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Home >> Volkswagen >> 1987 >> Cabriolet Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 6 (BOSCH Cis-E System) >> Testing >> Electrical Components >> Knock Sensor Control Unit
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Knock Sensor Control Unit

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 1987 Volkswagen Scirocco, 1987 Volkswagen Quantum, 1987 Volkswagen Jetta, 1987 Volkswagen Golf, and 1987 Volkswagen GTI. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ensure ignition coil and TCI unit are okay. Remove connector from knock sensor and turn ignition on. Check for battery voltage between connector pins No. 3 and 5.
  2. Measure battery voltage between terminals No. 6 and 3. Open throttle valve, voltage should drop to zero volts. If voltage does not drop to zero check throttle idle switch.
  3. Measure voltage between terminals No. 8 and 3 while opening throttle. Battery voltage should be present at full throttle. If battery voltage is not present check full throttle switch.
  4. Remove harness connector from TCI (Hall sender) at distributor. Turn ignition on and measure voltage between outer terminals of connector. Voltage should be 5 volts minimum. Turn ignition off.
  5. With ignition on, check voltage between terminals 1 (-) and 15 (+) of ignition coil. Touch center terminal of connector from TCI to ground. Voltage should increase briefly to 2 volts minimum. If it does not, replace knock sensor control unit.
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