I have installed an '86 auto w/overdrive in an '81 - which, of course, lacks the wiring - I installed the '86 shifter, so I have everything there, but have nowhere to plug in the grey connector w/ blue wire and red/yellow wire. One I think (but not sure which) is for +12V, the other I suppose leads to the speedometer, so I have to do without the minimum speed cutout of the OD - but I can't find a wiring diagram for the circuit, don't know which wire is which, or how to wire around the speedo.

Any help will be greatly appreciated!!!

WmB

There is nothing "electronic" about the OD control (manual or auto) except the control relay — and the cluster wire is just for the Auto's "Upshift Arrow" (OD OFF) light. But that might pose a problem, since the '81's OD ON light is tied to ground, so it lights when it gets power in parallel with the solenoid.

However, the '86 up Auto arrow light (OD Off) is tied to +12V, so when the solenoid gets powered (from the relay), the paralled indicator wire puts +12 on the other side of the arrow bulb, turning it off when the OD is On.

Getting an '86 cluster wired in (just for that arrow light) may be more trouble than it's worth. But you will want an auto OD relay I think (maybe not???). Here are the Auto OD relay connections as they'd be in an '86...

1) Terminal 15 has 2 wires -- blue from fuse 11. And gray from one side of the shifter switch BUTTON (this turns the relay on with key on, and later lets the switch toggle it off & on as needed)

2) Terminals 87 and 87a (common) go to the light (yellow-red, 87a) and to the solenoid (white, 87). Relay ON, both wires get +12v. Relay OFF, both wires are grounded.

3) Terminal 31 has a black wire to ground. This turns the light on when OD is OFF.

4) Terminal 86 has a gray wire from the other side of the shifter switch button. This pulses the +12V from terminal 15 to 86, "toggling" the relay.

If your '81 shifter had a push-button shifter switch, it's wiring (for a manual OD???) should be OK at the OD relay side of the BLACK 2-pin connector under the carpet. The blue wire goes to relay 15, where it's joined by another blue wire from fuse 11 - and the black wire (gray from the '86 shifter sw) goes to relay 86.

I have more, but will stop here to see if I'm helping or snowing you. Post back please.

--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

THANKS FOR YOUR HELP. I HAVE BEEN EMAILED THE WIRING DIAGRAM FOR THE '86 OD AND IT'S VERY SIMPLE: CONNECT THE BLUE WIRE TO SWITCHED 12V AT THE FUSE BLOCK AND FORGET ABOUT THE LIGHT! (WHICH IS BASICALLY WHAT YOU WERE SAYING, BUT THE DIAGRAM MAKES IT SIMPLE TO VISUALIZE (PUN INTENDED).

THANKS AGAIN -

WmB

That's good. Then you now know there is no "speedo controlled feature".

You didn't say if the '81 originally had a manual OD, but if so, AND you use the manual OD relay, you will have to connect terminal 85 to ground to simulate the 4th gear switch. Otherwise the relay won't operate.

In this case, the OD light will be ON when the OD is on, as with the manual OD.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

I connected the original ('86) ground lead to a body ground (I am using the '86 shifter and all attached wiring) so I now have a fullly serviceable OD without the (IMHO) unnecessary light. Thanks for the tips.

WmB

Hi, you need an 86 speedo (instrument cluster really) as it is electronic.

12 volt power can be run from the fuse block.
--
Stef (81 245 B21A SU M46 3.91) 327000km my volvo pages

Which lead goes to the power block? And is it possible to cheat by omitting the speedo-controlled feature? I'd have to install the '86 rear axle to get the speedo signal and do a lot of rewiring to install the 86 instrument cluster . . . I'd be happy with totally manual OD control.