Description

BMW 735i, 735iL, 750iL 1989 Troubleshooting Manual

Look, I’ve been turning wrenches for 28 years. When a 750iL rolls in with an intermittent no-start and the owner says “I just replaced the battery” — I don’t trust the battery. I trust the wiring diagram on page 73 of the official factory troubleshooting manual. This BMW 735i, 735iL, 750iL 1989 Troubleshooting Manual is the real deal. Not some aftermarket rewrite that merges three model years into one blob. It’s 461 pages of factory-issued diagnostic procedures, pinouts, and torque specs that BMW intended for dealer techs. If you’re working on an E32 chassis from 9/88 to 5/89 production, this is the only document that gives you the exact ground distribution, fuse locations, and component views. Anything else is a gamble.

Systematic Troubleshooting – Not a Wild Guess

Section 0130–00 is the Systematic Troubleshooting chapter. It forces you to follow a logical sequence instead of swapping parts until something sticks. You start with a symptom, then trace voltage, ground, and signal paths in order. For a dead instrument cluster, you don’t replace the cluster — you check the Check Control module (6200–00) and the power feed from the fuse box. This manual gives you the step-by-step decision tree that dealer techs used.

Power Distribution and Fuse Details: Where the Juice Flows

Chapters 0660 through 0672 cover every fuse, relay, and ground point in the car. Fuse 1 through Fuse 50 are individually numbered with location diagrams (0671–00). The ground distribution section lists X165, X166, X167, X172, X173 — every bolt-down point in the engine bay and cabin. If a 735i loses power to the central locking, you trace from fuse 14 (0670–04) through the ZKE module (6100–00). No guesswork. Page references are direct; you flip to the exact chart.

DME Injection and Electronic Throttle: The Brain of the M70 and M30

Section 1360 covers Injection Electronics (DME 1.3) for the 735i, and 1367 covers DME/EML 1.2 for the 750iL’s M70 V12. The Electronic Throttle Control (EML 1.2) is in section 1375. These are the systems that cause the most head-scratching — idle surges, no-start when hot, throttle lag. The manual includes pinout tables for the DME connector and voltage measurements at each pin. You need a DVOM and a breakout box. Don’t bother with generic scan tools; the manual tells you which pins to back-probe.

Transmission Control (AEGS): When the Shifts Get Erratic

Electronic Transmission Control is covered in sections 2460 and 2465. The AEGS module receives signals from the throttle and engine control to modulate shift pressure. If you have harsh 2-3 shifts on a 735iL, the manual walks you through the transmission control logic. It lists the exact resistance values for the solenoids (measured at the transmission connector). Don’t replace a valve body until you’ve tested the input signals from the EML or DME.

5 Critical Electrical Systems You Can’t Debug Without This Manual

1. Antilock Brake System (ABS) section 3450 – pump motor relay and wheel speed sensor testing.
2. Central Locking System (ZKE) section 5126 – actuator voltage and microswitch continuity.
3. Instrument Cluster / Check Control section 6200 – LED driver test points.
4. Automatic Climate Control (IHKA) section 6450 – blower motor final stage resistor values.
5. On-Board Computer section 6581 – processor reset voltage tolerances.

Every one of these systems has its own dedicated wiring diagram in the Power Distribution (0670) and Splice Location (8000) chapters. BMW 7 Series 1988-1994 Service Manual covers more general repair, but for electrical gremlins you need this troubleshooting manual. Pair it with BMW 735i 1988 Electrical Troubleshooting Manual if you need an earlier production variant. For the 1990 model, see BMW 735i 735iL 750iL 1990 Electrical Troubleshooting Manual.

Source Authenticity: Why OEM Beats Aftermarket

Aftermarket manuals cut corners. They redraw schematics to save space, combine model years, and omit the component location views (7100–00) that show exactly where a relay sits behind the glove box. This manual is a direct scan of the BMW dealer publication PN 01 00 1 467 833. The OCR excerpt shows the original index with page numbers like 0100–00. That means every connector view (8500–00) and splice location (8000–00) is exactly as BMW printed it. If you need to verify the diagnostic link pinout (0680–00), it’s there. No interpretation. For a broader understanding of automotive electrical systems, you might refer to Automotive Industry Overview but that won’t help you diagnose a dead ABS pump on a 735i. Automotive Industry Overview is generic; this manual is specific.

FAQ

Does this manual cover the V12 engine in the 750iL?

Yes. Section 1367 covers the DME/EML 1.2 for the M70 V12, and section 1375 covers the electronic throttle body. The wiring diagrams include all 12 injector circuits.

What tools do I need to use this manual?

A digital multimeter, a breakout box for the DME connector, and a test light. The manual gives voltage and resistance readings for each pin.

Are the fuse locations the same for all E32 models?

Fuse assignment varies slightly between 735i and 750iL due to the V12’s additional systems like the E-box fan (0690–00). The manual lists each fuse individually with its circuit. Check the Fuse Chart (0661–00) against your car’s production date.

Can I use this manual for a 1991 735iL?

This manual is specifically for vehicles produced 9/88–5/89. Later models have different DME versions and wiring changes. For later years, look at the BMW 735i 735iL 750iL 1990 Electrical Troubleshooting Manual.

You don’t have time to chase phantom electrical faults with a generic diagram. Access the Factory Manual now — 461 pages of OEM troubleshooting data for the 1989 BMW 735i, 735iL, and 750iL. Every pin, every ground, every fuse listed as BMW intended. No shortcuts, no reprints, no second guesses. Just the factory procedure.