🏷️ Basic Information

Make:

BMW

Model:

635CSi

Model Variant:

M6

Year:

1988

Chassis Code:

E24

Manual Product Name:

BMW 635CSi M6 Electrical Troubleshooting Manual 1988 ETM

Manual Type:

Electrical Troubleshooting Manual (ETM)

👋 Introduction

Target Audience:

BMW owners, independent repair shops, automotive technicians specializing in vintage BMWs.

Manual Value Proposition:

Provides essential, manufacturer-specific electrical diagnostic data for a classic performance coupe, often difficult to find in generic repair manuals.

Diagnostic Focus:

Dedicated electrical troubleshooting, crucial for complex systems of this era.

Convenience:

Instant digital download eliminates shipping time and cost, providing immediate access.

📋 Manual Details

Primary Focus:

Electrical systems and diagnostics for BMW 635CSi / M6 (E24) models of 1988

Estimated Page Count:

Varies by specific ETM release, but typically comprehensive for electrical systems.

Manual Format Digital:

PDF

Language:

English

Digital Delivery Method:

Instant Download

📖 Manual Coverage

Engine Management Electronics:

Bosch Motronic ECU, fuel injection, ignition system wiring, sensors (crankshaft, camshaft, knock, lambda), actuators (injectors, idle control valve).

Lighting System:

Headlights (low/high beam), taillights, brake lights, turn signals, interior lighting, fog lights, license plate illumination.

Instrument Panel And Gauges:

Speedometer, tachometer, fuel gauge, oil pressure, coolant temperature, warning lights (ABS, check engine, brake, oil, battery), OBC (On-Board Computer) wiring.

Power Windows And Locks:

Wiring diagrams for power window motors, central locking system, door lock actuators, switches.

Heating And Air Conditioning:

HVAC blower motor, climate control unit, compressor clutch wiring, temperature sensors, actuators.

Audio And Communication:

Radio wiring, speaker connections, antenna system, antenna amplifier.

Wiper And Washer System:

Wiper motor, washer pump, intermittent wiper module, controls.

Starter And Charging System:

Starter motor circuit, alternator wiring, voltage regulator, battery connections.

ABS Anti-Lock Braking System:

ABS control unit wiring, wheel speed sensor connections, hydraulic modulator unit wiring.

Cruise Control System:

Control module wiring, speed sensor input, actuator connections, steering wheel controls.

Body Control Electronics:

Central locking, power mirrors, seat adjustments (if power equipped), sunroof operation.

Fuse And Relay Locations:

Detailed diagrams indicating fuse box layouts, relay assignments, and fuse amperage ratings for various circuits.

Troubleshooting Flowcharts:

Systematic diagnostic procedures for identifying electrical faults based on symptoms.

Wiring Diagrams:

Comprehensive, color-coded wiring schematics showing component interconnections, wire colors, and terminal designations.

Component Location Diagrams:

Illustrations and descriptions showing the physical location of electrical components, modules, connectors, and ground points within the vehicle.

Connector Views:

Detailed views of electrical connectors, including pin-out assignments and terminal types.

Diagnostic Test Points:

Identification of specific points in the wiring harness for measuring voltage, resistance, or continuity.

Diagnostic Methodology:

Advanced diagnostic techniques tailored for automotive electrical systems, including symptom-based troubleshooting and component testing.

Repair Procedures Electrical:

Guidance on repairing wiring harness damage, replacing electrical components, and ensuring proper system function after repair.

Component Specifications:

Electrical specifications for key components, such as resistance values, operating voltages, and current draw.

📊 Manual Specifications

Digital File Type:

PDF (Portable Document Format)

Digital Readability:

Designed for clear viewing on various devices (PC, Mac, Tablet, Smartphone).

Printability:

Fully printable for hardcopy reference.

Physical Binding If Printed:

Not applicable for digital download, but implies printable for binding.

Physical Paper Type If Printed:

Not applicable for digital download, but implies standard print paper.

⚙️ Engine Specifications

Engine Type:

Naturally Aspirated Inline-6

Engine Code 635Csi:

M30B34 (3.4L)

Engine Code M6:

S38B35 (3.5L - M6 European Spec, US M6 had specific tuning)

Horsepower 635Csi Approx:

218 hp (DIN) / 208 hp (SAE)

Horsepower M6 Approx Eu:

286 hp (DIN)

Torque 635Csi Approx:

224 lb-ft (304 Nm)

Torque M6 Approx Eu:

251 lb-ft (340 Nm)

Fuel Delivery:

Bosch LE-Jetronic or L-Jetronic (depending on market and specific engine variant) with Electronic Fuel Injection (EFI).

Ignition System:

Distributorless Ignition System (DIS) or Distributor-based electronic ignition with individual coil packs for later models/M variants.

Fuel Type:

Premium Unleaded Gasoline

🔧 Transmission

Transmission Type 635Csi:

Getrag 5-speed manual transmission

Transmission Type Optional:

ZF 4-speed automatic transmission

Transmission Fluid Spec:

Dexron II (for automatic), Gear Oil GL-4 or GL-5 (for manual, consult specific manual for viscosity grade).

📐 Dimensions

Length:

Approx. 4755 mm (187.2 in)

Width:

Approx. 1720 mm (67.7 in)

Height:

Approx. 1360 mm (53.5 in)

Curb Weight Approx 635Csi:

Approx. 1500-1600 kg (3300-3520 lbs)

Curb Weight Approx M6:

Approx. 1600-1700 kg (3520-3740 lbs)

🛡️ Safety Features

Crash Test Data Availability:

Limited public crash test data available for this specific model year from independent agencies; rely on manufacturer design intent and era standards.

ABS:

Available as an option, standard on some M6 variants.

Traction Control:

Not typically available on 1988 models.

Seatbelts:

3-point inertia reel seatbelts with pretensioners (front).

Airbags:

Driver-side airbag was an option on later E24 models, but not standard for 1988.

💡 Technology Features

Audio System:

Factory AM/FM stereo with cassette player, optional premium sound systems.

Cruise Control:

Electronically controlled cruise control system.

Oem Diagnostics:

On-Board Computer (OBC) providing basic vehicle status and diagnostic codes.

🔧 Maintenance

Oil Change Interval:

Typically every 5,000-7,500 miles (8,000-12,000 km) or annually, depending on driving conditions. Consult ETM for specific recommendations.

Spark Plug Replacement:

Recommended every 30,000 miles (48,000 km) for standard plugs, potentially longer for platinum/iridium.

Coolant Flush:

Every 2 years or 30,000 miles (48,000 km).

Engine Oil Specification:

SAE 15W-40 or 10W-40 API SG/SH rated oil (e.g., Castrol GTX, Mobil 1) - consult owner's manual for precise recommendation.

Coolant Specification:

Ethylene Glycol based coolant, BMW Blue or equivalent, mixed 50/50 with distilled water.

Brake Fluid Specification:

DOT 4

Common Electrical Issues:

Failing fuel pump relays, aging wiring harness insulation (can become brittle and short), faulty ABS sensors, OBC display segment failures, door lock actuator issues, headlight switch failures.

Common Mechanical Issues:

Timing chain guides (M30 engine), fuel distributor issues (rare), rear subframe mounts, front control arm bushings.

📚 Vehicle History

Bmw Heritage:

BMW's reputation for building sporty, driver-focused luxury grand tourers with sophisticated engineering.

E24 Generation:

The E24 coupe, based on the E12/E28 platform, was produced from 1976 to 1989. The 635CSi evolved from earlier 6 Series models, receiving updates throughout its lifecycle. The M6 (E24 M) was the high-performance variant, introduced later and featuring the potent M88 or S38 engine.

Production Period:

1976-1989 (E24 generation)

Manufacture Location:

Germany

🏆 Awards & Recognition

Automotive Press Acclaim:

The E24 generation, particularly the 635CSi and M6 variants, were lauded for their performance, handling, and luxury GT capabilities, often compared favorably to contemporary Aston Martins and Jaguars.