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914World.com _ 914World Garage _ Ignition Harness
Posted by: bbrock Dec 4 2017, 09:42 AM
The ignition harness from my '73 is fried but I found a harness in my spare parts that needs a few minor repairs, but cleaned up pretty nice.
This may have come out of my old '74 VW bus but is identical to the fried harness with the exception of the size of the yellow wire running to the starter. The wire on the good harness is smaller (probably 2.0/14 gauge) compared with the original harness. I can't find wire sizes on the '73 wiring diagrams, but the '74 diagrams indicate a 4.0 mm^2 wire which would be about 11 gauge. Would you replace that wire? Seems like this one might be size critical. I'm thinking of replacing with 12 gauge. I think 10 gauge might cause fitment problems at the 12-pin terminal. Or is it fine like it is. What do you think? 
Posted by: 76-914 Dec 4 2017, 09:44 AM
I'd leave it and employee a relay to carry the load to the solenoid. 
Posted by: bbrock Dec 4 2017, 09:49 AM
I'd leave it and employee a relay to carry the load to the solenoid.
Thanks! I forgot to mention that I plan to install a relay. But I haven't looked at the schematics in Mark's how-to to understand how that would impact load on this wire. But now that I think about it, I guess this would be the relay trigger wire.
Posted by: 76-914 Dec 4 2017, 07:00 PM
I'd leave it and employee a relay to carry the load to the solenoid.
Thanks! I forgot to mention that I plan to install a relay. But I haven't looked at the schematics in Mark's how-to to understand how that would impact load on this wire. But now that I think about it, I guess this would be the relay trigger wire.
Correct. I prefer the Ford relay over Bosch. Ford requires only 3.8v to open. IIRC, th Bosch is around 9v.
Posted by: Jeff Bowlsby Dec 4 2017, 09:14 PM
Photo of the whole harness please. That brown wire is only on the 70-72 ignition harnesses if it is a 914 harness. Not correct for a 73 914. The yellow starter wire increased in size in 1973. Recommend to avoid the starter relays. It's one more thing to fail and if you think you need one, it's an indication of some other problem like dirty connections or grounds, or a bad starter.
Posted by: bbrock Dec 4 2017, 10:21 PM
Photo of the whole harness please. That brown wire is only on the 70-72 ignition harnesses if it is a 914 harness. Not correct for a 73 914. The yellow starter wire increased in size in 1973. Recommend to avoid the starter relays. It's one more thing to fail and if you think you need one, it's an indication of some other problem like dirty connections or grounds, or a bad starter.
Now it gets interesting! I think this is out of my old '74 bus. The two wires running to the tach were cut so I need to repair or replace them. Sounds like I'll be upsizing the starter wire too.
The brown and green wires threw me because they didn't show up on the '73 schematic. So, I clipped them just behind the male spades and pulled them out. But just as I did so, I thought, "hey, rear window defrost." So I looked at the schematic more carefully and then pulled out your schematic for the rear window defrost. And sure enough, it matched. Then I thought, "Doh! Why did I clip those?" And yes, my bus had a rear window defroster. What I don't know is whether this was how the ignition harness was configured on a '73 914 with the rear window defrost option. Or maybe that option ran with a completely separate harness up to the 12-pin connector? This configuration seems more tidy, and the brown pigtail you noticed is the other end of the brown wire terminating at the plastic connector for the defrost. I'm assuming this is intended to connect to the multi-spade ground on the engine block. I have a rear window with defrost, harness, and switch coming from Chris (tygaboy). So figured I'd sort out the final configuration once I had the defrost harness in hand. But since I have the attention of the expert...
I've owned a '70 914/4, two '73 914's, and a '74 bus. So this harness had to come out of one of those. I didn't think rear defrost was an option in '70. I also have an alternator harness with a blue pigtail wire that from some quick googling, connected to the aux heater blower on the bus. So I'm thinking both these harnesses are from the same vehicle. Both alternator harnesses are trashed, so you'll be seeing an order from me before this project is over.
Posted by: Jeff Bowlsby Dec 5 2017, 12:04 AM
See my comments interspersed below.
Photo of the whole harness please. That brown wire is only on the 70-72 ignition harnesses if it is a 914 harness. Not correct for a 73 914. The yellow starter wire increased in size in 1973. Recommend to avoid the starter relays. It's one more thing to fail and if you think you need one, it's an indication of some other problem like dirty connections or grounds, or a bad starter.
Now it gets interesting! I think this is out of my old '74 bus. The two wires running to the tach were cut so I need to repair or replace them. Sounds like I'll be upsizing the starter wire too.
No, I think it is a 1972-only 914 harness. It's hard if not impossible to replace the wires inside the casing. Don't think it's necessary.
The brown and green wires threw me because they didn't show up on the '73 schematic.
They would not be in a 1973 harness. They are the two wires for the heater fan in the 1970-72 engine bay.
So, I clipped them just behind the male spades and pulled them out. But just as I did so, I thought, "hey, rear window defrost." So I looked at the schematic more carefully and then pulled out your schematic for the rear window defrost. And sure enough, it matched.
Um no. The rear window defrost is a separate harness and it does not connect to the 12-pin connector and it routes through the forward fuse on the relay board. It has a special 2-pole female connector.
Then I thought, "Doh! Why did I clip those?" And yes, my bus had a rear window defroster. What I don't know is whether this was how the ignition harness was configured on a '73 914 with the rear window defrost option. Or maybe that option ran with a completely separate harness up to the 12-pin connector? This configuration seems more tidy, and the brown pigtail you noticed is the other end of the brown wire terminating at the plastic connector for the defrost.
The brown wire is the ground for the heater fan. Note the heater fan is not fused at the relay board other than thru the main fuse.
I'm assuming this is intended to connect to the multi-spade ground on the engine block. I have a rear window with defrost, harness, and switch coming from Chris (tygaboy). So figured I'd sort out the final configuration once I had the defrost harness in hand. But since I have the attention of the expert...
I've owned a '70 914/4, two '73 914's, and a '74 bus. So this harness had to come out of one of those. I didn't think rear defrost was an option in '70. I also have an alternator harness with a blue pigtail wire that from some quick googling, connected to the aux heater blower on the bus. So I'm thinking both these harnesses are from the same vehicle. Both alternator harnesses are trashed, so you'll be seeing an order from me before this project is over.
Posted by: bbrock Dec 5 2017, 09:28 AM
Thanks again Jeff! I guess a PO had replaced this harness in one of those other 914s with a '72. That doesn't surprise me. But I now see this harness fits the '72 schematic. I didn't mention that the largest casing near the connector is bunged up and will be replaced. So replacing the yellow wire shouldn't be difficult "while I'm in there". And I'm glad my first instinct to remove the brown and green wires wasn't wrong after all. Another difference is that this harness was missing the jumper between pins 10 and 11 to send power to the heater fan relay. I transferred that jumper over since it was the only wire not scorched by a shorted tach wire. This will be a proper '73 harness before I'm done. 
Posted by: bbrock Dec 6 2017, 11:43 PM
I've got another question. Can anyone tell me how long the lead for the tach wires is after it branches off from the supplementary air valve and oil pressure switch wires? Trying to figure out where to clip to crimp spade connectors on. Judging from pics on Jeff's site, I'm guessing 16-20 inches?
Thanks
Posted by: bbrock Dec 15 2017, 01:27 PM
I've got another question. Can anyone tell me how long the lead for the tach wires is after it branches off from the supplementary air valve and oil pressure switch wires? Trying to figure out where to clip to crimp spade connectors on. Judging from pics on Jeff's site, I'm guessing 16-20 inches?
Thanks
Hoping someone can help me with where to clip these wires to the coil before sleeving and crimping on new spade terminals. Rodents ran off with the originals so I don't have a reference for how long the leads should be.
Thanks.
Posted by: The Cabinetmaker Dec 15 2017, 02:20 PM
Just lay the harness where it goes and you'll see where to clip it. Btw. Don't make it the "exact" length. You need some extra(several inches) to replace the spade terminal when the wire breaks.
Posted by: bbrock Dec 15 2017, 02:51 PM
Just lay the harness where it goes and you'll see where to clip it. Btw. Don't make it the "exact" length. You need some extra(several inches) to replace the spade terminal when the wire breaks.
Thanks, but it won't be going in the car for another year or so. Was hoping to get all my harness repairs done so I can bag and store them until I'm ready to install. Fewer pieces to keep track of that way.
Posted by: 76-914 Dec 15 2017, 03:15 PM
I've got another question. Can anyone tell me how long the lead for the tach wires is after it branches off from the supplementary air valve and oil pressure switch wires? Trying to figure out where to clip to crimp spade connectors on. Judging from pics on Jeff's site, I'm guessing 16-20 inches?
Thanks
Hoping someone can help me with where to clip these wires to the coil before sleeving and crimping on new spade terminals. Rodents ran off with the originals so I don't have a reference for how long the leads should be.Thanks.
I have that harness in a box. If you can wait till this evening I'll lay it out, measure it and post the pic here.
Posted by: bbrock Dec 15 2017, 04:22 PM
I've got another question. Can anyone tell me how long the lead for the tach wires is after it branches off from the supplementary air valve and oil pressure switch wires? Trying to figure out where to clip to crimp spade connectors on. Judging from pics on Jeff's site, I'm guessing 16-20 inches?
Thanks
Hoping someone can help me with where to clip these wires to the coil before sleeving and crimping on new spade terminals. Rodents ran off with the originals so I don't have a reference for how long the leads should be.Thanks.
I have that harness in a box. If you can wait till this evening I'll lay it out, measure it and post the pic here.
That would be great! No hurry. I'll be working on harnesses off and on for a couple more weeks. But after that, I'm hoping to have good as new harnesses packed away in a box and check that off the project list.
Posted by: 76-914 Dec 15 2017, 09:41 PM
Crap. I forgot. I'll get it in the morning. Got caught up in fabbing my exhaust system, which led to installing the rear sway bar, which let to painting and on and on..... 
Posted by: bbrock Dec 15 2017, 09:59 PM
Crap. I forgot. I'll get it in the morning. Got caught up in fabbing my exhaust system, which led to installing the rear sway bar, which let to painting and on and on.....
That sounds WAY better than measuring a stupid harness. No rush!
Posted by: 76-914 Dec 16 2017, 06:55 PM
Here you go. I think this is the part you asked about. If not LMK.
Attached image(s)
Posted by: bbrock Dec 16 2017, 09:26 PM
That's it! Many, many thanks. 
Posted by: bbrock Dec 17 2017, 10:57 AM
Shoot! I was too tired last night and just looked at this again. I need the length of the other branch. The very longest two wires on the whole harness. should be a black/purple and black/red wire (at least on a '73).
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