1997 F150; 4.6l
Replaced faulty alternator this August (wasn't charging) and also starter (corroded lead strap to solenoid).

All good until yesterday. Cold snap (around 12'F). Started right up, but now voltmeter reads 16-18v and battery symbol is lit red.

After warmup and 30 mile trip, voltmeter drops to 14 (or so) v. at idle, but climbs right back to 18v cruising.

What 'cha think, guys?

Thanks in advance.

Jim

 

Alternator again.

 

That's NOT what I wanted to hear! Easy to replace in August; not so fun in unheated garage during Minnesota winter


Jim

 

Before you do it, drive to a parts store and get it tested in the lot.

 

You can get the cheapest digital multimeter you can find (I recommend spending $15-50) and confirm the actual voltage with the engine off, idling, & at 2KRPM. Test across the battery POSTS (not the clamps around the posts), and from the alternator output to its case.

Also, read this caption: