I got a new potentiometer. The old one had worn through the black coating around idle. Pins 2 and 3 give me the correct ohm range as expected. When I warm the car up and back probe pins 1 and 2 I get constant 5v. Is there something else that could be causing this? It should be 0.7v.

The 4 pin temperature sensor tests OK.

The TPS tests OK but I did have to use some force against the linkage for the full load switch to give me an ohm reading.

Just to update, I now get code 4 (air flow meter voltage implausible), cleared it, and it came back. I contacted the vendor and said it looks like a bad sensor.

I did notice a chip out of the board on closer inpection and hairline crack. Looks like a hack refurb...

I've had good luck on fleabay for numerous other things. Striking out on car parts.

Did you try to adjust it?

__________________
600SEL '91
300E 4Matic '88
240D '83
280SE '77
350SE '73
The most complex systems can fail in the simplest way.
Contra verbosus noli contendere verbis, sermo datur cunctis, animi sapientia paucis.

i don't believe in the lord! He's never bought me a Mercedes Benz.

If you mean sliding it back and forth, yes. No impact. From what I understand the small factory set flathead screw is not meant to be messed with.

I'm looking at how to bench test these things. Would a micro USB car charger provide enough amps to do this? My bench power supply does have a car charger jack which is convenient, and USB is 5.1v which is convenient.

The vendor did send me a new one and I installed it. When I move it around I get different voltage readings. I was able to stabilize it on a warmed up engine at 0.7 MV. Is this correct? I thought it was supposed to be 0.7v not mv.

OK, this thread is finally coming to a close. Results:

1. First air pot was dead as a door nail
2. Vendor sent second air pot without hassle or return
3. Second one works adjustments are just ultra sensitive
4. Original air pot was worn through to shiny metal around idle
5. No more engine codes

I'm getting readings from 0.6 - 0.8v. Don't know if that's normal but that's what I've got.

Still have a hunting idle on warm start up. I tapped the IAC with a screwdriver and heard it click. Idle seemed to smooth out. So on to the next thread!