Reading and Clearing Diagnostic Trouble Codes

Testing AUTOMATIC CLIMATE CONTROL WITH PULSE COUNTER
as of 09/87






013 Pulse counter 124 589 19 21 00
G1 Battery
X92 Test coupling for diagnosis

Notes on pulse output:
- The pulse output indicates existing faults; however, sporadic faults are not stored.
- The test with pulse counter should be performed to rapidly localize faults in the event of malfunctions in the automatic climate control.
- If the pulse output indicates one or more faults, these must be rectified and the pulse test repeated. This ensures that all faults registered by the pulse output are eliminated.
- If the pulse output indicates no fault but there is still a complaint, there may be a tolerance variation in the components, e.g. sensors with insufficient resistance. As the pulse test does not detect such variations, the entire system must be tested using the contact box and voltmeter/ohmmeter.






Testing:
- Connect pulse counter as illustrated in connection diagram.

Note: Battery voltage LED must light up; if it does not:
a) Check fuse
b) Test socket 1 on test coupling X92 against battery positive (11-14 V).
c) Test socket 1 against socket 7 on test coupling X92 (6-12 V).

- Switch on ignition.
- Hold down start key (1) for between 2 and 4 seconds. Read off and note pulse code reading.

A reading of 1 indicates that no fault was detected by the pulse output All other numbers are assigned to a certain fault circuit. If there are several faults in the system, the next fault is output automatically when the start key is next pressed.

- Again hold down the start key (1) for between 2 and 4 seconds. The first number reappears if there is no further fault in the system.

Rectify the noted fault (pulse output) and repeat pulse test after switching the ignition off and on again.

Note: During pulse output, the light-emitting diode in the fresh/recirculated air switch flashes at 1 Hertz.