Electrical

Tiny
DREGAN
  • MEMBER
  • 1967 CADILLAC DEVILLE
  • 0.7L
  • V8
  • AUTOMATIC
  • 120,000 MILES
Rear lights, power top, power seat, power windows, not working. What to look for?
Thursday, August 24th, 2017 AT 9:17 PM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,755 POSTS
All the rear lights are out or just some of them? I assume the power top and power windows only work when the ignition switch is on. Do the power seats work with the ignition switch off, or does it have to be on too.

To try to find what all of these things have in common, the place to start is in the fuse box. My diagram shows two columns with six fuses in each column. Leave the ignition switch off, then check for twelve volts on both sides of every fuse. If you find any fuse with twelve volts on one side and 0 volts on the other side, that one is blown and must be replaced. Tell me what you find.

Next, check for voltage on both sides of all the fuses again, with the ignition switch in the "run" position. It is normal for some to still have zero volts. Those are for circuits that are turned off, like the wipers or heater fan. We need to figure out if there are fuses with zero volts that should have twelve volts. That will tell us where to go next.
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Thursday, August 24th, 2017 AT 10:54 PM

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