yelcab2

Where do I find and how to test the throttle position sensor on a 1984 380SL?

Plutoe

You find a copy of MB WIS put your VIN in and look for the sensor documentation.

yelcab2

Thank you but I found my issue.

Someone before me replaced the Idle Controller unit with an after market one, then spliced in the 12V power to the unit from a stereo power supply line. I previously disconnected the power supply line and removed all the nasty stereo stuff, which also rendered the Idle Controller inoperative and causing the high idle issue. Separate to this issue is the fuel pressure accumulator not holding pressure and the fuel pump being weak. Changing the pump, accumulator, fuel filter, plugs, cap, rotors, ignition wires and then reconnected the power line solved all the issues.

But, thanks again for the pointer to the document. If I had it, I would not be asking this simple question.

yelcab2

And for future DIY who would like a little more help than the non-answers:

Look for youtube video: How to repair Mercedes High idle troubleshoot and cheap fix pt. 1
And How to repair Mercedes High idle troubleshoot and cheap fix pt. 2.

You will find a bunch of clues for your problems.

Hint 1: the 1984 380SL Idle Controller Unit is located under / behind the glove box, on the left hand side of the glove box. Held in by one screw
Hint 2: the Protection Relay is located on the right hand side of the passenger foot well, behind the kick panel.
Hint 3: the voltage to be applied at the idle valve is not 12V but a smaller voltage from 3V for an idle of 600 rpm to 5V for a higher idle speed.
Hint 4: the US 1984 380SL does not have ABS and therefore does not have an ABS warning light, don't look for one.

Good hunting,