Dash lights flicker but not from Grid heaters..

[Prairie Dog]

I have owned DC's since 1992 (bought present 03 new) so I know what grid heater cycling looks like and this aint it. When cold and idling, my dash lights will dim for about a 1/2 second and look normal for about 1 second. It will do this rhythmically until the eng warms up somewhat. It even does this during the grid heater cycling. Any ideas?



Thanks in advance,

Scotty

 

[CoastyAV8R]

Thats odd, it's not a wiring problem otherwise it would do it all the time. Heater grid cycling would seem to be the culprit but you sound like you're familiar with what that looks like.

 

[Prairie Dog]

It really is strange. . it flickers much quicker than the grids cycle and it continues to flicker during grid operation. It really looks like an old-time mechanical voltage regulator jumping. IT doesn't seem to be hurting anything so I'll probably just live with it.

 

[ryecreek]

at that time thats the highest battery load:

just started

grids cycling

fuel heater

(lights must be on)

batterys are cold too



aside from some elec. is PITA

maybe 1 or 2 batteries on the way out or a dieing alternator or a combo of the to

watch the volt meter when it does it maybe there is a pattern

 

[PBJ2500CTD]

Ditto on what ryecreek said. Do the headlights also cycle with the dash lights, or is it just the dash lights? Any gages "wandering" during the dimming? Could be a voltage regulaion circuit - either the main or instrument. Not sure how the '03 instruments are regulated though. Used to be a separate unit on the back of the cluster on the older vehicles.

 

[TDRdodgeman784]

I had a car that the lights would flicker like that. I changed the alternator and that fixed it. On that car the voltage regulator was in the alternator. Maybe have someone tap the alternator as you are looking at the dash lights and volt gauge see if it gets better or take the alternator to some place and have it tested. At some auto part stores they have a bench tester. The auto part store here has a bench tester and I think it only costs about $10 to have it tested and if it is bad and you buy the replacement from then the test is free. The flickering may not be your alternator but it is something to look into. Hope this helps you I hate electrical trouble.

 

[Prairie Dog]

Thanks for the insight everybody,. .

I installed two new batts and still had the same thing ~ they were 7 y/o and needed replacement anyway.

BJohnson, yes - the headlights go bright and dim with the dash lights.

I'm hoping it's not the regulator (which is in the computer I think).

I dont notice anything else wandering or changing during this little electron circus act and the volt meter doesnt move because its during that initial few moments when it doesn't move anyway. I may hook up my fluke to the power port and monitor it.

Is the fuel heater always on or only when it's cold?

 

[ryecreek]

if im not mistaken fuel heater cycles to it hits 45 or 65 says in the service manual just cant nail it (45 i just looked)

not sure on the voltage regulation hopefuly it is in the alt but may be built into the FCM,PCM. or ECM last i heard FCM's were on national backorder

least its an issue you can deal with if the FCM is it

BTW

i have an FCM from a 05 auto if ya need 1 in a pinch