S300 Usb Plug Issue (Weird)

AllMotorMatt · Post by **AllMotorMatt** » Fri Feb 29, 2008 1:19 pm

Hello all,
This is my first post on the forum and much needed. S200 died about a year ago so I have since been using S300. Works great and all that good jazz, only one problem. It seems that I always need to leave the USB cable plugged into the ECU. If I take the cable out the car seems to go into limp mode, example, it will not Rev beyond 4k. If I plug the cable back in its fine, drives like a champ! The main problem is that from time to time it throws a cell and goes all weird. Basically I have to pull over unplug the USB cable, plug it back in and its fine.

ANY IDEAS? :idea:
Thanks!
-Matt

Post by **Spunkster** » Fri Feb 29, 2008 2:45 pm

This sounds like you may have some kind of wiring problem in the car...especially with the grounds.

Is the USB cable connected to anything else?

AllMotorMatt · Post by **AllMotorMatt** » Sat Mar 01, 2008 10:17 am

Negative, the usb cable is just plugged into the ECU and that is all.

AllMotorMatt · Post by **AllMotorMatt** » Sat Mar 01, 2008 1:01 pm

Ok so I think the Port on the ECU may be dead. I did all the troubleshooting steps and it will still not recognize that Hondata is plugged into my laptop. Throwing a code :x

Post by **Spunkster** » Mon Mar 03, 2008 12:20 pm

Have you tried a different USB cable? Can you post a picture of how the ECU is mounted and also where the USB cable enters the ECU?

AllMotorMatt · Post by **AllMotorMatt** » Tue Mar 04, 2008 10:10 am

I have not attempted that yet but plan to do so this week. I have a buddy coming over and am going to try to:
1. Use his laptop and USB cable for my ECU
2. Put his ECU in my car to check the code
3.Put my ECU in his car to check the ECU
and any other config that comes to my mind.

I will get a pic up soon.
The ECU is in a DA so its mounted on the pass. side floor under the glovebox. The USB cable enters the ECU at the top right, farthest away from the wiring harness.

AllMotorMatt · Post by **AllMotorMatt** » Wed Mar 05, 2008 12:43 pm

Since you mentioned the possible ground issue it made me think. While I cannot be 100% sure about the USB issue, the check engine light came on after a Thermostat, Radiator and Slim Fan install. This makes me think that it could be the ground on the T-stat housing. Does that sound like a possible issue?

Post by **Spunkster** » Wed Mar 05, 2008 3:04 pm

That is a very important ground.

AllMotorMatt · Post by **AllMotorMatt** » Wed Mar 05, 2008 3:41 pm

Still waiting to test the ECU with another laptop and cable.
The ground is physically attached to the T-stat housing. Any recommendations?

AllMotorMatt · Post by **AllMotorMatt** » Tue Mar 18, 2008 7:06 pm

Ok so I got everything straightened out tonight and cleared my code. I guess the USB issue was with how everything was loaded on my laptop. Had a buddy come over with his laptop and we hooked it up and were able to communicate with the ECU. Let the engine idle and data logged and pulled a code, it was code 21 for the Vtec Spool Valve. Well I enabled the Check box to disable spool error check and cleared DTC's. The code went away. A second code appeared for the ECT which was just a loose connection, plugged it in correctly and away I went.

Thanks for all the help!!!!

AllMotorMatt · Post by **AllMotorMatt** » Thu Mar 20, 2008 8:45 am

AH! I let myself get off track. Back to my original Issue.

Why would the USB cable need to be plugged in all the time? I checked all the grounds and they all seem to be ok. It happened again last night. I was driving and there was a REV limiter at 4K. Unplugged then plugged the USB cable back in and everything was good....

Post by **Spunkster** » Fri Mar 21, 2008 10:05 am

IT sounds like there may till be a ground issue. The USB cable is acting as a ground which is a very bad thing. Try your ecu in a known good vehicle.

AllMotorMatt · Post by **AllMotorMatt** » Fri Mar 21, 2008 12:51 pm

Hmm Ok I will check. Planning on redoing the Engine Harness tommorow. I'm still confused though, the plug is plugged in and the other end if like sitting on the seat. How could that be grounding out on Fabric?

Post by **Spunkster** » Fri Mar 21, 2008 1:15 pm

Who socketed this ecu? Can you take a picture of the usb port in the ecu?

AllMotorMatt · Post by **AllMotorMatt** » Mon Mar 24, 2008 6:35 am

I am almost positive it was done by you guys. I can find out for sure when I get home or get in touch with my buddy whom I ordered it through.
I will also take the picture when I arrive home.

Thanks!