Without Scan Tool

Heater - Air Conditioning Control Display For On-Board Diagnostics:

On-Board Diagnostic System Check Operation:

ENTERING ON-BOARD DIAGNOSTICS
Entering diagnostics is accomplished by simultaneously pressing the "OFF" button and the "TEMP" up button. The immediate indication upon entry into diagnostics is that all enunciators, and display segments light for 5 seconds. The numerical display will then show the pointer number -00, (pointer numbers, which indicate what system or system parameter is being viewed, are described in Diagnostic Modes). Diagnostic Modes

AIR DELIVERY MODE PRESERVED
Upon entering the diagnostic mode, the climate control will operate in whatever mode was being commanded just prior to entering the diagnostic mode. The prior operating mode is remembered and will resume after the diagnostic mode is entered.

CHANGING POINTER NUMBER
The "Fan Up" and "Fan Down" keys are used to increment and decrement, respectively, the diagnostic pointer number. There is a wrap around feature if the pointer number sequence is continued past either end.

DIAGNOSTIC TROUBLE CODE (DTC) DISPLAY ORDER
DTCs will be continually displayed, accompanied by an identifying system pointer, in the Heater and Air Conditioning (HVAC) control display starting with the lowest current DTC through the highest current DTC. If more than one DTC exists, the DTCs will be shown cycling sequentially, 1.6 seconds at a time. This will be followed by the lowest history DTC through highest history DTC. Current DTCs will then repeat followed by history DTCs. This will continue until diagnostics are "exited" or the ignition is shut "OFF."

TOGGLING BETWEEN DTC/PARAMETER AND POINTER NUMBER
The "OUT TEMP" button will toggle the display between the diagnostic pointer number and the diagnostic trouble code/parameter. Pressing either "Fan Up" or "Fan Down" while displaying the DTC will cause the display to show the pointer number.

EXITING DIAGNOSTIC
To exit the diagnostic display mode, the user must press any mode function key except for "OFF," "Rear Defog" or "DEFOG."