Lights flickering

[vigman]

Going to put this in the mix as well.. the ALT bolts to the block I ASSUME that connection was wire wheeled ( or other method ) cleaned ? Are the batt terminals OE or aftermarket ?

 

[rtbrjason]

The bolts were not wire wheeled or cleaned, but they didn't look that bad. With the wiring upgrade, I ran a second fused line (0 awg) from the alternator to the battery, as well as a new ground line (also 0awg) that runs right to the back of the alternator.

I will dig around under the kick panel a bit. I do recall digging around there a bit trying to get the courtesy lights to come on with the remote starter/unlock. It's possible one of those connections I tried and removed is wonky I guess..

 

[stamp11127]

Since changing alternators didn't solve your problem it would indicate the problem is in the charging circuit wiring harness or ground connections.
I would do voltage drop tests on the charging circuit next. You'll need a decent dmm for this that can range down to 2-3 volts.

 

[1955moose]

I agree. I had a Lincoln Mark 7 that charged fine till you loaded it with lights,heater, radio, then charging dropped. On Ford cars and trucks they need proper amperage and voltage. Best advice , see if you can buy new alternator not remanufactured. Works the best. Reman alternators and starters have cheap parts from China. They fail or give weird symptoms constantly. For what it's worth like your Daddy said you gets what you pay for.

 

[rtbrjason]

I agree. I had a Lincoln Mark 7 that charged fine till you loaded it with lights,heater, radio, then charging dropped. On Ford cars and trucks they need proper amperage and voltage. Best advice , see if you can buy new alternator not remanufactured. Works the best. Reman alternators and starters have cheap parts from China. They fail or give weird symptoms constantly. For what it's worth like your Daddy said you gets what you pay for.

This is why I tried not one but 2 alternators with the most recent being an upgraded 160amp unit from DB electric. No change to the flickering issue.

I'm not really having much luck with this. I think I might either try some kind of filtering device (expensive) or perhaps run everything through a large capacitor like they use for car stereos..

 

[stamp11127]

When you can, check the battery with a dmm set on a/c volts and take a reading, let us know what it is please. At idle and any higher rpm.

Spent some time digging through the books looking for other possibilities that will cause a flicker other than the alternator. Everything comes back as varying voltage causing the flicker - the alternator is the culprit. The only real way to determine if that is the case is to look at the alternators output wave form on an oscilloscope while in the vehicle.

 

[rtbrjason]

When you can, check the battery with a dmm set on a/c volts and take a reading, let us know what it is please. At idle and any higher rpm.

Spent some time digging through the books looking for other possibilities that will cause a flicker other than the alternator. Everything comes back as varying voltage causing the flicker - the alternator is the culprit. The only real way to determine if that is the case is to look at the alternators output wave form on an oscilloscope while in the vehicle.

I've got a programmer tool hooked up for logging, I'm seeing around 14.3v at idle and 14.1-14.3 while cruising since putting in the new alternator. Prior to that it was a few 10th's lower if anything. I did double check with a volt meter and got the same reading at idle.

My mechanic friend did hook up a fancier scan tool with an oscilloscope built it. There was a very visible spike in the wave as it flickered. Not sure how seeing that in the oscilloscope helped any. It did this with the stock Motorcraft Alternator. It did it with the first replacement alternator from advance which was a reman unit and it is still doing it with the new 160amp so I'm not sure how it could be the alternator. I may have mentioned it above, but with this last replacement, I also replaced all the wiring from the alternator, including the 2 wire plug with a new pigtail.

 

[stamp11127]

What shape did the wave form have? Normal is a continuous series of humps, all being the same in height and the same length.
When you ran new wire did you completely replace the old wire? Specifically the sense wire from the voltage reg to the battery?

 

[rtbrjason]

What shape did the wave form have? Normal is a continuous series of humps, all being the same in height and the same length.
When you ran new wire did you completely replace the old wire? Specifically the sense wire from the voltage reg to the battery?

I don't recall on the shape but can probably get him to hook it up again sometime.

The new wire I purchased was a 3 wire pigtail, where one of the pins has a 2-3" line that runs to a single spade terminal on the alternator. The other 2 wires run from the alternator plug back toward the passenger firewall area to a 2 wire harness clip. That is the new wire I was mentioning. I also ran a 0 awg power wire ( 175 amp fused) from the Main alternator output to the battery.

 

[stamp11127]

I'll look at the wiring diagram later tonight to find the color code for the sense wire. As a test it would be interesting to see if a straight shot from the battery to the sense and another to alt case ground has an effect on the wave form.
A good wave form looks like continuous string of lower case "m".
It would also help to know the high and low voltage reading on the scope. Even though a dmm shows 14.3 volts it may not respond fast enough for the spike to register.