MMCD on PC, can transmit, but not recieve

[tkelly27]

Hi, I've been trying to setup MMCD on my laptop. I've got the software setup, and now I've been wondering about the cable. The pins 2 and 3 have to be reversed from the standard palm cable, this I've figured out, however I'm having problems receiving data from the ECU.

I can have it prime the pump, and pulse the injectors, but nothing else. The pump will prime with the diode wire and the non wire. Checking the codes does not work on any of the wires hooked up to pin 2. Any ideas as to why?

I do have the "prolific" style cable, and I will be bringing it back and getting the other style soon, but even then, other people get it to log, even if it is wrong.

Also tried this on two different ECU's, a '90 turbo and a '91+ NT some thing.

 

[68442]

I have pretty much the same issue, can run the fuel pump. I made 2 cables just to be sure I did it right. I ended up ordering a cable off ebay, I'll let you know if that works.

 

[tkelly27]

Did you try switching the pins? If you search on here for "null modem" (as if anyone would know to look for that) and also the palm cable instructions vs. the PC DB9 pinout you'll see pins 2 and 3 have to be swapped. Are you using a serial port, or a USB to serial adapter? I'll be changing out my adapter today.

 

[tkelly27]

Now I've tried it on two different USB to serial cables, and a computer with a real deal serial port with the same results. I can prime the pump and have the solenoids go with either of the two wires connected to the transmit pin, but when a wire is connected to the recieve pin it will do nothing.

No pins, nothing
Ground and transmit, can do all outgoing things (prime pump, etc.)
ground and receive, nothing
ground, transmit, and recieve, nothing.

I know we've made the cable properly, and I'm stumped. I downloaded a serial port listener. The logs are exactly the same for priming the pump when only ground and transmit are connected as when all 3 are connected, the only difference is that nothing happens. Searched and searched, can't find any information.

 

[68442]

Got mine to work tonight. Got a ebay cable and of course its made to talk to a serial port on a pda/computer(male). I had to buy the null modem and a gender changer since the null had 1 female side and the other was male. I suspect the pin switch would've worked but I didnt want to chance it.