LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Audi >> 1990 >> 100 Base, Automatic >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Basic Testing >> Ignition Checks >> Cis Digital Control >> Tachometer Signal Output
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Tachometer Signal Output

  1. Peel back ECU connector boot. Attach voltmeter positive lead to ECU terminal No. 7. Connect negative lead to a good ground. Start engine and check for steady voltage increase as RPM is increased.
  2. If engine does not run, check engine speed sensors. If engine runs but voltage does not increase, replace ECU. If voltage increases but vehicle tachometer did not respond, check wiring between ECU terminal No. 7 and tachometer. If okay, repair or replace tachometer.
scientia non olet · About LEMON Manuals