DTC 73

DTC 73 PCM-EBTCM TCS Internal Malfunction (4.6L Only)






Circuit Description

On vehicles equipped with the 4.6L Northstar engine, the PCM and EBTCM communicate traction control information with each other directly. A breakdown in this communication will set DTC 73 in the EBTCM and/or DTC 93 in the PCM.

If "DELIVERED TORQUE" is damaged and the EBTCM loses this input, DTC 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 "DESIRED TORQUE" 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 circuit problem and the EBTCM sets a Code 73.

DTC will set when

A Code 73 may set if either the torque requested or torque delivered circuits are shorted to ground, shorted to voltage or open.

Action Taken

1. Code set.
2. TCS Switched "OFF."
3. "TRACTION DISABLED" message displayed.

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 463.
2. Checks for an open or high resistance in CKT 464.
3. Checks for a short to ground in CKT 464.
4. Checks for a short to voltage in CKT 464.
5. If no problem is found up until this point, CKT 463 should be checked.
6. Checks for an open or high resistance in CKT 463.
7. Checks for a short to ground in CKT 463.
8. Checks for a short to voltage in CKT 463.
9. If CKT 464 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 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. A Code 73 may set by itself if the PCM PROM has been improperly installed.