alternator charging issues

[jim68127]

Ok, I got the motor back in the car and sounds great. However I am having an issue with the alternator/charging circuit. Alternator is outputting 14+ volts at the alternator. alternator idiot light is on and I get 11.5-11.75 volts at the battery. Battery is new and I had it load tested before I left the store. Alternator is used but was tested at two different shops and they verify it is working correctly. I meticulously cleaned all the wiring to block grounds before putting the engine back in the car. Battery cables are clean and in good shape. Contact at alternator is good. I also replaced the starter with a "new" rebuilt.

The one questionable thing I found is when checking the continuity of the output circuit I get a reading of .022 ohms. IIRC you want a reading of .5ohms and a failed circuit should yield an infinity reading. Does this indicate the problem?

Every on car diagnostic site refers to a in line fusible link that will keep the battery from charging if the circuit tests open. I went on line at Mitchell to get a wiring schematic. One diagram of the power distribution system shows a fusible link (10 GA Brown) between the alternator and starter selenoid. However, when I look at the diagram for the charging circuit no such fuseible link is on that diagram. Does anyone know if there is a fusible link and where it actually is on this car?

Also, the connector coming from the alternator in the schematic for an 03LS shows 3 wires: orange going to the 10A GEN BATT fuse, red going to the GEN Terminal L Control on the PCM and Grey going to GEN terminal F Input on the PCM. My car only has the red and orange wires and only those two metal connectors in the plug. Anyone know what the F Input is for and is that a problem? Why does the diagram show a grey wire and my car (03 supposedly matching the wiring diagram) doesn't?
Other info that may be pertinent: Alternator is the Bosch 2nd generation 105 amp.

[pocket-rocket]

What kind of vehicle is this in?

I would rather see .022 ohms vs half an ohm on a charge supply leg. Anything much over half an ohm on a run that short and I would worry.

Just for giggles I would wire in a temporary wire between the alternator and battery just to see what it does. It's unlikely that there is a break in the wire somewhere that makes a connection when you bend it to test, but you never know. Although if that were the case I don't think it would have such a good reading (.022 ohms). Maybe try wiggling the wire while the car is running and see if you start charging.

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[jim68127]

I edited the post for the vehicle type

[robertisaar]

when it comes to really high current stuff, resistance checks aren't enough. you can have .1 ohms or less on a 20 guage wire of that length and it will be the restriction.

if you're getting good voltage at the alt, but it's not making it to the battery, you have some kind of significant restriction somewhere between the two. bad wire, bad fusible link, loose/corroded connection, something along those lines.

[TGP37]

I'm with Robert on this one, bad fusible link. The fusible link is IN the wire, can't change the link w/o changing the wire itself. You won't see it but it is there.

Try a jumper cable....alt out to batt +, then test batt voltage