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Hey guys, I am a new owner of a VW Rabbit 1977 1.6 fuel injection rabbit. A week ago my alternator and battery died, I checked the bentley's book and it said I need a 55 amp alternator because my car does have AC. I could not determine if i had a Bosh or Motorola or 55amp or 65 amp alternator so i went to autozone and bought a 55amp motorola alternator, I installed it and also put a new battery. after a week my alternator light came on again ( only drove the car twice). took the car to autozone they checked and said that the alternator(voltage regulator) was bad.

Why this new alternator only last 1 week?
someone told me that the new alternator needs to be the same brand that car had before, is that correct?
the past owner changed the radio for a new aftermarket radio (nothing to fancy CD and bluetooth), BUT I think he installed wrong because you did not need to open the switch for the radio to work (i disconnected for now). because this new radio do I need 65 amp alternator?

any information would be appreciated!!!!!!!!!!
thanks
Oscar
 

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Only if you have a 400Jig-awatt sub.

If you didn't have the alternator tested prior to leaving the store oppsie.

Have you replaced the battery to frame and frame to engine ground? Do it.

I got 4 bad alternators in a row from Napa once.

The big difference between the alternators is that the Motorola style has a Plug on the back side.
The Bosch has 2 studs a big one and a little one. The Big one goes to the battery and the little one goes to the blue wire.

I would also suggest that you tie a ground wire on a Case nut to the Block of the engine.

A new radio needs a Constant b+ 12V to the one yellow wire, and a Switched 12V+ to the REd one.
That way it doesn't drain the battery, and turning the key off stops the radio, the 12V+ constant is for the channel pre-sets.

In the original VW, the red power lead is a constant 12 and should be used on the yellow wire, and the Switched needs to be on the switch for the defroster. :)
 

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Discussion Starter #3
Only if you have a 400Jig-awatt sub.

If you didn't have the alternator tested prior to leaving the store oppsie.

Have you replaced the battery to frame and frame to engine ground? Do it.

I got 4 bad alternators in a row from Napa once.

The big difference between the alternators is that the Motorola style has a Plug on the back side.
The Bosch has 2 studs a big one and a little one. The Big one goes to the battery and the little one goes to the blue wire.

I would also suggest that you tie a ground wire on a Case nut to the Block of the engine.

A new radio needs a Constant b+ 12V to the one yellow wire, and a Switched 12V+ to the REd one.
That way it doesn't drain the battery, and turning the key off stops the radio, the 12V+ constant is for the channel pre-sets.

In the original VW, the red power lead is a constant 12 and should be used on the yellow wire, and the Switched needs to be on the switch for the defroster. :)
Thanks Briano.
I did not check the alternator in the store BIG OOPPS. i got another 65amp bosch i installed yesterday when to oreilly's today to have them check with the tester they connect into the battery to see if everything was right, they said the voltage regulator was bad again!!! i am thinking I only drove this car once to come here to oreilly's. on my way back i stopped in an auto electrical shop i told them my story they connected they tester and checked the alternator 5 times and it came out good.??????, maybe oreilly's machine is bad??? i don't know???.

for the radio the red cable is connected to the cigaret lighter that someone told me gets power all the time, so should I move that red cable to the defroster switch and that would fix the problem of the radio having power all the time?. sorry this may be a simple thing to do but I am new to cars and electrical work.

I do have to improve my ground from the battery to the frame, now I only have that little skinny cable that come out of the negative cable of the battery. for the improvement do I use a 6 gauge or 4 gauge cable to anywhere into the frame?

thanks again briano!!!!!!1
 

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Sorry I didn't see this till this evening.

The Radio to the ciggie lighter is fine but needs to be switched, for Switched I usually go with the Defroster Switch
New Radios Standard wiring is RED is Switched and Yellow is for the constant.

Grounds replacement I usually go for off the shelf cables at my parts store, they sell them both power and Grounds with additional take off's so I can get rid of the extra ringed spad connections.

Yes Places have their meters that go screwy, and or they don't really know how to use them.
If you start your car and are getting between 13.85 and 14V running your good to go.
 

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Discussion Starter #5
Sorry I didn't see this till this evening.

The Radio to the ciggie lighter is fine but needs to be switched, for Switched I usually go with the Defroster Switch
New Radios Standard wiring is RED is Switched and Yellow is for the constant.

Grounds replacement I usually go for off the shelf cables at my parts store, they sell them both power and Grounds with additional take off's so I can get rid of the extra ringed spad connections.

Yes Places have their meters that go screwy, and or they don't really know how to use them.
If you start your car and are getting between 13.85 and 14V running your good to go.

also Briano how can i do a positive voltage drop test in my car when the positive cable is in a harness? and which of the two big cables in the harness is the positive one?.
Thanks
sorry for so many questions, but i trying to figure this out
 

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You have 2 large cables on your battery, one is ground or Negative, and one is positive.
The Positives (usually on the mk1 is on the left side of the battery as you are looking at it). Goes to the Starter, the Alternator with large leads, and a smaller one to the fuse panel. There are more but that is the basics, some of the positive leads go thru fusible links on the Westy see Chris's pages
http://chris.chemidl.in/vw-wiring-diagram-pdf-1982-1983-1984/

The one on the right side of the battery as you are looking at it is the Negative cable and goes to the Frame horn under the Airbox on the CIS or Digifant and same place on the Diesels. Then from that attachment point to the tranny mount or the double ended stud on the transmission.

So from Ground or Frame you have a voltage, that voltage from frame to the positive is some value that should be 13.8-14Vdc.
 
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