915 tranny electrical connections?

rickeolis · 07-08-2004, 12:15 PM

I need a picture or drawing showing where the wires for the backup lights and speedometer go on my stock 915 tranny.

What colors are the wires coming from my 1977's body for this?

Additionally, how about a circut list for the fusebox in the front? I never had a cover for it...

Thanks-

john walker's workshop · 07-08-2004, 12:18 PM

the backup wires are on the engine loom, not the body. they are on the end of the loom that goes to the starter.

rickeolis · 07-08-2004, 12:29 PM

Thanks John,
I have a loom with 2 wires that had broken ends coming from the engine bay just long enough to reach the fitting right at the very end of the tranny (near the rear seats), but when I hooked them up to it, I get neither backup lights or speedometer readings...
Where is the part on the tranny that feeds the backup lights? (Or was that it)??

-Rick-

rickeolis · 07-09-2004, 09:42 AM

Still need to know where the backup and speedo fittings are on this tranny- (I see one, but not the other...)
Anyone???

john walker's workshop · 10:06 AM

backup light switch on the end cover, speedo sender on the passenger side of the trans by the drive flange, secured in a recess with a wire clip and has a 2ft, 2 wire loom on it. loom for speedo goes into the tunnel and connects to a 2 wire connector by the shift coupler. loom for backups as previously described. shift to reverse and with an ohm meter across the terminals, see if the switch gets continuity.

Bones · Bones's Garage

Speedo assuming it's electronic is fed from a sensor on the box - near the output to the right side driveshaft. It's behind a disklike cover held on by a single screw and should have two wires running off to a plastic connector with a rubber shroud surrounding it.

rcecale · rcecale's Garage

Close up of reverse switch plug...

Both connectors...

Hope these help!

Randy

rickeolis · 07-09-2004, 11:38 AM

Guys, especially Randy, that was exactly what I was needing, thanks-

John W. thanks for noting that the reverse light is a normally open switch and how to check it-

Randy, using the pics, I can identify wire colors too, I really appreciate it!

-Rick-

rcecale · rcecale's Garage

Rick,

I meant to add this...

Ischmitz pointed out to me that since the switch is just a simple on/off switch, the wires should be able to connect either way. Mine is working just fine, connected the way you see it in the pic, so that should be a great place to start!

Randy

rickeolis · 07-09-2004, 12:19 PM

Thanks Randy, at least with this info, I can trace the wiring from its source and fix what it needs!

rickeolis · 07-12-2004, 09:34 AM

OK, no wonder I couldn't find the speedo connections (see pic); there is no mechanical connection on the end of the tranny either... What can I do?

Also: I have used my multimeter to determine that my backup light sending unit is working fine (thanks to John's suggestion), the problem must be in the wiring now. The correct colors of wires are the ones going to the sender.

Jim Sims · 07-12-2004, 09:42 AM

"OK, no wonder I couldn't find the speedo connections (see pic); there is no mechanical connection on the end of the tranny either... What can I do?"

If the car is set up with an electronic speedometer readout (gage on the dash) then order the speedometer pickup and retaining clip and install it. The speedometer pickup comes with the wiring, connector and boot to seal the wiring through the end of the tunnel. The 915 should have the magnet ring installed inside on the differential unless some one has removed it or replaced the differential. Jim

Bones · Bones's Garage

Jim are you saying that earlier 915 gearboxes have the speedo magnet ring too? For instance my '74 911S has a mechanical drive but will it have the magnet ring in there too so it could be upgraded for use with an electronic speedo?

Jim Sims · 07-12-2004, 11:01 AM

No, but if the tranmission housing (1976 and later) has the pickup recess and tapped hole cast into it (per the image posted) then the differential inside likely has the magnet ring attached. Check with a compass held against the recess in the housing and turn the transmission over and see if the compass needle deflects periodically as you turn the tranmission. Jim

Bones · Bones's Garage

wow ...thanks Jim I'll try.

rickeolis · 07-12-2004, 12:17 PM

That's pretty cool.
And here I thought I was going to be sh%^ out of luck...
Thanks VERY much again Jim!

-Rick-

rickeolis · 07-13-2004, 06:40 AM

As for the reverse light, I hooked it up as per the picture, and when I shifted it into reverse, it blew the fuse for the taillights!
I guess there's an exposed wire along the circuit somewhere that I need to find...

Any ideas on where I might find the speedo-sensor and cabling?

k9handler · 07-13-2004, 07:44 AM

I had that problem before rick, I would hit a bump and the backup switch would short out on the crossmember....so Nathan and I rewired it and that fixed it.

rickeolis · 08:04 AM

Thanks Smitty! At least I know where to go on that issue.

I took it out on a 40 mile run again last night and all the lights worked (except reverse) which haven't up until now. I think that circuit was affected by this problem, so I feel better about it all.

It still runs too hot as I push it, but an updated front cooler will fix that. It's on my list. I FINALLY have an appointment to get the windshield replaced on Thursday.

The car is fast but not as agile as the ‘69, it's getting though there as I keep tinkering, TTYL-

Alan.UK · 07-13-2004, 08:17 AM

I don't suppose anyone has a close up picture of the,

speedometer pickup and retaining clip

Thanks

Alan.UK