With Bosch Tester

Checking electrics/electronics

With Bosch tester

The Bosch tester should only be used when the test adapter 126 589 09 21 00 is not available as a special tool. Since 1986 only a test program with adapter has been prepared for all models.

Special Tools:

Commercially available tools
Tester e.g. Bosch Model ETT 016.00
Multimeter e.g. Sun, DMM-5

Note: All test steps must always be performed, starting with test step 1, except with the ABS control unit with green Bosch designation plate and Bosch no.0 265 101 011 or blue type rating plate and Bosch no.0265 101 016 phased in as of February 1984. This ABS control unit can no longer be tested with the Bosch tester. Test steps 13,16, 17, 18 and 19 are omitted.

As a result of the modified ABS control unit the ABS cable harness is also changed, since the stop lamp switch is also included in the logic of the ABS. The stop lamp switch is connected to the 35-pin plug at pin 25 and is checked as follows:

Actuate brake and measure voltage between pin 25 and ground with a voltmeter. To prevent contact damage on the cable plug the use of a suitable connecting cable from the "electric connection set" is recommended.

Connection of tester

1 Remove ABS control unit (20) with ignition switched off.

2 Connect multiple plug (35-pin) (21) of cable harness for ABS control unit to plug (060a) of tester.

3 Attach plug (060b) of tester to ABS control unit. The retaining spring should engage audibly in plug.

4 Switch on ignition, make sure that all other ancillaries are switched off.

Note: Do not drive vehicle with tester connected.

Test Procedures

Test Preparation:

Test Step 1:

Test Step 2:

Test Step 3:

Test Step 4:

Test Step 5:

Test Step 5 (cont):

Test Step 6:

Test Steps 7, 8 & 9:

Step Step 10:

Test Step 11:

Test Step 12:

Test Step 13:

Test Step 14:

Test Step 15:

Perform test steps 16-22 with engine running.

Test Step 16:

Test Step 17:

Test Step 18:

Test Step 19:

The remainder of the test steps require a brake test bench.

Note: Prior to test on roller dynamometer, perform test steps 1-19.

Test steps 20-23 require a perfectly functioning service brake. Rollers of test bench and tires should be dry during the test. When testing front axle, actuate parking brake.