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How to read codes from the BP26 (GTX) and BPC8 (GTR) ECUs

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    How to read codes from the BP26 (GTX) and BPC8 (GTR) ECUs

    This is what you do to read the codes from a BP26 and BPC8 ECUs. I have done it on my BP26 when I had one and it works great. I will make this into a sticky.

    FIRST STEP: Make tester

    Buy LED and appropriate resistor (red = 1kOhm, green/yellow/amber = 470 Ohm). Alternative is 12V dc packaged LED from electronics store.

    Make up test lead so it follows this circuit (insulate all exposed wire, leaving the two contacts for the +B socket and the FEN socket, make sure you can see the LED from the drivers seat):

    +B socket (12V)

    --> Red wire (solder end of wire to make acceptable stiff end to stick in diagnostic socket)

    --> Resistor (red = 1kOhm, green/yellow/amber = 470 Ohm)

    --> LED - Longest leg of LED (positive)

    --> LED - Shortest leg of LED (negative) Wire with stiff end (eg. paperclip)

    --> FEN socket (diagnostics)

    eg:

    +B #------- Resistor -------*----------- LED ----*-------# FEN

    (* = soldered join, # = solid end)

    Use another insulated wire between TEN and GND on diagnostics socket. Ensure it cannot touch anything else.




    SECOND STEP: Test ECU codes

    1. Do above
    2. Try/run engine
    3. Turn off engine
    4. Turn ignition back on
    5. Observe LED

    Car is OK then LED lights up like the dash lights e.g. for 4 seconds and then goes dark.

    Fault code is one second light/ one second dark followed by 4 second intervals for a new fault code. e.g. Disconnect air mass flow meter, run car and you get 8 +1, disconnect timing pickup on camshaft and try and run car then you get 8 + 4+ 1 (codes are stored until you erase them).

    6. To erase the codes - make sure you stereo etc is not code protected, then remove battery terminal for 30 seconds.

    Note it is also possible to force the fuel pump (F/P), coolant fans (TFA) and have an electronic source for a timing device (IG-) from the diagnostic socket.

    There is still the MEM tag -

    Note on FEN to +B signal - this will only source 35.7mA maximum current drain so a normal 12V test bulb will not light. I was using the test bulb to drag the voltage up then measuring the voltage of
    FEN, it would dip to 11.57V but the scan/refresh rate of my digital multimeter is about 0.5 second hence difficult to be certain of pulses. This practice is strictly dubious - hence the need for an LED
    circuit or similar.

    To know what the codes mean, read the GTR supplement of the 90-94 Mazda Familia FSM.

    #2
    On my bp55 ecu, I had to also attach a jumper between ten and ground.
    sigpic
    -BP-VF10-FMIC-2.5 Magnaflow-Eibach-Tokico-Megasquirt II-Zeitronix-

    Comment


      #3
      cant i just buy a tester at autozone?

      Comment


        #4
        Originally posted by smoke187 View Post
        cant i just buy a tester at autozone?
        Likely no, unless they specifically sell a Mazda tester for these years. The OBDI standard was not as standard as OBD2.

        Also, the method mentioned above costs you under $1. There are not enough codes to warrant a tester.

        Comment


          #5
          would a test light work the same way?

          Comment


            #6
            i don't get the resistor colors thing is it 1 resistor that i need?

            Comment


              #7
              Yes, you will only need 1 resistor and the size of the resistor is dependent on the color of LED you get. Just get a red LED and a 1K resistor.

              Comment


                #8
                i got a tackle box full of spair parts from when i was repairing car amps, im gonna make one for me and doug, you wouldnt have a pic of what the one you made looks like do ya lex? also if i can scan my 95 egt with our snap on scanner and the mazda plug, will it read the codes from the gtr/gtx ecu's? im probably gonna try it on dougs when i get back to work in a few....
                92 protege lx-

                94 protege lx-

                95 escort gt-ms2e/ms2extra pre3.3alpha5 gslender v2.8-e85-vj23@12lbs----dead--

                are you a thinker, or a believer?

                Comment


                  #9
                  So I can't just use a light already in my dash because of low amperage?
                  1990 Protege 4WD
                  GT-X BP26 swap [AT->MT]|Cup holder cut to fit|Synthetic gear oil|Synthetic brake fluid|Corksport SS brake/clutch lines|Mazdaspeed HV oil pump|GT-X front STB|Corksport type I rear STB|Matching full-size spare wheel|Homebrew Brass shifter bushing|Speed Source brass shifter cable bushings|EDM headlights/corners|FMIC|EDM cabin vents

                  1 3 5
                  ├┼┤
                  2 4 R


                  Seeking: Canadian 4WD seatbelts.

                  Comment


                    #10
                    I dont have the gtr supplment what do the codes mean

                    Comment


                      #11
                      You can get the GTR service manual supplemental here:

                      '91 Escort GT

                      Comment


                        #12
                        found out today our snap on solus will get into the gtr ecu. didnt get any codes, but it had the same menu as my egt ecu did, the timing adjust, and o2 readings and such....
                        92 protege lx-

                        94 protege lx-

                        95 escort gt-ms2e/ms2extra pre3.3alpha5 gslender v2.8-e85-vj23@12lbs----dead--

                        are you a thinker, or a believer?

                        Comment


                          #13
                          well i was bored the other day when i had the soldering stuff out. figured id post a pic incase anyone wants to make one of these but isnt so sure how to do it..... first off i used a yellow led and 470 ohm resistor, its just what i had around or id have used red. i twisted the short leg of the led and a piece of wire together facing each other to make them smooth. the longer leg i twisted the resistor too ( it honestly doesnt matter the direction, but i alway use the side you start reading as in to keep it simple) sorta like the neg side. then i twisted a piece of wire onto the resistor. i made the ends equal length, stripped the ends a tiny bit and twisted them straight. about then the soldering iron was ready, i soldered all the joining parts together and tinned the ends of the wire, and covered them with shrink wrap. i also made a short piece to connect the ten to ground to make the led flash on the fen circuit, same as how i tinned the wire ends just heat it enough to suck solder into the wire and your set... just something to keep it from fraying when you push it into the terminals... well on to the pics, i normally wouldnt upload them this big, but its easier to see as theyre small parts... and my batteries died after 2 pics so i didnt get one of the finished product. ill have to plug it in once before i get ms back and see if it works.
                          Attached Files
                          92 protege lx-

                          94 protege lx-

                          95 escort gt-ms2e/ms2extra pre3.3alpha5 gslender v2.8-e85-vj23@12lbs----dead--

                          are you a thinker, or a believer?

                          Comment


                            #14
                            hey did this end up working man?
                            -Jack

                            ONTARIO MAZDA CLUB! Join! https://www.facebook.com/groups/500055016671733/

                            91 626 LX - basically stock and pretty slow still
                            http://www.clubprotege.com/forum/sho...my-GD-626-LX-)

                            01 E53 3.0i - FOR SALE! pm if interested

                            91 USDM Protege LX - SOLD! turbo/manifold up for sale!
                            http://www.clubprotege.com/forum/showthread.php?t=46606

                            Comment


                              #15
                              I used a #74 LED replacement bulb and wired up the dash harness. It looks stock except for being green and unlabeled.
                              1990 Protege 4WD
                              GT-X BP26 swap [AT->MT]|Cup holder cut to fit|Synthetic gear oil|Synthetic brake fluid|Corksport SS brake/clutch lines|Mazdaspeed HV oil pump|GT-X front STB|Corksport type I rear STB|Matching full-size spare wheel|Homebrew Brass shifter bushing|Speed Source brass shifter cable bushings|EDM headlights/corners|FMIC|EDM cabin vents

                              1 3 5
                              ├┼┤
                              2 4 R


                              Seeking: Canadian 4WD seatbelts.

                              Comment

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