MSefi.com read only forum (Jan.15,2018)

This has been a problem since I completed the assembly. At first I thought it was a flaw in the stim since all the other values worked perfectly. Did a temporary hookup to the diagnostic port on my 1990 Mercedes (where a keyed +12v, ground, and coilNEG terminal exist), and not a twitch from the tachometer in tunerstudio.
Any clues on where to start troubleshooting?

Does the MS1 get RPM on a Stimulator?

Nope. All the other values work flawlessly except for the RPM.

Are there any unusual mods to the tach input circuit?

No sir, it's a by-the-book assembly. Nothing awkward sticking up off of the board.

When you check the RPM on a Stim, do you jumper any diodes?

You are running standard B&G code, correct?

Yes, it is standard B&G.
I'm always wary of shorting things, lest they release their magic smoke. That, and I wouldn't know where to start. Input circuit (as diagrammed in the megamanual) I assume?

You usually have to short the diodes when testing on the Stim.

Tried all the diodes installed in the input and output circuit. None of them elicited a response in Tunerstudio.

Are you using a normal Stim or a JimStim?

It is a normal stim.

Does it have a switch by the RPM pot? If so, what's it labeled?

Yes, it says PNP and NPN. I've tried it in both positions.

Try applying 12 volts and ground to DB37 pin 24 while checking the voltage at processor pin 14. You should have 0 volts at pin 14 when the input is 12 volts, and 5 volts at pin 14 when the input is grounded.

i use this topic so i dont have to do another.
Hi all, im new megasquirt user, and ofc i already have problems. Im running MS1 V2.2 and my processor code is 029y4. The problem is, that when i try it with my stimulator, it seems that my "engine" wont start. It just keeps fuel pump few secs on and then stops, but voltage is still on. In megatune all other gauges are on but not rpm and pulse width1. Also i cant adjust duty cycle, which is TPS? I´ve checked all connections and seems like there is no problems. But when i accidentally touched one of that little 6-pin processors pin below board, it "starts", but rpm is 1500 and i cant change it. Duty cycle can be adjusted, BUT it keeps coming down to 15% like in mSecs. And when i release my finger from that pin, stimulator goes back to like it was. I´ve put jumper over D8, and read megamanual, but i cant fiqure out what is wrong. Can u guys help me out?

Liquid wrote:i use this topic so i dont have to do another.
Hi all, im new megasquirt user, and ofc i already have problems. Im running MS1 V2.2 and my processor code is 029y4. The problem is, that when i try it with my stimulator, it seems that my "engine" wont start. It just keeps fuel pump few secs on and then stops, but voltage is still on. In megatune all other gauges are on but not rpm and pulse width1. Also i cant adjust duty cycle, which is TPS? I´ve checked all connections and seems like there is no problems. But when i accidentally touched one of that little 6-pin processors pin below board, it "starts", but rpm is 1500 and i cant change it. Duty cycle can be adjusted, BUT it keeps coming down to 15% like in mSecs. And when i release my finger from that pin, stimulator goes back to like it was. I´ve put jumper over D8, and read megamanual, but i cant fiqure out what is wrong. Can u guys help me out?

Are you using the wheel decoder? What sort of Stim are you using?

Im using stimulator what should be ok for v2.2. I just realized that regulator U5 is hot like heck, somewhere is grounding problem?

That's not a grounding problem, it's a short circuit. To check for a short in the Megasquirt PCB, power up the Megasquirt on a Stimulator or on the car and check the following points for voltage with a multimeter.

You should find the same voltage as the battery voltage on the following points: S12, S12C, the center legs of Q9 and Q12, the left (non-banded) end of D3, the left leg of U5, and the left (banded) end of D9.

You should have 5 volts at the following points: S5, the two +5V holes in the proto area, the right (non-banded) end of D9, the right leg of U5, the left (banded) end of D19, and pins 1, 20, and 31 of the CPU.

Let me know where you find the correct voltages, and where you find the wrong ones

Thanks, i will check those soon as i go to home, i dont have multimeter here. But i got bigger problem now. Some dudes told me that if u dont see rpm in megatune, try to click 5v to the pin 24 (which is coil), so i did, and i think that my prosessor is now dead all gauges in megatune shows now red.

Matt, just confirming, i can check those voltages without processor?