Not the alternator !

[JEK]

Hi All, I have a 1997 Explorer

When it is very cold -degrees my headlights and fan dim and my voltage gauge goes low, only when I come to a stop, as soon as I give it a little gas or put in neutral the gauge goes back up. Put a new alternator in , but still does it only when very cold ??

Any help would be great

Thanks, John

 

[colintrax]

I donno much about electrical stuff but maybe it's the battery? Sounds like you got more of a load than the alt can take though. Got a system? Extra lights?

 

[1996BLKBauer]

makes sure your connections to the battery, and alternator are clean, otherwise you would be dropping volts there.

 

[jremington59]

How's your belt tensioner? Get a meter and check the voltage at the battery.

 

[1992fordgreen]

A healthy battery should read 12.6 ohms exactly. Not that if it's a couple .ohms off it means your battery is bad. Alternator brushes could be getting weak...even in rebuilt alternators it happens often.

 

[JEK]

Thanks guys, i'll have the battery checked. It's only 3 years old !

 

[SoNic67]

A healthy battery should read 12.6 ohms exactly. Not that if it's a couple .ohms off it means your battery is bad.

It's volts you need to measure, not ohms (trying to measure ohms will damage the meter).
And it's 14.0-14.4V when engine is running.

Idle rpm might be too low (IAC?) and battery weak (not holding capacity at cold) - those two would make the voltage to drop too much at cold.
This is because most alternators are generating substantial power only above 900-1000 rpm and also they have a temperature compensation for output voltage.

 

[1992fordgreen]

I meant volts lol

 

[JEK]

Thanks sonic67 !