Voltage regulation/ fluctuations during idle?

[FisHn2DMax]

Hi,
I'm relatively New to the D-Max and was wondering if anyone else has noticed their lights going slightly dimmer or suddenly brighter during a stop light idle? I've also noticed it with the interior heater/AC fan suddenly going faster or slower at Idle. I know this could be related to the altenator voltage regulation, or Intake heater cycling, but is this normal for the D-Max to see such a wide voltage regulation? Could the Intake Heater be causing this much of a variation?

Just seems to have a large voltage variation at times, and I'm wondering if this is just a normal characteristic of the D-Max, or If I have a problem? In Dash voltage meter ranges from approx 13.5-14.5 volts depending on engine RPM. Has no problems starting and with engine not running, voltage (in Dash) reads approx. 9.5 Volts during glow plug period and 12.0 volts post glow, with lights on.


Thanks for the help..

G.S.
tongue.gif smile.gif

[ 12-13-2002: Message edited by: FisHn2DMax ]</p>

[hoot]

Yep. Mine does that.

[polaris800]

My 2003 does that say thing and also my 2001 did it to. I think it is a normal thing. I had my 2001 alternater replaced because of this problem but it never changed a thing. I was told that it is normal and occures because you dont want full voltage going to the fuel/engine system.

[Jim Cobler]

I have a digital voltage meter that plugs into the cigarite lighter which has revealed some intereting information for me at least.

When you turn the key on and the warmup starts, you should expect the voltage to drop and it does because the fuel filter heater and the glow plugs are pulling a lot of amps. When you start the engine, the voltage will often be less than 12 volts until the heaters turn off. Usually does not take long.

However, when you start driving, the voltage may read about 14 but as you drive it will gradually increase to around 15.8. This may take as much as 20 to 25 minutes. This gradual increase in voltage does not seem to be speed related and puzzles me somewhat but I have no reason to believe it is anything unusal.

I will watch the meter at idle to see what happens.

[mcfly]

My '02 does the same thing. It is slightly annoying. After it warms up and usually while driving in stop and go traffic or through a parking lot with very little throttle. If I let off the go pedal, the heater/AC fan will slow then pick up and I will notice the volt meter swing from slightly more than 14 to slightly less than 14 then back to slightly more than 14. I attributed it to the addition of the Juice? I do not think it happened prior to that addition, but I could be wrong.


-Rick

[mackin]

Rick

I don't think a Performance box would do anything to voltage draw,or discharge....

Jim Cobler


If that device is accurate,and the truck is at operating temp, you are over charging and will sooner than later cook the battery.....I would get a voltmeter and check at the battery 14 .2 or near there is about right, give or take....Just a heads up.....

MAC

[ 12-13-2002: Message edited by: mackin ]</p>

[Dinkie Diesel]

Boy am I glad to see this topic. I have been wrestling with this same problem since my 2001 was new. I had it back to the dealer to complain about the usual problems associated before a re-flash. I also pointed out that my dash gauge was reading way in excess of 14 volts. The flash was taken care of but the reply to the voltage said it was with in spec. It has slowly been creeping ever higher as the vehicle gets older. I finally put a digital (expensive) voltmeter on it and it read 14.7. According to the dash gauge it is just under the half-way point between 14 and 19. That means the gauge is off as well. If my math serves me correctly half way between 14 and 19 would be 16.5? I can already tell it is having its affect on the batteries as it does not spin as fast as it used to when starting. I plan on taking it in to the dealer again to make them aware and have it checked again. Any bets they tell me it is within spec? Who's going to buy me 2 new batteries when it fries these? I'd have to agree with Mackin about the 14.2. It has been my experience that 13.8-14.2 is right where you want it. A few tenths of a volt don't sound like much but it can make the difference between your batteries and bulbs lasting or not lasting.

On another note I used to work at a Target Store automotive shop. All I did was simple things like change tires and oil changes, etc. The shop didn't do anything complicated. Anyway the store manager brought his Firebird to me one day and said he had it back to the dealer and they could find out what was going on. Long story short the voltage was fluctuating. I finally found the problem. It was a loose connection inside the alternator. Don't remember what but something like the bridge rectifier or diod trio had come loose. When it made good contact the voltage was correct. When it broke connection voltage spiked way up.

Just a thought! Thanks for listening!