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On-Board Diagnosis Mode

The CJ2 air conditioning is equipped with an on-board diagnostic feature
which allows the heater-A/C control to detect certain system faults. The
diagnostic feature may also be used to display certain data parameters.
If the heater-A/C control detects a fault in the system, the man symbol
will flash during the first 2 minutes of vehicle operation.

Entry into the diagnostic mode is gained by pressing in on both
temperature knobs at the same time for 5 seconds. The following display
modes are found within diagnostics:

   * The diagnostic pointer
   * The diagnostic value

Important

A 2-digit trouble code indicates the fault is current. A 3-digit trouble
code indicates a history fault.

By rotating the driver temperature knob one position in either
direction, the display is toggled between pointer and value. The value
displayed is the decimal equivalent of the RAM contents. A 2 is formed
using the minus sign and the leading 1 in order to display values over
199.

A diagnostic pointer mode is identified by a minus sign preceding the
pointer number. The pointer provides an index, which identifies the
corresponding diagnostic value. The diagnostic trouble codes (DTCs)
reside under diagnostic pointer -00. The pointer will be set to this
position upon initial entry into diagnostics. If more than one code
exists, the codes will be displayed sequentially at a rate of 2 seconds
per fault. Rotating the passenger temperature knob will switch the
diagnostic pointers. A wrap around feature is provided if the pointer is
continued past either end. Other data used by the computer resides under
different diagnostic pointers, and may not be of use in observing the
system. Press any mode button in order to exit the diagnostic mode.