Acura Coupes and Sedans 1986-1993 Repair Guide

Bypass Control System

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This system is used on the Vigor and functions similarly to the Chamber Volume Control System used on the Legend. In this system the by-pass valve is used to select the one of two intake tracts to route fresh air through. When the air is routed through the long intake tract, high torque is achieved at low rpm. When the air is routed through the short intake tract, high power is achieved through higher engine rpm.

INSPECTION



Vigor

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Chamber volume control system-Vigor

  1. Start the engine and allow it to idle.
  2.  
  3. Remove the No. 13 vacuum hose from the bypass control diaphragm and connect a vacuum gauge to the hose.
  4.  
  5. If vacuum does exist, skip to Step 4. If it does not, proceed with the next step.
    1. Disconnect the 2 pin connector from the bypass control solenoid valve.
    2.  
    3. Measure the voltage between the Black/Yellow (+) and the Blue/Red (-) terminals.
    4.  
    5. If there is battery voltage, repair the blockage or vacuum leak between the intake manifold and the diaphragm; if the vacuum is OK, replace the bypass control solenoid valve.
    6.  
    7. If there is no battery voltage, measure the voltage between the Black/Yellow (+) connector and the body ground.
    8.  
    9. If there is no battery voltage, repair the short in the Black/Yellow wire between the 2 pin connector and the No. 2 fuse.
    10.  
    11. If there is battery voltage, turn the ignition switch OFF and connect the 2 pin connector to the bypass control solenoid valve.
    12.  
    13. Connect a test harness to the main wire harness. Turn the ignition switch ON and connect a jumper wire between ECU terminals A17 and A26.
    14.  
    15. Check to see if the solenoid valve clicks when the jumper wire is connected.
    16.  
    17. If the solenoid valve clicks, substitute a known-good ECU and recheck. If the voltage is now present, replace the original ECU.
    18.  
    19. If the solenoid valve does not click, repair the short in the Blue/Red wiring between the ECU (A17) and the 2 pin connector. If the wiring is OK, replace the bypass control solenoid valve.
    20.  

  6.  
  7. Raise the engine speed to 4900 rpm and check for vacuum at the No. 13 vacuum hose.
  8.  
  9. If there is no vacuum, the bypass control system is OK.
  10.  
  11. If vacuum is present, disconnect the 2 pin connector from the solenoid valve and check for vacuum.
  12.  
  13. If vacuum is present, replace the bypass control solenoid valve. If vacuum is not present, turn the ignition switch OFF .
  14.  
  15. Disconnect the A connector from the ECU and check for continuity to ground on the Blue/Red wire. If there is continuity, repair the short to the ground at the Blue/Red wire between the ECU (A17) and the 2 pin connector.
  16.  
  17. If there is no continuity to the ground, substitute a known-good ECU and recheck.
  18.  

 
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