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furgo
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Joined: September 06, 2016
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Location: Southern Germany
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 Posted: Tue Jul 11, 2017 11:41 am Post subject: Starter wiring questions |
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I'm trying to understand some of the hacks that were made to my starter to fix them in a cleaner way. So far I've figured out some of it, but I have some questions regarding the rest.
Here's a picture of what it looks like down there:
And here is what stock should look like:
I must also say that I've got a cut-out relay to charge my auxiliar battery. The theoretical connection should be as in the diagram. However, mine is slightly different I believe
The cut-out relay is the Bosch metal box that looks like the old-style mechanical voltage regulators.
Some more detail on the wiring that goes through the gromments on the driver's side of the engine compartment:
Some notes on the starter wiring:
Terminal #50
No questions here. Whoever did the wiring failed to see there is an additional spade terminal for the extra cable, so they just cowboy-taped them together into one terminal.
I'll just need to undo the join, crimp a new connector to the cranking signal wire and bring it to the additional spade terminal
Terminal #30
• B+ from alternator (6 mm²): this should have been originally directly connected to terminal #30 on the starter. However, it was cut off and joined with a wire that runs into harness #2. Not sure how it's routed, but it runs towards the aux battery/cut-out relay
• Unknown wire #2: comes from the same harness as above. Seems to be about 6 mm²
• Unknown wire #1: comes from harness #1.Seems to be about 6 mm²
Harnesses
While I know the alternator harness is independent from the main harness, I'm not too sure whether the other ones are just some sheating bringing a couple of cables from A to B or part of the main harness.
• Alternator harness: no questions here. I know where it goes and from the state of it on the engine compartment side (partly burnt isolation), I'll need to rebuild it.
• Harness #1: Seems stock: Houses the cranking signal wire and unknown wire #1
• Harness #2: Seems modified. Houses the two 6mm² red wires: B+ from alternator and unknown wire #2. Runs over the transmission to the other side of the engine compartment.
• Harness #3: Seems stock. Houses the ignition switch wire, B+ supply to the whole system, and the supply to the heater air blower.
Any help in understanding the routing and function of the unknown wires, greatly appreciated!
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'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
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telford dorr
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Location: San Diego (Encinitas)
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| Posted: Tue Jul 11, 2017 11:52 am Post subject: Re: Starter wiring questions |
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Unfortunately, the only way to deal with 'unknown' wires is to trace them and see where they go. The nice thing about harnesses is that the wires travel as a group. Should have the same wires on either end.
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'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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furgo
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Joined: September 06, 2016
Posts: 944
Location: Southern Germany
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| Posted: Tue Jul 11, 2017 12:00 pm Post subject: Re: Starter wiring questions |
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| telford dorr wrote: |
| Unfortunately, the only way to deal with 'unknown' wires is to trace them and see where they go... |
Indeed, the added trouble here being they seem to be all the same color and have the same cross-section. As they look like supply cables, they might be interconnected at some point too, to add to the fun.
But I'm aware I'll have to be prepared to do some disconnections and find longer multimeter probes to trace/test for connectivity.
I was just hoping part of this might be standard hacks that someone might recognize.
But also "Unknown wire #1" seems to be stock by looking at some of the pictures I've seen on the forum, and I'm also hoping someone might just know what that one is!
E.g. from this post, terminal #30 has also got two 6mm² wires, of which I can only see one in the circuit diagrams:
| Wasted youth wrote: |
This was on my 1977 fuel injected bus. Never had a 'hot start' relay... and I never had problems.
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Tue Jul 11, 2017 12:48 pm Post subject: Re: Starter wiring questions |
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One of the unknown wires may lead to the test network socket if your bus has (had) one.
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furgo
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Location: Southern Germany
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| Posted: Tue Jul 11, 2017 1:10 pm Post subject: Re: Starter wiring questions |
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| busdaddy wrote: |
| One of the unknown wires may lead to the test network socket if your bus has (had) one. |
Thanks for the pointer. I would have loved to have had one to do some measurements more comfortably, but it was never there on my '79 bus.
I guess it's back to crawling under the bus tomorrow...
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telford dorr
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| Posted: Tue Jul 11, 2017 1:57 pm Post subject: Re: Starter wiring questions |
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Some guesses:
1) The tape splice mess is someone's attempt to put two wires onto a starter which has only one terminal (for some reason).
The fix: undo the mess and restore the black/red wire with some heat shrink tubing. Crimp a piggyback terminal onto the (lengthened) red/white wire. Plug both onto the starter.
2) Unknown wire #2 and the one underneath it (harness #2) probably go to the dual battery relay on the left side firewall. The open wire splice with the two screws severely needs some insulation. Heat shrink, at a minimum. They probably used this connector so that they could disconnect to pull the engine. The terminal on the red wire (unkknown #2) is a hack of some kind. I'd replace it with a proper ring terminal
3) Harness #3 is from the front of the bus. Red/white is the main feeder. Red/black is the starter wire from the ignition switch. Black is ignition coming from the ignition switch.
4) Harness #1 goes to the double relay; the red wire (unknown #1) feeds power to the FI; red/white starter signal drives the fuel pump relay
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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furgo
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Location: Southern Germany
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| Posted: Tue Jul 11, 2017 3:40 pm Post subject: Re: Starter wiring questions |
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Thanks for the follow-up, really appreciated!
| telford dorr wrote: |
1) The tape splice mess is someone's attempt to put two wires onto a starter which has only one terminal (for some reason).
The fix: undo the mess and restore the black/red wire with some heat shrink tubing. Crimp a piggyback terminal onto the (lengthened) red/white wire. Plug both onto the starter.
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Indeed, that's what I was mentioning on the original post when talking about terminal #50. I had not realized the motivation of the PO, so good point about the starter having one terminal only.
I assumed that the other terminal that you can see on the picture was the second one, but I'll do some more cleaning and double-check it with the multimeter to be certain.
| telford dorr wrote: |
| 2) Unknown wire #2 and the one underneath it (harness #2) probably go to the dual battery relay on the left side firewall. The open wire splice with the two screws severely needs some insulation. Heat shrink, at a minimum. They probably used this connector so that they could disconnect to pull the engine. The terminal on the red wire (unkknown #2) is a hack of some kind. I'd replace it with a proper ring terminal |
Good point. I'd actually payed no attention at the massive terminal on unknown #2, as I was fixed on tracing wires. Will replace.
| telford dorr wrote: |
| 3) Harness #3 is from the front of the bus. Red/white is the main feeder. Red/black is the starter wire from the ignition switch. Black is ignition coming from the ignition switch. |
Yep, thanks for the pointer on the harness coming from the front. One thing, though. I'll need to double-check, but I believe the black wire (25 mm²) is not part of the harness. In any case it's the main (or "common") battery supply line.
| telford dorr wrote: |
| 4) Harness #1 goes to the double relay; the red wire (unknown #1) feeds power to the FI; red/white starter signal drives the fuel pump relay |
That brings a really good point: I can see the harness and those two wires going to the double relay on the last pic of the original post. Although the (non-starter-related, I think) black wire on the same harness does puzzle me a bit. I'll double-check that and find where it goes.
Here's what I think happened with unknown #1: it is indeed a dedicated power line to the FI system. On the circuit diagrams it is the red 4 mm² wire that connects directly to the battery (+) terminal.
However, for some reason that connection point was changed and now the junction is made at the starter. That is, at the end of the 25 mm² "common" battery wire. Like this:
I wonder if that was a common modification.
A somehow related question: on the circuit diagrams I see two instances of something that looks like a connector, with "a" to "e" terminals at the top, and "f" to "i" at the bottom. However, I fail to see a reference to it in the key to the diagrams. Would someone happen to know how to interpret this?
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telford dorr
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Location: San Diego (Encinitas)
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| Posted: Tue Jul 11, 2017 5:22 pm Post subject: Re: Starter wiring questions |
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| furgo wrote: |
| I assumed that the other terminal that you can see on the picture was the second one, but I'll do some more cleaning and double-check it with the multimeter to be certain. |
You're correct - there is a 2nd starter terminal! Missed that in the pic. In that case, you don't need the piggyback terminal - a regular one will do. Each wire to it's own terminal.
| Quote: |
| One thing, though. I'll need to double-check, but I believe the black wire (25 mm²) is not part of the harness. In any case it's the main (or "common") battery supply line. |
That's the cable from the battery '+' post. It's replaced occasionally, so it's never included in a harness.
| Quote: |
Here's what I think happened with unknown #1: it is indeed a dedicated power line to the FI system. On the circuit diagrams it is the red 4 mm² wire that connects directly to the battery (+) terminal.
However, for some reason that connection point was changed and now the junction is made at the starter. That is, at the end of the 25 mm² "common" battery wire. |
Unless one uses a special factory battery positive cable which has an extra 'pigtail' wire crimped into the battery lug, these connections were always made at the starter. The pigtail battery cable was likely replaced sometime with an off-the-shelf generic cable, and the FI connection was moved. I personally see no reason it shouldn't be at the starter - surely 25 mm² is a big enough wire between the two points to be insignificant. They must have been worried about tough cold weather starts dropping too much voltage across this cable for the FI to cope with...
| Quote: |
| A somehow related question: on the circuit diagrams I see two instances of something that looks like a connector, with "a" to "e" terminals at the top, and "f" to "i" at the bottom. However, I fail to see a reference to it in the key to the diagrams. Would someone happen to know how to interpret this? |
The rear harness is separate from the front harness, and this is where they interconnect. It's generally a yellowish plastic strip of connections up under the dash, near the fuse block.
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Tue Jul 11, 2017 5:53 pm Post subject: Re: Starter wiring questions |
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| telford dorr wrote: |
| The rear harness is separate from the front harness, and this is where they interconnect. It's generally a yellowish plastic strip of connections up under the dash, near the fuse block. |
On a late bus it's a translucent white plastic rectangle that clips to the top of the steering column support just below the speedo.
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furgo
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| Posted: Tue Jul 11, 2017 8:13 pm Post subject: Re: Starter wiring questions |
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| telford dorr wrote: |
| Unless one uses a special factory battery positive cable which has an extra 'pigtail' wire crimped into the battery lug, these connections were always made at the starter. The pigtail battery cable was likely replaced sometime with an off-the-shelf generic cable, and the FI connection was moved. I personally see no reason it shouldn't be at the starter - surely 25 mm² is a big enough wire between the two points to be insignificant. They must have been worried about tough cold weather starts dropping too much voltage across this cable for the FI to cope with... |
I agree that the connection at the starter is fine. However, my objection is that it does not match the circuit diagrams and it is thus confusing. I've already spent a few hours on it plus the help of folks on this thread to find out (and it is still a guess until I double-check it), so I'll be considering bringing back the connection to the battery directly when I tackle this, so that I don't trip on it next time I need to do work on the starter and I've forgotten about this mod.
So to recap again:
• From the factory, there were two cables connected directly to the battery (+) terminal: the 25 mm² black wire that is the "common" to the permanent +12V supply lines, and the 4 mm² that is the dedicated supply line to the fuel injection
• Folks replacing the factory 25 mm² cable or hacking on the starter/battery circuit tended to replace the big black cable with an off-the-shelf one with a single connection to the battery, and then move the connection for the FI supply to the starter.
If so, I'd be curious to see what the factory 25 mm² battery (+) black cable with the extra connector/terminal looked like. Any pictures anyone?
| busdaddy wrote: |
| telford dorr wrote: |
| The rear harness is separate from the front harness, and this is where they interconnect. It's generally a yellowish plastic strip of connections up under the dash, near the fuse block. |
On a late bus it's a translucent white plastic rectangle that clips to the top of the steering column support just below the speedo. |
I think we are talking about different things. I'm familiar with the connector you're describing on the steering column support. It's T8 and that is clearly illustrated in the circuit diagrams and in the key to the diagrams.
I am talking about the rectangle with the letters which has got no connector description, neither next to it nor in the key.
Looking at the Bentley again (yay, I finally got it last week  ), I think I've figured out what that is, and it's not a connector.
The diagrams on paper on the Bentlay are separated in two halves right at the middle. Back then the long diagram was probably printed in two sheets, and these rectangles with the letters were simply the cross-reference to match the tracks from one page to another.
The scanned diagrams here on The Samba simply had the two halves joined and the a, b, c, etc. cross-references removed, as they're no longer needed if the diagram is all in one piece.
The diagrams on vintagebus.com (that's where the pic on my last post came from) also join the two halves but confusingly leave one half of the cross-references in place.
Long story short: ignore the single a, b, c, d, e, f, g, h, i markings unless you are looking at diagrams split in half.
In any case, I think other than the routing of unknown wire #2, which I have to trace myself, all my questions have been answered. Thanks all!
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Abscate 
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| Posted: Wed Jul 12, 2017 12:33 am Post subject: Re: Starter wiring questions |
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If that connector doesn't have a Tx designation it's a virtual connector, not a physical one. That being said, sometimes wiring diagrams are wrong just to F with you... 
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sun-bug74
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Location: Gloucester, MA
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| Posted: Thu Aug 01, 2024 7:10 pm Post subject: Re: Starter wiring questions |
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Hi Folks:
I was having problems with my 1978 bay starting consistently. I always got my two red lights on the dash and running lights would work in the middle position. The issue was with that final position - the starting with spring back to run position.
I changed out the ignition switch itself and had the same problem. I could start it but it sometimes took a few tries to get anything to happen and, toward the end, I had to reach up under the steering column and apply pressure to the plastic harness end that connects to the spades on the bottom of the ignition switch. I took a look at that harness and some wires were frayed and loose. I finally was not able to start the bus at all. Seemed like the connector was the issue. Also, the ignition would still open in the run position and I could and still can push or hill start the bus with the key in the run position, so the problem is not with keeping it running, it is with getting it to start.
Next, I went and bought a new harness and spliced the five wires that were nice and tight in the new plastic end to the five wires leading to various things from the ignition. I used snap lever connectors that have a way to test current with a test light in the middle.
The plain red wire has power at off, middle, and start.
The black wire has power at middle and start.
The black wire with yellow stripe has power on middle only (goes out at start).
The thin grey wire with the black stripe has power after turning to start and backing off.
The first four wires seem to be doing what they should be doing.
The fifth wire (red with black stripe) has NO power at any position. I know that this wire goes to the fuel pump and the fuel pump starts if I put power to it but it will not get power from trying to start the vehicle.
With the above symptoms, does anyone have any ideas? Could it be that the circuit in the ignition that goes to the spade for this wire is fried and is not passing current down it when the other wires are getting their proper currents? I could replace the switch again but it is new.
Thanks.
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sun-bug74
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| Posted: Thu Aug 01, 2024 7:48 pm Post subject: Re: Starter wiring questions |
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Wanted to also mention that I hear a relay open and close when I turn the key to start.
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airschooled
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| Posted: Fri Aug 02, 2024 9:16 am Post subject: Re: Starter wiring questions |
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| sun-bug74 wrote: |
| Wanted to also mention that I hear a relay open and close when I turn the key to start. |
This is the FI double relay turning the injection system on. Normal, and mandatory if the car runs  It gets the signal from the black #15 wire to coil from the switch.
Your comments about the plug confuse me. It sounds like the the plug may be compromised? Instead of splicing wires, can you take the plug out and photograph it? Sounds like one of the internal connectors may have failed, or the crimp to plug retaining tab is broken.
Robbie
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sun-bug74
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| Posted: Fri Aug 02, 2024 10:14 am Post subject: Re: Starter wiring questions |
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Hi and thanks for replying. The old plug was original and was shot. I already did my splicing and the results I posted are with the new plug. I am starting to think I had 2 problems, the bad plug and a failing starter or solenoid. What do you suggest just to test the starter and its solenoid, to rule those out?
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frankvw
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| Posted: Wed Jul 16, 2025 6:45 am Post subject: Re: Starter wiring questions |
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Furgo asked:
If so, I'd be curious to see what the factory 25 mm² battery (+) black cable with the extra connector/terminal looked like. Any pictures anyone?
here a picture.
I have 1978 with FI, and I do not have it, I have one wire from battery and the extra wire comes from the starter junction, not from the battery. |
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