Always disconnect battery or ground cable (located on right rear seat frame) when working on electrical systems, charging the battery or welding.
The secondary (high voltage) side of ignition system must be loaded with at least 4000 ohms. Never connect a shielded capacitor or test light to coil terminal No. 1. Never connect lead of ignition coil terminal No. 1 to ground or battery voltage.
When checking compression, the DME master relay must be removed. DO NOT disconnect lead of ignition coil terminal No. 1 to prevent engine from starting. Never disconnect battery or leads on alternator or starter while engine is running.

NOTE: The DME master relay, on 525, 535 and 735 Series, is located on right rear corner of engine compartment, next to DME control unit and fuel pump relay. On 325 Series, the fuel pump relay is located in fuse/relay block on left rear corner of engine compartment. On 318 Series, the fuel pump relay is located behind cover along engine compartment firewall. The first relay (viewed from left to right) is the DME master relay, followed by the fuel pump relay, and then the oxygen sensor heater relay.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Non-DIS Ignition System

Use the Manual With the Right Hardware

When to See a Mechanic

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