MS3X no connection to laptop in car

[74bluefish]

Sorry, I'm reposting this. Trying to get an answer for the weekend. Its my 2nd post.
My unit connects to the laptop in tuner studio using the stim, but won't connect to the laptop when powered by the car

I had it connected to the car and it worked for 3 days but then I changed the circuit for the crank sensor, and now won't connect to com 1
I have the crank circuit setup now for the hall sensor from DIYautotune (3 wire and I believe built in pullup).

The unit seems to still work normal on the stim after I changed things. Connects to Com 1 no problem.
Won't connect to com 1 powered by the car.

I have power 12v to the unit at the connector and good grounds.
Changing the crank circuit cause this problem?

[billr]

How about the 5Vref is it staying OK when installed in the car? I assume you are measuring voltage right at the MS DB37 mainboard connector, using one of the grounds there (DB37) for the meter reference, correct? If you disconnect the CKP sensor from the harness does com revive?

[74bluefish]

Yes , I measured voltage at the connector not plugged into the MS3.
I will check tonight for the 5 volts while it is plugged in and connected to car. and disconnect the crank position sensor.

Thanks,

[billr]

Also check the 12V again, with the harness connected to the MS, using an MS ground pin for voltage reference.

[74bluefish]

Ok, I hooked up the MS to the STIM and am getting 12volts on pin 28 (crank sensor pin) and 5.0 volts at pin 26 (TPS 5Vref).

THEN, I hooked up the MS powered by the CAR and am getting 12volts on pin 28 (crank sensor pin) and 1.0 volts at pin 26 (TPS 5Vref).. I guess that's the problem.

What do I check next? Also I am realizing when I assembled the board 2 years ago I was planing in a distrubutor,..Now I have a crank wheel and coil near plug.
Not sure why I didn't install these jumpers, maybe that was why.

I didn't install jumpers
JS6 - CAN H
JS8 --- CAN L
and jumper s-12 -to D1 (from MS# to MS#X card)

I believe I must install these, Correct? I have a 4 wire stepper motor for idle.
Thanks for your help,
Dan

[billr]

Connect it to the car, but disconnect anything external to the MS that is drawing 5V. Things like the MAP sensor, TPS, and Hall trigger sensors. Did you look at the 5Vref with the CKP sensor disconnected? Unfortunately, if something about the CKP sensor circuit is pulling the 5V down, it is probably a problem in the wiring; so you will probably have to disconnect that (all 3 wires) right back at the MS DB37.

[74bluefish]

Woo HOO, Thanks Bill,

Yes, I did cut the spice to the crank trigger but that didn't help. Sorry I forgot to post that.
Then disconnected the TPS and a second MAP and I got 5 volts.
Reconnected the TPS and still 5 volts
Problem is the MAP I probably have to swap 2 wires.

Anyway, I left it unplugged and got the connection to the laptop.

Now must figure out if I need those jumpers to be installed. I believe I do need them.

Thanks once again,
Dan