1999 S70 Alternator wiring questions

thinkoutside1 · Post by **thinkoutside1** » 06 Aug 2017, 10:11

I have a 1999 Volvo S70. I pulled the old alternator, bought a new one online and installed it two weeks later. When I went to hook it up I connected the large red wire (Hot) and a tiny wire (some sort of control wire from what I understand) but there was no ground wire I could remember or see. A guy at the parts store said it should always have a ground. Is there a ground on this alternator or is it naturally grounded because its attached to the engine?

Car seems to run fine. Alternator is putting out correct voltage. Guy from store says there is some noise in the line (could be a short). He also says my battery is almost dead (putting out 300 cold cranking amps) It's a rare high end battery that stores often misread so I'm not sure if there is any issue there.

Is there a ground I'm missing? And if so where does it attach?

Post by **jimmy57** » 06 Aug 2017, 20:14

The only alternators that have a ground wire connection are ones that have rubber isoalting mounts. The 5 cylinder ones and new (2000-2004 s40/v40 and the 15 and later using the new 2 litre "Drive-E" engines) have direct to bracket or engine mounting so the case is grounded by way of the direct mount.

thinkoutside1 · Post by **thinkoutside1** » 13 Aug 2017, 10:50

jimmy57 wrote: ↑06 Aug 2017, 20:14 The only alternators that have a ground wire connection are ones that have rubber isoalting mounts. The 5 cylinder ones and new (2000-2004 S40/V40 and the 15 and later using the new 2 litre "Drive-E" engines) have direct to bracket or engine mounting so the case is grounded by way of the direct mount.

This is what I suspected. Thanks Jimmy for taking the time to reply!