The wiper and dimmer wiring is the only real challenge and that's if you don't want to leave the button on the floor and the switch on the dash.
I will say that delay wipers are easier to retrofit onto the 84-91 column because the parts are easier to come by.
The 1978-86 CK & 87-91 RV column harmonica plug with brake/turn/hazard, and key in ignition warning are the same plug and pinout.
73-77 use different plugs but it's a good excuse to upgrade the cab harness from 73-78 with the glass AGC fuse panels to the 1979 on up with the ATC fuse panels.
Here's my post from Chris's board...
I thought about doing this a while ago because the 85+ tilt/manual transmission 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.
The wiper switch routes grounds to the wiper motor not power.
There are no 12v power leads to the motor from the wiper switch contacts... Some Genius decided to make the 78-83 wiper switch panel lamp and the park ground wires the same color wire so be careful of which gray wire you move to the column plug.
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The Pak Con I 12020492 connector shell is obsolete but the individual terminals # 12040508 are available from Mouser etc...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
Wiper circuit # & Function table by year...
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