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The old driver 69 is having a little trouble with the brake lite switch on the junction block on the frame below the M/C. If I plug the switch in I get a lite on the tach. The brakes work fine--I mean the car stopps great! I think the little pressure switch is bad. If I unscrew it will I have to re-bleed the whole brake system? Is the switch still avaliable? Thanks Thad LeJeune
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Re: 69 brake lite trouble
Thad-----
I'm not completely sure that the switch can be removed from the block. However, if it can be so-removed, you should be able to do it without the need for subsequent bleeding of the system (as long as you don't depress the brakes while the switch is out).
Inside, you will find a "toggle" like switch. If it is "off-center", all you may need to do is to re-center it and re-install; that should reset the switch and stop the dash light from coming on.
The switch was never available from GM as a seperate part. Only the complete block assembly with switch was available. This was a one-year-only design for 1969, and it's long-since discontinued. As a matter of fact, there were several of these distribution blocks used over the 67-82 period. 1967-68 used GM #3904303; 1969 used GM #3956727; 1970-73 used GM #3980797; 1974-77 used GM #339780; and 1978-82 used GM #1257208. Only the latter 2 switches remain available from GM. The 67-77 units are a brake system distribution block and pressure differential sensing switch ONLY; they have NO proportioning function as many folks think. The 78-82 switch is a true COMBINATION valve having brake fluid distribution, pressure differential switch, and NON-ADJUSTABLE proportioning function. It was added to Corvettes to help deal with the higher vehicle weights which Corvettes "grew" to in the late 70's.
The thing that I've NEVER understood is why all the different valves used from 67-77? The brake systems were, basically, all the same from 67-77 and, for any given year within this range, the valve was the same for both manual and power brakes, so that wasn't a factor. In fact, except for the fact that the brake lines associated with each valve are slightly different, I don't see why the still-available 74-77 valve wouldn't work just fine for any 67-73 model.In Appreciation of John Hinckley -
Thanks JOE! *NM*
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