Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSBMW1993740IL (E32/2) V8-3982CC 4.0L DOHC (M60)REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSDESCRIPTION AND OPERATIONDIGITAL MOTOR ELECTRONIC (DME)FUNCTIONAL DESCRIPTIONSRELAY CONTROL
1993 BMW 740iL (E32/2) V8-3982cc 4.0L DOHC (M60)
Relay Control
1993 BMW 740iL (E32/2) V8-3982cc 4.0L DOHC (M60)SECTION Relay Control
OPERATION
The Digital Motor Electronic (DME) main relay is activated by the DME control unit as of ignition ON. After shutting down the engine, the relay remains on for a further 3 sec. in order to avoid post-ignition.
The fuel pump relay (EKP) is activated as of ignition ON as soon as the DME control unit receives engine speed signals from the crankshaft pulse generator.
At ignition ON. power is briefly applied to EKP relay for approx. 0.5 sec in order to build up the fuel pressure. The fuel pump runs continuously after the engine has started.
The oxygen sensor heating relay is activated as of ignition ON. It is switched off dependent on engine speed and load.
The Digital Motor Electronic (DME) main relay is activated by the DME control unit as of ignition ON. After shutting down the engine, the relay remains on for a further 3 sec. in order to avoid post-ignition.
The fuel pump relay (EKP) is activated as of ignition ON as soon as the DME control unit receives engine speed signals from the crankshaft pulse generator.
At ignition ON. power is briefly applied to EKP relay for approx. 0.5 sec in order to build up the fuel pressure. The fuel pump runs continuously after the engine has started.
The oxygen sensor heating relay is activated as of ignition ON. It is switched off dependent on engine speed and load.
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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.