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I have a bad habit of tearing something apart without making notes. This of course leads to problems down the road.
I've done a couple searches and came up empty. The wiring diagrams I found were good, but they were small and the lettering was blurry, so here goes.

1) Where does the ground strap connect to on the transmission and the body.

2) There are two wires with blade connectors coming out of the same place above the starter. One obviously goes to the starter, where does the other one go?

3) In the picture below (or link if it doesn't show), Where do the labeled wires go? Correct me if I'm wrong, but I believe the two I've labeled go to the heater fan.



http://www.geocities.com/ecdez/wiring.html

I could figure most of these out if I had a voltmeter, but I don't so any help is appreciated. Thanks.

Hey, where is the backup fush holder for the backup lights that mounts in the clip over the coil in the fan shroud? I have the one you think is fan?? with two leads a red and a green/? wire, red going to my aux air regulator valve in front of the filler breather box and the green/red stripped going to the oil sender on top of the oil cooler base above the dist top left in the tin. I have a single wire coming off the harness that is a yellowish with greenish strip going to the neg coil term. The big yellow with black strip I thought was the fan and then it has a brown to ground also making up a four wire coupler plastic same to same color.
Cant see the starter to help but are there white wires? I think there is a two wire harness that goes to the heater? I see a harness of whites that go to the starter term. Bill

Ok...lets see. For the heater fan...the ground is that little brown one on the case, mounted with a screw. The hotside for the fan...is yellow and black. It may be that long one up to the left in the picture. The green wire from the condensor goes to the negative side of the coil. The fat black wire to the positive. There is a blue and green wire that hooks to the oil pressure switch. It looks like you have a red wire in there. That should be hot when the ignition is on. It goes to the auxiliary air reg. The back-up lights should have a black wire coming through the left firewall near the pressure regulator....that goes to an inlione fuse...then to the hot side of the coil. There may be...and this is strictly memory now...a brown and green wire..kinda short....that only leads to the coil. That goes to the hot side if you have one. I would need to know what kind of connectors and what collor the wires are near the starter. there are only one or two varieties...but it pays to be careful. Ray

Here's what I saw when I got under my '73 412 wagon just now, with references to the schematic diagram, too. 412 gurus, please correct me if I'm wrong!

If you've got "factory" VPC air conditioning, there's a red wire that goes to the starter's solenoid terminal (labelled 50, on top) along with the red wire from the starter terminal of the ignition switch (manual trans) or starter interlock safety switch (auto trans). Its purpose is to inhibit the A/C power relay while starting, to turn off the A/C loads and (most importantly) the compressor clutch. This wire goes to one end of the main A/C relay coil, the other end of the coil goes to an ignition switch feed. The low resistance to ground presented by the starter solenoid allows the relay to close while running, and when the ignition switch is in "start", the relay coil sees 12 volts on both ends, and de-energizes.

Also, there are one or two wires going to the fuel injection harness, white, hopefully with a "18" or "18-31" stencilled on the wire. The FI wire connected to ECU pin 18 lets the ECU know you're starting for enrichment purposes, and the second wire powers the cold start valve. If there's only one wire, the cold start valve and ECU pin 18 wire are joined together downstream from the starter. These go to the bottom spade terminal on the starter.

Be careful with the FI wiring, test it out with an ohmmeter (with both ends disconnected) to be sure what you've got. The ECU has minimal reverse voltage protection at its inputs, so be cautious with those white wires. I'm looking at building an external protector box for the ECU to make me sleep better at night.

Not really necessary for the ECU...in fact it may prohibit connectivity or change the overall resistance. In over 20 years of working on D-jet....I have never seen a voltage issue do any damage to the ECU. Generally the only thing that may damage it is jump starting with a really high amp source. Ray

Thanks for the help guys. I got the ground strap figured out last night. I still havn't figured out where the wire goes that comes out with the ignition wire for the starter. It has a blade connector, and the wire is fairly long.

I have updated the first picture from the info I recieved. I'll have to check some of the colors when I get home tonight to make sure they're labeled right.

I have another question. There are two bundles of wires coming out of the alternator. One houses the wires that go to the regulator. The other has two wires with ring connectors on the ends. I'm sure that one of those wires connects to the positive side of the starter, but what about the other one? Does it go to the positive side of the starter also? It's slightly longer than the one for the starter.

Does anybody know where I can find a good wiring diagram?


http://www.geocities.com/ecdez/wiring.html

The black plug should go to a relay mounted on the aircleaner shelf on my 2dr. right eng compartment relay is kinda big and the connector is to the left side of the relay. The Bid Red with white strip go together with the one straight down with the two on one side tee coming from the battery and alt. I have a three wire plastic coupler that has the same colors together for the three wires coming from the right harness under the taillight and going to the engine harness. I think black green brown.
The circled one I cant tell but is it either the Alt back wires?? I dont know about that one yet! Bill

Maybe Ray can confirm some of this.. Bill

Ecdez...wiring diagrams online...

http://www.type4.org/technology/wiring

The late 412 diagram is from a Mitchell manual (I know because our local library has the exact same diagram in a Mitchell manual), and is sort of hard to read and may not be 100% accurate. The earlier diagrams should suffice for engine compartment wiring, though, and one of them's in living CoLoR!

Thanks guys, I got it almost all hooked up this weekend. There's still a couple wires I need to sort out.

There is a spot on the drivers side of the tranny where a blade connector plugs in. What is this for. Once I know what it is for, I can track down the wire that goes to it.

ecdez wrote:Thanks guys, I got it almost all hooked up this weekend. There's still a couple wires I need to sort out.

There is a spot on the drivers side of the tranny where a blade connector plugs in. What is this for. Once I know what it is for, I can track down the wire that goes to it.

I think that is one of those pesky diagnostic wires.

There are no diagnostic wires on the tranny. That is either an oil pressure switch for the electronic version of the deceleration valve, or possibly for the air injection systems of some cars. There may even be the rare use of a back-up light switch...but I doubt it. Those switches were usually on the shifter. Ray

bizarre

While doing my tranny work, I ran across the same connector. There was a wire hanging in the vicintiy, but not connected. I'll climb under there this afternoon and take a pic and send to you.

On reinstallation, I subsequently hooked the wire back up. Reading this thread has made me wonder if it was disconnected on purpose.

The wire has a very elongated rubber cover on it, way to much for the requirement. Might not suppose to go where I have it connected.

Aaaah!!!! If that switch is on the left hand side...it is the kick down solenoid switch for the passing gear in the automatic....you do know about that part don't you? Its hooked to a switch under the gas pedal. When you floor it and press the switch....the tranny automatically downshifts to the next lower gear...with the throttle wide open. Great for getting on the interstate. Ray