ZF 4HP 16 - Automatic Transmission

DTC P0601

Circuit Description

A normal function of the transmission control module (TCM) programming is to perform an internal check that verifies the integrity of the random access memory (RAM) memory allocations.

The DTC P0601 sets when the RAM is not operating correctly when checked on initialization. An area of RAM is failed a read/write test.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0601 Transmission Control Module (TCM) Read Only Memory (ROM)

Conditions for Setting the DTC

* The EEPROM checksum test is separated in 2 independent parts, the code checksum test and the calibration checksum test. For each area the checksum is calculated and compared with the corresponding checksum valve. If the valves are different, the fault will be set.
* System voltage is too high or too low.
* Transaxle input voltage is too high or too low.
* Immediately after the above condition occurs

Action Taken When the DTC Sets

* The hold lamp will blink.
* The TCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.
* Adopt Emergency/Substitute mode and constant 4th gear by hydraulic control.
* After ignition OFF/ON : 3rd gear by hydraulic control. P, R and N also possible.
* Power supply cut off to the pressure control solenoid valve.

Conditions for Clearing the Hold Lamp/DTC

* The hold lamp will turn OFF when the malfunction has not occurred after 3 ignition cycle.
* A history DTC will clear after 40 consecutive warm-up cycles without a fault.
* Using a scan tool can clear history DTCs.

Diagnostic Aids

When DTC P0601 sets, the possible cause of fault could be the TCM.