Volt Meter Bounce

[NNovak]

So this weekend I put on the winter kit as in Wisconsin we will start to see the low teens and below zero in a couple months. I pulled the batteries to put the battery heater blankets on, no problems did one battery at a time so not to loose any memory for the radio.



Now when I start the truck I notice the volt meter will drop to around 9 then back up to 15 about 2 sec later, even my lights will dim when this happens. Now I did read that with the Gen 1's this flux was the grid heater cycling. But it has been 50 degrees for the last week and this is the first time I noticed it. After I drive about a mile or so it stops and the volt meter stays at 15. The only difference in weather is before when it was 50 it was dry this week it is 50 and wet.



Could I have messed up re-attaching the batteries or is it the coil cycling? If it is the grid heater cycling that is fine, but I wouldn't expect the lights to dim so much.

 

[CSkal]

It sounds like something isn't right; normally the grid heaters will cycle for about three minutes and then stop. The thing is, if you exceed 18 mph road speed the grid heater cycle will terminate prematurely. If you are traveling down the road and the voltage fluctuation takes a mile's worth of driving to stop, either there is a problem with the grid heater system, there is another electrical problem, or you just drive too slow :-laf.

The ambient temp may not be the same as what the ECM is seeing when it activates the grids so the ambient temp is kind of a hit and miss indication for grid activation until temps get and stay consistently low (<40 or so).

 

[NNovak]

It does it when I am idling and as I drive through the two blocks of my neighborhood where I don't go over 15mph. (kids walking to the buss stop get in the way) Once I get on the main road it goes away and I noticed at lunch today it didn't do it at all.



So it must be the grid heater causing it. Of course it happens right after I did something to the truck.



I doubt it is the driving too slow

 

[SDunkle600]

It takes into consideration the ambient air temp to determine whether or not to kick on the grid heaters. I think mine always kick on when it gets to around 50 outside and it even does it when it is cooler than 50 at night then rises to above 50 by the time I am ready to fire it up, they still kick one because the ambient air temp of the sensors is colder. It is completely normal and I wouldn't worry about it.

Stuff like that always makes me nervous too when you haven't noticed it before then after you change something you are more sensitive to everything.

 

[nickleinonen]

sounds like grid heaters to me

 

[rbattelle]

Did they change the ECM programming for the instrument cluster volt meter? Up through at least 2004. 5 the ECM supressed the voltmeter readings until the grid cycle finished.

My voltmeter holds steady at something like 10 volts until the grid heaters finish cycling, then it jumps up to normal.

Ryan

 

[wheatman]

its just the grid heater... no biggie. humid days it will kick in at higher temps than dry days. think getting the rpm's up to like 1500 kicks off the cycle.

 

[ENafziger]

Did they change the ECM programming for the instrument cluster volt meter?

Yeah, they must have. On my '06, you can clearly see the volt meter swing back and forth on about 20 - 30 second intervals. I also have a digital volt meter built into to a Beltronics STi Driver, and it tracks the OEM gauge almost perfectly during grid heater cycling. --Eric