I’m presently tinkering with the wiring setup. 96 Caprice LT1/4L60E into 82 XJ6. I’m about to attempt integrating the OEM GM CC. I have a few schematics and some info on it; probably not enough to effectively complete the install.
The one hangup I struggle the most with is disengaging the cruise. I understand that it will operate similar to the VSS / torque lockup, in that it requires a ground to deactivate. However, the signal must be wired through the CHMSL (third brake light), which I do not have. I’ve been convinced that a resistor of some sort could be used in lieu of the brake light; they are, after all, simply providing resistance.
Google led me to GM Service bulletin #92-8-160. From 1992, but same model car, same principle(?).
From the bulletin:
---------- The cruise control system may not operate on the 1992-93 B-cars. On wagons, the cruise control may be intermittent, may drop out while driving, or may fail to engage.
------ The ground for the brake switch signal to the cruise control module (part of the stepper motor assembly) goes thru the Center High Mounted Stop Lamp (CHMSL). If the stop lamp bulb is burned out, there will be no ground path for the cruise control. On wagons, the contacts for the CHMSL on the tailgate glass may corrode, causing intermittent operation. Adding a resistor will allow a ground through the brake switch without going through the bulb.
3. Locate the blue 8-way connector (C405), as shown in Figure 1. Find the yellow wire in cavity A, and the black wire in cavity F. The complete circuit is shown on page 8A-110-4 of the Service Manual.
- Obtain a 390 ohm, 2 watt, 5 percent resistor from a local electronics supply store. Splice the resistor from the yellow wire to the black wire, as shown in Figure 2. Be sure to solder the connections, then tape the wires."
I’m still contemplating where this fits into the system, and how it will interact with the brake pedal status relay per Andrew’s Tech Tip #5. Or should I try this on it’s own new circuit off the brake pedal switch?