560SL - KE-Jetronic Sensors, Controls & Verifying Idle Speed

In this video, I dive deep into the KE-Jetronic system on my 1987 Mercedes 560SL, using an oscilloscope to test and verify each sensor and control unit responsible for maintaining proper idle speed. From live waveform analysis to pinpoint diagnostics, this walkthrough highlights how each component works together to keep idle smooth and stable. Whether you're chasing a high idle, rough running, or just learning KE-Jetronic fundamentals, this video lays out a methodical approach you can follow step by step.

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My videos are not sponsored by anyone. The products and tools I use are products and tools I have purchased with my own money. I include links below to any special tools or products used in this video.

The multimeter I have I purchased years ago, but this one has about the same specs:

The Oscilloscope I purchased is the FNRSI 2C53P. This one I could afford and it seems to do the things I need to do. I got a smoking deal when I purchased it.

Here is a link to the on-line manual used (450SL, 450SLC, 380SL, 380SLC & 560SL):

OR:

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It shows us something is wrong with the engine idle speed control when you disconnect the ISCV Connector and nothing changes. One path of the intake air is metered at the throttle body. Then there is a second path of intake air metered by the ISCV. So the throttle body is mechanical and the Idle Speed Valve is electronic.

So far my understanding is the ISCV has a constant 5v and the ECU/ISCU controls the operation on the ground side. At 1amp draw the Idle Valve Should be fully closed stopping the second path of intake air.

When you disconnect the ISCV the idle should raise, then plug the connector in and idle should be around 550-600, then if you complete the ground side all the way to 1 amp the valve should close and stall the engine out.

Keep up the good work!!! I hope you get this figured out and you finally can enjoy your Benz.