ECVT Check Lamp - ON Intermittently, Trouble Code 21
90subaru02NUMBER 16-38-90
DATE 04-02-90
APPLICABILITY 89MY JUSTY ECVT
SUBJECT: INTERMITTENT ECVT CHECK LAMP ILLUMINATION, TROUBLE CODE 21
Unique vehicle operating conditions occurring at the same time for more than one (1) second may cause the ECVT check lamp to illuminate along with a "false" trouble code 21 (torque signal system).
The operating conditions which must occur simultaneously are:
1. Driving in "D" range.
2. Speedometer reads between 12 and 38 mph.
3. Engine speed is between 3000 and 4000 RPM.
4. Accelerator switch is open, foot is on accelerator pedal.
5. A/C is off.
6. Torque signal is received by clutch control unit.
The torque signal is generated by comparing engine output torque with transmissible steel belt torque capacity under low line pressure. The engine and belt torque are then calculated in the MPFI control unit and networked to the CCU.
A momentary loss of traction on wet or icy roads is an operating condition example where trouble code 21 could occur. Keep this information in mind when diagnosing "CHECK ECVT" lamp illumination and no accompanying driveability complaints.
Field Fix
Adjust the throttle position svitch open (non-conducting) point to as close to 20 mm (0.79") as possible. Although the service manual states a range of 16-24 mm (0.63" - 0.94") as being acceptable, 20 mm is the preferred setting for optimum performance. Of course, the proper adjustment sequence should always be followed when making these sensitive adjustments. This sequence is:
1. THROTTLE CABLE ADJUSTMENT - Ensure the throttle is fully opening by depressing the pedal inside the vehicle. Adjust as necessary according to service manual.
2. SWITCH ADJUSTMENTS - Adjust both accelerator and throttle position switches as described in the service manual. Use the new spec. suggestion as stated above for the throttle position switch. Keep in mind both switches are closed and conducting with the pedal at rest and your foot not touching the pedal. Both switches remove a ground when the switches open and stop conducting.
3. CONTROL CABLE ADJUSTMENT - Check and adjust the transmission control cable adjustment. Be sure to push and pull the cable rather than deflect when checking free play.
FHI testing has proven these suggestions will address most customer complaints.
NOTE: The possibility of a malfunction in the torque signal system should not be overlooked. See the 1989 Justy Service Manual 3-2 pages 89 and 90 for a listing of the systems related to the torque signal system which should be thoroughly checked as well.
1990 MY Justy vehicles use a control unit which has a higher tolerance to these vehicle operating conditions. This should prevent the occurrence of a false trouble code 21.