Bosch Tech 2 User Manual

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6.  TROUBLESHOOTING
This section is a general troubleshooting guide for all vehicle applications of the Tech 2 scan tool. Some of 
the information may differ for your particular vehicle application. 
When the Tech 2 appears to be operating abnormally, refer to this section for probable causes and solutions.
The following two types of self tests are available on the Tech 2: 
• Power On Self Test (POST) :checks the major functions of the Tech 2 at power-up. 
• Self Tests :check the major and minor functions of the Tech 2. 
If errors are detected, a Tech 2 malfunction is present which may result in vehicle misdiagnosis. For 
Customer Support information, refer to the inside cover of this users guide.
POWER ON SELF TEST (POST) 
Power On Self Tests run automatically each time the power [PWR] button on the Tech 2 keypad is pressed 
on. 
The screen displays pass or fail results for each area tested. POST automatically 
checks the following: 
• MC68332 processor 
• External RAM (Random Access Memory) 
• Flash memory 
• Display controller and display 
• Sound transducer 
• MC68332 RAM  
						

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• Real-time clock 
• Keypad controller and keypad 
• Main UART (Universal Asynchronous Receiver/Transmitter) 
Results of POST may include fatal errors that do not allow you to continue, or non-fatal errors that allow 
you to continue without full Tech 2 operation. If normal Tech 2 functions are stopped or limited, contact 
Customer Support to determine if service is required. 
At completion of POST, the following audible signals indicate a pass or fail 
condition: 
• One beep - No problem. Your Tech 2 is operating normally. 
• No beep - Sound transducer has failed. Contact Customer Support. 
• Three short beeps - Tech 2 has failed POST. Contact Customer Support.
SELF TESTS 
Tech 2 self tests verify that the Tech 2 is functioning normally. The self tests evaluate all critical areas of the 
Tech 2 and display pass or fail messages for each subsystem tested. Self tests isolate user error from system 
hardware failures. The self tests should be performed periodically to insure that the Tech 2 is operating 
properly. 
The Tech 2 must meet the following requirements in order to do a self test: 
• Screen display must be fully readable 
• Keypad must be operational 
Begin the Tech 2 self-testing program by following these steps: 
1. Press ENTER while viewing the Tech 2 start-up screen (Figure 6-1). 
2. Select F3: Tool Options from the Tech 2 main menu (Figure 6-2). 
3. Select F3: Self Test from the tool options menu (Figure 6-3). 
						

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FIGURE 6-1. Tech 2 Start-Up Screen
FIGURE 6-2. Tools Options Selected on Main Menu 
						

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TECH 2 SELF TEST MAIN MENU 
Each Tech 2 Self Test main menu selection is explained in detail on the following pages. All users have 
access to all the options listed (see Figure 6-5). Read all screen instructions and connect or disconnect the 
appropriate cables and loopback adapters. Screen messages display when external loopback connectors are 
connected. For specific loopback connection information, refer to Figure 3-2, Figure 3-4, and Figure 6-4. 
F0: Automated Main PCB and VCI Test 
Selecting Automated Main PCB and VCI (Figure 6-5) is a quick way to test the performance of the main 
Printed Circuit Board (main PCB—the Tech 2 main circuit board) and the Vehicle Communications 
Interface (VCI). The Tech 2 displays a test-in-progress screen (Figure 6-6) while performing all the PCB 
and VCI tests in sequential order.
FIGURE 6-3. Self Test Selected on Tool Options Menu 
						

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The Automated Main PCB portion tests the following components: 
•RAM / ROM 
• RS-485 loopback 
*
• RS-232 loopback *
• Keypad 
• PCMCIA slot 1 
*. Each of these tests requires the conenction of a loopback adapter to the Tech 2.
FIGURE 6-4. Connection of DLC Loopback Adapter to the Tech 2 VCI ConnectorTech 2 VCI connector 
DLC loopback adapter
(P/N 02002953) 
FIGURE 6-5. Tech Automated Main PCB and VCI Test Selected on Tech 2 
Self Test Main Menu 
						

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• PCMCIA slot 2 
• Display controller 
• Sound transducer 
• Real-time clock 
Refer to Ta b l e 6 - 1 and Ta b l e 6 - 2 for help in diagnosing problems that involve the Tech 2s PCB and VCI. 
If the Tech 2 passes all Automated Main PCB and VCI tests, you do not need to run any more tests to verify 
that the Tech 2 is working properly.
The following test results are displayed: 
Once tests are complete, select the soft keys Main Details or VCI Details (Figure 6-6) to review the results 
of the main PCB or VCI tests (see Figure 6-7 and Figure 6-8). 
If any failures occur, select F3: Selectable Main PCB (Figure 6-11) or F4: Selectable VCI (Figure 6-13) 
from the Tech 2 Self Test main menu to further isolate the failure. Report failure information to Customer 
Support.
Total Pass 1 - indicates that Tech 2 passed test 
0 - indicates a test failure 
Total Failures 0 - indicates that Tech 2 passed test 
1 - indicates a test failure
PCMCIA Cards Present 1 or 2 indicates how many cards present in Tech 2 
FIGURE 6-6. Automated Main PCB and VCI Test Results Screen 
						

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FIGURE 6-7. Main Details Selection
FIGURE 6-8. VCI Details Selection 
						

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TestResultsSolution
RAM/ROM 0-Pass
1-ROM read fail
2-RAM read fail
3-RAM write and read do not compareRecord type of failure.
Cycle Tech 2 power (press [PWR]) and retest.
If problem persists, contact Customer Support.
RS-485 loopback Pass
Fail-Loopback may not be connectedCheck loopback connection.
If problem persists, contact Customer Support.
RS-232 loopback Pass
Fail-Loopback may not be connectedCheck loopback connection.
If problem persists, contact Customer Support.
Keypad Test successful
Keypad failed
Exiting test before all keys are pressed 
results in a failed keypad testCycle Tech 2 power and retest.
If problem persists, contact Customer Support.
PCMCIA (tests 
both card slots)Card detected
Card not present
FailCheck that card is inserted properly.
Cycle Tech 2 power and retest.
If problem persists, contact Customer Support.
Display controller 
(contrast and 
characters)User determines if display is correct. If the display shows a noticeable failure during 
tests, contact Customer Support.
Sound transducer User determines if sound transducer is 
working.If no sound is emitted by repeatedly selecting 
Automated Test or Sound On, contact Customer 
Support.
Real-time clock Time is displayed correctly.
Invalid values are displayed for date, 
year, hour, minute, or second.Reset clock.
Cycle Tech 2 power and retest.
If time is not retained, contact Customer Support.
TABLE 6-1.  PCB Diagnostic Chart
TestResultsSolution
MUX 
(Multiplexer) MUX A: S5 & S14
pass/fail 
MUX B: S1 & S3
pass/failIf MUX A or B fails, cycle Tech 2 power and 
retest. 
If problem persists, contact Customer Support.
VCI adapter ID 
(performed only 
during selectable 
VCI test)Recognized adapter 
Cannot identify adapterIf adapter fails, use a different adapter to make 
sure that the VCI correctly identifies the adapters. 
Cycle Tech 2 power and retest failed adapter. If 
adapter fails second test, contact Customer 
Support.
VCI ADC
(Analog to digital 
converter)Channel A - pass/fail 
Channel B - pass/failIf channel A or B fails, cycle Tech 2 and retest. 
If problem persists, contact Customer Support.
Cross point Pull up - pass/fail 
TPU5, TPU1, and TPU0 - pass/fail 
(results from selectable VCI test)If a failure occurs, cycle Tech 2 and retest. 
If problem persists, contact Customer Support.
TABLE 6-2.  VCI Module Diagnostic Chart 
						

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SIPO (Serial In 
Parallel Out) Pass/fail for each area tested If a failure occurs, cycle Tech 2 and retest. 
If problem persists, contact Customer Support.
DLC 
(Data Link 
Connector)DLC1 - DLC2
pass/fail count 
DLC2 - DLC1
pass/fail countIf a failure occurs, cycle Tech 2 and retest. 
If problem persists, contact Customer Support.
CCD 
(Chrysler Collision 
Detection)CCD - pass/fail 
CCD - loopback not connected Connect loopback and retest if loopback not 
connected. 
If test fails, disregard results. Test is not for GM 
vehicles (other than Saab) at this time.
GND FET 
(Ground Field 
Effect Transistor)GND FET - pass/fail Check loopback adapter to make sure it is 
connected, cycle Tech 2 retest. 
If problem persists, contact Customer Support.
VCI HBCC 
(Hosted Bus 
Control Chip) HBCC - pass/fail If HBCC chip fails, cycle Tech 2 and retest. 
If problem persists, contact Customer Support. 
VCI DUART 
(Dual Universal 
Asynchronous 
Receiver 
Transmitter) Channel A - pass/fail 
Channel B - pass/fail If channel A or B fails, cycle Tech 2 and retest. 
If problem persists, contact Customer Support.
VCI I/O 1 - I/O 16 
Te s tPass/fail messages displayed for each of 
the I/O lines (results from selectable 
VCI test).If test fails, was loopback installed? 
Once an error has been detected on one of the I/O 
lines, you can test the specific line by selecting F3 
or F4 tests. 
If the test fails continuously or intermittently, 
contact Customer Support. 
VCI loopback  Pass/fail message for each I/O loopback 
test.For any failure, make sure the loopback is 
connected. Use F:1 Check ID to verify that the 
loopback is found. 
Cycle Tech 2 and retest. If problem persists, 
contact Customer Support.
VCI short L & M  Open I/O 7 - pass/fail 
Open I/O 9 - pass/fail 
Hi I/O 7 - pass/fail 
Hi I/O 9 - pass/fail 
Lo I/O 7 - pass/fail 
Lo I/O 9 - pass/fail For any failure, cycle Tech 2 and retest. 
If problem persists, contact Customer Support.
VCI J1708  Internal transceiver - 
pass/fail 
Differential - pass/fail 
Differential - pass/fail (results from 
selectable VCI test)For any failure, cycle Tech 2 and retest. 
If problem persists, contact Customer Support.
Te s tResultsSolution
TABLE 6-2.  VCI Module Diagnostic Chart (Continued) 
						

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F1: Automated Main PCB Test 
This test works the same as the Automated Main PCB and VCI test, except the VCI portion of the test is not 
included (Figure 6-9). 
VCI TPU (Time 
Processor Unit) TPU0 - pass/fail 
TPU1 - pass/fail 
TPU5 - pass/fail 
TPU12 & TPU15 - pass/fail (or not 
tested if no loopback) 
TPU13 & TPU14 - pass/fail (or not 
tested if no loopback)For any failure, cycle Tech 2 and retest. 
If problem persists, contact Customer Support.
VCI level shifters  MUX A 2.5 V Hi - pass/fail 
MUX A 2.5 V Lo - pass/fail 
MUX A 5.0 V Hi - pass/fail 
MUX A 5.0 V Lo - pass/fail (results 
from selectable VCI test)For any failure, cycle Tech 2 and retest. 
If problem persists, contact Customer Support.
TestResultsSolution
TABLE 6-2.  VCI Module Diagnostic Chart (Continued)
FIGURE 6-9. Automated Main PCB Test Selected on Tech 2 Self Test Main Menu