Jimstim 1.5 12V supply for MS2

[boxerdave]

Hi I'm new to the MS world and I hope you can help me out. From DIY, I sourced my Jimstim 1.5 and MS 3.0 board. After building the JS, all available tests worked fine. I then built my MS2 board with 3 BIP ignition drivers and the PMW idle control circuit as well. All went well with much help from Matt, thanks! The first tests before the CPU was in place was my first clue something is wonky. The Jimstim would not supply 12V to the MS2 board but using the direct method through the MS wiring harness, all voltage checkpoints were good so I finished the board. I flashed the firmware to the ECU and fired up Tuner studio (registered). The TPS calibration was always changing and the range of the JS pot was not linear, it would go from 0% to 100 within a slight turn. Also, the O2 sensor pot would affect the TPS setting. I never could get the RPM to sync and that was with lots of research on it. No diodes on either side would flash so something is not right.

So I went back and tested everything and again, with the CPU out, the Jimstim will not supply 12V to the rights side of U5 as per the test. Weird. And here's a couple of clues, when the JS is operating the MS (yes it would connect on TS), the JS INJ1 diode glows dimly all the time and the F1 fuses gets too hot to touch. Current draw with the MS connected is 140 ma, 63 with just the JS. Doing some digging, pin 28 from the JS shows zero volts yet it is my understanding it is 28 on the MS that is 12 v in. I confirmed this checking the harness and used pin 28 (red wire) to check voltage points on the MS with the CPU out. Now in searching, I found that pin 29 on the JS does supply 12 V and as a matter of fact, the pin is marked as 12V beside pin 29 on the row of 20 pins. My guess is the MS is powering itself through the js via another means (that's why the INJ1 diode is glowing and the F1 is hot)

My question is: why is there no 12V on pin 28 of the Jimstim? Am I missing something? Thanks

[Matt Cramer]

This sounds as if the MS2 has an internal 12 volt short.

[boxerdave]

Thanks Matt If it can help in the diagnosis:

1. Powering up the MS2 from the MS harness on pin 28 (12+ red lead) and ground (12- black lead) shows a current draw of 67 ma. Is that current draw in the ballpark for MS2?
2. The Jimstim never has any voltage on pin 28 standalone or connected to the MS2.
3. All the mica insulated devices on the MS2 have been double checked for case resistance to ground and all OK.

[racingmini_mtl]

I'm not sure from your description if that's what you mean but you need to run the JimStim troubleshooting tests described here: http://www.jbperf.com/JimStim/JimStim_v ... ml#testing

Jean

[boxerdave]

Thanks Jean Yes, it was those tests that I was referring to. All LED tests and the RPM one performed as they were supposed to do. I didn't perform the 3.3 volt one as the polyfuse only gets hot when plugged into the MS2. I wasn't sure if I could safely perform it while connected to the MS2, can I?
What is usual pathway to supply 12V to pin 28 on the JS? Thinking perhaps the pin 28 trace is open, do I dare run a jumper from the switched 12V to pin 28?

[racingmini_mtl]

Do you have 12V at the 12V pin header? What about the screw terminal? If you say that the tests all pass then the only possibility is the trace between the screw terminal and the D37 connector or a bad solder on pin 28 if the DB37. And you should have 12V at the pin header and the screw terminal otherwise the tests would fail. Those 2 places are safe places where you can get 12V.

But if the polyfuse gets hot when and only when you connect the JimStim to the MS then the issue is on the MS side and this is where you need to trouble shoot the issue. You likely have a short and the first thing I would check is D19 on the MS main board. That a common failure and that creates a short.

Jean

[boxerdave]

Thanks Jean Yes, I do have 12V both at the pin header and on the screw terminal marked 12v ( the forth terminal down from the top on the right side terminal block). On the DB connector, 12V at pin 29 but nothing on 28. Should there be 12V on pin 29? ( I checked many times to make sure I am counting the pins correctly). So assuming the trace has opened, it would be OK to jumper from the 12V terminal to the solder joint of pin 28 on the DB connector as a go around?

For sure, I'll check D19 on the MS board for issues. With the MS board connected via the harness (no JS) and drawing 65 ma, all the IC's and both polyfuses stay cool. Both the JS and MS draw about about 65 ma each (on their own). Will 130 ma combined through the JS polyfuse be enough to heat it up excessively? Thank you for your help, this glitch shall be overcome!

[racingmini_mtl]

I think your issue is simply that you're not counting from the right pin and that you indeed have 12V on pin 28 as it should. Check on the MS board if you have 5V on the proto area (which I think you will) and if so, you're fine.

Jean

[boxerdave]

I'm a huge idiot but not for not counting pins correctly. It's much worse than that and I can't believe I messed up as I have. If you were to solder the DB37 on the bottom side of the JS board, you too will get 12V on pin 29 and zero on 28. So, once I finish beating myself up, I'll unsolder the DB and move it to the topside of the board.

And of course, the MS2 must be very unhappy that a fool fed 12V to pin 29. Jean, Matt any thoughts on what damage may have occurred with 12V to the IAC2A terminal (with the jumper to JS2 in place)?

[boxerdave]

Hi Jean Well a guy has to get lucky once in while and I think I did. I moved the 37 pin connector to the topside of the JS board. I had to run jumpers from the soldered pins to the respective terminal block as some the traces were damaged. A continuity check from each pin inside the DB37 to the terminal block was done to double check my work. The TP pot. seems to be the only casualty (I hope), it was open, so I moved the spare over to the TP position. The MAT, CLT, TPS and wideband O2 all work flawlessly on Tuner Studio. The problem I am having is I can't get Tach sync (with a twist).
In researching this forum for sync issues, I set the following parameters: In Ign settings on TS, I have set it to basic trigger, JS10 output, rising edge, going high, MPA, flip polarity - Normal. If I set the Tacho output to ON, JS10 and normal I get a Config error. The only way to stop this error is to change the output on either Ign or Tacho so the outputs don't match, which doesn't make sense ( so JS10 and D14 etc). The Primary tach pull up jumper is in the VR position (upper two pins) and both primary and secondary 12V jumpers in place (on the right side of the jumper block). All the DIP switches are off. I have 3.3 volts on the left side terminal of each RPM pot with the centre pin of each varying from 0 to 3.3. With the VR jumper in place, there is no voltage at the TACH pin or the TACH terminal regardless of the RPM pot settings. With the jumper in the HALL position, the voltage varies from 5.8 to 11.6 at the TACH terminal using the FINE or COARSE pots. The JS board passed the RPM test. Any suggestions? Thanks

Dave

[racingmini_mtl]

You can't check the VR signal with a multimeter; you need an oscilloscope. But you should be able to get a tach sync with the hall setting if you adjust the trim pots on the MS v3.0 board.

Jean

[boxerdave]

Hi Jean Thanks very much all for your assistance, Success! Now I'm digging into the 202 pages of the Tuner Studio Help manual, absolutely fascinating the work that has gone into MS and TS and the various options for control. Looking forward to getting it all together on a running engine.

Dave