speedometer disabled when datalogging

[FLIPTION]

I just got a datalogger from ebay and everytime I plug the cable into the ECU, the speedometer gets disabled for some reason. I unplug it, everything's cool. Anybody else ever have this problem? What do you guys think?

Thanks!

 

[luv2rallye]

The speedo connects to the data link connector pin 14 (yellow w/white stripe wire) so if your cable or datalogger mistakenly grounds that pin, it would do exactly that.

 

[FLIPTION]

anyway to fix this problem besides purchasing a new cable?

 

[luv2rallye]

Plug the cable in without the datalogger attached. If speedo gets disabled your cable is bad and you need a new one.
If ok now try with datalogger attached. This I assume will disable speedo since it is the way you said you tryed it. Now turn datalogger on. Is speedo still disabled? If yes your datalogger is bad by shorting data link connector pin 14 to ground (you might try opening it up to see if anything is obviously wrong like frayed/broken wires). If no it's probably just the way it's designed (technical explaination if you care: usually due to an internal pullup resistor in the datalogger design to not load down the circuit when datalogger is on and the speedo signal is off/floating which raises signal to it's high state, like it should be, and so speedo works correctly - ie. it's not then pulled low during the speedo off/floating state) and I wouldn't worry about it - just use it.

 

[FLIPTION]

Very useful info! Thanks!