500E limp mode and ASR

[seacoast_benz]

OK, as sequel to my recent lengthy series of posts about removing the throttle actuator from an M119 engine in a '93 500E, I have the TA back in the car after inspecting and cleaning it.

TA looked great internally. No signs of trouble. After re-install, I turned the engine over with the coil leads off, which is responsible practice any time that the intake has been opened. All sounded great.

Re-connected the coil leads, fired the engine up. Spotty idle at first, settled into smoothness within 30 seconds.

ASR light stayed on.

I let it warm up stationary, then gently drove it around the block. Obviously in limp mode, with ASR illuminated and poor throttle response.

When I got it back in the driveway, and shifted to Park, the idle surged rhythmically at around 1000 to 1200 RPM. Shifted back to drive, idle settled in properly. Back to Park, and surging again.

Shut down the engine and restarted. Smooth idle. ASR on again. Check Engine light on.

Pulled the positive battery terminal to reset the Check Engine light. This doesn't cure the ASR warning, which is a DTC code stored in nonvolatile memory.

Went to the diagnostic panel, found that the engine was throwing code 6, which is _Idle speed control inoperative_.

I reset that code and shut the ignition off for one minute, then restarted. Check Engine light was out. ASR light was on. Engine diagnostic is throwing a 6 code again.

Am wondering what I did to cause this, and how to get rid of it. This car has zero previous history of ASR bugginess -- the reason I removed the TA unit was because I was curious as to how well it was holding up, and wanted to get a visual inspection.

There isn't any way to force-reset ASR, is there?

s/b

-