DTC 73

Wiring Diagram:

CIRCUIT DESCRIPTION
Traction control is simultaneously controlled by the EBTCM and the PCM. The PCM receives a TORQUE request via a pulse width modulated (PWM) signal from the EBTCM (CKT 1714) requesting the desired torque level for proper traction control system operation. Torque reduction will be indicated if the duty cycle of the PWM signal is between 10% (100 % torque reduction) and 90% (no torque reduction and at least one (up to five) cylinder is requested to be disabled. The percent duty cycle will indicate the percent torque required. The PCM will selectively disable fuel to certain cylinders to achieve this reduction and communicate the actual torque output back to the EBTCM (CKT 1715).

TEST CONDITION(S)
1. Tested continuously.

FAILURE CONDITION(S)
1. While Standing or Driving: PWM interface between EBTCM and PCM is lost.

ACTION TAKEN
1. Code set.
2. "TRACTION DISABLED" message ON.

A Code 73 may set if either CKT 1714 or 1715 is open, shorted to ground or shorted to voltage.

If CKT 1715, Delivered Torque, is damaged and the EBTCM loses this input, a TCS Diagnostic Code 73 will be set. The PCM monitors the serial data line to see if the traction control has been disabled. If it has, the PCM will not set Code 93.

If CKT 1714, Torque Request, is damaged and the PCM loses this input, the PCM monitors the serial data line to see if the traction control has been disabled. If not, the PCM sets a Code 93 and then tells the EBTCM, via serial data, that there is a PWM circuit problem and the EBTCM sets a Code 73.

TEST DESCRIPTION
Test numbers refer to circled numbers on the diagnostic chart.
1. Checks if the PCM Diagnostic Trouble Code 93 is set. If it is, there is likely a problem with CKT 1714.
2. Checks for an open or high resistance in CKT 1715.
3. Checks for a short to ground in CKT 1715.
4. Checks for a short to voltage in CKT 1715.
5. If no problem is found up until this point, CKT 1714 should be checked.
6. Checks for an open or high resistance in CKT 1714.
7. Checks for a short to ground in CKT 1714.
8. Checks for a short to voltage in CKT 1714.
9. If CKT 1715 has not been checked, proceed to the left hand side of the trouble tree. If it has, continue downward. Problem is intermittent or in one of the controllers.
10. Checks if Code 73 and/or 93 are intermittent. If not, trouble is in either PCM or EBTCM.

DIAGNOSTIC AIDS
^ It is theoretically impossible for only a PCM Code 93 to set. If only a PCM Code 93 is present, either the TCS Code 73 has been cleared or there is a problem with the PCM. Refer to Computers and Control Sytems. Computers and Control Systems
^ A Code 73 may set by itself if the PCM PROM has been improperly installed.