glroland

Hi, where does the alternator ground wire connect to the engine block on a 1972?

Thanks!

lionelhutz

Through the mounting brackets. The ground wire on the alternator grounds the radiator support to the engine. It doesn't ground the alternator even though it's commonly assumed that's what the wire does.

lars

There is no "ground wire" on the alternator - the alternator grounds through its mounting brackets. There is a black wire in the wire harness, wrapped with the big red "+" charging wire, that is attached to the "GRD" alternator terminal, but this wire ties into the harness and runs up to the radiator support as a convenient way of grounding the radiator support to the engine and chassis. It does not ground the alternator to the engine.

Peterbuilt

Doesn't the black wire start at the alternator, go into the harness and the other end attach to the radiator support.






'72 schematic:
https://docs.google.com/viewer?a=v&p...GE5N2EzZGI2Mjc

7T1vette

Yes. That's the wire which grounds the radiator support. The body of the alternator is grounded (electrically) and it is tied electrically to the engine via its metal mounting brackets. The engine is grounded via the cable running from the front-right frame to the right-side motor mount (and front starter mounting bracket). And the frame is grounded via direct connection to the battery, under the battery box.

terrys6t8roadster

My 69 also has a braided copper wire [OEM] from the alternator housing to the lower front driver side valve cover bolt. T

derekderek

the alternator has 6 big diodes in it. 3 are mounted to the alternator frame and send the negative pulse to the alternator frame and straight to the engine it is mounted on. the positive diodes are electrically isolated from the alternator and connected to the large hot terminal. if the alternator was not frame-grounded, it would need a ground wire as large as the hot charging wire. any little ground wire grounds light bulbs and such.