Alternator, Battery, Ground?

cracra · Post by **cracra** » 19 Jun 2018, 22:13

Good evening,

Battery not getting the charge from alternator??

93Regina · Post by **93Regina** » 20 Jun 2018, 06:35

cracra wrote: 19 Jun 2018, 22:13Battery not getting the charge from alternator?

Rev it up to 2,300 RPM while monitoring voltage output...if this don't work, get another alternator

cracra · Post by **cracra** » 20 Jun 2018, 11:40

My RPM gauge does not work... And this is my second alternator. 1st on I bought used, 2nd one I bought brand new. When installed voltage was 14.5, now reads like 12.

Post by **jimmy57** » 20 Jun 2018, 15:55

The alternator needs a power feed on the small gauge wire in order to begin to charge reliably. This power feed is through the warning light circuit. If the cluster is not working and there is no alternator light function and no charging can result.

cracra · Post by **cracra** » 20 Jun 2018, 17:11

Parts of the cluster works fine, but some of it doesn't. I have owned the car for about 4 years with no problem with the charging system. Then about 4 or 5 weeks ago it all started. Would I find that power feed wire underneath the dash on the driver's side? I am getting ready to start a new job and really would like to figure this out before I start.

Thank you for your reply and idea. That sounds like what is going on.

93Regina · Post by **93Regina** » 20 Jun 2018, 20:22

cracra wrote: 20 Jun 2018, 17:11power feed wire

Two items:

1. Ground strap to alternator....

2. Instrument Alt light power feed to alternator.

If both are hooked to alternator, then no wiring issue. If ground strap/wire is not hooked up, then you have a problem. If alt's warning light bulb is not working, then power can not be sent to alternator to energize it.

You don't need a RPM gauge...I do this all the time with my 93-245....take up RPM to around 2,300, and idiot light lits up brightly....which means in this vehicle, alternator is working.

Bosch OEM alternator works this way, if ground strap is hooked up. If your idiot Alt light is never seen, most likely it needs to be replaced.

cracra · Post by **cracra** » 20 Jun 2018, 21:49

what if I didn't buy a Bosch OEM?

cracra · Post by **cracra** » 20 Jun 2018, 21:54

Sorry so how many wires should be coming off back of the alternator?

cracra · Post by **cracra** » 20 Jun 2018, 22:19

could it be the voltage regulator

93Regina · Post by **93Regina** » 21 Jun 2018, 22:46

cracra wrote: 20 Jun 2018, 21:54Sorry so how many wires should be coming off back of the alternator?

Three wires for a Bosch...Ground, Battery Hot, and indicator light wire.

what if I didn't buy a Bosch OEM?

Kurt Vonnegut says, “In this world, you get what you pay for.”

could it be the voltage regulator

It is possible, but there is more to go wrong:

ALTERNATOR & REGULATOR
Article Text 1990 Audi 100

2nd one I bought brand new

So, have it tested...