Output Diagnostic Test Mode (DTM)

The Output Test Mode (OTM) aids in servicing output actuators associated with the PCM. It allows the technician to energize and de-energize most of the system output actuators on command. When entering OTM, the outputs can be turned off and on without controlling the cooling fans. The low and high speed cooling fans may be turned on separately without energizing the other outputs.

CAUTION: Safety must be observed when using output test mode. When all outputs are on and the electric fuel pump is energized, make sure the fuel system is intact and is not being serviced at that time. When low speed or high speed cooling fans are turned on, make sure fan blades are clear of any obstruction.

NOTE: As a safety precaution, the Output Test Mode will default to its normal state after ten minutes, after the vehicle is started or after cycling the ignition switch off and on.

Performing Output Test Mode
New Generation Star
Enter OTM with the ignition key on and the engine off.
- Perform the necessary vehicle preparation and visual inspection.
- Connect scan tool to DLC. Select VEHICLE and ENGINE SELECTION menu.
- Select NEW VEHICLE YEAR & MODEL.
- Enter year, engine, model with the appropriate qualifier, if needed (i.e., transmission, 49-State or California).
- Select DIAGNOSTIC DATA LINK.
- Select PCM - POWERTRAIN CONTROL MODULE.
- Enter ACTIVE COMMAND MODES.
- Enter OUTPUT TEST MODE.
- Turn key on.
- Follow operating instructions from the menu.
- Select the mode (i.e., ALL ON, ALL OFF, HIGH SPEED FAN or LOW SPEED FAN).
- Select START to turn outputs ON (may link up to PIDs).
- Select STOP to turn outputs OFF.