MAZDA RX8 EPS ELECTRIC POWER STEERING PROBLEM

[AvechuchoAxel]

As many Mazda RX8 the electric power steering failed.

What I'm looking for is some info about control module repair procedures or tips.

Everything was double checked, wiring harness tested for continuity, Torque sensor pins A B C shows 15 ohms normal resistance (AB CB), Fuse 60A is ok, Electric motor itself tested supplying straight current switching polarity for few seconds to make wheels move from left to right, CAN L - CAN H shows 1.3 / 1.5 volts, all grounds are ok.

So no power coming out of the ECU.

Diagnostic only shows the lapidary B1243 DTC CODE

Module info: F151-67880 00
J601+221587 3C21
J6 F151+67880
XJ60X-YEO-03
SHOWA ELESYS


Thanks

[Dunker]

CAN L - CAN H shows 1.3 / 1.5 volts

What does the data look like when scoped? Is the signal clean?

[AvechuchoAxel]

What does the data look like when scoped? Is the signal clean?

The waveform seems to be OK. No spurious signals apparently...

I will perform detailed scope testing this Friday ..

[Roy Suryadwiananda]

CAN line should as resistant (60 ohm) not voltage, please check back perhaps troubled on CAN line, will cause the communication problems.
Another function of the ECU is working properly?

[AvechuchoAxel]

CAN line should as resistant (60 ohm) not voltage, please check back perhaps troubled on CAN line, will cause the communication problems.
Another function of the ECU is working properly?

I checked can line today... 60 / 61 ohms constant resistance.

Also checked NOISE FILTER.

So looks like just the module is the last in the list.... does anyone have info about circuitry repairs?

Thanks!!!

[bonecrusher]

I had a similar issue with an rx8. The main feed from the controller to the motor. trace the 2x thick wires, they run under the air intake it has a connector this connector usually gets melted. Just cut it off and join the wires directly and problem should be solved

[daniersms]

Yes this connector shows up in all Mazda forums and I had the same problem

[AvechuchoAxel]

Finally problem was solved replacing EPS ecu with a second hand one. Zero point position learned and voila!! No more annoying indicator in dashboard.
Thanks all for helping me with the diagnostic process. ..
Axel

Sent from my SCH-R530M using Tapatalk 2

[bonecrusher]

Thanks for the update and well done