Wiper Switch

[tymartin1991]

I have an 81 Sierra Grande K15 that I switched the stock manual trans out for a TH400/NP208 out of an 85 GMC K25 and I am using that column in the truck. My problem is, I would like to eliminate the stock wiper switch in the dash and use the integrated one on the column, but the wiring in my truck is 6 wires and the new column only has 5? Any help would be wonderful before I go cutting wires and mess my wiring all up!

[hatzie]

I thought about doing this a while ago because the 85+ tilt columns are a bit easier to find and the Pulse wiper setup seems a bit more robust.

Wire #6 on the 78-83 dash switch is the panel lamp.  You don't need it...

GM uses a switched ground system on all of their wiper motors on this series of trucks.
There are no 12v power leads on the wiper switch contacts.
The wiper switch routes grounds to the wiper motor not power.

The wiper motor has constant ignition power from the WIPER fuse on two circuit 93 leads. Washer and Motor.

The optional CD4 delay option is plug N play after 1978.  It's a matter of buying the module and switch and plugging them in.
The 1978-1983 wiper plug from the cab harness plugs directly into either the 2 speed wiper switch or the pulse module and switch with no changes.
The 1984-1991 Pak Con 12020492 wiper plug from the cab harness plugs directly into either the 2 speed wiper switch pigtail on the column or the pulse module with no changes. 
The difference is the additional control wires between the pulse module and the wiper switch and the potentiometer in the wiper switch itself.
According to the schematics 1984 used a three wire control. 1985-1991 used a 2 wire control.  I've read you can use the 85-91 modules with the 84 switch and wiring so I wonder if the 1984 CD4 schematics may be wrong.
The Pak Con I 12020492 connector shell is obsolete but the individual terminals # 12040508 are available from Mouser etc...  You can use the shell from a dead pulse wiper column switch to build a new harness plug rather than chopping one off a cab harness.

Circuit #s and functions will be valid for all diagrams from 78-91.
1973-1977 do not have a Park Ground so are incompatible with either of the 78-91 Pulse wiper controllers and motors.
1973-1983 have dash mounted switches with panel illumination bulbs.
1984-1991 have column mounted switches with no illumination.
1985-1991 wiper motors no longer have the washer integrated into the motor. 

ON THE SWITCH
---------------
ON PULSE SWITCHES ONLY

1978-1983 (1984?)
    901 Pulsed Ground to Low circuit 91
    902 Potentiometer Wiper
    903 Potentiometer Element

(1984?) 1985-1991
   96 (two connections to pulse box) Loop up through the Potentiometer Wiper and Element and back to the pulse module.

ON BOTH SWITCHES

    94 ground out to motor Wash
    150 ground
    92 ground out to motor Hi
    91 ground out to motor Low and Park Low
    97 OFF Ground out to (Park) (this connection is not present on 73-77 wiper switches)
    8F variable power from dash lamp rheostat for switch illumination ONLY. This does not route to the switch contacts and is not present from 1984 on.

-----------------

WIPER MOTOR
-------------
PARK SWITCH

    97 Ground from OFF switch  (this connection is not present on 73-77 wiper motors)
    91B Ground from Low switch

WASHER

    94 Ground from Wash switch
    93B Washer Power from WIPER fuse

MOTOR

    92 Ground from Hi switch
    91A Ground from Low switch
    93A Motor Power from WIPER fuse

[hatzie]

Wiper wire color by circuit and year.

[hatzie]

You could move the dimmer to the column too but you don't have to.  It's three wires.  Power from headlamp switch, Low Beam and, High Beam.

The turn, brake, hazard, horn and, "ignition key inserted switch" harmonica plug may need to be adapted to mate with the 81 cab harness harmonica plug #12004147.
The 85 & 81 wiring diagrams show the same pinout and the same 12004147 plug so it may just plug in.

[tymartin1991]

I finally got the chance a few weeks back to get under my dash and get everything switched over to the new column. You were a huge help!! The dimmer was an easy one, just had to make the wire a little longer. The wiper switch was also very simplified with your explanation of what wire did what. Thanks a bunch!

[hatzie]

I finally got the chance a few weeks back to get under my dash and get everything switched over to the new column. You were a huge help!! The dimmer was an easy one, just had to make the wire a little longer. The wiper switch was also very simplified with your explanation of what wire did what. Thanks a bunch!

Thanks for letting me know. 

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