Without Scan Tool

On-board Diagnostic System Check Operation Flow Chart:

Diagnostic Chart:

ENTRY INTO DIAGNOSTICS
The Heater and Air Conditioning (H-A/C) control is used to display all of the vehicles' modules that will set a Diagnostic Trouble Code (DTC). Even though the CCM cannot display any other systems DTC's the "On-Board Diagnostic System Check" has been repeated here for the convenience of the reader.

If a fault is detected, there will be no flashing or any indication to the customer that an error has occurred, though he/she might detect a system malfunction. The system faults will be indicated and recorded in the diagnostic pointer numbers. When working on systems controlled by the CCM, the technician should always refer to this section and check for Diagnostic Trouble Codes (DTCs).

Diagnostics is entered through a two button simultaneous push by pressing the "OFF" button and the "TEMP" button. The mode of air delivery and blower functions will be preserved through the diagnostics entry process.

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. Refer to the illustration of "entry into diagnostic display" and pointer-00.

To exit this diagnostic display mode the user must press any mode function key (except "OFF," "Rear Defog" or "Defog1,).

DIAGNOSTIC POINTERS,INPUTS/OUTPUTS
There are two types of display in this mode, a diagnostic pointer (indicated by a minus sign) which indicates what system you are looking at, or what Automatic Control Air Conditioning (ACAC) input/output (parameter) you are observing. The second type of display is the actual Diagnostic Trouble Code (DTC) that you are viewing for pointer selection 0.00 through 0.04.

The "Fan Up" and "Fan Down" keys will be used to increment and decrement, respectively, the diagnostic pointer number. There will be a wrap-around feature if the pointer umber. There will be a wrap-around feature if the pointer number sequence is continued past either end.

The "Out Temp" button will toggle the display between the diagnostic pointer number and the diagnostic trouble code/parameter. A "Fan Up"/"Fan Down" press while displaying the DTC will cause the display to show the pointer number.

In addition to CCM diagnostic trouble codes, the H-A/C control can also display Powertrain Control Module (PCM) Diagnostic Trouble Codes (DTCs),

Supplemental Inflatable Restraint (SIR) Diagnostic Trouble Codes (DTCs), Antilock Brake System/Traction Control (ABS/TC) Diagnostic Trouble Codes (DTCs), and HVAC (ACAC) (DTCs).

DTCs can be cleared from the H-A/C control while DTCs are displaying for the selected pointer being observed by pressing the "OFF" button. After DTCs are cleared, the display will show "00". The Tech 1 can also be used to clear DTCs.

Whenever the H-A/C control display shows - - this indicates the H-A/C control is not receiving serial data because of a fault on the serial data line to and including the H-A/C control.