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I have a 2006 Hyundai Azera with an electrical gremlin. Over the years, I've had occasional episodes where the vehicle would crank but not start. Cycling the ignition key 2 or 3 times seemed to solve it, and it has not reoccurred since replacing the battery 2 years ago.
Now I have a problem when driving at night, where the headlights and instrument panel momentarily go dim then brighten again. Problem can often be induced by braking. I've read on CarGurus that this has frequently been traced to a faulty positive battery cable. Other obvious suspects are the alternator/regulator. Any recommendations?
UPDATE: I can now also reproduce the issue consistently. Sitting at idle in park, if I rev the engine to about 2500 RPM and then simply take my foot off the gas, the headlights and panel dim almost every time at about 1000 RPM and then come back to full strength as the engine settles down to idle at about 800 RPM (based on the dash tach.) The battery checks as good, so I'm thinking either alternator or a glitch with the ECU programming. Thoughts? Suggestions?
Hello and welcome to JustAnswer!
I see that your question has been up for an extended time without a response and while although this vehicle is not in my area of greatest expertise I would like to try to help.
It's possible that you may have an alternator or software issue but there is actually a service bulletin for headlamps dimming during deceleration because of voltage drop in the battery cables. It wouldn't hurt to have the alternator tested but the cables definitely should be tested for voltage drop.
Voltage drop testing will just require a digital voltmeter. With the engine running, headlamps, blower motor and rear defrost on to load the system down. Set the meter to the 20v DC scale and place one end at the alternator output stud and the other end at the battery. If the meter shows more than .2v then the cable is bad and will need to be replaced. You can also do the same test between the battery and power distribution center. You can also do the same test on the short negative cable, and also between the battery negative post and the body to check the ground side of the system.
Thanks for responding. I pretty much arrived at the same conclusion. When I didn't get a reply, I dug a little further and found Hyundai TSB-08-BE-004 which details the voltage drop issue with battery cables.
I have an "old school" (non-digital) VOM, and can detect a slight voltage drop across the cable. If I can see it on a 20v scale, it must be at least 0.2v. With the engine running, I can see about 14.4v to 14.8v from the alternator to ground, so I'm pretty much convinced that the alternator is okay. Will tackle replacing the battery cables.