Engine and brake light go on and off together
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Engine and brake light go on and off together
Hello. I have a 2004 Hyundai Santa Fe, and recently the engine and the brake light come on together, but not all the time. The first time it happened was the other day when both lights came on when I started it up 2 miles from my home. I drove it and made it home. After I unloaded the groceries I started it up again, and it didn't even hesitate. Now today I started it up, went to the same location 2 miles away and came back. The lights never came on once. But when I started it back up about 5 minutes later the lights were on. However yet again the car started up right away. I checked the battery terminals for corrosion and tightness. I checked the brake fluid level. I bought a multimeter but it looks like a pain in the butt to access the alternator to test it. And I'm also thinking if the lights aren't on when I'm testing it everything may read normal even when something is apparently wrong, so I'd be wasting my time. So before I do that I was wondering if anybody had any ideas as to what it might be?
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Joined: Apr 2023
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Very interesting. I was having a weird intermittent problem that went away after replacing the battery and the cracked positive battery connector - possibly didn't need to change the battery, but I was taking a trip in stormy weather so I went a little overboard - I didn't regret it.
Using your multi-meter, put it on the 20V DC setting and check the voltage of the battery with the engine off, black on - post and red on + post. A good battery should be around 12.5 volts, give or take a bit; if it's below 12 volts replace it. Then start the engine and check the battery again with the engine. If you get around 14 to 14.5 volts, the alternator is OK.
My first guess, is that the problem could be an old battery, or corrosion at one of the fuse connections. I would check the fuse(s) for the brakes and see if that solves the problem. If not, then check all of the fuses - pull each one out, check it and put it back in and see if refreshing each connection solves the problem - there's no need to check the rest of the fuses once you find the problem.
If all of the fuses, both inside and in the engine bay, check out, then check the battery ground cable and wherever it is grounded - I don't know - engine block or chassis. A 21 year old battery cable could be failing.
If replacing the ground cable doesn't solve the problem, do the same for the positive battery cable.
And report back with what you find.
Using your multi-meter, put it on the 20V DC setting and check the voltage of the battery with the engine off, black on - post and red on + post. A good battery should be around 12.5 volts, give or take a bit; if it's below 12 volts replace it. Then start the engine and check the battery again with the engine. If you get around 14 to 14.5 volts, the alternator is OK.
My first guess, is that the problem could be an old battery, or corrosion at one of the fuse connections. I would check the fuse(s) for the brakes and see if that solves the problem. If not, then check all of the fuses - pull each one out, check it and put it back in and see if refreshing each connection solves the problem - there's no need to check the rest of the fuses once you find the problem.
If all of the fuses, both inside and in the engine bay, check out, then check the battery ground cable and wherever it is grounded - I don't know - engine block or chassis. A 21 year old battery cable could be failing.
If replacing the ground cable doesn't solve the problem, do the same for the positive battery cable.
And report back with what you find.
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Johnny English
Hyundai Santa Fe
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Jul 30, 2010 03:42 PM
