For 1990-2009 cars

# SERVICE MANUAL UPDATE SEC.8A-ELECTRICAL DIAGNOSTIC

#### VEHICLES AFFECTED: 1989 "C" CAR ONLY

The following reflect product changes. These pages are contained herein:

8A-44-4 ANTILOCK BRAKE SYSTEM:

Location of the Electronic Brake Control Module (ECM) with (SIR) was added.

8A-64-2 AIR CONDITIONING: COMPRESSOR CONTROLS

Reflect updated component location.

8A-65-2 AIR CONDITIONING: TEMPERATURE CONTROL

Reflect updated component location.

8A-201-8 COMPONENT LOCATION VIEW:

Figure C showing the location of the Electronic Brake Control module (EBCM) (without SIR) has been added.

8A-201-20 COMPONENT LOCATION VIEW:

Figure C showing the location of the Electronic Brake Control Module (EBCM) (with SIR) has been added.

Please update your respective Service Manuals accordingly.

SYSTEM DIAGNOSIS

Refer to Section 5E and 5E1 for System Diagnosis.

Refer to Cell 41 for BRAKE Warning Indicator diagnosis.

COMPONENT LOCATION Page-Figure

Anti-lock Diode ...............Behind LH side of I/P, near shroud.. 201-16-A Brake Hydraulic Unit...........Engine compartment, LH front of dash.201-3-A Brake Light Switch.............Behind LH side of I/P, right of......201-14-A steering colunm Electronic Brake Control Module (EBCM)..................Behind LH side of I/P, near shroud...201-8-C Electronic Brake Control Module(EBCM)(with SIR).........Behind center of I/P.................201-20-C Fluid Level Sensor............Part of Brake Hydraulic Unit.........201-3-A Fuse Block.....................LH side of I/P, behind access door...201-5-B Fusible Link N.................Center front of dash, at Jump Start Junction Block.................201-4-A Fusible Link P.................Center front of dash, at Jump Start Junction Block.................201-4-A Hydraulic Pressure Switch......Part of Brake Hydraulic Unit ........201-3-A Hydraulic Pump Motor Relay.....LH front of dash, left of............201-3-C Wiper Motor Module ignition Switch............... Behind I/P, on center of steering column Main Relay.....................LH front of dash, left of........... 201-3-C Wiper Motor Module Main Valve Solenoid .......... Engine compartment, part of Brake Hydraulic Unit.................201-3-A Park Brake Switch..............Behind I/P, on park brake ...........201-7-B assembly Pump Motor.................... Part of Brake Hydraulic Unit ........201-3-A Speed Sensors ............... On brake assembly, at each wheel 201-4-D Valve Block................... Part of Brake Hydraulic Unit ........201-3-A C200(60 cavities)............. Behind LH side of I/P, right........ 201-14-A of steering column C206(48 cavities)............. Below LH side of I/P, on bracket.....201-16-A C309(4 cavities)...............At RH front door sill................201-18-A G100...........................Engine compartment, ahead of.........201-2-A LH wheelhouse S208...........................Composite harness, behind center.... 201-8-B of I/P S212.......................... Composite harness, behind LH.........201-16-A side of I/P S216.......................... I/P harness, near C200...............201-12-A S252.......................... Composite harness, LH rear compartment of engine................201-3-A S266.......................... Composite harness, behind LH.........201-16-A side of I/P S268.......................... Composite harness, at LH.............201-3-A front strut tower

#### TROUBLESHOOTING HINTS

Try the following check before doing the following System Diagnosis.

Make sure that all sensor connectors are firmly seated.

Go to System Diagnosis for diagnostic tests.

#### SYSTEM DIAGNOSIS

Check for the presence of BCM Diagnostic Codes using the procedures in Section 8D. These refer to the Trouble Code Diagnostic Charts in Section 8D for the appropriate diagnostic procedures if codes are set.

If no codes are set, refer to Section 1C.

#### CIRCUIT OPERATION

The Temperature Sensors provide input signals to the Body Computer Module which are used by the Body Computer to control the Compressor Clutch, Blower Motor, and Air Delivery.

COMPONENT LOCATION Page Figure ------------------ ----------- Body Computer Module (BCM)......RH side of I/P, behind glove box.... 201-11-A Electronic Climate Control (ECC)Programmer................Behind RH side of I/P, on RH side of.201-17-A plenum Fuse Block................... LH side of I/P, behind access door.. 201-5-B In-Car Temperature Sensor.... Top RH side of I/P, behind name......201-10-A plate Outside Temperature Sensor... Center of radiator support.......... 201-1-C C108 (1 cavity)...............Lower LP side of engine compartment, in front of ELC Compressor Assembly..201-2-A C200 (60 cavities)............Behind LH side of I/P, right of..... 201-14-A steering colunm. C210 (7 cavities).............Behind LH side of I/P, taped to composite harness ..................201-16-A G100 ........................ Engine compartment, ahead of........ 201-2-A LH wheelhouse G101..........................RH side of engine, on generator......201-0-A mounting bolt S218......................... Composite harness, behind RH........ 201-17-A side of I/P S235......................... Composite harness, behind............201-8-B center of I/P S250......................... Composite harness, behind RH........ 201-12-B

#### SYSTEM DIAGNOSIS

Refer to Section 1 C for diagnosis.

#### CIRCUIT OPERATION

The Compressor for the Air Conditioning System is belt-driven by the engine through the Compressor Clutch. The clutch allows the Compressor to be disengaged from the engine whenever air conditioning is not required.

The operation of the Compressor Clutch is controlled by the Electronic Control Module (ECM) by grounding the 366 circuit at connector C1, terminal C6. This energizes the A/C Compressor Control Relay and voltage is applied to the Compressor Clutch.

The Climate Control Panel (CCP) accepts input requests from the driver via the front panel push buttons. The input signals determine the operating mode for the Climate Control System and are sent to the Body Computer Module (BCM) over a data line (Circuit 718). If the BCM senses that cooling is required, it will signal the ECM to turn on the Compressor

COMPONENT LOCATION Page Figure

A/C Compressor Control Relay RH front of dash, on bracket... 201-4-B A/C Low Pressure Switch .......Near RH fender, on A/C......... 201-5-A accumulator Body Computer Module (BCM) RH side of I/P, behind glove box201-11-A Compressor Clutch.................RH front of engine, on A/C .....201-2-B compressor Compressor Clutch Diode........Lower front of engine, in.......201-2-B engine harness Coolant Temperature Sensor........Top center of engine, behind....2014-C distributor Electronic Control Module (ECM)...Behind RH side of I/P, near.... 201-12-B shroud Fuse Block........................LH side of I/P, behind access...201-5-B door Power Steering Pressure Switch... Lower rear of engine compartment, on steering box... 201-1-E Refrigerant High Side Temperature Sensor............................Engine compartment, near RH....201-5-A strut tower Refrigerant Low Side Temperature Sensor............................RH front of dash, on A/C line.. 201-4-A Relay Center......................Behind RH side of I/P, at RH... 201-17-A shroud Throttle Position Sensor (TPS)....Top of engine, behind throttle..201-0-A body C108 (1 cavity)...................Lower LH side of engine compartment, in front of....... 201-2-A ELC Compressor Assembly C200 (60 cavities)................Behind LH side of I/P, right of.201-14-A steering column C210 (7 cavities).................Behind LH side of I/P, taped to composite harness...............201-16-A C225 (56 cavities)................Behind RH side of I/P...........201-12-B G100 .............................Engine compartment, ahead of....201-2-A LH wheelhouse G101 .............................RH side of engine, on generator.201-0-A mounting bolt S144............................. Engine harness, on RH side of...201-0-C rear valve cover S201 ............................ Composite harness, behind LH....201-16-A side of I/P S218 .............................Composite harness, behind RH....201-17-A side of I/P S235 .............................Composite harness, behind.......201-8-B center of I/P S250 .............................Composite harness, behind.......201-12-B RH side of I/P S262 ............................ Composite harness, behind.......201-8-B center of I/P S293 .............................Engine harness, behind RH.......201-12-B side of I/P

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.