one final sweep around the car before taking to the shop to fix the blowing fuse. I was checking the rear high mount brake light wiring. I noticed that the rubber connector hose, that the wires are in between the body and trunklid, was loose. In the process of checking I gently tugged on it and it totally came away with the wires inside. Apparently the trunklid hinges had severed the 5 wires inside the rubber connector. I spliced, soldered, and heat shrank new wires in there. the rubber boot hose had no slices in it, but the wires inside were severed. If I hadn't decided to just check that wiring, I would have had the shop charge me $250 to find that out. So if anyone else is blowing brake light fuses, check inside that rubber boot hose.
Last edited by 3puttjay; May 28, 2025 at 09:53 PM.
Glad to have been assistance. As I said I have repaired a few cars that have had that problem. I use very flexible wires (the type used for multimeter leads) to carry out the repair and hopefully they don't break a second time.
Glad to have been assistance. As I said I have repaired a few cars that have had that problem. I use very flexible wires (the type used for multimeter leads) to carry out the repair and hopefully they don't break a second time.
I used the same gauge wire (16 ga) as the existing wires. I'm wary of changing gauges between wires because of resistance and heat. Going to a lower gauge might have worked but I only like to repair once and forget about it then to try something different that may work but will always be on the back of my mind.
