Understanding Diagnostic Information

WARNING: This page is about a different car, the 1997 Mercedes-Benz E420, 1997 Mercedes-Benz E320, and 1997 Mercedes-Benz E300. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: To properly identify components or connectors being tested, see COMPONENT IDENTIFICATION .

For reading and understanding fault code diagnosis, as an example, using AIR BAG SYSTEM under DIAGNOSTIC TESTS, read step 3.0 (HHT Fault Code 002) under TEST STEP column. Read TEST SCOPE/HHT ACTUAL VALUE NO./TEXT column. Driver-side air bag squib (R12/3) is being tested. HHT will identify if problem is with too much resistance or not enough resistance in driver-side air bag squib circuit. Read TEST CONDITION column. Test circuit with HHT connected to DLC, with ignition in position "1". Read NOMINAL VALUE/HHT DISPLAY column. HHT will display a check or an "F". If HHT displays a check, circuit is okay. If HHT displays an "F", go to step 3.1.

Read TEST CONNECTION (NOT FOR HHT) column. Driver-Side air bag squib connector (R12/3) terminals No. 1 and 2 are identified. Read TEST CONDITION column. Test circuit with HHT connected to DLC and ignition key removed. Remove driver-side air bag module. Disconnect driver-side air bag module squib connector (R12/3). Connect Resistance Substitution Unit (124 589 09 63 00) to driver-side air bag module squib connector (harness side). Set resistance substitution unit to 2 ohms. Turn ignition key to position "1". Read NOMINAL VALUE/HHT DISPLAY column. If HHT displays a check, replace driver-side air bag module. If HHT displays an "F", go to step 3.2.

Read TEST CONNECTION (NOT FOR HHT) column. Horn/air bag clockspring connector (A45x1) terminals No. 1 and 2 are identified. Read TEST CONDITION column. Test circuit with HHT connected to DLC. Remove ignition key. Connect Resistance Substitution Unit (124 589 09 63 00) to horn/air bag clockspring connector (A45x1). Set resistance substitution unit to 2 ohms. Read NOMINAL VALUE/HHT DISPLAY column. If HHT displays a check, check horn/air bag clockspring for continuity. Replace horn/air bag clockspring as necessary. If HHT displays an "F", go to step 3.4.

NOTE: Some testing is identified by model number. To identify models by model number see MODEL IDENTIFICATION.

MODEL IDENTIFICATION

Model Number	Model
210	E Class

COMPONENT IDENTIFICATION

Component	Manufacturer's Designation
A45	Horn/Air Bag Clockspring
A53	Driver-Side Air Bag Sensor
A54	Passenger-Side Air Bag Sensor
B41/1	Passenger-Side Seat Occupied Recognition Sensor
N2/2	Control Module
R12/1	Driver-Side ETR Squib Connector
R12/2	Passenger-Side ETR Squib Connector
R12/3	Driver-Side Air Bag Squib Connector
R12/8	Passenger-Side Air Bag Squib Connector
R12/9	Side Air Bag (Driver-Side)Squib Connector
R12/10	Side Air Bag (Passenger-Side) Squib Connector
S68/3	Driver-Side Belt Buckle Switch
S68/4	Passenger-Side Belt Buckle Switch
W26	Control Module Ground
X11/4	Data Link Connector