Is this an alternator issue?

[camozzi2009]

My truck does this funny thing with the lights when it first starts. The headlights will brighten then dim repeatedly for about 10 seconds. Then it returns to normal. This includes the dome light as well. Possibly everything. This has been going on for 6 years. Ive changed battery periodically. What is it?

 

[kc0stp]

My slightly educated guess is the after glow on the glow plugs dropping the voltage down slightly.

 

[stumiister]

What I would do is check all grounds on the front of the block on either side of the crank and the wire on the back of the block between the cab and engine, the wires on either side of the crank are grounds from the battery.

 

[Blind Driver2]

What I would do is check all grounds on the front of the block on either side of the crank and the wire on the back of the block between the cab and engine, the wires on either side of the crank are grounds from the battery.

It's the afterglow from the glow plugs.

 

[franklin2]

Don't worry about it. Like was said, it's just the automatic glowplug controller cycling the glowplugs after the truck has started, to keep down the smoke and keep the tree huggers happier, and try to get rid of the bad rap diesels have for smoking and pollution.

 

[camozzi2009]

Okay, its a little annoying but toleratable.thanks for the input.

 

[X-NRCan_IDI]

sweet, I have the exact same thing with mine too and I was a bit curious about it... only noticed it to happen more recently with the cold temps. Since it went away shortly after startup I didn't think it'd be anything serious, but now I know!
Thankyou camozzi for asking the question and kc0stp and Blind driver for answering! I love this forum...

 

[turbo elk]

My '91 does the same thing...unplug the glow plug positive wire and you will see it not happen.

 

[sassyrel]

^X's 2