RS-232 Loopback plug

When you have inserted the RS-232 plug first make sure that the RS-232 is functioning according to the specification.

Creating a RS232 Loopback connector

  • Cut off an eight-pin connector about three inches from the end.
  • Number the pins 1 thru 8 as you like.
  • Splice the pin wire pairs as follows:
    • 1-3
    • 2-7
    • 4-5
    • 6-8

Tech2 keyboard and RS232 loopback self test

  • Attach (p/n 3000112) RS232 eight-pin loop back connector to left side port of Tech2.
  • Attach (p/n 3000095) cable to the VCI in the bottom on the TECH2.
  • Attach (p/n 3000109) loop back adapter to the other end of the cable.
  • Connect a 12vdc power source to the TECH2.
  • Press ENTER.
  • Select TOOL OPTIONS.
  • Select Tech2 Self Test
  • Read the screen and press EXIT.
  • Select Automated Main and VCI.
  • Read the results.

Testing the RS232 loopback plug

Test the plug by attaching it to the serial port of the Techline computer or into a certified Tech2 USB-2-serial adapter. Download a serial terminal application like RealTerm to diagnose the loop-back functionality.

Now plug your RJ-45 loop-back adapter into the Tech2 device and navigate to the RS-232 test. Depending on the software version there are various options to get to the RS-232 test menu.

While using the (SAAB 44.000 .bin file)[/content/which_.bin-files_are_available/SAAB.html] you need to follow this procedure;

  • Insert the loop-back plug into the RJ-45 port
  • Press PWR to turn on the Tech2
  • Title screen, press ENTER
  • F2: Tools Options
  • F3: Field Services Diagnostics
  • F3: Selectable Main PCB
  • F2: RS-232 LoopBack

While using the (SAAB 148.000 .bin file)[/content/which_.bin-files_are_available/SAAB.html] you need to follow this procedure;

  • Insert the loop-back plug into the RJ-45 port
  • Press PWR to turn on the Tech2
  • Title screen, press ENTER
  • F2: Tool Options
  • F0: Tech2 Self Test
  • Press EXIT on the notification screen
  • F3: Selectable Main PCB
  • F2: RS-232 LoopBack

Now the Tech2 should respond with the following: RS-232 Test: Passed

If the Tech2 responds with RS-232 Test: LoopBack Not Connected or ADDRESS ERROR - PROCESSOR HALT the chances are high that the MAX202 or the MAX232 is borked, which means replacing the SMD mountec RS-232 communications chip (SOIC type), noted as U202 on the main PCB.

Reference: The three dudes and their cars…