Today my 240 stopped charging and started running down the battery. The book says the Alternator/battery warning light must come on in order for the alternator to charge the system. Well the light does not come on when the ignition is turned on. I swiched the bulb and no luck. Any other ideas? After removing the instrument cluster and pulling all the associated wiring I now can't figure out where to connect the single wire with the larger connection. What a disaster! Thanks for any help. Brad

I had a similar sympton on my car recently. I thought for sure it was the brushes. After all, the car has over 177K miles on the original alternator. However, it turned out that the insulation on the thin red wire to the alternator had deteriorated to the point where the electrical connection on the alternator was intermittent.

I thought that my car had somehow escaped the notorious wiring harness deterioration problem. No such luck. As a temporary fix, I coated the wire with black silicon and am now looking for a replacement harness.

Good luck,

Leon

Worn brushes will cause this. It's common.

Unscrew the voltage regulator from the back of the alternator and you'll probably find short nubs instead of usable brushes. New ones can be soldered on the old regulator, or replace the whole assembly. You do not have to unbolt the alternator.

Boy you have got yourself into a pickle messing with the instrument cluster. The lights should come on when you turn on the key with the engine stopped. All of the circuits are close to ground and the lights burn. As each sensor opens the light goes out. The oil pressure light,

etc.

The alternator circuit light stays on because there is no opposing voltage out of the alternator to ground. In your case you have lost the ground on the alternator and/or regulator system or the wire from the bulb to ground is broken. Bulb out.

The light has nothing to do with the charging of the battery. It just indicates nothing at all coming out of the alternator, when lit. It won't tell you anything more than that. Thats why they call it an "Idiot" light. The alternator can put out just a little bit and that light will go out.

One diode of the three can go bad (open or short) and the alternator will charge only enough to keep the battery up during the daytime if it is driven long between drains. A bad diode can short and drain the battery too! There is no way for the regulator to know how much the battery needs without good connections. The regulator controls output of the exciter diodes to increase the field winding (magnetic flux) to control total output of current to the battery by watching tenths of a volt change in demand. 13.5 to 14.2 is its operating range. A volt meter tells you all you need to know about how it is working and to keep it all working good.

As far as the instrument cluster goes there is one wire that you think came off the cluster. Well to the best of my recollection that wire is an extra, it goes to nothing! If there is not a single spade, or round pin, to put it on, its a freebe!

Take the alternator off and take it to a parts house and have them spin it up and test it. It cost nothing because they have you in there hopefully to sell you one! Check for bad connections or broken wires in the tear down process. Good Experience to get to know your car! If you dare its not hard to check the brushes as a fellow brickboarder recommends Its usally about a ten dollar fix. Pass that get a rebuilt from a good supplier.

Also, judge how old the battery is, sometimes they short and take out diodes! Just in case it is that bad a fix!

It's likely that your alternator brushes are worn and no longer making contact with the slip ring. Pull the regulato/brush holder and check; min. length is 5 mm.