LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Honda >> 1988 >> Civic Base, 2D Hatchback >> Repair and Diagnosis >> Engine Performance >> System >> Air Intake Control System >> System Testing >> Tandem Control System >> Civic Throttle Body Injection
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Civic Throttle Body Injection

  1. With engine coolant temperature less than 160°F (70°C), disconnect vacuum hose from tandem valve control diaphragm. See Fig 1 . Connect vacuum gauge to hose. Start engine. If vacuum is present, go to step 3). If vacuum is not present, increase engine speed to 2000 RPM for automatic transmission or 3000 RPM for manual transmission.
  2. If vacuum is not present, go to step 5). If vacuum is present, warm engine to operating temperature (cooling fan comes on). Slowly open throttle. If vacuum is present, tandem control system is functioning properly. If vacuum is not present, substitute a known good ECU and retest. If symptom is rectified, replace original ECU.
  3. Disconnect 2-wire connector from tandem control solenoid. See Fig 2 . If vacuum is now present, replace solenoid. If vacuum is not present, turn ignition off. Disconnect "B" connector from ECU. Check for continuity to ground on Orange wire.
  4. If continuity exists, repair short to ground in Orange wire between ECU terminal B2 and 2-wire connector. If continuity to ground does not exist, substitute a known good ECU and retest. If symptom is rectified, replace original ECU.
  5. If vacuum was not present in step 2), disconnect 2-wire tandem control solenoid connector. See Fig 2 . Measure voltage between Black/Yellow (pos.) and Orange (neg.) terminal at 3000 RPM. If battery voltage is not present, go to next step. If battery voltage is present, remove solenoid valve and check port for blockage. If port is okay, replace solenoid.
  6. Measure voltage between ground and Black/Yellow wire terminal. If voltage is now present, go to next step. If voltage is not present, repair open in Black/Yellow wire between 2-wire connector and No. 14 fuse.
  7. Turn ignition off. Connect System Checker Harness (07999-PD6000A) between ECU and ECU connector. Check for continuity in Orange wire between ECU terminal B2 and 2-wire connector. If continuity does not exist, repair open in Orange wire.
  8. If continuity does exist, substitute a known good ECU and retest. If symptom is rectified, replace original ECU.
Fig 1: Tandem Control System (Civic)
G93637Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig 2: 2-Wire Tandem Control Solenoid Connector (Civic)
G93638Courtesy of AMERICAN HONDA MOTOR CO., INC.
scientia non olet · About LEMON Manuals