Lower idle when headlings turned on
 

Break out the Volt Meter get some real world voltage numbers .

Might just be a poor connection loose corroded

My 2000 3.4 has 225,000 on the original alternator yet

It is not surprising to me that the engine would idle slower with more load (via the alternator). It may even be slow enough that the alternator is no longer able to hold up the regulated voltage, leading to voltmeter bounce with turn signal draw.

You can check the idle spec to be sure. The correct idle should be on the under-hood sticker.

Yes, check idle specs like scope103 says^^^


Not enough. Need to verify with volt-meter and thorough, not quick, inspection of ALL connections between battery and alternator. ALL Connections should have bare, shiny metal tightly against bare, shiny metal. That is ALL connections between battery and alternator, not just the cliched "check grounds".

Mine is 31 YO and does not have that issue.

THERE YOU GO!

I'll be keeping my eye on this thread. I also switched instrument clusters because my cluster did not have the tachometer/oil gauge/voltmeter. After swapping clusters, my voltmeter flickers side to side when I have a blinker on as well. It never bothered me enough to fix it. My RPMs also are reduced when I turn on my headlights. I figured it was the weak stock wiring because I upgraded the bulbs to Osram 55w instead of the typical 35w (before swapping clusters). I was planning on wiring up relay harnesses for the headlights sometime soon.

Forecast for next few days....no dry, warm garage or barn to work in! yarg!

https://cimg4.ibsrv.net/gimg/www.yot...52f3ac8e0a.jpg

Doesn't the 5vze of this era use a motor actuated idle valve, someone correct me if I am wrong and state when this was implemented..

Unless there is an issue with the idle control, out of range limit, the computer should open the control valve to compensate for load from the alternator and increase the airflow.

This is more of a question than solution..

It's not UN common for dash lights to dim with blinkers on.
my brake indicator light does that.
Yes, there must be a problem with wiring that causes too much voltage drops to dash circuit when blinkers come on. Maybe wires that are too thin or too long. Also the fact that blinker and headlight circuits take power closer to the battery than the dash (tails) backlighting.

I've got the same issue with my 89 3vze. I didn't notice the headlights until recently when I set a new TPS and messed with the idle adjust screw. My buddy and I were setting the idle speed after it got warm and realized turning on the headlights would drop it by about 50-100 RPMs. The ticking voltage meter with every blink of my turn signals has been that way since I got the truck, I just assumed that's the way they were supposed to be...