Unusual ETM problem

[gokhanors]

Hi everybody,

CEM-1A62 faults appear to be intermittent/stored faults rather than permanently active faults. When I remove and reinstall fuse 23, the fault temporarily disappears. The ETM has been converted to a contactless Hall-effect sensor system. During the VIDA ETM test, the maximum difference between the two throttle position sensors was 2.12 degrees.

The engine idles smoothly both when cold and when fully warmed up, and throttle response is normal. However, after switching the ignition off and then back on again, the “ENGINE SYSTEM SERVICE REQUIRED” message sometimes returns. At the exact moment the warning appears, the idle speed drops briefly and I can hear a distinct “click” from the engine compartment.

Charging voltage at idle is 14.02 V.

Could this be caused by an intermittent electrical contact problem in the ETM or ECM power supply, the system/main relay, the ECM connectors, the fuse/relay box, grounds, or the wiring harness? Could there also be a momentary voltage drop or loss of communication between the ECM and ETM during the ignition/self-test sequence?

I am especially interested in whether anyone has seen a similar case where removing and reinstalling fuse 23 temporarily clears the fault, but the problem returns after one or more ignition cycles.

[dikidera]

It could be yes. OR:

It is caused by the magnet shaft shorting to ground because of expanded magnet grinding on the coil.

A simple test is with engine off, try to move the throttle plate by hand, if you feel any resistance that is in a specific spot - you can be sure it is shorting.

Be sure to test it in the opposite direction, to fully close the throttle plate. It should move freely in its fully closed position as it will in fully open. Usually it starts to bind near the fully closed position - exactly where a startup problem will reveal it.

[gokhanors]

If I do feel binding near the closed position and confirm the magnet/rotor is rubbing the coil, what is the recommended repair? Do you normally reposition the magnet, reduce its diameter/clearance, or replace the rotor/ETM