SERVICE MANUAL UPDATE SEC. 8A CRUISE MODULE BRAKE SWITCH

Subject: CRUISE MODULE MECHANIZATION, NORMAL BRAKE SWITCH STATE

Model and Year: 1992 CAPRICE

1992 "B" cars were built with a cruise module that has to have the brake signal input pulled low at terminal "G" for cruise control to function. This is accomplished by a small amount of current flowing from the cruise module, through circuit 820, to the Center High Mount Stop Lamp (CHMSL) bulb to ground. When the brakes are applied and the brake switch closes, the cruise module and circuit 820 receive BATT voltage. This allows the CHMSL bulb to illuminate and the cruise module to sense that the brakes are applied.

Please replace pages 8A-34-0 and 8A-34-1 of the 1992 Service Manual with the attached.

The brake switch mechanization, as shown on page 8A-34-0, has been re-drawn to show it in the "normally open" state. Step 2 of the troubleshooting hints, on page 8A-34-1, includes checking the CHMSL in the event cruise control is disabled.

COMPONENT LOCATION 201-PG FIG./CONN ------------------ ---------------------------------------- --------- Brake Light/Cruise Release Switch ........ Attached to Brake Pedal Bracket (Bottom Switch) 14 24

Cruise Control Module ... Fastened to LH Front Wheelhouse 40 61/202-6

Fuse Block .............. Mounted to LH I/P, accessible with LH Front 14 24

Multi-Function lever .... LH side of Steering Column 18 29

Torque Converter Clutch (TCC)/Cruise Release Switch ................ Attached to Brake Pedal 14 24 Bracket (Top Switch)

Vehicle Speed Sensor (VSS) Module .......... LH I/P, top of Convenience 14 24/202-10 Center

C204 (37 cavities) ...... Body Harn to Engine Harn, 23 37/202-2 behind RH I/P, between Blower Motor and I/P Compartment

C215 (4 cavities) ....... Body Harn to Steering Column 17 27/202-3 Harn, on Lower Steering Column, to Cruise Control Switch

G104 .................... RH Rear Cylinder Head, below 9,10 16/18 Exhaust Manifold

P100 .................... RH I/P, forward of Blower Motor 6 13

P102 .................... Visible from Engine Compartment, 40 61 behind LH Wheelhouse

S109 .................... Engine Harn, approx 12 cm from A/C Pressure Cycling Switch Conn Breakout

S237 .................... Body Harn, approx 12 cm from C101 Breakout

S240 .................... Body Harn, approx 4 cm from Turn/Hazard Switch Conn Breakout

S259 .................... Body Harn, approx 15 cm from Fuse Block Breakout

TROUBLESHOOTING HINTS

(Perform before beginning System Diagnosis)

1. Check that Cruise Control Module Linkage is connected and moving freely.

2. Check Cruise Cable Adjustment. See SECTION 9B.

o Make sure that Center High Mounted Stoplamp is working. If inoperative, Cruise Module will be disabled.

o Refer to System Diagnosis.

SYSTEM DIAGNOSIS

o Perform the System Check and refer to the Symptom Table for the appropriate diagnostic procedure(s).

o If speedometer is inoperative, refer to "Vehicle Speed Sensor," page 8A-33-2.

SYSTEM CHECK

ACTION | NORMAL RESULTS ------------------------------------ | -------------------------------- [1] | o Drive vehicle above 25 mph. | Vehicle maintains set speed. o Cruise Switch to "ON." | o Depress Set Switch once and release. | o Remove foot from accelerator pedal. | | [2] | o Depress and hold Set Switch until| Vehicle decelerates and vehicle speed decreases by 4 to 5 mph.| maintains a new lower set speed, | if speed is above 25 mph. o Release Set Switch. | | |

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.