Dimming/Pulsing Lights FAQ/Overview STICKIE PLEASE

[scrupul0us]

First Things First:
I am by no means an electrical expert/genius but I've been through the whole issue with pulsing/dimming lights, fixed them and decided
this would be a good resource for others.

Disclaimer:
ALWAYS disconnect your battery negative and isolate the terminal lead so whilst working it cannot make contact with the battery
terminal easily whenever doing electrical work.

I'm also keeping it basic here for the purposes of diagnostics. If your experiencing pulsing b/c your 1000W amp is slamming 3 subs then it's prolly just time for a high output alt and new hearing aids

How does an alternator work?
Basically, as your alternator spins it creates amperage and voltage that charges your battery and helps supply the car with what extra it may need. As you drive the alternator spins faster than at idle and has the ability to produce more amps and volts than at idle.
Theres a little wire on the alternator called a "voltage sensing wire" that (by stock installion) runs up to the fuse box and reports back to the alternator the load the car is producing. As the load increases the alternator will output more and more amps/volts until it either satifies the load or peaks out at it's maximum output.

What causes the dimming/pulsing?
Well theres a few factors. One of them is the crappy electrical system in the Cougar. The wiring simply isn't the best and overtime it can/will deteriorate. This affects the way the system works. If the wiring isn't good, the flow of amps and volts isn't going to be very good and as a result your car won't opperate properly. If they don't all work together there will be issues. Think of that as an echo in the electrical system. By the time the alternator knows the loadis, the load has changed and causes pusling of extra amps/votls in the system. If the voltage sensing wire isn't accurately reporting the load then the alternator can't accurately supply the correct balance. This is basically what causes the pulsing. In addition to, the wiring harness that the sensing wire attaches to can burn out or corrode and cause similar issues.

How do I diagnose my real problem?
Now, people have experienced pulsing/dimming at various times, whether its bad when its idling, or bad when driving or both. I use the term "bad" loosely because there is a big difference between the slight pulsing/dimming you might see in your gauge cluster and the dimming/pulsing in your headlights that looks like you are flashing your high beams.

-If you have just a slight pulse in your gauge cluster (which is pretty common across the board) then I'd suggest that you leave well enough alone. Really all you are experiencing in my opinion is just some slight resistance issues due to degredation in the wiring.

-If you experience pulsing in your headlights when you are driving (not when idle) then most likely you have a voltage regulator issue and or voltage sensing issue.

-If you experience pulsing when idle and NOT when driving (if you rev the car and it goes away) then you prolly have degraded wires.

What can I do?
Fixing the issue isn't overly complicate or expensive. It'll just take some time under the car and a few tools and some basic electrical intuition. It involves running some new lower gauge wiring to allow for better conduction and less resistance.
Search the boards for "big 3" or "the big three" or "fixing dimming headlights"... these are the most informative on fixing the problem.
I have also written a barebones how-to in the how-to section that you can take a look at.


Feel free to PM me or post here with any questions or comments you may have.

[azbobbybooshay10]

Bump, this should definitaly be stickied!

[scrupul0us]

thanks for the stick

[montyburns23]

does anyone have the wiring diagram still? I want to do this to my car tomorrow.

thanks

[ClaymoreWW]

Ihave been suffering with pulsing lights for a time now. I read through all I could find on this site several times before I bit the bullet. I found some of the instructions rather confusing in spots, but I eventually got if figured out and did this today. It took me a couple hours, but I took my time. Also, I left the alternator in - it would be much easier to get to the wires if you do this while taking out the alternator - but that adds a few more hours.

I took some pictures to clarify the confusing (to me) things - maybe they can help others. Also, here it the FORD SERVICE BULLETIN that covers this situation. It is a PDF file, so you will need Acrobat Reader.

Step 1. Jack up the front of the car and put it on jack stands. Get it high enough that you can get under the car with plenty of room. For safety, make sure to block the back wheels or put your emergency brakes on.

Step 2. Disconnect your battery. You are working with always-on hot wires at the alternator if you don't. Be safe and disconnect the battery.

Step 3. Crawl under the car and disconnect the three wire connections on the alternator. This can be done from underneath, but it is a little tricky and takes some time. This is where actually taking out the alternator allows you to get to the wires better. I would recommend doing this pulsing-lights mod if you ever have to replace your alternator.

Step 3a. Disconnect the easiest and largest wire first. This is under the rubber boot that is right in front of you when you are under looking at the alternator. Lift the boot out of the way and use a 10mm wrench to unscrew the nut holding the wire on. When the nut and wire are off, push this wire to the side for now.

Step 3b. Disconnect the stator wire. This is the single gray wire in the gray plug on the "corner" of the alternator. If you are under the car with your feet sticking out the front, it is a little above and to the right of the big power wire you just undid in Step 3a. The plug is a push-snap-on, so you will need to lift the clip a little to get the plug off the alternator. This is not real easy, so be careful.

Step 3c. This is a larger plug that you can barely see more towards the top of the car (but still on the alternator). It is a typical plug that is held on with a spring clip. Snap the clip off with a screwdriver and wiggle the plug off the voltage regulator.

Step 4. The big red wire stays down under the car (at least in my installation). The other two plugs are in a harness together and need to be pushed up as far as you can from underneath. You need to push it up because you can't really see which harness it is from above.

Step 5. Get out from under the car and go up top. Look between the firewall and the engine on the passenger side and find the wire harness that you just pushed up. Pull it as far out as you can easily. It should look like this when you are done:





Step 6. Cut the RED WIRE. If you don't have a red wire (some report none of their wires are red), study the images above, especially the wires and their location relative to the position of the plug. Cut the one that is in the same position as the red wire in my picture. It's the wire OPPOSITE the green-black wire. When you cut the wire, make sure you leave plenty because you have to strip the end. I cut mine close to where the wire goes in the harness. I did not take the harness apart and use that wire as described in other how-tos.

Step 7. Cut a 5 or 6 inch wire from a spool of new wire. Strip both ends. I didn't have a terminal large enough to go over the bolt on the alternator where you unscrewed the 10mm nut, so I made my own by stripping a long length and wrapping the wire around a rod larger than the screw. on the other end, wrap that with the stripped red wire. Solder both this connection and the loop. See this picture:



Step 8. Thoroughly and completely wrap the wire junction and the unused snipped end of the red wire. be sure to protect this unused end, too - because it is a hot wire. Also, bend the new wire in an arc toward the plug. See this pic:



Step 9. Push the harness back down toward the alternator. You might need to use something to reach up from below and pull the wires back down to the right place.

Step 10. reattach the wires to the alternator in the reverse order: the large, three-wire plug, the single gray plug and finally, the large red wire with a boot. HOWEVER, put the new wire with the loop on the screw FIRST and then the big red wire. Tighten down the nut and snap the boot over the wire and nut. See the pic below:



Step 11. Lower the car, reconnect the battery - start your car and happily realize your dash lights and headlights are no longer pulsing!

I hope this helps someone out there - I'm glad I did it!

--george

[michcougar]

Did you take the Y-pipe out? or did you leave it in to get @ the wires?

My stock and 2nd alternator didnt pulse, but this 3rd one for some reason is. Thinking of doing this fix.

[CougarRida]

Arent you supposed to cut about 4 inches away from the harness on the red wire? U seemed to have cut maybe and inch tops from it?

[michcougar]

Originally Posted by CougarRida

Arent you supposed to cut about 4 inches away from the harness on the red wire? U seemed to have cut maybe and inch tops from it?

Step 6. Cut the RED WIRE. If you don't have a red wire (some report none of their wires are red), study the images above, especially the wires and their location relative to the position of the plug. Cut the one that is in the same position as the red wire in my picture. It's the wire OPPOSITE the green-black wire. When you cut the wire, make sure you leave plenty because you have to strip the end. I cut mine close to where the wire goes in the harness. I did not take the harness apart and use that wire as described in other how-tos.

[ClaymoreWW]

I did not take the y-pipe out.

I did not take apart the harness to get 4 or so inches of wire...I added new wire instead.

--george

[michcougar]

Awesome!

Thanks