Charging System Issues

[joepieper]

My son has a 1998 contour with the 2.0L 4 banger. alternator went bad so we changed it and put in a new battery. Still no charge getting to battery. Removed alternator and took back to Autozone for a bench test. It passed with flying colors. I put it back on and double checked that all of the connections were tight, especially the output wire. Still not working. In thinking of checking the wires going to the starter and back up to the battery next but ny other ideas would be greatly appreciated.


Thanks


Joe

[Selectron]

This is the wiring diagram for the charging system, in the Repair Info section at Autozone - if that link doesn't work then try this one. Only the diagram in the upper half of the page is for the charging circuit - the diagram in the lower half is for the starter.

Starting at the upper right corner of the diagram, fuse F30 (interior fuse panel) feeds current to the voltage regulator via the charge indicator light when the ignition switch is at the Run or Start positions - this switches the alternator on. So the first question is - does the charge indicator light illuminate when you switch the ignition to the Run position? If it does then the fuse must be good so there's no need to check it. If it doesn't illuminate though, then check that fuse.

Moving to the top centre of the diagram, Fuse F5 (I think that's in the engine compartment fuse box) feeds current to the alternator field coil via the voltage regulator - the alternator cannot produce an output unless it receives that input current, so check fuse F5. If the fuse is good, and if you have a multimeter or 12 volt test lamp, then check for 12 volts at the alternator plug on the orange wire. That wire is hot at all times, so you can do that with engine and ignition switched off.

Finally, at the top left of the diagram you can see that even if the alternator is producing output current, it can only reach the battery if the 175 amp mega fuse is intact. Not sure where that is on the '98, but the Ford manual for the '97 says that it's "Clipped to engine main harness, at the rear of the engine". Just follow the heavy gauge output cable as it heads from alternator to battery positive terminal, and that will lead you to the fuse. Another way to check the fuse is, with engine and ignition still switched off, check for 12V at the alternator output terminal - it should have 12 volts at all times - if it does then the mega fuse is intact, but if not then there's a good chance that the fuse is blown.

[joepieper]

Fuse 30 was blown so I replaced it. Now the Battery light will not go out. However when I disconnected the battery with the engine running it continued running so Im sure the alternator is now putting out. Wont know exactly how much til I throw a voltmeter on it. Now Im concerned with why te battery light is staying on. Could it just be because the battery itself was low to begin with?

[Selectron]

That does sound like you do have output current from the alternator now. With the engine idling, check the voltage at the battery - it should probably be towards the high end of thirteen-point-something volts, maybe even a little over 14 volts. If access is reasonable and you can safely check the voltage at the alternator's output terminal then check there too - it should be only fractionally higher than the voltage which you measure at the battery. The reason for doing both checks is that if you have a bad connection between alternator output and battery positive terminal then you will lose some voltage, and that could cause the charge indicator light to remain lit.

It could also be though that your battery is indeed somewhat flat, and the warning light might extinguish after you've driven a few miles and put some charge back into the battery - don't stray too far away from home though until you know for sure that the battery is receiving a charge. Or better still, hook the battery up to a bench charger and bring it back up to full charge that way, upon which the warning light should extinguish for sure.

[joepieper]

Turns out the small plug on the alternator with one wire had to be cut off to remove alternator. I rewired it with a butt connector but the wrong size. One end came out of the connector. I did redo it with the smaller size and used a male/female spade connector combo. sealed it up and now the light functions as it should. Have 14.35-14.4 volts even with wipers, headlights, and blower on high. Thank you very much for the quick reply as I would have never thought it could simply be a fuse causing all these issues. And the Speedo works now too so all is good.

[Selectron]

That's good news; the alternator output is obviously healthy if it's giving 14.4 volts even under load. Well done, and thanks for letting us know.