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 MANUALSBMW1987L7 (E23) L6-3430CC 3.4L SOHC (M30)REPAIR AND DIAGNOSISSTARTING AND CHARGINGCHARGING SYSTEMTESTING AND INSPECTION
1987 BMW L7 (E23) L6-3430cc 3.4L SOHC (M30)
Charging System: Testing and Inspection
1987 BMW L7 (E23) L6-3430cc 3.4L SOHC (M30)SECTION Testing and Inspection
1. Connect suitable volt/ammeter, and oscilloscope if available, following manufacturer's instructions.
2. Start engine and run until it reaches normal operating temperature.
3. Switch on electrical accessories to create load and maintain engine speed of 900-1000 RPM.
4. Regulated voltage should be within specifications, charge rate should be greater than 15 amperes and scope pattern, if applicable, should show a ripple of less than 6%. Refer to oscilloscope manufacturer's instructions to diagnose variances in scope pattern.
5. If charge indicator lamp goes out while engine is running and scope pattern is acceptable, but regulated voltage is less than specified, or if regulated voltage is greater than specified, check for defective voltage regulator.
6. If voltage or amperage are not as specified, or if charge indicator remains illuminated, check for open or grounded D+ lead.
7. If wiring is satisfactory and charging system malfunction persists, repair or replace alternator as needed.
8. After performing test, turn off accessories and return engine to idle.
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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.