SRS Diagnostics (72 02 91 (3338))

Publication date: 1994-12-01
Reference number: 72 02 91 (3338)

SRS DIAGNOSTICS

TECHNICAL SERVICE BULLETIN

Reference Number(s): 72 02 91 (3338), Date of Issue: December, 1994

BMW:	E30 and E24 (equipped with Siemens SRS Control Module)
GROUP:	72 - Equipment and Accessories

Superceded Bulletin(s): 72 02 91 (3338), Date of Issue: August, 1991

NOTE: This Service Information bulletin supersedes orange S.I. 72 02 91 (3338) dated August, 1991, which should be removed from your S.I. binder and discarded.

SUBJECT

SRS Diagnostics

SITUATION

The BMW Service Tester can be used to call up fault codes via the RxD and TxD lines on the control module. This will provide a convenient and reliable method for testing and diagnosis, as well as eliminate any confusion as to the interpretation of flash codes.

As the vehicle wiring harness was not equipped with TxD and RxD leads connecting the SRS control module and the Diagnostic Connector, the special tool/procedure below must be followed in order to connect diagnostic equipment to the SRS control module on the affected vehicles. This procedure allows fault codes to be recalled/cancelled.

PROCEDURE

Using the special cable connector (SD# 91-020), connect the Service Tester Diagnostic cable to the SRS control module side of C250 (E24), C280 ('92 E30 Convertible), or C240 (E30) as appropriate. Note that jumper leads contained in the BMW Connector Test Kit (P/N 88 88 6 900 322) can be used if the SD# 91-020 adapter is not available. [Each Dealer was sent one adapter. Refer to S.I. 04 29 91 (3446) .] Use the table below and Fig 1 as a guide to the connections.

DIAGNOSTIC CABLE CONNECTIONS

Model	Diagnostic Cable	SRS Connector
E24	Pin# 15 (RxD)	C250 Pin# 6 (WT/YL)
E24	Pin# 20 (TxD)	C250 Pin# 2 (WT/VI)
E24	Pin# 19 (Ground)	Good Vehicle Ground
E30 '92 Convertible	Pin# 15 (RxD)	C280 Pin# 6 (WT/BK)
E30 '92 Convertible	Pin# 20 (TxD)	C280 Pin# 7 (WT/VI)
E30 '92 Convertible	Pin# 19 (Ground)	Good Vehicle Ground
E30	Pin# 15 (TxD)	C240 Pin# 6 (WT/YL)
E30	Pin# 20 (TxD)	C240 Pin# 2 (WT/VI)
E30	Pin# 19 (Ground)	Good Vehicle Ground

Once the proper connections are made, the control module can be surveyed using the Service Tester. The new DIS Tester does not support this procedure at this time.

Fig 1: Diagnostic Cable Connections

Fig 1 shows connections between Diagnostic Cable on BMW Service Tester and SRS control module in vehicle. Refer to table above for detailed description of connector Pin numbers.