12 13 009 Check ignition pencil coils with diagnosis and information system tester or oscilloscope (M54, M56, N40, N42, N43, N45, N46, N52, N62, N62TU, N73)

Special tools required:

12 1 301
12 7 050

Necessary preliminary tasks:

Read out fault memory in DME (Digital Engine
Electronics)
N40: Remove sound absorption hood
N42: Remove sound absorption hood
N43: Remove sound absorption hood
N45: Remove sound absorption hood
N46: Remove sound absorption hood
N52: Remove sound absorption hood
N62/N62TU: Remove sound absorption hood
N62/N62TU: Remove ignition coil cover
Open control unit box
Remove M54/56 ignition coil cover

Unlock plug fastener (1) of ignition coil.

Fig 1: Unlocking Plug Fastener Of Ignition Coil

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Detach plug (1) in direction of arrow. Pull out ignition coil (2) towards top.

NOTE: Procedure applies to all rod-type ignition coils.

Fig 2: Detaching Plug

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Install special tool 12 7 050 .

Installation:

Special tool 12 7 050 is attached between spark plug and rod-type ignition coil.

Fig 3: Identifying Special Tool (12 7 050)

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Secondary measurement:

Connect KV clip-on probe (1) of DIS Tester to special tool 12 7 050 .

Procedure on DIS Tester:

Select <Measurement>.
Select <Preset measurement>.
Select <Secondary ignition signal>.
Connect <TD cable to diagnostic head>.
Select <static ignition distribution>.
Select <Number of cylinders>.

For subsequent procedure, follow DIS instructions.

Fig 4: Identifying DIS Tester

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NOTE: Illustration shows: KV clip-on probe (1) US version.

Primary measurement:

Connect 26-pin pin box with special tool 12 1 301 to connector (1) DME module 5.

Procedure on DIS Tester:

Select <Measurement>.
Select <Preset measurement>.
Select <Ignition signal term. 1>.

For subsequent procedure, follow DIS instructions.

NOTE: Pin assignment acc. to connection scheme.
Illustration N42.

IMPORTANT: Ignition signal is a multiple spark ignition .

Fig 5: Identifying KV Clip-On Probe

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Illustration of multiple spark ignition

Start of ignition peak.
Level of ignition voltage.
Level of sparking voltage.
Spark duration.
Sparking voltage curve.
Start of decay process.
Decay process.

Fig 6: Multiple Spark Ignition Waveform

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M54 / M56 / N40 / N42 / N45 / N46 / N62 / N73:

The following ignition oscillogram applies to engines with multiple spark ignition from a production date of April 2001:

Depending on engine temperature (approx. -20° to 100°) and engine speed (<2000 rpm.), some ignition voltage peaks (approx. 1-5 ignition peaks) can occur before the typical ignition voltage characteristic.

The additional ignition peaks play no role in diagnosis. The last ignition peak (1) on the oscillogram is decisive.

Fig 7: Multiple Spark Ignition Waveform

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NOTE: The display of the ignition voltage peak is approx. 20-25 % lower than the real value.
It is not the height of the ignition voltage peaks but rather the uniformity of all the cylinders that is important.
Differences of 3000 to 4000 volts are permitted.