black wire in engine compartment...

[chitwnvw]

'79 FI bus.

Hey,

Finally got the engine back into the Troutmobile. Got most of the wiring figured out...except, I've got one wire in my engine compartment and I can't figure out what it is for.

It comes into the compartment on the drivers side, there are two black wires which are joined by one from the double relay. One black wire goes to the fuse for the back up lights/coil, the other goes to the tail lights...then there is this other black wire. What is it supposed to power?

Thanks.

[vdubyah73]

to the switch on tranny?

[chitwnvw]

to the switch on tranny?

Hmmmm, that might make sense, are there two black wires coming from the trans into the engine compartment...I'll have to crawl under there and take a look in the morning.

[Sylvester]

How about some pictures of the Troutmobile?

[chitwnvw]

You nailed it Bill, it is the two wires coming from the Trans. Are they both black because when the switch is closed they are both hot? Do they both go to the backup lights?

[vdubyah73]

can't remember how it all hooked up on an FI application. b/u lites need at least power then fuse then switch then b/u lites andthey ground thru the tail light ground, which would be the brown wires spade connected to body on either side of the rear engine hatch. can't remember anything with double relay, or , after a quick glance at bentley, the heater blower relay. remember my bus had had a pretty good engine fire before i got it 6-7 years ago. i spliced a '76 harness into my '77. at first with carbs then FI then back to carbs.

[chitwnvw]

So I finally got a look into another FI bus.

Black from double relay to fuse, then splits with part going to coil, the other to the backup lights. The other black wire connects into the downstream portion of the fuse. Still don't fully understand what is going on here, are the backup lights powered by the coil?

[dtrumbo]

... are the backup lights powered by the coil?

No, they're powered by the same power that powers the coil.

[chitwnvw]

... are the backup lights powered by the coil?

No, they're powered by the same power that powers the coil.

Haha! I think I finally understand, Dick. So power comes from the double relay through the fuse and then is sent back to the switch on the tranny. When the backup switch is closed power flows to the backup lights!

[dtrumbo]

You're on the right track. The power comes from the ignition switch when it's in the 'on' position. It travels via a black wire to the relay that powers your heater blower that's in the engine compartment. It splits off there and goes via another black wire to the coil where it splits again and goes via more black wires to the double relay and the fuse that protects the black wire that goes to the switch on the transmission that when closed provides power via yet another black wire to your back up lights. Your actual Troutmobile may vary due to modifications by previous owners.

[Amskeptic]

You're on the right track. The power comes from the ignition switch when it's in the 'on' position. It travels via a black wire to the relay that powers your heater blower that's in the engine compartment. It splits off there and goes via another black wire to the coil where it splits again and goes via more black wires to the double relay and the fuse that protects the black wire that goes to the switch on the transmission that when closed provides power via yet another black wire to your back up lights. Your actual Troutmobile may vary due to modifications by previous owners.

Dick? We gots to clean up this dizzying journey.

Black wire from ignition switch goes to junction at heater blower relay to coil +15.
Coil +15 then feeds double relay and reverse light inline fuse to the reverse switch on transaxle . A black wire comes back from reverse switch that branches to each reverse light.
Colin

[dtrumbo]

Since this is 'Type 2' rather than 'Electrical', I thought we could make the journey a little more fun. Clean as needed.