flickering dash/headlights

[ian choplin]

I know this topic has been brought up a few times over the years, but maybe my situation is different enough to warrant another thread.
On my 80' Terra diesel, the headlights and dash lights have flickered together since I've owned it. It came to me with a stock alternator.
First, I installed a Brite Lights kit, it obviously didn't affect it. Next, I did away with the stock alternator and its wiring and installed a 63 amp 10si alternator. At this time, I bypassed the ammeter on the dash and have a volt meter installed. Still have the flicker. Next, i changed headlight switches, still have the flicker.
I usually don't drive it at night, but I drove to Dallas, Tx(280miles) this evening and the lights were crazy. I eventually blew the fuse for the panel and running lights twice. When the fuse was blown, the headlights were brite and steady. Weird.
Where do I look now? BHC's? Wiring at the headlight switch?
I left home without my service manuals and won't be back until Thursday so I don't have wiring diagrams in front of me. I'd like to get this fixed so I can get home safely.
Thanks,
Ian

[watermunky]

if you shut off the dash does the headlights get brighter also? This sounds to me like a bad wire or connection in the dash.


edit: actually I think I remember from my rewire that the ground for the headlights goes through the running lights. I would pull your running lights and make sure the ground wire has a good connection. Might have something to do with the plastic housing vs. metal housing thing also. quick fix would be to splice in a new ground to a temporary bolt on block or body so that you can get home.

[ian choplin]

When the dash/running lamp fuse was blown, the headlights were steady. Leads me to wiring issue.
I was told that a bad dimmer switch can cause troubles. My lights switch from hi to low as they should. Any thoughts on that?
Thanks
Ian

[Eric VanBuren]

First step is to check the voltage while the lights are flickering. It sounds like the alternator's output voltage is varying greatly causing the brightness of the lights to vary also. The most common cause of this is a bad connection on the alternator's voltage sense wire, on the 10si it is the wire attached to the #2 terminal. If the voltage sense wire isn't sensing the actual battery voltage then the alternator will keep cranking up it's output voltage to it's max. The voltage being too high would cause the fuses to blow.

[ian choplin]

With my headlights on, my voltmeter reads 14volts. When they flicker, the volts jump down to 12-13ish for that instant.
Will check the connection at the alt.
Thanks
IanI

[ian choplin]

Here are some more symptoms
This morning I drove in to work and decided to turn the dash lights off with the headlight switch. My headlights didn't flicker....until I went over some bumps. Then they seemed to flicker and the fuse blew.
Maybe there is some loose connection in the dash?
Ian

[steve graham]

I worked through the same problems on my Scout with a Dodge alt. Had to run a ground wire directly from the negative post on the battery to the alt case and the voltage regulator. Don't rely on chassis grounds, run a ground wire.

[ian choplin]

Since my alt has an internal v/r, Would adding a ground to the case suffice?
I'll give this a try this evening.
Thanks
Ian

[steve graham]

Yea, just wire to the alt case.
Another Item I had to do was add a relay to give the alt full battery power. Going through the ignition switch voltage dropped to 11 volts. So make sure your getting full battery voltage at the alt, (switched power).

[ian choplin]

Just left the parts store with stuff to build grounds.
Ian