4 days ago, my '04 Chevy Aveo (89,300 miles) would not shift out of park and no brake lights were coming on. I had to use the shift lock release to start the car in neutral, and I took it to dealer. Dealer replaced the brake switch. One day later, the problem returned. I took back to dealer, and they showed me that the light blue “15” stop fuse (the right column of fuses, second one down) had blown. They replaced. It again worked for a day, and the problem came back. Each time I put a new 15 fuse in now, it works temporarily, but now fries either immediately or within an hour. In order to drive, I still have to use the shift lock release, which isn’t great, because it means I have to drive without brake lights.
I already had to put $120 bucks in for the brake switch, which is annoying, now that I found out the part only costs about $10 bucks. The rest was in diagnostics and labor.
Ideas on what the problem really is and how to fix? Thank you to all who can provide helpful insights.
You must determine what keeps blowing the fuse. Driving around without brake lights is waiting for an accident. The “15” means the amp rating of the fuse is 15 amps, and something in the circuit is causing more than 15 amps to go through, blowing the fuse. This is important, because the wires in the circuit were sized to handle 15 amps. More amps than that can cause an electrical fire as the wires would begin to overheat. The fuse protects the circuit from overload.
The fix is going to have to be finding the problem. Electrical problems are sometimes hard to find and many times require a lot of diagnostic time to locate. Especially in today’s cars with a lot of modules and circuits in them. And, this sounds like an intermittent problem that happens under a certain set of conditions. Recreating those conditions where the fuse blows can be a hit-or-miss deal, costing a lot of time.
Busted Knuckles - sorry to imply I’ve been driving without brake lights. Only times this has been is with the hazard lights on and going to the dealer right down the block. Electrical problems is what I’m concerned about - hoping some strong ideas out there will help focus repair efforts.
So, had an idehates a temp fix, what if I put a greater fuse in, like a 20? I’m assuming this is a answer is a bad idea, as the wires aren’t meant for the higher level.
Yes - a higher rated fuse is a bad idea. Its one good way to just create more trouble for yourself.
Do you know anyone who knows things about electronics? A computer “geek” perhaps? Or audiophile? Electrician? Hobbyist of any kind that plays around with electrical stuff? As BustedKnuckles said, tracking down issues like this can be time consuming. But if you know someone who knows how to read a wiring diagram and use an electrical meter you may be able to get somewhere without a shop’s labor time.
The obvious place to start is actually just checking your brake lamps themselves.
Well I’m sorry to say the shop has not done a very good job in getting this fixed for you. They replaced the brake switch needlessly and it cost you a service charge. Any good tech should know that this short problem is most likely not with the switch itself and could easily be verified by proper testing. The trouble is after the switch. The shifting trouble is due to the safety system tied the brake circuit. There is a solenoid in the circuit that needs power from the brake switch in order to unlock the shifter. This problem will go away once the short is fixed and the fuse doesn’t blow out.
It is interesting you mention the emergency flasher circuit. Are you sure the flashers are working in the rear when the trouble is happening? The brake lights and emergency flashers share the same lights in the rear so a short on the line should effect both areas. The brake light circuit passes through the flasher circuit so the trouble may be between those points but it could be after the flasher switch also. If I was working on this I would replace the fuse with a brake light and bypass the brake switch. Then start moving wires around to see if I could locate the trouble that way. Once the short happens again the brake light in the fuse slot will glow brighter. Intermittent trouble like this can be hard to find. Sometimes wires get pinched behind the brake pedal and can short out. Another area to check is the light sockets themselves. I have found melted wires in one that caused a short on the brake circuit.
I am having the same problem with a 2006 Ford Focus (38000 miles). I replaced the brake switch even tho it tested okay (figuring it was maybe an intermittent problem with the switch and only a $14 part). Didn’t help. I’ve taken apart the tail lights, checked the bulbs and wire and traced the wires to the front seat area with no problems noted anywhere to that point. THEN, by chance, I discovered the fuse will burn out immediately if I turn on the radio or use the horn. A decent mechanic on electrical problems in my part of the country is difficult to find and then takes a significant “wait” to get in to him. I’m on the “waiting list”, but need the vehicle fixed quickly. While I wait, is there some kind of electronic control unit that might be faulty and allowing the power to “bleed” across unrelated areas since the horn and radio are not fused with the tail lights/trans. locking device? The horn and radio fuses DO NOT burn out. Thanks for your comments!
I assume the fuse you are talking about is the 10 amp fuse for the brakes inside the dash fuse panel. I also assume the fuse blows out when you press the brake pedal. If that is correct then you might check for a problem on the back side of the fuse panel. I am having trouble seeing how the trouble you describe can happen. One way the trouble appears to be after the brake switch and the other way it seems to be before the switch.
vnpnt, do you have access to a multimeter that can read ohms? I use mine to check for grounding problems at the lights when I have strange brake lighting issues. If the grounds become disconnected, it can cause some pretty strange problems with the rest of the lighting circuit.
Other than that, have there been any modifications to any of the under-dash wiring? By that, I mean custom radio install, remote starter install, alarm systems, etc.
I’d forgotten about it until reading this, but many years ago on my Jeep the parking light fuse would blow immediately on turning on the head/parking lights. The problem ended up being an internal short in one of the bulb sockets. So it’s a shot in the dark (pun intended), but might be a worthwhile thing to check.
For the OP, try unplugging both tail light sockets from the wire, then see if it shifts into gear (after replacing the blown fuse, of course). If it does, replace one of the tail light sockets and re-test. If no brake lights/no shifting, there’s your culprit. If it checks out, do the same with the other side. Your problem may or may not be here but it’s a (relatively) quick and very cheap way to self-diagnose it. All you’ll have invested is a couple of fuses. If you isolate the problem, those sockets are very cheap and you’ll be able to replace it yourself.
Cougar, BustedKnuckles and CCCommander35- Thank you for the suggestions! I’ll give them a try while I wait for the auto tech’s time Cougar- Yes, it is that 10 amp brake light fuse I don’t understand how this could happen either with the horn and radio. I HATE electrical problems! Busted Knuckles- Yes, I’ve got an ohm meter and will try it again. No mods that are apparent to the wiring or under the dash. I purchased the Focus used 3 yrs. ago and have had no problems, but when I was tracing the wires, there have obviously been previous problems( or at least tampering) as the carpet had not been secured under the plastic rocker panels ( probably not the correct term to use) beside the back seat and some of the plastic screws were stripped and the friction clips stripped from previous removal on the interior panels. (They were just loose and easily removable with my fingers.)
Cougar- Yes, it is that 10 amp brake light fuse I don’t understand how this could happen either with the horn and radio. I HATE electrical problems! Busted Knuckles- Yes, I’ve got an ohm meter and will try it again. No mods that are apparent to the wiring or under the dash. I purchased the Focus used 3 yrs. ago and have had no problems, but when I was tracing the wires, there have obviously been previous problems( or at least tampering) as the carpet had not been secured under the plastic rocker panels ( probably not the correct term to use) beside the back seat and some of the plastic screws were stripped and the friction clips stripped from previous removal on the interior panels. (They were just loose and easily removable with my fingers.)