Hey guys - trying to help out my father-in-law's girlfriend. She has an '02 Legacy. Problem is: intermittently, the lights dim, speedo and tach go to 0 and the car shakes (misfire?). Goes away fairly quickly - only once has she been stranded. Seems to happen more in rainy weather, but not exclusively in the wet. Car is still under warranty. Dealer has replaced the battery, battery cables, and alternator - no help. Of course, they cannot get the problem to occur when the vehicle is in the shop. They live in Honolulu, so there is only one dealership group to take the vehicle to. They don't have any faith in the techs at the one they've been patronizing (understandably), so I told them I would post it to you all here on New Gen.

 

Thanks!

Try hosing down the engine good and looking for arcing. This would be best done at night, and you should rev the engine some. I found a bad sparkplug wire on a subaru once this way when the dealer could find nothing.

 

Keith

See, I'm thinking more along the lines of power or ground feeds, since the lights dim and the speedo/tach go to zero. What do you think?

Bump - nobody has any other ideas?

Bump - nobody has any other ideas?

You are correct. Personally I think you are on the right track. Like you, I would concentrate on why the lights dim. I presume you mean dim (not dip). If the lights dip then this is an electronic problem similar to the tacho. But if the lights dim it is probably a power problem and should be more easily traced.

I think you should look for either

a short to earth that is enough to drop the electronic voltage but not enough to blow the fusable link. Somewhere between the battery and the ignition switch.

 

or

a dry joint

Perhaps the ignition switch is the problem. I presume that on your vehicle the ignition switch also turns off the lights. A faulty switch explains all the problems you describe.

Sorry - what do you mean by "dip"?

Sorry - what do you mean by "dip"?

When using the word "dip" I mean the action one takes by lowering the head light beam so as to provide better visibility to on coming traffic. The headlights are "dipped" by operating the lever provided for this purpose on the steering column. Do you use another word for this?

 

If the lights appear to be dimmed this could be as a result of the dipping relay chattering as a result of poor voltage caused by an open joint or a short circuit

You might try tapping on suspected areas with a screwdriver handle to see if you can find it that way.

I agree. See if you can get it to reproduce the problem by hosing the engine bay down. If you can I'd wait an hour for it dry off then tell them to take it into the dealer and do the same thing for them. My best guess is there's a short in the wiring harness. If they can't find it... they can just change it. You could spend days testing each wire (I know, I have)... and since it's shorting out the system you'll probably never get a computer code on where the error is. The simple solution is to change the main engine harness.

One update: apparantly the positive cable has NOT been changed yet - they say it is backordered. Anyone experienced problems with the positive cable?

 

What you all are saying sounds right to me. Not used to cars being under warranty (as you can see from my sig ). Should just make them change the whole flippin' harness as well as the positive cable.

When using the word "dip" I mean the action one takes by lowering the head light beam so as to provide better visibility to on coming traffic.

Gotcha. I don't think they use hi beams too much in Honolulu, so no dipping.

Along with checking the the main power lead to the fuse panel also check the fusible links for a connection problem. Since it seems everything powered is effected by this problem it must be in the main power somewhere. It may also be a power relay or the ignition switch.

Thanks for all the help. If you need any dinosaur help, come on over to the Old Gen side!