Transmission Diagnosis

ALLISON AUTOMATIC TRANSMISSION

DTC P0562
Circuit Description for Allison Automatic Transmission
The transmission control module (TCM) requires a switched ignition voltage to operate. The voltage signal should be direct from the ignition switch to avoid any interference.
DTC P0562 is a type C DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0562 System Voltage Low

Conditions for Running the DTC
^ The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts.
^ The engine speed is greater than 450 RPM for 10 seconds.

Conditions for Setting the DTC
DTC P0562 sets when the TCM detects ignition voltage below 8.0 volts at 0°C (32°F) for a total of 5 out of 7 seconds. The voltage threshold is temperature dependant, varying from 5.0 volts at -60°C (-75°F) to 9.0 volts at 20°C (68°F).

Action Taken When the DTC Sets
^ The TCM does not illuminate the malfunction indicator lamp (MIL).
^ The transmission fails to hydraulic default.
^ DTC P0562 will be stored in TCM history.
^ The TCM inhibits torque converter clutch (TCC) engagement.
^ The TCM freezes shift adapts.

Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.

Diagnostic Aids
^ Inspect for the presence of aftermarket accessories, such as a remote starter, etc. Depending on how these aftermarket accessories are installed, they may interfere with the required voltage for proper operation of the transmission.
^ Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions:
- A bent terminal
- A backed-out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation
^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
^ You may have to drive the vehicle in order to experience a condition.

Test Description





The numbers below refer to the step numbers on the diagnostic table.
2. This step tests B+ voltage.
3. This step tests the status of the charging system.