Head lights dims down when letting go off the gas or stepping on the breaks

Tiny
OUELLO
  • MEMBER
  • 2007 HYUNDAI SANTA FE
  • 3.3L
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 80,000 MILES
When I'm driving and I let go the gas to then break or decelerate, my head lights dims down. If my CD player is also running at the same time, It stops the music for a full second. The vehicle also seems to be very quiet for that full second, like everything is going to shut down. (Scary on the high way!) A couple of times the car kind of coughed and jerked. I also have a hissing sound from the speakers. Especially when I hit the 4 window up button when they are already up.

What I checked so far: Battery voltage: 12.55V, running: 14V at start up, 13.55V after a ride, Full load seems to be fine! I've checked if I'm loosing voltage from the alternator (positive of voltmeter on battery negative, negative of voltmeter on alternator casing) Checked ground straps battery to chassis, chassis to motor. I just saw the AC test for the alternator, to see if a diode failed.I'll do that in a couple of minutes?

Could it be the break switch? Very strange, but the problem seems to be less apparent when it's raining outside? Any other test to know if I'm loosing negative/ground somewhere?
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Sunday, October 18th, 2015 AT 6:19 AM

5 Replies

Tiny
KEN
  • ADMIN
Hi Ouello,

Yes a bad diode in the alternator could definitely cause this problem. Please follow this guide and get back to me.

http://www.2carpros.com/articles/how-to-check-a-car-alternator

Best, Ken
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Sunday, October 25th, 2015 AT 3:41 PM
Tiny
ED-WEEZY21
  • EXPERT
Just to add to this one real quick. There is an open recall right now for these vehicles for the front valve cover gasket and the alternator. The valve cover causes oil to leak out right onto the alternator causing the alternator to go bad. I would perform this recall and see if it fixes your problem. Its worth the shot before diving into anything strenuous since it is a free recall. Best of luck.
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Saturday, October 31st, 2015 AT 5:46 PM
Tiny
KEN
  • ADMIN
Hey Ed-Weezy21

Nice work on the follow up :-)

Best, Ken
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Saturday, October 31st, 2015 AT 11:11 PM
Tiny
OUELLO
  • MEMBER
Thanks for your replies everyone! I'll definitely look into the recall since there is fluid coming out of the engine right above the alternator, but I looks more like the coolant. The alternator is squeezed at the worst spot, so I tried everything else. I cleaned and grind off the paint on the frame to reattached all ground straps the it. And the one for the battery negative was squeezed behind the fuse box, and this one wouldn't come off, so I drilled and tap right into the frame and added a new strap! So far so good! I'll still look into the recall. (Hope this one exists in Canada.
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Monday, November 2nd, 2015 AT 2:29 AM
Tiny
KEN
  • ADMIN
Glad we can help, thanks for using 2Carpros. Com tell a friend!
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Monday, November 2nd, 2015 AT 11:39 AM

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