1999 Subaru Outback Various "light" problems afte

MITCHELT

MEMBER
1999 SUBARU OUTBACK
4 CYL
AWD
AUTOMATIC
110,540 MILES

I was hit on the right hand side and after $6800 (thank you State Farm Insurance) in bodywork my 1999 Outback is back and running fine except for some issues with lights.

Here are the problems:

- As I am driving, if I press on the brake pedal the headlights dim. This also happens if I press the window buttons. This did not happen before the accident. It does not seem to be anywhere as bad if I shut the engine off and try the same thing on battery power.

- It looks like as I am driving the headlights will flicker for half a second and I can swear I hear a slight clicking sound from under the dashboard when it happens.

- All of a sudden the lights on the gear shifter have gone out. Some of the other lights like the seat heater and a few others on the dashboard have gone out over the last few years.

I'm not a car guy, but after doing some research online it sounds like I may have an Alternator or Illumination Control problem. Some sites suggest a battery problem but that does not sound right?

Any advice would be greatly appreciated.

Thanks!

Mitch

3 Replies

CARADIODOC

MECHANIC
33,741 POSTS

Hi mitchelt. Welcome to the forum. It does sound like it could be a charging problem depending on how much the lights dim. Some people wouldn't be aware of the slight change unless they went out completely, and some people notice little details. The place to start is to determine why the voltage is dropping. It could be an unusually high current demand that the generator can't keep it with or it could be a lack of output capacity. Think of a garden hose. Two things can cause low pressure at the end of the hose. Someone steps on it and kinks it, or you hack the end off so lots of water flows but there is nothing to build up pressure against.

You have an advantage in being able to make the problem occur at will by pressing the brake pedal. Start by measuring battery voltage with a cheap digital voltmeter. With the engine running you must find between 13.75 and 14.75 volts between the battery terminals. See if that voltage drops when a helper presses the brake pedal. Measure the same voltage between the engine block and the large wire bolted to the back of the generator, again while the engine is running. Those two voltages should be nearly the same. If both drop when the brake pedal is pressed, suspect a high current demand. That is what needs to be found. To verify that, you'll need the help of a mechanic with a battery / charging system load tester with an inductive current probe. The actual current value isn't critical. What you're looking for is an unusually high increase. If the output voltage drops but current output only goes up a little when pressing the brake pedal, suspect a defective diode inside the generator.

Your mechanic can also perform a load test on the charging system at the battery that will be more informative.

Caradiodoc