LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Honda >> 1994 >> Civic Si >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing >> Ignition Checks >> Electronic Ignition System >> Tach Pulse Signal
September 30: LEMON manuals is back up on a temporary server! Slowness is possible

Tach Pulse Signal

  1. Timing control and triggering of fuel injectors are based upon input signals from TDC/CRANK/CYL sensors. These sensors are simple Permanent Magnet (PM) generator pick-up coils.
  2. Using a DVOM on low voltage scale (preferably with a bar-graph function), check for a pulsed low-voltage signal at proper Engine Control Module (ECM) harness terminals with engine cranking. See WIRING HARNESS & SENSOR RESISTANCE TEST  table. See Fig 1 . If a pulsed signal is present, fault does not exist. If pulsed signal is not present, check sensor and wiring integrity.
    Fig 1: Identifying ECM Wire Harness Connector Terminals
    G92E26660Courtesy of AMERICAN HONDA MOTOR CO., INC.
  3. To test sensor and wiring integrity, turn ignition off. Disconnect connectors from ECM. Lightly probe appropriate ECM harness terminals to check for proper winding resistance of each sensor. See WIRING HARNESS & SENSOR RESISTANCE TEST  table. If resistance is within specification, go to step 5). If resistance is not within specification, go to next step.
  4. Check resistance of TDC/CRANK/CYL sensor directly at sensor connector. See Fig 2 . See TDC/CRANK/CYL SENSOR RESISTANCE TEST  table. If sensor resistance is within specification, repair open, short or corrosion in wire harness between sensor(s) and ECM. If resistance is not within specification, replace sensor.
  5. Check continuity to ground at each ECM sensor terminal. If continuity is not present, replace distributor housing. If continuity is present, go to next step.
  6. Disconnect sensor(s) and recheck for continuity to ground at ECM harness sensor terminals. If continuity no longer exists, go to next step. If continuity to ground is still present, repair short to ground in ECM harness between ECM and sensor(s).
  7. Check continuity to ground on each sensor connector terminal. See TDC/CRANK/CYL SENSOR RESISTANCE TEST  table. See Fig 2 . Continuity should not exist. If continuity to ground exists, replace sensor.
    WIRING HARNESS & SENSOR RESISTANCE TEST

    Application Terminals Ohms
    CRANK B15 & B16 350-700
    CYL B11 & B12 350-700
    TDC B13 & B14 350-700
    TDC/CRANK/CYL SENSOR RESISTANCE TEST

    Application Terminals Wire Color
    CRANK Sensor Wire
    1 Of 2 "B" Blue/Green
    2 Of 2 "F" Blue/Yellow
    CYL Sensor Wire
    1 Of 2 "D" Orange
    2 Of 2 "H" White
    TDC Sensor Wire
    1 Of 2 "C" Orange/Blue
    2 Of 2 "G" White/Blue
    Fig 2: Identifying TDC/CRANK/CYL Sensor Connector Terminals
    G90J04371Courtesy of AMERICAN HONDA MOTOR CO., INC.
scientia non olet · About LEMON Manuals