Diagnostic Tool's Screen Doesn't Come Alive When On Is Pressed

The Diagnostic Tool's Screen Does Not Come Alive When The ON Button Is Pressed.

Fault symptoms
The diagnostic tool's screen does not come alive when the ON button is pressed. No system can be contacted.

Condition
The following condition is applicable:
- Battery OK.

Diagnostic help
First check that no slide-out of the data link connector pins for current supply (+30 circuit) and ground has occurred. Then use a test lamp to check whether any lead and/or fuse supplying the data link connector with current is faulty.

Following this, check whether the diagnostic tool works on another car.

If no fault can be found, decide whether to repair or replace the diagnostic tool.

Checking the wiring harness
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short-circuits in the leads. Observe the multimeter, test lamp or diagnostic tool during the test.

Diagnostic procedure

1 Checking the diagnostic tool's current supply
- Connect test lamp 86 11 857 to pin 16 of the data link connector and a good ground.





- The test lamp should light.





Function OK?
YES
- Go to point 2.
NO
- Repair or replace the relevant lead.
- Go to point 5.

2 Checking the diagnostic tool's ground connection
- Connect test lamp 86 11 857 to pins 16 and 4 of the data link connector.





- The test lamp should light.





Function OK?
YES
- Go to point 3.
NO
- Repair or replace the relevant lead.
- Go to point 5.

3. Checking the diagnostic tool's ground connection
- Connect test lamp 86 11 857 to pins 16 and 5 of the data link connector.





- The test lamp should light.





Function OK?
YES
- Go to point 4.
NO
- Repair or replace the relevant lead.
- Go to point 5.

4 Checking the diagnostic tool
- Connect the diagnostic tool to another car.





- Check whether the diagnostic tool's screen comes alive when the ON button is pressed.





Function OK?
YES
- Go to point 5.
NO
- Repair the diagnostic tool or change it, if necessary.
- Go to point 5.

5 Final check
- Carry out a function test.





Function OK?
YES
- The steps taken to rectify the fault were correct.
NO
- Go through the fault diagnosis procedure once again.