P1790

DIAGNOSTIC TROUBLE CODE (DTC) P1790 ROM CHECKSUM ERROR
Circuit Description
A normal function of the Powertrain Control Module (PCM) programming is to perform an internal check that verifies the integrity of the RAM and ROM memory allocations. This function is called a checksum. When the PCM runs this check and the memory allocations do not agree with the previous checksum, then DTC P1790 will set.

Conditions For Setting The DTC
- Ignition ON.
- PCM checksum is incorrect.

Action Taken When The DTC Is Set
- PCM commands maximum line pressure.
- PCM commands 2nd gear.
- PCM inhibits TCC engagement.
- Freeze shift adapts from being updated.
- PCM flashes the Malfunction Indicator Lamp (MIL).
- DTC P1790 will be stored in PCM memory.

Conditions For Clearing The DTC
- The PCM will turn the MIL off after the PCM checkSum is correct for three consecutive ignition cycles.
- History DTCs can be cleared by using a scan tool.

Diagnostic Aids
- Flashing the PCM is not recommended. When DTC P1790 sets, the PCM must be replaced.





DTC P1790 - ROM Checksum Error