A couple of weeks ago the automatic function stopped entirely, which was great except when I needed the windshield wiped. At the same time, I also lost the “wiggle the switch to operate” function.
I did what I felt like was an adequate amount of searching, and didn’t come up with a complete how-to for replacing the windshield wiper switch on a ’76 era J-Truck. There are several threads on adding intermittent wipers to other era trucks, but I didn’t see anyone document the replacement of the switch, so I decided to write this.
The first thing I noticed that was that no one on the entire internet showed a picture of the square bodied switch found under the dash of this truck. I tried the usual helpful places, NAPA and O’Reilly with no luck. The counter guy at O’Reilly even got “the book” out, but with no results!
At least one of the threads http://www.ifsja.org/forums/vb/showthread.php?t=167063I found referenced a Chevrolet part that was electrically identical to the Jeep part. From here I decided to run with the Chevy part interchange plan.
Based on the info in that thread I went with a switch for a ’68-’72 Chevy truck. I did some internet shopping, didn’t like any of the prices I saw, and since I really wanted to put my hands on this switch to verify it would work I headed back to O’Reilly. No luck! Even in “the book” they couldn’t sell me a Chevy switch! The internet for the win I guess, so with my fingers crossed I ordered from this place http://restorationpartssource.com/store ... wAodlB8Jvg, they seemed to have the best price.
When the switch arrived I noticed several differences right out of the box; 1. the body of the switch is round, 2. the thread pitch for the retaining nut is different than the stock Jeep part, 3. the switch shaft where the knob installs is a different length than the stock Jeep switch, and 4. the terminals on the back of the switch are oriented differently.
So the switch body is round, who cares. Moving on, the thread pitch is different. No big deal right, I’ll just get a new nut for the switch. HA! For whatever reason this took me an inordinate amount of time to locate. I tried two different local nut and bolt stores with no luck, the only thing I came away with was a piece of information – the thread pitch is ½-28. Hopefully that will help someone else!
What I ended up doing is ordering a windshield wiper switch retaining nut for a ’66 Corvette. I don’t care that it’s an overall insignificant part, I’m counting this as the truck having Corvette parts! Of note, is that based on the picture of the Corvette switch itself, it looks like the switch shaft might more closely match that of the Jeep. If I had it to do again, I’d consider ordering the switch and nut for a ’66 Corvette.
Part of the “wiggle to turn off” issue we had was related to the condition of the switch knob – the longevity of plastic from the 1970’s isn’t as great as one would hope and the guts of the switch had given up the ghost. The metal connector was still attached to the switch shaft, but the plastic had cracked and separated from the metal. This made it really easy to pull the knob off the switch, but also made it so that the knob could turn independently of the switch shaft. Crap. To remedy this problem, I went with super glue and a custom glue drying fixture (read: zip tie).
There was still one more switch knob issue; the switch shaft on the Chevy switch is considerably shorter than the Jeep switch shaft. The issue this causes is that when the Jeep knob is installed on the Chevy shaft, the depth of the knob won’t allow the knob to be fully depressed to engage the wash function. Not cool; anyone who’s joined us at ECI knows about the dust at Uhwarrie; no way are we going to go without a windshield washer! To solve this problem either the switch shaft has to get longer or the knob has to get shallower. Lengthening the switch knob seemed like it wouldn’t be as easy as making the knob shallower, especially since I was already working to repair the cracked knob.
To make the knob shallower I carefully cut the rubber way from the metal body of the knob, and then used a Dremel to grind the metal down to the depth that I had trimmed the rubber. After a couple of careful cycles of this, test fitting in-between, I had the knob just barely shallow enough to let the wash function work!
The last tweak to the knob was to shorten the metal clip that holds the knob to the switch shaft. This was as simple as using a pair of side cutters to remove the tang from the metal clip.
Remember that the Chevy switch is electrically identical to the Jeep switch; that doesn’t necessarily mean that the wires plug right in. The stock Jeep switch is connected with a plastic plug containing two wires, and a stand-alone wire with plug. Using a table (Figure 17-13) from a wiring diagram http://restorationpartssource.com/store ... wAodlB8Jvg and a multi-meter I was able to determine the pin letter of the Chevy switch as it compares to the Jeep switch. When examining the printed board of the stock Jeep switch, you can see a tiny “A” and “F” stamped into the plastic, and a “W” stamped into the flat pin itself.
Armed with this information, I unpinned the wires from the stock Jeep plug and attached them to the correct terminals on the Chevy switch. I got excited during this part and didn’t take a detailed pic, but I did get one of the switch mounted in the dash and you can see the individual wires attached to the back of the Chevy switch.
Almost there! The last thing I had (chose) to do was open up the dash hole in the J truck ever so slightly with a file. I think if I pushed hard enough the Chevy switch would have popped through, but with extra fine threads on a $30-ish switch I decided to err on the side of a slightly larger dash hole.
Once the dash hole is enlarged slightly, you can slide the switch (with the wires connected!!) through the back side of the dash. The bezel fit without issue, and I was able to use a straight pic tool to tighten the retaining nut inside it. I installed the modified knob permanently; I say permanently because part of the modifications I had to make to make it shallower necessitated removing the metal tang that lets the knob be removed from the switch shaft. If this thing has to come back apart if will be moderately violent and will require a new knob – most likely one out of a Chevy truck!
There you have it, all done! Much to my surprise the J-tuck’s washer pump still works!! All I needed to do was replace the 7 or so feet of what was rubber hose to the washer nozzles and fill the tank with fluid! I know this was a long write-up, what can I say, I just felt like typing! I hope this information helps someone else!
