CODE 56 XX -- RANGE VERIFICATION RATIO TEST (BETWEEN SHIFTS)

WTEC III ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL

CODE 56 XX -- RANGE VERIFICATION RATIO TEST (BETWEEN SHIFTS)

Main code 56 indicates a failed range verification speed sensor ratio test. The ratio test occurs after a shift and

determines if a clutch has lost torque carrying capability. If output speed is above programmed output speed for a

range but the correct speed sensor ratio is not present, the DO NOT SHIFT response is commanded and a range

which can carry the torque without damage is commanded or attempted. Turbine and output speed sensor readings

are used to calculate the actual ratio that is compared to the commanded ratio. Main code 56 can also be caused

by the ECU being calibrated for a close ratio transmission and installed with a wide ratio transmission, or

vice versa.

Main

Code

Subcode

Meaning

Range verification ratio test (between shifts) L

Range verification ratio test (between shifts) 1

Range verification ratio test (between shifts) 2

Range verification ratio test (between shifts) 3

Range verification ratio test (between shifts) 4

Range verification ratio test (between shifts) 5

Range verification ratio test (between shifts) 6

Range verification ratio test (between shifts) R

Active Indicator Clearing Procedure:

Power down

Manual -- subcodes 11, 44, 66, 77 only

NOTE:

When a code 22 16 (output speed fault) is also present, follow the troubleshooting sequence for code

22 16 first. After completing the 22 16 sequence, drive the vehicle to see if a code 56 XX recurs.

NOTE:

Before troubleshooting, read Paragraph 56. Also, check battery and ECU input voltages.

NOTE:

Intermittent connections or lack of battery-direct power and ground connections may cause this and

other codes.

Troubleshooting:

1. After the transmission is at operating temperature, allow vehicle engine to idle on level ground for

34 minutes. Check the transmission fluid level. If improper fluid level is found, correct as

necessary. Improper fluid level could be the cause of the code. Not enough or too much fluid may

produce inadequate clutch pressure.

2. Connect a pressure gauge and check main pressure. If the pressure is not adequate, the pump is

probably worn. See Appendix B for main pressure specifications.

3. If main pressure is adequate, check clutch pressure for the range indicated by following the

procedure in Appendix B. The transmission range indicated by the trouble code can be found by

referring to the solenoid and clutch chart in Appendix C. Drive the vehicle or use the diagnostic

tool's clutch test mode and check clutch pressure.

4. If a clutch is leaking pressure, drain the fluid, remove the control module and check for damaged

control module gaskets and stuck or sticking valves. Also look for damaged or missing face seals.

If no problems are found, replace the solenoids for the clutches used in the range indicated by the

code.

0021 00107