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I recently had a problem with our '76 Cutlass Salon wherein the headlights would go out altogether when the high beams were switched on.
First, let me explain that this car has the apparently-standard-for-Salon dimmer switch mounted on the steering column and activated by the signal lever, with the switch's integrated wiring harness entering the column beneath the switch and exiting at the bottom of the column jacket. Instructions probably apply in some measure to other Colonnade-era cars with column-mounted dimmers, but may differ (I am supposing) in some ways such as wiring colors. Moreover, our car has the tilt wheel option; the procedure for cars with standard column and tilt/telescope may differ.
Second, let me explain that the '76 Olds Factory Service Manual is of practically NO HELP WHATSOEVER with this particular job. I had to search forever to find any mention of this type of switch (inexplicably under "Accessories"!!!) and then the only useful info is that the gap between the button on the switch and the lever at rest should be adjusted to .020".
Unable to determine any other likely cause for the problem, I decided to replace the dimmer switch . . . which turns out to be AC Delco P/N D62360D, GM P/N 19106994 (don't mess around with cheap aftermarket switches unless you think you'll enjoy doing frequently what is described below). Here is what the new switch will look like (wiring harness coiled):
And here is the process, which will hopefully save someone else hassle and time (beyond having to read this detailed article!).
First, disconnect the battery.
Second, remove the knee bolster beneath the column (2 Phillips screws, 2 1/4" head hex screws) and carefully pull loose the a/c duct hose if your car is air conditioned.
Next, remove the dimmer switch cover by removing the one screw (1/4" hex head), pull it to the end of the signal stalk (but don't try to force it off the end!) and loosen the dimmer switch by removing 2 Phillips screws holding it to the column, sliding it toward the dash slightly and gently prying outward on it. Since it is attached to a wiring harness, you can't remove it altogether yet --- nor do you want to!
Then remove the four bolts (1/2" hex head) holding the steering column to the column mount, then the two nuts (9/16" hex head) holding the column mount to he dash. The mount will drop from the column, and the column will drop a few inches and hang under its own weight. You do not need to remove the steering wheel at all.
Now you can see the dimmer switch harness which exits the column at the bottom of the jacket and see its connector about 6 inches beyond. Disconnect it if you wish (and if you can), but I suggest that you simply cut it from the harness as close to the two connector plugs as you can. You will soon see why.
When I got to this point, I found a melted-together mess which took me (pointlessly) about ten minutes to separate, using a knife blade and a small screwdriver to cut and pry it apart!
I have no doubt that the 40-year-old original switch had developed resistance and was probably the cause of the melted connection I found coupling the switch harness to the dash harness, but I cannot say for certain. No way was I going to re-use those tiny, overheated connectors . . . not when much larger Delco Delphi 56 type terminals and insulators are readily available! I get them from Waytek Wire https://www.waytekwire.com/ See bottom of page for links to part numbers. Compare old-to-new terminal sizes here:
Now pull the old switch out of the column a few inches but don't pull the bottom of the harness into the column! Cut the old switch form the harness leaving as much wire as possible. Strip about 1/4" of insulation from the ends of these wires.
Then cut the three tiny terminals from the new switch's harness (yes, you read that right) and strip about 1/4" from them as well. Do NOT cut the new switch off the new harness, just the three tiny terminals at the opposite end! Using three non-insulated 18-22 ga. crimp connectors, crimp one old wire to each new wire (hint: it's easier if you crimp the connectors onto the new switch first --- that way you have only three crimps to make while crouching beside the column!). I matched the colors (blue replaced white in my new switch's harness, BTW) but it probably doesn't matter if you do so since by now you have no doubt figured out that you are about to use the old harness as nothing more than a "fish wire" for the new one.
Lube the exposed part of the old harness at the top of the column with some dielectric grease, and lube the lower half of the new harness as well. The fit is tight inside the column jacket, and you don't want it to bind! Then slowly pull the new harness through by pulling straight out of the column on the old wires at the bottom. If it binds, "back up" and try it again; be patient. Be sure that the harness is not twisted or kinked where it enters the column. Pushing gently at the top while pulling at the bottom helps, too. If the rest of the new harness needs a bit more lube, use it. It took me only about five minutes to pull/push it through this way.
Now "hook" the new switch into place on the column and slide it toward the steering wheel. Make sure that the harness is pulled as far into the column as you can get it and try to "snap" the barbed fitting on the bottom of the switch into the square "window" in the column; install the two Phillips screws which secured the old switch but do not tighten completely. Once you have done so, give the new harness one more tug at the bottom to pull it completely into the column. Place a .020" feeler gauge between the switch button and lever, pull the switch tightly to the gauge and tighten the screws.
Cut the new harness wires at the crimp connectors. Don't worry about the 1/2" total of length you have now removed from it; it is still more than long enough to do the job (at least it was on mine).
Here is where the larger (hence less likely to heat-up in high-amp circuits) Delphi 56 terminals come in. Strip about 1/4" from the end of the wires in the column and dash harnesses, and crimp male connectors to one and female connectors to the other. The inner "trough" of the connectors is for crimping to the bare wire, the outer trough is for crimping to the insulation. Now snap the insulators securely onto the terminals, being sure to connect green wire to green, tan wire to tan and black in the dash harness to blue (or possibly white) in the switch harness. Use a dab of dielectric grease in the end of the male connector/insulators for ease of disassembly and insurance against corrosion.
Assembly is essentially the reverse of disassembly. While installing the column mount to the column and the assembly back to the dash, be certain that switch wires (and none of the other column wires, especially the cruise control wire) are going to be pinched by column, bracket or dash!
I recommend that you route the new dimmer harness out of the lower left side of the column jacket and around the outside of the column mount for future ease of diagnosis and repair, though you may still have to drop the column to pull it out for eventual switch replacement (hopefully the new Delco switch will last 40 years as my original did!). Tie any excess wire length out of harm's way with a zip-tie.
At the bottom of the page you will see two different styles of insulators. Either can be used. I like the idea of having all of the circuit's connections in one insulator (just as they are in dozens of other places in the car), but admittedly this is where the problem developed before . . . albeit partly due to undersized terminals, in my opinion. So using three sets of individual insulators, one for each wire, is certainly an option. I did it this way since I didn't have any 3-wire insulators on hand and I wanted to use the car the next day.
I hope this helps someone; please feel free to copy and circulate if doing so is acceptable to the Classic Oldsmobile Forum administration.
I would note that for those who do not wish to change to the larger terminals, they can always run the circuit through a relay (like GM should have done in the first place).
I don't often post something like this, but when the factory service manual doesn't offer detailed (or really any) instructions --- and the job is somewhat involved --- I don't want to leave everyone else hanging. I'll bet that a lot of these great cars got scrapped over this problem or something equally as small which the manual doesn't adequately cover.
I would note that for those who do not wish to change to the larger terminals, they can always run the circuit through a relay (like GM should have done in the first place).
- Eric
Eric,
Relay or not . . . the problem that I have is that, assuming the old switch/wiring is bad, how will you fish the new harness through the column jacket without cutting off the new terminals anyway? I don't know what series terminals those tiny ones are. Do you know what they are called so that replacements can be found?
I don't mean to sound contentious; I simply don't know the answer to this one.
Jeff
Last edited by 76CutlassSalon; July 4th, 2016 at 07:09 PM.
I have no idea what they are called, and unfortunately, I can't speculate as to other ways of pulling the wires through, since I've never seen one of these columns.
I will say, though, that GM seems to have thought that you could get the wires pulled through without removing the terminals, as they supplied the new part with the terminals attached.
I'm guessing that GM might have once made available a special tool for exactly that purpose . . . but can we acquire one today? If so, I'd love to know what to call it (or a part number for it); perhaps one can be found on eBay if we can put a name/number to it.
Any retired Mr. Goodwrenches out there who can fill us in on this?
July 4th, 2016, 06:00 PM
