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

Hi,

I hate for this to be my first post because I'm sure I could probably find the answer if I searched hard enough. But I'm not quite sure what to search for. I have an MS1 with a V3 board that connects to my PC and functions fine when the megastim is connected. But when I connect it to the harness there's nothing. I checked the voltage at pin 29 and to any number of the grounds on the harness, and where I have it grounded to the chassis, and I get a nice 12v +- a volt or so. Any ideas where I messed up? Any input is appreciated. Thank you for your time.

-kent-

Does the pump run for a few seconds at switch on? Apart from that, it won't do anything without a tach signal. You could log an attempted start using Tuner Studio, then view that on Megalog Viewer. That will show the various input signals to MS - including tach.

Was pin 29 a typo? Because you should be sending 12 volts to pin 28. A standard MS1 build won't have anything connected to pin 29.

OK...Pin 29 was a mistake, power is being supplied to pin 28. It's the 9th pin from the left...I forgot to take in account for pin 20

I guess I have more work to do. I just have the harness run and the TPS CLT and IAT sensors wired up. I don't have the injectors, O2 or Crank sensors wired up yet. I was just trying to verify my work up to that point. I will continue with at least the Crank and report back. I knew it had to be something simple. Thank you for your help.

Assuming you have Tuner Studio working, you should see readings from all those sensors without the engine running.

TunerStudio is communicating with the MS using the MegaStim, but not on the car. Is there a different setting? I wouldn't think so, but I guess I don't know. So what you are saying is I should be able get readings from the sensor I have hooked up? I'm not trying to start the car yet. I just have the ignition tuned on. Just for a little information that might help. Right now I still have the cars stock ECU controlling the fuel pump. And this is a fuel only install, at least until I get smarter about how this all works....baby steps I guess you would say.

TS should communicate with MS as soon as it is powered up regardless of how the MS is powered. In other words it should show 'online' If it's not doing this on the car sounds like it has no power or ground.

micyek wrote:TunerStudio is communicating with the MS using the MegaStim, but not on the car. Is there a different setting? I wouldn't think so, but I guess I don't know. So what you are saying is I should be able get readings from the sensor I have hooked up? I'm not trying to start the car yet. I just have the ignition tuned on. Just for a little information that might help. Right now I still have the cars stock ECU controlling the fuel pump. And this is a fuel only install, at least until I get smarter about how this all works....baby steps I guess you would say.

Something is keeping it from being powered up on the car - either not getting power, not getting ground, or VREF shorted to ground are the usual suspects here.

Mmmm...I'm starting to feel like a world class simpleton. I can't figure this out. I even tore apart the case and checked the voltage at the solder joints of the MS. Just to make sure it was getting good contact from the harness. I'm using the cars stock Vref because of this from DIYAutoTune "You should not try hooking the Megasquirt's VREF wire to the TPS, as tying two VREF signals together can cause problems." But I did splice the MS sensor ground with the stock ECU's sensor ground, because I wasn't sure what do there and figured it wouldn't hurt. Could that be the issue? This is an OBDI GM vehicle BTW.

For anyone that might care, it turns out I am a world class simpleton. I had the DB37 connector solder bass ackwards. Fixed that, and the MS turns on and connects to TS no problem.

micyek wrote:For anyone that might care, it turns out I am a world class simpleton. I had the DB37 connector solder bass ackwards. Fixed that, and the MS turns on and connects to TS no problem.

Don't beat yourself up - you're not the first to do this. The numbers on the connectors are hard to read.
When I draw out a schematic I always label the connector as say 'female, solder side' or whatever.