No tach, only I1 lights up

[DKdekes]

Ok so I built up my V3 MS2 following MegaManual instructions for hall/opto input. I do not currently have an idle setup. Once the board was completed as per MegaManual instruction, and ran perfectly on the Stim, I decided to go MS2extra as well as get an idle output. Well I did all of the mods for extra and the idle, and changed the code and everything, went to bench test it and...no tach. Out of frustration I decided to revert back to the original MegaManual build I had previously had. But the problem is I still have no tach. I realized I had accidentally jumped s12c to JS10, instead of JS9, which I really really regret. Seeing JS10 is ignition input into the MS2 (right?), I'm not wondering why I don't have tach anymore haha. I ordered a new MS2 and fixed the jumper mistake. But another problem arose from the journey to MSextra and back. Whenever I power up the stim, even when the MS2 is out of the socket, I1 lights up. I have checked with a video recorder and have found that it is a solid light. So I am assuming I have blown something else up. Thanks a lot for the help and feel free to call me an confused person for blowing up my processor haha I deserve it

[trakkies]

It may help to know you can have an MS2 daughter board repaired for about half the cost of a new one.

[DKdekes]

Thanks that is very good to know for future situations. Unfortunately my board arrived yesterday, and I am in somewhat of a time crunch to get this board done.

[DKdekes]

Can anyone explain why I1 is always on on the stim? If it counts for anything, when the processor is in, I get all signal inputs, but no tach. Also, when the processor is in, the fuel pump light goes on for one second then shuts down.

[trakkies]

The pump running for a second at switch on is normal. It will then start up again when it sees a tach signal.

By I1, do you mean D1 (LED) on the Stim? That shows a ground being present at pin 36 (ign) of the DB37 connector. If this is so with no processor in place I'd say you have a short on the PCB somewhere. Of course it could be a problem with the Stim itself, as that gets its power from the MS, so will only worked when plugged to it.

Unplug the Stim, and check for continuity between Pin 36 and one of the ground pins - there should be none. Do the same with the MS, with the processor unplugged.

[DKdekes]

I switched the Stim's RPM POT to PNP instead of NPN, and I am now getting tach. The led's on the main board are all working and respond the way they should now. The pump light is also on always like you said. So I am getting tach, but still have that short on the LED on the Stim. By I1 I actually meant LED 3. It is labeled I1, and is the injector signal for one bank (there is also I2). I checked continuity between pin 28 and ground on the main board to check the injector circuit, and there is a short. Along with the Injector 1 LED always being on, Injector 2 and Ignition never come on

[trakkies]

Ah - sorry. So the LED for Inj 1 is permanent on.

First thing I'd do is check very carefully with a strong light and magnifying glass for a solder bridge at Q10 and Q14. Double check all the diodes and transistors and U4 are correctly fitted. Check that Q9 is correctly fitted and insulated from the heatsink. Since Inj2 is ok, look for differences between the two before going further.

[DKdekes]

I don't have an idle setup at the moment, so I do not have Q10 on. I do have Q14 though, and I checked that. The soldering looked clean, but I checked for continuity between the transistor leads on Q14 and there is obviously a short. I took Q14 out and checked for continuity between the holes on the board. The board is shorting somehow. I have already cleaned it but I will try again to see if it does anything.

Also, I'm not sure if Inj2 is actually ok, because it never lights up, even with the processor in. I ran through and checked for bridges on all of the small transistors and found another on Q19 so I'm going to try to address that in the next day.

[Matt Cramer]

I put together a detailed article on injector circuit troubleshooting that may help:

http://www.DIYAutoTune.com/tech_article ... ooting.htm

[DKdekes]

I cleaned the board again after finding the short on q14. Now Inj1 doesn't light up anymore. Went through my board all over again and found that I forgot to jumper for ignition so now I have everything! Thanks for the help you guys!