I finally finished with my ETA rewiring. When I connect the ETA and turn the ignition on, it will not hum, only jerk the butterfly valve once. Is this normal? I am afraid to reinstall it, unless I know it works.

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2004 E500 4Matic 138,000 miles

Congrats on completing the re-wiring . . . I'll bet it wasn't easy!

Now is the hard part . . if it doesn't work after you re-install it, what do you do next?

It's been my experience that when the ETA's input/output cable crumbles, failures occur in the ETA. So it needs to be tested to ensure that it's ok.

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Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page

Thanks, Jim! It was very challenging and time-consuming. Sourcing Teflon wires and finding the right sheathing was difficult. Mapping the stripped wires between the connector and board was almost impossible. Cutting the connector was tough. My wife and I spent about two days desoldering, soldering, creating the harness, and testing. I am fortunate to have two heads and four hands.

I will reinstall then and hope for the best. Based on the Mercedes CD wiring diagram for the ETA (which seems to be messed up between the engines) the motor, actuator, 2 potentiometers, and two switches are fine. I tested with an ohm meter. Also watched and followed Victor's excellent video: http://www.restoreyourmercedes.com/Mercedes%20throttle%20body%20rewire.html

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2004 E500 4Matic 138,000 miles

That is a great video . . . very impressive, indeed! Have added the link to my ETA page so all can see another source for ETA repair. Price is excellent also!



Also added a Wire-Gauge Table showing the AWG sizes required along with the corresponding connector pins. Very handy table!.



A caveat via my story: when my ETA failed, certainly the wires were toast so it's amazing that it worked as long as it did. However, the butterfly "clutch" burned open and that was the "real" failure that caused the LH and other ETA going-bad anomalies. The wires, as bad as they were, were not the problem (at that time) b/c the ETA harness had never been disturbed. Also the reference pots were worn but still ok.

So the point is that you still need to inspect (and dis-assemble) the complete unit if you are a DIYer; the wires are certainly one large factor in the failure mode but they are not the only one that can cause a ETA failure.

Using Victor's "ETA-static-test" video should show if there are some gross failures, so, absolutely, it should be done.

Shops like Beckmann Industries have a real M119 test-jig that completely tests the ETA in a closed servo-loop. Bad parts are immediately spotted either BEFORE or AFTER re-wiring of the unit. That test jig is a wonderful thing . . .

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

That was a very informative video, especially the bottom video where he shows how to test the ETA with an ohm meter. Thanks for posting the link.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles