RE: 1997 S500
Still working on my high oil pressure indication problem. Tried to run an instrument cluster test by pressing small button in clock adjust knob to initiate test. Could not get the cluster to enter test mode. With ignition in position 1, by pressing on small button I could get the trip meter to display " 12u" but thats it. Any ideas on what I'm doing wrong? Except for oil pressure indication, cluster performs flawlessly.

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Paul Hansen

1997 S500 (100,000mi)

PC

I did find some resistor values for the OP cicrcuit. However, my books shows a two wire sensor circuit for 140 chassis and single for 124 . Fastlane shows the single sensor for your car and the one you changed is a single .. so, I do not know which circuit is used here ..
the circuit with the microproccesor in line with the gauge does show a feed fuse #5 and #9 .
You may want to check them both [ if they look good, give them a spin.]

The res/pres values listed are:
bar OHM
0-10
1-69
2-129
3-184

If you email me , I can send you both circuits that may help . One has the warning lamp in ther circuit and one does not, so you should be able to tell right from that.
If the single wire sensor is the same as the old pre OBD11 circuit, then the test listed by $Pit would be valid , in which case you would have an open between the line and gauge.
I also checked several code manuals and they all list the OP codes I mentioned as being valid for your chassis 1997 S500, chassis 140.051

Does your AllData show any info?

As per the chart listed above, I installed a 47ohm resistor inline with the sender lead and a good ground. The result was a solid .9 bar on the gauge- just where it's supposed to be! It was a bad sender out of the box!
I contacted the parts vendor (***************) and they are promptly sending a new sender- no questions asked.
Thanks to all and especially Arthur Dalton for helping me though this!

Still wondering why the cluster won't enter it's diagnostic mode though.

__________________
Paul Hansen

1997 S500 (100,000mi)