Distributor Ignition N1/3

EZL/AKR Ignition Control Module
The EZL/AKR ignition control module (N1/3) contains a microcomputer, pressure sensor and power output stage for control of the two ignition coils (one per cylinder bank).

The EZL/AKR control module receives information concerning:
- Voltage supply (+12.5V)
- Engine speed from CKP sensor (L5)
- Cylinder #1 position from CMP sensor (L5/1)
- Engine load condition from intake manifold vacuum signal
- Selection of ignition map from EZL/AKR reference resistor (R16/2)
- Shift preconditions from transmission overload protection switch (S65)
- Combustion knock from knock sensors (A16)
- Fuel injection information from LH-SFI control module (N3/1)
- Throttle position from EA/CC/ISC module (N4/1)
- ABS/ASR information from ABS/ASR module (N30/1)

The EZL/AKR ignition control module compares information from these inputs with ignition maps for typical load and speed ranges that are stored in the microcomputer. The optimal ignition timing for each operating condition is instantaneously determined from stored maps and the power output stage switches the primary current of the ignition coils.

Also, a engine speed (TN) reference signal is provided to the LH-SFI module (N3/1), tachometer, on-board diagnostics connector, and the diagnostic socket. To further increase operating reliability, a data exchange circuit has been added between the EZL/AKR ignition control module and the LH-SFI control module. Information concerning the coolant temperature, intake air temperature and the intake manifold absolute pressure is continuously compared by the control module of each system.

During cranking and up to appox. 450RPM, the ignition timing is controlled via the segment edges (fixed) of the flywheel. After appox. 460RPM has been attained, a transition from fixed ignition timing to dynamic ignition timing is made by instantaneous ignition map comparison. Various ignition characteristics curves are inhibited in the warm-up range depending on the coolant temperature (ECT sensor) in order to reach the normal operating temperature as rapidly as possible.

When a full load signal is received from the electronic accelerator control module (N4/1), the EZL/AKR control module adapts a fixed full load ignition map characteristic. At temperatures above appox. 203 deg F, the ignition will be retarded to counter any further rise in temperature.

Control Functions
Diagnostic Function:
If the EZL/AKR module detects a specific fault more than eight (8) sequential times (ignition switch turned ON and OFF), a fault code is stored in the control module memory. Only malfunctions which prevent/severely influence starting or operating of the ignition system are immediately stored in the fault memory. The CHECK ENGINE light is also illuminated.

Malfunctions occurring in the following areas are stored immediately:
- Crankshaft position sensor defective (DTC code 17)
- Magnets for crankshaft position sensor not recognized (DTC code 18 for Engine 119 only)

Engine Torque Reduction (w/ ABS):
In order to obtain instant engine torque reduction during wheel slip, the ignition timing is retarded during the first part of ASR engagement. This signal is received via the Controller Area Network (CAN) from the ABS/ASR and EA/CC/ISC module.

Fault Table, DTC Readout, Ignition Control Module (N1/3)

Socket 1: Black (Ground)
Socket 3: Red (+12.5V)
Socket 17: Yellow (Pin for DI DTC readout)

* Spark plugs, ignition wires of respective cyclinder, high-voltage distributor
DI Diagnostic Tests refer to MB's service manual tests that further fault isolate the problem

DTC Readout	Possible Cause	Remedy/Test Step
1	No Faults in System	-
2	Maximum retard setting on at least one cylinder has been reached	Increased knock due to poor fuel quality, carbon buildup, mechanical damage
3	Not Used	-
4	Load Sensor in ignition control module (N1/3) defective	Check vacuum supply to Ign control module (N1/3): Replace N1/3
5	Knock Sensor (A16) 1 and/or 2 defective	Knock sensor not plugged in at Ign module: Replace knock sensor
6	Camshaft position sensor (L5/1) defective	Run DI Diagnostic tests: Step 1.0
7	Knock control output switch in ignition control module (N1/3) defective	Replace N1/3
8	Transmission overload switch (S65) does not close	Run DI Diagnostic tests: Step 5.0
9	Transmission overload switch (S65) does not open	Run DI Diagnostic tests: Step 6.0
10	Not Used	-
11	Reference resistor (R16/2) in ignition control module (N1/3) defective	Run DI Diagnostic tests: Step 4.0
12	TN-Signal (engine RPM) is outside of tolerance range	Run DI Diagnostic tests: Step 7.0
13 - 14	Not used	-
15	Ignition coil 1 output from ignition control module (N1/3) defective or primary winding of ignition coil has open circuit	Run DI Diagnostic tests: Step 7.0
16	Ignition coil 2 output from ignition control module (N1/3) defective or primary winding of ignition coil has open circuit	Run DI Diagnostic tests: Step 8.0
17	Crankshaft position sensor defective (L5)	Run DI Diagnostic tests: Step 4.0
18	Magnets for crankshaft position sensor (L5) not recognized	Run DI Diagnostic tests: Step 5.0
19	Not used	-
20	Ignition control module (N1/3) DTC memory defective	Replace N1/3
21	Load sensor in ignition control module (N1/3) defective (recognized with engine running)	Replace N1/3
22 - 25	Not used	-
26	Ignition control module (N1/3) data exchange fault	Run DI Diagnostic tests: Step 8.0 - 9.0
27	LH Control Unit (N3/1) data exchange fault	Run DI Diagnostic tests: Step 8.0
28	Electronic accelerator control module/idle speed control data exchange fault	Run DI Diagnostic tests: Step 8.0
29 - 33	Not Used	-
34	Ignition misfire cylinder 1 (engine 104) 1 (engine 119)	*
35	Ignition misfire cylinder 2 (engine 104) 2 (engine 119)	*
36	Ignition misfire cylinder 3 (engine 104) 3 (engine 119)	*
37	Ignition misfire cylinder 4 (engine 104) 4 (engine 119)	*
38	Ignition misfire cylinder 5 (engine 104) 5 (engine 119)	*
39	Ignition misfire cylinder 6 (engine 104) 6 (engine 119)	*
40	Ignition misfire cylinder 7 (engine 119)	*
41	Ignition misfire cylinder 8 (engine 119)	*