Need Voltage info for V12 coil pack Ignition Trigger and Ignition Change (a/b)

Jun 26, 2025 | 05:33 PM

rgdeja

Thread Starter

Junior Member

Joined: Jan 2003

Posts: 65

Likes: 2

From: Norcal Walnut Creek

SLK55, S65

Need Voltage info for V12 coil pack Ignition Trigger and Ignition Change (a/b)

I am trying to troubleshoot my coil pack and got all the signals fiigured out but need to know two signals

1. Ignition change - is this GND, Vcc (12 or 5V)
2. Ignition Trigger - is this GND, Vcc (12 or 5V)

I can then jerry rig and manually test the coil pack. Jerry used to build and sell testers but he is no longer doing them. I have a spare transformer

Also it would be nice if someone knows the part numbers for the connectors.

Pinout for Transformer and coil pack

N91 - Voltage Transformer:

Pin4/5 - 12V Supply Voltage - Connected to Battery
Pin 7/8 - 23V Aux Voltage
Pin 9/16 - 180V Ignition Voltage
Pin 11/14 - Ground
Pin 12/13 - 12V - Battery Voltage
Chassis - Ground

N92/1 and N92/2
Pin -1 Ignition Trigger CYL-1
Pin -2 Ignition Trigger CYL-2
Pin -3 Ignition Trigger CYL-3
Pin -4 Ignition Trigger CYL-4
Pin -13 Ignition Trigger CYL-5
Pin -12 Ignition Trigger CYL-6
Pin -10 Ignition Offset Cyl 1-6
Pin -11 Ignition Change (circuit a/b)

Pin -8 Ground - Connected to Voltage Transformer
Pin -14 - 23V Aux - Connected to Voltage Transformer
Pin -15 - 12V - Connected to Voltage Transformer (Battery Voltage
Pin -16 - 180V Ignition Voltage - Connected to Voltage Transformer

Pin - 5,6,7 - Ion Current Signals

Last edited by rgdeja; Jun 26, 2025 at 05:39 PM.

Nov 16, 2025 | 04:30 PM

mrvedit

Super Member

Joined: Sep 2021

Posts: 537

Likes: 115

From: Ann Arbor, MI

2004 SL600

Did you ever figure out the signal voltages?
Where is the source for that electrical diagram? The diagram is new to me and super educational. It gives me a much better understanding of the ignition "transformer".
Do you happen to know if the pins 4&5 on N91 are on circuit 30 (constant power) or circuit 15 (switched power)?

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