Serial to USB Comms - Not Working

[planetcaravan]

Hi All,
Could anyone point me in the right direction with this one as I’m stumped. I’ve been running a MS2 V3 board for a few years now with great results. I’ve always used the serial port for tuning purposes, but my old laptop finally died, so I decided to add the DLP-TXRX Internal USB adapter, that way I could buy a modern laptop too. The system was running perfect before the addition but since doing the mod I now do not get fuel pump priming or operation. On checking the wiring it now appears that PIN 37 is not grounding when ignition is turned on. I checked all the other relay wiring and it seems fine and re-connected as it was prior to the mod. I did the following mods to install:

removed MAX232CPE (U6) - it was on a socket so I just pulled it out.
wired GND from the proto area to the GND on the DLP-TXRX (with plug to the right and facing upwards) 3rd pin from the top
wired +5V from the proto area to the +5V on the DLP-TXRX (as above) 5th pin from the top
wired RX from 13th pin of EPROM socket to the DLP-TXRX (as above) 1st pin from the top
wired TX from 12th pin of EPROM socket to the DLP-TXRX (as above) 2nd pin from the top
did not cut any of the traces

It all went pretty smoothly until I put the ECU back together and into the car and found no fuel pump operation. I shorted across the relay wires and the fuel pump works fine. I didn’t try starting the car like this incase it causes any damage to the ecu, as something is obviously wrong here.

Any advise would be much appreciated.

Thanks.

[Matt Cramer]

Can you try reloading the firmware and loading a tune from before the issue surfaced?

[planetcaravan]

Hi Matt,
I actually never tried hooking up my new laptop. I did this today and found some interesting results. When the usb cable is connected to the ecu and the laptop the fuel pump priming and operation works fine. Started the car fine and runs as it used to before the mod.

I found this on the forum and it seems the exact same issue as I am having. It was fixed by a suggestion from you to add a ZTX-553-ND Transistor.

http://www.msextra.com/forums/viewtopic ... RX#p396051

I will try this and see if it provides the same solution for me. Also, can you tell me if I have the Communication Settings correct for the USB driver (I have attached a screen shot).

Thanks.

[Matt Cramer]

Yes, we should have the note about that transistor now in the DLP-TXRX catalog page. Let me know if that fixes it.

Not seeing any obvious problems in the screen shot. If it's working, the settings must be right.

[rickb794]

Prepare yourself to go back to RS232 due to interference on the USB.

Some installs have issues with USB picking up noise.

I have 5 different USB adapters and have to run through them to find which will work with a certain install.

Some won't flash firmware, some lockup TS, some blue screen XP, and yet work fine on other installs.

FTDI adapters are recommended with short or no USB cable.
I don't know if this is a FTDI but has been tested.
http://www.diyautotune.com/catalog/usb- ... -p-67.html

I used one of the DLP-RXTX units and battled with it for 6 months before giving up and going back to RS232.

It is super frustrating to battle with comm problems while trying to tune.

[planetcaravan]

Hi All,

Follow up on this one, the USB conversion is now working fine. I don't need to have the laptop plugged in for the fuel pump circuit to work. I just added a ZTX553 Transistor as suggested on the DIY Autotune website and mentioned on the link above. Simple job, just had to source the transistor from the UK as it was not available in Australia. That's what you get for living out in the middle on nowhere!

Thanks.