So last week I posted to this board with temperature gauge troubles, which I was able (finally!) to repair by running a new wire from the grey connector on the firewall to the sensor. Ever since then, the instrument lights have stayed on while I drive. I didn't realize until yesterday, but the alternator is apparently no longer charging, as I discovered when my car left me stranded. So my thinking: it's clearly a wiring issue (the new wiring work and charging issue were simultaneous). I then ran a new red wire from the grey connector to the alternator, without effect. Is that the only wire in that grey block that affects the charging system? Also, there's a Red/Blue wire in that grey block that I noticed is not connected to anything (now at least - maybe it did before my rewiring work started, I don't know). Related?

Thanks so much guys!

Alex

Disconnect the red wire from the alt. Lights should go out. This is just to make sure you are getting power to the idiot lights through the red wire and nowhere else. Reconnect red wire.

If the idiot lights are on while the engine is running then there is a problem with the alt charging as you have noted. If the lights are dim and go out when engine revved then probably a voltage regulator problem (eg. short brushes). But if the ligths are bright then you should pull the alt and get it tested (maybe some blown diodes).

Check that ground connection from block to body to batt is good. And also thick red from alt to starter to batt is good.
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1980 245 Canadian B21A with SU carb and M46 trans in Brampton, Ont.