surging lights

2000 MERCURY COUGAR
190,000 MILES • 6 CYL • FWD • AUTOMATIC
Avatar
JOE0621
  • MEMBER
  • 1 POST
all my lights on my 2000 mercury cougar are surging,i have unhooked the positive terminal on the battery to test the altenator,what could it be
Feb 10, 2011 at 7:56 AM
Advertisement
Avatar
MHPAUTOS
  • ✓ASE Certified Mechanic
  • 31,937 POSTS
  • ASE Certified Mechanic
Firstly you should never undo the battery terminal with the engine running, the voltage spike created when touching it back on can do serious damage to the ECU, now, i would be getting the alternator checked as this may be a faulty voltage regulator, the surge in the lights may well be the voltage increasing and decreasing due to a faulty reg, start here.

mark (mhpautos)
Feb 10, 2011 at 10:22 AM
Avatar
RASMATAZ
  • ✓ASE Certified Mechanic
  • 75,992 POSTS
  • ASE Certified Mechanic
Also a dimmer and headlight switch -as advised with the voltage regulator can be integral with the alternator or the alternator's field generation of the alternator is being controlled by the computer
Feb 10, 2011 at 10:57 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.