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Resolved ECMlink sporadic connection

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2fast2evo

Proven Member
88
16
May 17, 2015
Kingston, ON_Canada
Hi everyone, I'm having a bit of an issue with my link connection and was wondering if anyone could offer insight.

I recently got my car out from storage. When I put it away ~beginning of December, I was able to connect normally and log/tune just fine. Now, my laptop will only connect under very specific circumstances:

1. I have been going >30km/h AND
2. I am decelerating to stop e.g. for a stop sign AND
3. The car is in neutral (not in gear slowing down)
(*all of the above at the same time*)

It will remain connected until I depress the throttle to accelerate (or will disconnect after 30 sec-1 min). The car otherwise runs and drives as if nothing is wrong.

It doesn't appear to be the cable at fault (?) because I can log and tune once it is connected (verified by adjusting idle etc while stationary to make sure data were transferring). I have tried on two laptops and the result is the same (one is even new!).

Electrically speaking the ONLY difference is that my dad took out the fuse in the driver's footwell fusebox (my car is right-hand drive so on the right side of the car :p) because I'm having a battery drain issue on that circuit, which has not affected my link connection before. Could this be somehow related? I'm struggling with this one because the car did not actually move in the time that this 'problem' cropped up :banghead:

Will be doing research of my own as well, but thought I would try to elicit opinions.
 
Honestly it sounds like your laptop is moving around while you're driving. If that's the case, you sure the USB isn't coming loose to make you lose connection? If I set my laptop on the passenger seat while I'm driving, sometimes it slides back and the USB cable will come a little loose and I'll lose the connection.
 
My money's on the cable being bad, or the wiring in the diag connector is loose/messed up. The conditions where it connects makes me think if you push in on the connector and try to connect the laptop at the same time it might work.
 
Most likely a wiring connecction, grab the ecu and cable and slowly move them around see if you get connection .. move to the cable and laptop and move those connections around ...

Personally I hate those damn cables, I have had 2 go bad during storage or just a long period in between tuning ...
 
Have you tried putting the fuse back in to see if it makes a difference? Don't know if it is related or not, but may as well eliminate it as a possibility.
 
So what I've done so far is try to remove the fuse again (fuse #14 in my car, which controls my interior light circuits, radio, rear popup antenna, etc) and my A/F gauge is now working (wasn't before, as well). The connection is better and I can connect stably at idle (YAY)...but still not able to connect whilst driving.

I contacted Thomas at ECMtuning and he also thinks it may be the cable going off. Honestly, the fact that nothing really changed makes me wonder if that is it even though I can connect at certain times. I'm going to order a new cable and keep messing around in the meantime. Worst case scenario, I may end up with a spare cable that works for when one of them inevitably DOES fail :p

I'm thinking right now to check the wiring for my head unit, it has always been a bit...strange since I bought the car 2 years ago. Perhaps a straw finally broke the camel's back. The weather has been awful up here lately and I've been swamped at school, so no chance to go out and work on it. I'll update this thread as I progress for the sake of having the information out there :)

EDIT: To address Kody's response above (I took too long writing this...), the fuse was already back in and now I have removed it again.
 
OK folks, I got her working . The issue was a bit peculiar as I believe it is specific to Evo 1-3 cars, but in case anyone wants to know...

So I mucked around with the fuses more. No dice, tried replacing them etc. Checked my wiring for all of my gauges to see if there were shorts, and there were none that I could find. I also added another ground to my trunk-mounted battery, made no difference.

Then the breakthrough...one of my friends who has more Evo experience than I suggested adding a pull-down resistor between pins* 26 and 42. The video link is located here for anyone interested. I added a 4 kΩ resistor (actually 2x 2 kΩ resistors in series, but who's counting?) between those pins on my ECU main board, crossed my fingers and fired it up. It worked like a treat! :thumb:

The takehome message here is that electrical noise, possibly due to inadequate grounding, can cause a crappy connection. CHECK YOUR GROUNDS.:p

*I think that these are different than on a DSM, they correspond to my timing ground and diagnostic pin, respectively.
 
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