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#1 |
Registered User
Join Date: Nov 2014
Location: Alameda, CA
Posts: 877
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Column update (early column to late column with dimmer, wipers)
I was wondering whether swapping in a newer column with more modern features (wipers mainly, don't care where the dimmer is) is reasonable. I understand I'd have to do some custom wiring but hopefully not everything.
My wipers are moving especially slow so I need to go figure out why, I can swap the motors if needed. Has anyone done this?
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1973 C20, 350/350 |
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#2 |
Registered User
Join Date: Oct 2009
Location: Buhl, Idaho
Posts: 1,438
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Re: Column update (early column to late column with dimmer, wipers)
Would like more info on this as well.
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86 c30 crew cab dually 454/400 4/6 drop SOLD 1-8-11 1981 chevy K10 short Bed Scottsdale SOLD 10-26-2020 67 GMC Stepside Straight six/3 on the tree "The Peach" 2020 Silverado Double Cab LT Z71 5.3 8 speed Daily Driver K10 build http://67-72chevytrucks.com/vboard/s...d.php?t=671934 The Peach build http://67-72chevytrucks.com/vboard/s...d.php?t=733903 ![]() |
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#3 |
Registered User
Join Date: Jun 2011
Location: St Robert, Mo
Posts: 730
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Re: Column update (early column to late column with dimmer, wipers)
Its easier to just add delay wipers to your truck... just change the switch and you are good to go...
On your motor try cleaning the connections and grounds first, but more than likely you need a new wiper motor. |
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#4 |
Registered User
Join Date: Nov 2009
Location: Sherman, ME
Posts: 2,359
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Re: Column update (early column to late column with dimmer, wipers)
In 1978 GM changed these trucks over to a new design permanent magnet wiper motor with an externally wired park switch. That resulted in some changes to the switches & wiring.
The older 73 - 77 wiper motors will not work correctly with the 78+ switches. To use a 78 or newer switch, you also need to change to a 78 or newer wiper motor (I believe they still bolt up the same). And you'll need to change the wiring to match. |
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#5 |
Senior Member
![]() Join Date: Jun 2009
Location: Phoenix AZ
Posts: 4,557
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Re: Column update (early column to late column with dimmer, wipers)
I would really like to know what is involved in wiring in one of the newer motors. If it is just involving cutting off one plug and splicing another one on, it wouldn't be too bad.
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AZPartsLocators on Instagram 1972 Cheyenne Super Short Bed big block "Blackie" 1977 Crew Cab GMC Short bed with 4BT Intercooled Cummins Diesel and a 4L80e "The Junkyard Dog" 1985 Crew Cab Chevy dually with 5.9 Cummins "The Big Dog" This is what my dad liked to be called by the grandkids before he passed so it seems fitting for his old truck. |
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#6 |
Registered User
Join Date: Nov 2009
Location: Sherman, ME
Posts: 2,359
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Re: Column update (early column to late column with dimmer, wipers)
Yes, I suppose it could be done by splicing on different plugs (at both the motor & switch). The externally wired park switch in the 78+ motors also requires an extra wire to be run between the motor & switch. And the wire color coding is different so you'd have to keep track of what wire you splice where so they match on both ends.
Another alternative would be to remove all of the wiper wiring from a 78+ donor truck and transfer it over into the 73-77 truck that's being converted to the newer style motor. This could be done without cutting or splicing any wires by extracting the terminals (wires & all) from the bulkhead connector. The engine compartment side probably wouldn't be too bad since the wiper motor wiring is mostly out on it's own & easily separated from the rest. But the under-dash side is bundled / taped together and would be a bit harder to extract. I believe the connectors are different for the 78-83 dash mount switch vs. the 84+ column switch so you'd have to factor that into your donor truck search. Also, I think it's 85+ that have the electric washer pump mounted in the reservoir (instead of the mechanical pump driven off the wiper motor). This 2nd method would definitely be more work extracting & swapping all the wires. But I think the end result would be a cleaner installation without any splices. And should a person ever have to do any troubleshooting, not having any inconsistencies of one wire color spliced to another would make that process easier. |
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#7 |
Registered User
Join Date: Nov 2014
Location: Alameda, CA
Posts: 877
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Re: Column update (early column to late column with dimmer, wipers)
I'm not sure mine even has washers at this point. With no snow here it isn't too important.
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1973 C20, 350/350 |
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#8 |
Moderator
![]() Join Date: Oct 2008
Location: Wentworth, NH
Posts: 4,950
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Re: Column update (early column to late column with dimmer, wipers)
One thing that's worth noting is the intermediate shaft from the rag joint to the column end will need to be changed to match the new column. Good time to do a Jeep XJ U-Joint shaft swap.
This is what I posted on another board about the electrical part of this swap... I thought about doing this a while ago because the 85+ tilt columns are a bit easier to find and the later Pulse wiper setup seems a bit more robust. 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 will need to be changed from the 73-77 cab harness harmonica plug to the 78 and later piece. There are a couple different harmonica plugs between 73 & 77 so get your wiring diagrams and the diagrams for the donor. 78 to at least 86 were the same and I believe all the way to the end in 91. Chase the wires using the GM circuit #s. GM was consistent about the circuit #s in the wiring diagrams across multiple years but not the wire colors on the chassis. As Ray noted the 73-77 wiper motor will need to be swapped to a 78-80 motor. Wire #6 on the 73-83 dash wiper 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... 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.ON THE SWITCH --------------- ON PULSE SWITCHES ONLY 1978-1983 (1984?) (1984?) 1985-1991 ON BOTH SWITCHES ----------------- WIPER MOTOR ------------- PARK SWITCH WASHER MOTOR Wiper wire color by circuit and year.
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And please let us know if and how your repairs were successful. Last edited by hatzie; 05-29-2016 at 08:54 AM. |
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