SERVICE MANUAL UPDATE SEC. 8A ELECT. DIAG. HORN FUSE CIRCUIT

Subject: HORN FUSE AND HORN CIRCUIT IDENTIFICATION

Model and Year: 1991 CAPRICE

Some early 1991 Chevrolet Caprice Sedan/Wagons, were built with Fuse 8 supplying battery voltage to the horn relay through Circuit 393. A change was made to supply battery voltage to the horn relay from Fuse 1 through Circuit 40. Fuse 1 and Fuse 8 are both 15 amp fuses.

Please update the 1991 Service Manual art, component location, and Chart #1 in the Service Manual Section 8A-40 Horns. Please update fuse block details in Section 8A-11 Fuse Block Details.

Revised pages are attached.

FUSE BLOCK DETAILS - SEDAN

FUSE DESCRIPTION PAGE ----- -------------------------------------------------------- ------ 1 Dome Lamp, Compass/Lighted mirror, Underhood Lamp, interior 8A-11-1 Courtesy Lighting, Keyless Entry Module, Power Antenna Relay, Power Door Locks, Power Mirrors, Vanity Mirror, Horn Relay

2 Audio Alarm Module, Cigar Lighter, I/P Compartment Lamp, 8A-11-2 Luggage Compartment Lamp, Radio Memory, Deck Lid Release, "Low" oil Module

3 ABS Overvoltage Relay 8A-11-2

4 Delco-Bose Amplifier 8A-11-2

5 Interior Dimmer Lighting 8A-12-2

6 Generator, Heater and Air Conditioning Controls, Keyless 8A-11-3 Entry Module, Cruise Control, Daytime Running Lights (DRL) Module

7 Not Used ---

8 Circuit not utilized 8A-11-4

9 Radio 8A-11-4

10 Windshield Wiper/Washer, Washer Fluid Level Switch 8A-11-4

11 Fuel injectors 8A-11-5 12 Arming Sensor, Diagnostic/Energy Reserve Module (DERM) 8A-11-5

13 Electronic Control Module, Electronic Spark Control 8A-11-5 Module, Emission Control Solenoids, instrument Cluster, Vehicle Speed Sensor Module

14 Panel Dimmer, Park/Marker/Tail Lights 8A-12-0

15 Rear Defogger 8A-11-6

16 Heated Mirrors 8A-61-0

17 Audio Alarm Module, Defogger Relay/Timer, Diagnostic/ 8A-11-7 Energy Reserve Module (DERM), Compass/Lighted Mirror, Fluid Warning Center. Headlight Switch Illumination, instrument Cluster, "Low" Coolant Module, Overvoltage Protection Relay, TCC Brake Switch, Twilight Sentinel Module, Daytime Running Lights (DRL) Module

18 Backup Lights, Turn Flasher, Turn Lights 8A-11-8

19 Brake Lights, Hazard Flasher 8A-11-8

20 Diagnostic/Energy Reserve Module (DERM), Electronic Control BA-11-8 Module (ECM)

CKT BRKR DESCRIPTION PAGE ----- ---------------------------------------- ------- A Power Seat Switches, Power Door Lock Relay 8A-11-6 C Power Window Switches 8A-11-3

FUSE BLOCK DETAILS - WAGON

FUSE DESCRIPTION PAGE ------- --------------------------------------- -------- 1 Lighted Mirror/Courtesy/Reading Lamps, Underhood 8A-11-10 Lamp, interior Courtesy Lighting, Power Antenna Relay, Power Door Lock Switch, Power Mirror Switch, Vanity Mirrors Lamps, Rear Glass Release Relay, Tailgate Lock Switch, Horn Relay

2 Audio Alarm Module, Cigar Lighter, VP Compartment 8A-11-12 Lamp, Rear Wiper Motor, Radio, instrument Cluster

3 Overvoltage Protection Relay 8A-11-12

4 Delco-Bose Amplifier 8A-11-12

5 Interior Dimmer Lighting 8A-12-3

6 Generator, Daytime Running Lights (DRL) Module, 8A-11-13 Heater and A/C Selector Switch ---- 7 Not Used

8 Rear Window Wiper/Washer Switch 8A-11-13

9 Radio 8A-11-13

10 Windshield Wiper/Washer Switch 8A-11-13

11 Fuel injectors 8A-11-14

12 Arming Sensor, Diagnostic/Energy Reserve Module 8A-11-14 (DERM)

13 Electronic Control Module (ECM), Electronic Spark 8A-11-14 Control Module, Emission Control Solenoids, Instrument Cluster, Vehicle Speed Sensor Module

14 Panel Dimmer, Park/Marker/Tail Lights 8A-12-0

15 Rear Defogger 8A-61-0

16 Heated Mirrors 8A-61-0

17 Audio Alarm Module, Defogger Relay/Timer, 8A-11-14 Diagnostic/Energy Reserve Module (DERM), Headlight Switch Illumination, Electronic Level Control (ELC) Height Sensor, instrument Cluster, Overvoltage Protection Relay, TCC/Cruise Release Switch, Daytime Running Lights (DRL) Module

18 Backup Lights, Turn Flasher, Turn Lights, Cruise 8A-11-18 Control

19 Brake Lights, Hazard Flasher 8A-11-18

20 Diagnostic/Energy Reserve Module (DERM) 8A-11-18 Electronic Control Module (ECM)

CKT BRKR DESCRIPTION PAGE ----- ------------------------------- --------- A Power Seat Switches, Power Door Lock Relay, 8A-11-15 Tailgate Lock Relay

C Power Window Switches 8A-11-15

CAUTION:

To avoid deployment when troubleshooting the SIR system do not use electrical test equipment, such as test lights, battery powered or A/C powered voltmeter, ohmmeter, etc., or any type of electrical equipment other than specified in this manual. Instructions in this manual must be followed carefully otherwise personal injury may result.

COMPONENT LOCATION 201-PG FIG.

Convenience Center.... LH side of I/P, left of ............... 18 26 Steering Column Fuse Block............ Mounted to LH side of I/P, accessible with LH Front Door open............... 18 26 11-0 Fusible Link A........ RH side of engine compartment, bolted to Battery Junction Block......22 31 Horn Relay ........... In Convenience Center...................31 43 Horn Switches......... One on either side of Inflator Module,in Steering Wheel Horn #1............... In LH front fender, at front of ........25 35 LH wheelhouse Horn #2............... In LH front fender, at front of ....... 25 35 LH wheelhouse C210 (11 cavities).... Body Harn to Turn/Hazard Switch Assembly Conn, under Steering Column.. 20 28 202-3 P102 ................. In dash panel, visible from engine compartment, behind LH front wheelhouse...................... 25 35 S225 ................. Body Harn, approx 36 cm from Fuse Block

TROUBLESHOOTING HINTS

(Perform before beginning System Diagnosis)

Check Fuse 1. If Fuse 1 is open, check for a short to ground in CKT 40 or CKT 29.

o Refer to System Diagnosis.

SYSTEM DIAGNOSIS

o See Symptom Table for the appropriate diagnostic procedure(s).

SYMPTOM TABLE

SYMPTOM PROCEDURE PAGE NUMBER ---------------------------- -------------- ------------- Horns inoperative from both Chart #1 8A-40-2 switches

Horns inoperative from one Check for open in circuitry on back side switch only of inflator Module. If OK, replace Horn Switch as necessary.

One Horn inoperative Remove connector from inoperative Horn. Attach one end of a fused jumper to B +. Momentarily touch the other end to the Horn's connector. If the Horn activates, repair open in CKT 29. If the Horn does not activate, check the Horn for a clean and tight ground at its case. If OK, replace Horn.

Horns "ON" at all times Chart #2 8A-40-3

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.