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Noise in rear speed sensor

Posted: Sun Dec 09, 2018 3:22 pm
by RallyCivic
Hi,

When the engine running I'm am seeing noise in the rear wheel speeds. It is there with/without the rear sensors plugged in. I've tried moving the ground from the thermostat housing to the chassis, along with trying to shield the rear speed wires without success. The front wheel speeds work fine. I think the interference is coming in at the traction box. I have it mounted on the side of the HVAC blow behind the glove box. I also tried spark plugs with resistors.

Re: Noise in rear speed sensor

Posted: Mon Dec 10, 2018 10:36 am
by Spunkster
Are the wires for the sensors all twisted pairs all the way to the box?

Re: Noise in rear speed sensor

Posted: Mon Dec 10, 2018 11:31 am
by RallyCivic
Yes, I was able to use the supplied twisted pair harness.

Re: Noise in rear speed sensor

Posted: Mon Dec 10, 2018 11:33 am
by RallyCivic
20181202_211345.jpg
20181202_211345.jpg (3.67 MiB) Viewed 1697 times
Ran down the center and split near the fuel tank.

Re: Noise in rear speed sensor

Posted: Mon Dec 10, 2018 3:46 pm
by Spunkster
IF you completely disconnect the harness form the traction control box do you still see noise with it just powered and connected via the USB?

Re: Noise in rear speed sensor

Posted: Mon Dec 10, 2018 4:11 pm
by RallyCivic
No noise powered by USB with the car running. I don't have the tool to de pin the connector so that was with the connector un plugged but module in the same location.

Re: Noise in rear speed sensor

Posted: Mon Dec 10, 2018 4:17 pm
by RallyCivic
Ecu is a new HAsports p28 with a new s300

Re: Noise in rear speed sensor

Posted: Mon Dec 10, 2018 4:55 pm
by RallyCivic
I cut the ELD wire and the noise in the rear wheel speeds is gone. In the S300 calibration I have traction control enabled box checked on D10. On the Misc tab i have Disable ELD checked.

Re: Noise in rear speed sensor

Posted: Mon Dec 10, 2018 5:32 pm
by Spunkster
Was the ELD still wired to it's original location or was it cut?

Re: Noise in rear speed sensor

Posted: Mon Dec 10, 2018 5:48 pm
by RallyCivic
ELD was cut and ECU was wired directly to the Traction control box at pin D10. Currently with the connection to pin D10 cut there is not noise. Power is coming from IGP1 and Ground is at the thermostat.

Re: Noise in rear speed sensor

Posted: Tue Dec 11, 2018 10:03 am
by Spunkster
*Note that if the ELD input (D10) is used then R136 and R138 (US ECUs) may need to be removed.

Has this been done?

Re: Noise in rear speed sensor

Posted: Tue Dec 11, 2018 11:25 am
by RallyCivic
Not sure. Is a new unit and I haven't pulled the cover off yet. Also I didn't see that note in the instructions.

I'll check once I get home.

Re: Noise in rear speed sensor

Posted: Tue Dec 11, 2018 7:02 pm
by RallyCivic
I've cut 136 and 138. Not sure why but now with the ELD disconnected it still has the wheel speed noise. I've moved the power wire away from the ECM closer to battery directly and it did improve the noise with the TCS connect to D10. I need to extend wires to run directly to the battery, to see if this further improves the issue.

Re: Noise in rear speed sensor

Posted: Wed Dec 12, 2018 7:01 pm
by RallyCivic
The USB light is always on or flickering even with the computer not connected. I put an oscilloscope on the power wire and nothing really stood out.

Re: Noise in rear speed sensor

Posted: Thu Dec 13, 2018 10:04 am
by Spunkster
Where are you connecting for power and ground?