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1987 560SEL Astral Silver/Silver blue leather,Michelins,SONY
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Discussion Starter #1
Can you please identify the objects shown in these photos. I have no clue what the large ones at top of firewall are for. What is that cute little round thing? I KNOW the EZL and the OVP, but that's it. All the little square shiny cubes?
I hope the replies will help other people too. Or perhaps I am the only relatively clueless one here?!!
 

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2013 MINI Copper S Clubman, '84 300CD-weekend car
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As mentioned, the large screw on cap under hood is an rpm diagnostic port.

Older cars had a tach amp that screwed into the socket.

What is the complete part number of the item on the right?

_04 545 55 32
 

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2013 MINI Copper S Clubman, '84 300CD-weekend car
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I searched the epc, (004 545 55 32) on a 126.045 and 126.039 it's an "ignition control box".
 

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1987 560SEL Astral Silver/Silver blue leather,Michelins,SONY
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Discussion Starter #4
I did not think there was a "plug in" diagnostic port on my 1987 560SEL. Perhaps it is something more basic than what came later?
The bottom photo, with the green wire, is the EZL. At least I know THAT much. Ha Ha!
 

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Follow the gray wire leading away, if it goes to a sensor on the crank, that is a hold over for a tach unit, at least on diesels.

The arrow points to a pin that contacts the other end, a Hall effect set up.

The two arrows point to the other end.

After 83, the tach takes its signal from the transmission, this is where a mechanic would plug in a tach to make any adjustments necessary, as I understand it.
 

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2012 CL550 4MATIC Coupe
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After 83, the tach takes its signal from the transmission, this is where a mechanic would plug in a tach to make any adjustments necessary, as I understand it.
Partially correct.

The RPM Diag port does NOT get it's RPM signal from the transmission. Neither port does.

The RPM signal that goes to the EZL takes its signal from the RPM Sensor on the back side of the engine housing. It actually bolts onto the engine housing, but looks like it's attached to the Transmission. There is a black plastic cover plate. There are protrusions on the flywheel, and as it spins the sensor detects that in a certain pattern and the EZL reads that pattern to know where it is in the rotation. It gets its TDC signal from there.

The RPM 'Port" as you say also reads engine RPM. However it gets its signal frm the front of the engine. If you look on the front of the motor, by the SLS pump if so equipped, there is a sensor there and it detects rotation from the Harmonic Balancer. As you pictured correctly. That front sensor feeds the big round plug on the fender.
 

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2012 CL550 4MATIC Coupe
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I mis spoke, sorry.
Not a problem, I was just trying to clear things up a bit. I didn't know which was what for until last year when I was putting my car back together. Only thought there was one sensor, so I ordered that one, then realized the more important one in the back also needed replacing, and why.
 
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