Points to Note

Fault diagnosis: ETS (TCS man/TCS auto)

Points to note

1 The diagnosis socket (black) is located underneath the right-hand front seat. On M 1992 and later model year cars, the socket is covered by a flap of the carpet.
2 During fault diagnosis, the ignition key must always be in the Drive position.
3 The ETS has system number 3 in the SAT system.
4 Read and note down all stored fault codes before disconnecting the battery or ECU.
5 If communication cannot be established between ISAT and the ECU, start by checking fuse 21 and then the leads between ECU start by checking fuse 21 and then the leads between ECU pins 9 and 34 and the diagnostics socket (347). Also check that the power supply and earth circuits to the diagnostics socket are OK and that the connector pins are undamaged.
6 Once the fault codes stored in the system's ECU have been transferred to ISAT, the diagnosis function is finished. The next step is to use the appropriate command code or codes for the fault codes in question. It may sometimes be helpful to enter all command codes to check the status of certain input signals or components before continuing with the fault diagnosis according to the fault diagnosis schedule.
7 A list of fault codes for TCS manual. Diagnostic Trouble Code (DTC) Descriptions
8 A list of fault codes for TCS automatic. Diagnostic Trouble Code (DTC) Descriptions
9 A list of all command codes. Command Codes, ETS
10 To avoid damaging the ECU, always make sure that the ignition is switched off (and the main relay released) before unplugging the connector.
11 Before tracing faults on a vehicle's electronic systems, always start by checking that the earthen circuit for the ECU concerned is OK and that all supply voltages are correct.

Note: On completion of fault diagnosis, always enter command code 900 to clear the fault memory.

TIPS
On M91-and early M92 cars, certain malfunctions are more common than others. Some useful fault-tracing information will be found in Fault Diagnosis Hint and Tips. Fault Diagnosis Hints and Tips: M91 and Early M92

12 Unplug connectors and plugs to check that the terminals and pins are undamaged. After checking, plug in the connectors and plugs again and clear all fault codes. Start the engine or drive the car again to check whether the fault or faults persist.
13 When first detected, a fault will be assigned a permanent- fault code. If the fault later disappears, the fault will be classified as intermittent.

14 All signals around the 12-volt level are proportional to battery voltage. These levels should therefore be used only as a rough guide.
15 Zero-voltage signal levels indicate earth, although a sensitive multimeter may indicate a value slightly above 0 V.
16 If a system fault occurs, the main relay cuts off the power supply to the ECU and valves.
17 All fault codes beginning with a 4 or a 5 denote permanent faults. Fault codes beginning with a 2 or a 3 denote a transient or intermittent fault.
18 Remember that fault codes can also be set in connection with fault tracing. For example, if the ignition switch is in the Drive position and the ETS control unit is disconnected so that a certain test can be performed, a fault code for defective communication with the ETS control unit will be set. It is partly for this reason that fault codes should always be cleared after fault tracing, the car should be driven on test, and a check should be made to ensure that no new fault codes have been set.
19 Never change from one quantity or unit of measurement to another (e.g. from V via I to ohms) when using a test instrument without first disconnecting the instrument's test probes.

Checking the isolator valve for the Turbo's bypass valve. Control Valve For the Turbo By-Pass Valve

Checking the Cruise Control system. Cruise Control

Checking the AC/ACC. AC/ACC

(•-#3)
This means that the ISAT should be connected to the black diagnostics socket and that the ETS has system number 3.

Breakout-box = BOB
Always use the breakout box when tracing faults in circuits or leads in the ETS system. In the following text, the abbreviation BOB is used for the breakout box.