I am thoroughly frustrated with this, my headlights, tails, dash cluster, and dome light all pulsate mildly together. It happens when idle or driving, with or without other electronics going, but not when engine is off. These are the things I have done recently and none of them helped.

-new ground wires
-cleaned battery terminals
-new positive to alternator wire
-new battery(1 month)
-alternator replaced about a year ago
-timing belt change and tightened drive belts
-new plug wires/plugs
-cleaned distributor cap

-Fuse 15 problem (I checked the fuse, it was not blown, but I went under the car anyway. When I checked I found a patch of brown residue on the mount and the wire bundle, but it wasnt broken open. I opened it up anyway and none of the wires looked melted, burnt or cut so I wrapped the wires in a peice of vinyl notebook cover and wrapped the vinyl and the mount with electrical tape. could I have missed something? wonder what the brown rust on the mount was from if wires were fine?)

anyone have any ideas? im very tired of this.

 

You need to check that battery voltage is reaching the "I" terminal of the alternator (one of the small wires) with the key on. If not, find out why.

 

Check fuse 15 while installed by measuring voltage at both of the small metal test tabs at the top of the fuse. This is done with the key in ON(II). Click here.

 

I dont have a testing tool, so I just replaced the fuse with a spare of the same amperage and reset the ecu, but the lights still pulsate : / It might be my imagination, but when I have ac/defrost/blower on max, the pulsating seems less noticeable if that helps at all.

MK378, im not sure what you mean, as far as i could see my alternator only has the wire going to the positive battery (which I replaced), and the green plastic plug with a bundle of wires. is it an individual wire in the bundle you are referring to?

Any other possibilities?

 

If you only replace fuse 15, you don't know whether it just blows immediately after you install it. Get a test light or multimeter to know for sure. You don't want to guess.

 

You have an electrical problem. You will need a voltmeter to find it. Buy a voltmeter.

I think the "I" wire is the yellow and black one in the plug with 4 wires. If the label is still on the alternator, it would have a drawing of the names of the 4 pins in the plug.

 

so I bought a test light and checked the fuse, it is good. would the test light also work for the wires on the alternator plug, or would I need a voltmeter to know actual voltage passing through?

I have a su****ion that it might have something to do with the ELD, because I am also having a problem where I will have to use my headlights or a/c to kick on the alternator at stop lights because sometimes the idle will drop to like 400 and be very rough until I turn the alternator on.

I have tried replacing the pcv valve and cleaning the iacv as well as adjusting the idle screw to no avail, so Im pretty sure its an alternator electrical problem. Also I replaced the alternator to positive wire and still the same problem.

any suggestions on the next step?

 

Buy an inexpensive digital multimeter. I paid $15 for mine on sale.

Make these three DC voltage measurements across the two battery posts:

1) Engine off
2) Warm engine idling to spec with no electrical accessories on (no load)
3) Warm engine idling to spec with brights on and A/C set to MAX (high load)

Post your results.