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This is related to Test 5 of this question: OBD II Scanner refuses to communicate with the vehicle!

Funny that I should be asking this but then .....it happens

Unfortunately, I cannot remember.

I'd appreciate pointers.

I have a strong suspicion that maybe the correct expression should have DLC Bus terminals and not DLC Bias terminals, courtesy of the diagram below courtesy of Wikipedia.

ISO Description of the DLC Connector

Thank you.

OPTION 1: (My thoughts) TEST 5: Connect positive DMM lead to either DLC BUS terminals (DLC Pin 2 or DLC Pin 10)

Connect negative DMM lead to the ground terminal

With the ignition key ON and no bus activity, BUS + should read 0V BUS - should read 5V

With the ignition key ON and bus activity, the voltage should vary from 0 to 5V depending on the amount of bus activity!

OPTION 2: (Suggested by narkeleptk) TEST 5: Connect positive DMM lead to either DLC BUS terminals (DLC Pin 7 or DLC Pin 15)

Connect negative DMM lead to the ground terminal

With the ignition key ON and no bus activity, BUS + should read 0V BUS - should read 5V

With the ignition key ON and bus activity, the voltage should vary from 0 to 5V depending on the amount of bus activity!

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  • whats your model year? – narkeleptk Jun 11 '20 at 0:41
  • Mazda MPV 2000 LX – ElectronicsNewbie Jun 11 '20 at 20:31
  • Pretty sure its uses 9141-2 protocol for data line so it would be Kline pin 7 / Lline Pin 15. Unless I am not understanding your question. – narkeleptk Jun 11 '20 at 22:36
  • @narkeleptk Question updated to make it clearer, yes it uses 9141-2 protocol – ElectronicsNewbie Jun 13 '20 at 18:17
  • You have "KEY ON" twice for both. Did you mean KEY OFF? DMM set to dc isn't all that good for checking data lines but If its active you probably wont see 5 V at all, more likely the dmm will try to average out the 0 low/5 high pulses to around 2-3V. – narkeleptk Jun 13 '20 at 22:33

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