Quick question about testing for alternator function.
I am not sure the alternator is working on a 78 bus.
The light does not come on on the dash before start, for one thing, but likely unrelated.
Is it not possible to test for function by volt metering before start at the positive of the coil (ie- ignition on, one probe grounded and one on hot at coil) to get an initial voltage, and then after starting get another reading. After starting there should be an increase with the juice from the alternator?
Also can anyone scan a fuse block page and the wiring diagram for a 78 FI bus.
Trying to avoid buying a Bentley for a bus I don't own.
'78 Bus Alternator Test
- Gypsie
- rusty aircooled mekanich
- Location: Treadin' Lightly under the Clear Blue!
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'78 Bus Alternator Test
So it all started when I wanted to get better gas mileage....
- dtrumbo
- IAC Addict!
- Location: Mill Creek, WA
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The wiring diagram is online here.
http://www.thesamba.com/vw/archives/inf ... _77-78.jpg
The key is here.
http://www.thesamba.com/vw/archives/inf ... 78_key.jpg
Your test procedure is valid, except I would test the voltage at the battery instead of the coil. Nothing in the way that way.
Good luck!
http://www.thesamba.com/vw/archives/inf ... _77-78.jpg
The key is here.
http://www.thesamba.com/vw/archives/inf ... 78_key.jpg
Your test procedure is valid, except I would test the voltage at the battery instead of the coil. Nothing in the way that way.
Not so, the light has to work in order to provide excitation voltage to the alternator. No light, no charge from the alternator.Gypsie wrote:The light does not come on on the dash before start, for one thing, but likely unrelated.
Good luck!
- Dick
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
- RSorak 71Westy
- IAC Addict!
- Location: Memphis, TN
- Contact:
- Status: Offline
At rest not running you get about 12.3 volts. Running with a good alt. you should see at least 14 volts.
Take care,
Rick
Stock 1600 w/dual Solex 34's and header. mildly ported heads and EMPI elephant's feet. SVDA W/pertronix. 73 Thing has been sold. BTW I am a pro wrench have been fixing cars for living for over 30 yrs.
Rick
Stock 1600 w/dual Solex 34's and header. mildly ported heads and EMPI elephant's feet. SVDA W/pertronix. 73 Thing has been sold. BTW I am a pro wrench have been fixing cars for living for over 30 yrs.
- hambone
- Post-Industrial Non-Secular Mennonite
- Location: Portland, Ore.
- Status: Offline
Yeah, don't you just test at the battery terminals?
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it balances on your head just like a mattress balances on a bottle of wine
your brand new leopard skin pillbox hat
- Gypsie
- rusty aircooled mekanich
- Location: Treadin' Lightly under the Clear Blue!
- Status: Offline
I will use the battery. It's kind of tucked away but the positive terminal is easily reachable. The coil is right there and requires less contortioning.
Thanks Dick for the diagrams and links.
The first steps I will make for the charging system will be to track down the dash light issue to make sure the connections are good and...uh...connected.
Thanks Dick for the diagrams and links.
The first steps I will make for the charging system will be to track down the dash light issue to make sure the connections are good and...uh...connected.
So it all started when I wanted to get better gas mileage....
- AirCooledNut
- Getting Hooked!
- Location: Portland, Oregon
- Contact:
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Check the bulb, make sure it's not just burned out -- you need to operate on vehicles the same way I look for women, cheap and easy first! (Okay, just kidding...you breathe a word of this to my fiancé and I'm dead meat!)
Toby http://www.aircoolednut.com/
Did I mention that I'm an original Darksider?
DDB Forum
'72 VW Squareback, 2007cc, GB 5-speed, rag top; '76 VW Riviera Sundowner; '95 VW Jetta GL, Solo II EP; '81 Goldwing 1100
http://www.frappr.com/type3volkswagenowners & http://www.type3registry.com/
Did I mention that I'm an original Darksider?
DDB Forum
'72 VW Squareback, 2007cc, GB 5-speed, rag top; '76 VW Riviera Sundowner; '95 VW Jetta GL, Solo II EP; '81 Goldwing 1100
http://www.frappr.com/type3volkswagenowners & http://www.type3registry.com/
- AirCooledNut
- Getting Hooked!
- Location: Portland, Oregon
- Contact:
- Status: Offline
Since the stock alternator B+ wire goes to the big terminal on the starter, you can also check there. The other big wire on there goes to the battery you know, if you like crawling under a Bus and gettin' grimeyhambone wrote:Yeah, don't you just test at the battery terminals?
Toby http://www.aircoolednut.com/
Did I mention that I'm an original Darksider?
DDB Forum
'72 VW Squareback, 2007cc, GB 5-speed, rag top; '76 VW Riviera Sundowner; '95 VW Jetta GL, Solo II EP; '81 Goldwing 1100
http://www.frappr.com/type3volkswagenowners & http://www.type3registry.com/
Did I mention that I'm an original Darksider?
DDB Forum
'72 VW Squareback, 2007cc, GB 5-speed, rag top; '76 VW Riviera Sundowner; '95 VW Jetta GL, Solo II EP; '81 Goldwing 1100
http://www.frappr.com/type3volkswagenowners & http://www.type3registry.com/