Pulse Counter (California Only)

On-board diagnosis system California

Fault Detection Table:

All exhaust emission-relevant components of the CIS-E injection system and of the exhaust gas recirculation system are monitored by the CIS-E control unit. Malfunctions resulting from open circuits or failure of one of these components are indicated by the "CHECK ENGINE" indicator lamp in the instrument cluster and at the same time stored in the CIS-E control unit.

Note: Push-button switch and LED have been developed to enable customer and independent repair facilities to specifically pinpoint the fault path in conformity with the legislation relating to "On-board means". A pulse counter has been developed for MB workshop personnel which presents a readout of the stored fault(s) on a digital display.

The control unit is switched over to on/off ratio output for testing the lambda control by pressing the push-button switch. Refer to "Testing Lambda Control" under "System Tests". Lambda Control Test

The on/off ratio is output only after the CIS-E control unit has been programmed to on/off ratio output. Otherwise the readout shows 0 % or 85 %, respectively, when the "CHECK ENGINE" indicator lamp lights up, with the engine running.

A test connector (X92) with push-button switch (2) and LED (4) is provided on the component compartment partition wall of Model 126 and on the left wheel house (ill.) of Model 107. When the push-button switch is operated (ignition: ON) for between 2 and 4 seconds, the flashing pulse output is initiated and the fault path indicated by the number of flashes.

Model 107:

Model 126:

Testing on-board diagnosis with pulse counter

Complaint:
'CHECK ENGINE' indicator lamp in instrument cluster lights up.

Test conditions:
Battery, overvoltage protection relay and control unit must not be disconnected prior to and during the test otherwise the stored fault is erased.
Battery voltage 11 - 14 Volts.

Notes regarding pulse readout
The digit 1 indicates that no fault is stored in the system. All other digits are assigned to a particular fault. if several faults exist in the system, the fault with the lowest pulse number is output first.

The digits from 1 - 12 appear on the pulse counter display.

^ If the LED U Batt lights up after connecting the counter, pulse counter and power supply for pulse counter are in proper order.

^ If no further display appears during the test after one or several pulse readouts (digits), there is no further fault stored in the system.