Scan Tool (Impulse Counter ) - Failure, Improper Hook-Up

REF.NO.: 54/71

TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS

DATE: August 1993

SUBJECT:
IMPULSE COUNTER SCAN TOOL FAILURE DUE TO IMPROPER HOOK-UP





An impulse counter scan tool (124 589 19 21 00) failure can be caused by a short circuit in the signal input circuit.

As described in the Diagnostic Manual, connect the yellow lead (signal) to only those sockets from which DTC's can be read. The terminal layouts for the 38-pole diagnostic test (data link) connector shown on page 372 of the Model Year 1992, Model 140 Introduction Manual and on page 81 of the Model Year 1993 Models 124, 129, 140, 201 Introduction Manual are invalid. (Socket 2 is for voltage from circuit 87, not for checking the base module). Refer to section 0 of the respective Diagnostic Manual for complete terminal layout identification.

A short in the signal input circuit can be caused as follows:

1. Connecting the yellow lead to socket 16 (circuit 15) of the 16-pole data link connector (X11/4).

2. Connecting the yellow lead to socket 2 (circuit 87) of the 38-pole data link connector (X11/4).