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Engine Controls - Pin Voltage Charts: Introduction

Pin voltage charts are supplied to reduce diagnostic time. Checking pin voltages at the DME/Motronic control unit determines whether it is receiving and transmitting proper voltage signals. Charts may also help determine if control unit wiring harness is shorted or opened.

NOTE: Unless stated otherwise in testing procedures, perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance. Voltage readings may vary slightly due to battery condition or charging rate.
DME/MOTRONIC CONTROL UNIT PIN ASSIGNMENTS (1) (740i - 4.0L M60 ENGINE; DME 3.3 - 1 Of 2)

Pin No. Function/Description Signal Type Or Voltage Value
1 Fuel Pump Relay Ground Circuit Term. 85
2 Idle Speed Control Valve (Close) Zero Volts Or Ground (Output Signal)
3 Fuel Injector (No. 1) Pulse (Duty Cycle) Duration In % (Output Signal)
4 Fuel Injector (No. 4) Pulse (Duty Cycle) Duration In % (Output Signal)
5 Fuel Injector (No. 5) Pulse (Duty Cycle) Duration In % (Output Signal)
6 Fuel Injectors (Ground) Ground Circuit
7 Fuel Injector (No. 4) Pulse (Duty Cycle) Duration In % (Output Signal)
8 CHECK ENGINE Light (2) Ground Circuit (Output Signal)
11 Potentiometer Electronic Throttle Control Module (Square Wave Output Signal)
12 Oxygen Sensor (No. 5-8) PCM Monitored (5 Volt) Signal Circuit
13 Oxygen Sensor (No. 1-4) PCM Monitored (5 Volt) Signal Circuit
14 Air Mass Sensor Ground Circuit
15 Injection Signal Resistor Circuit Input
16 Crankshaft Sensor Input Signal (Inductive)
17 Camshaft Position Sensor Hall-Effect Signal
19 Air Pump Solenoid Control Circuit
22 Ignition Coil (Cylinder No. 7) Primary Circuit Output Signal
23 Ignition Coil (Cylinder No. 6) Primary Circuit Output Signal
24 Ignition Coil (Cylinder No. 4) Primary Circuit Output Signal
25 Ignition Coil (Cylinder No. 1) Primary Circuit Output Signal
26 Battery Voltage (Permanent) (3) 12 Volts (Battery Voltage Input)
27 DME Master Relay (4) Output Signal
28 PCM Ground Ground Circuit
29 Idle Speed Control Valve (Open) Zero Volts Or Ground (Output Signal)
31 Fuel Injector (No. 5) Pulse (Duty Cycle) Duration In % (Output Signal)
32 Fuel Injector (No. 8) Pulse (Duty Cycle) Duration In % (Output Signal)
33 Fuel Injector (No. 3) Pulse (Duty Cycle) Duration In % (Output Signal)
34 PCM Ground Internal PCM Circuit Ground Point
35 Fuel Injector (No. 2) Pulse (Duty Cycle) Duration In % (Output Signal)
36 Fuel Tank Vent (Evaporation) Control (5) Pulse (Duty Cycle) Duration In % (Output Signal)
37 Oxygen Sensor Heater Relay Output Signal (With Ignition On)
39 Oxygen Sensor Signal (No. 5-8) Sensor Ground Circuit
40 Oxygen Sensor Signal (No. 1-4) Sensor Ground Circuit
41 Air Mass Sensor 0-5 Volts Input Signal
42 Vehicle Speed Signal Square Wave Input Signal
43 Camshaft Ground Ground Circuit
44 Crankshaft Sensor Ground Ground Circuit
45 Shield Ground Ground Circuit
46 Instrument Cluster (Fuel Consumption) Square Wave Output Signal
47 Engine Speed Signal Ignition Interval (TD) Output Signal
48 A/C Compressor Shutoff (6) Output Signal
49 Ignition Coil (Cylinder No. 2) Primary Circuit Output Signal
50 Ignition Coil (Cylinder No. 3) Primary Circuit Output Signal
51 Ignition Coil (Cylinder No. 8) Primary Circuit Output Signal
52 Ignition Coil (Cylinder No. 5) Primary Circuit Output Signal
54 Battery Voltage (DME Relay Operation) (3) 12 Volts (Battery Voltage Input)
55 Ignition (Ground) Ground Circuit
56 Start (Ignition) Input 12 Volts (Battery Voltage Input)
59 Throttle Position Sensor 5-Volt (Reference) Output Signal
60 Programming Voltage (7) Voltage (Input Signal)
62 ABS/ASC Throttle Control Traction Control Module Input Signal
64 A/C Switch (8) 12 Volts (Battery Voltage Input)
65 A/C Pressure Signal Input Signal
66 On-Board Computer Input Signal
67 Knock Sensor (No. 7-8) Input Signal
68 Knock Sensor (No. 5-6) Input Signal
69 Knock Sensor (No. 3-4) Input Signal
70 Knock Sensor (No. 1-2) Input Signal
71 Knock Sensor (Ground) Ground Circuit
73 Throttle Potentiometer (TPS) (9) 0.5-5.0 Volts (Input Signal)
77 Intake Air Temperature Sensor 0-5 Volts (Input Signal)
78 Engine (Coolant) Temperature Sensor 0-5 Volts (Input Signal)
81 Headlight Switch Input Signal
82 Engine Coasting Signal Traction Control Module Input Signal
83 Traction Control Regulation Traction Control Module Input Signal
84 Heated Oxygen Sensor (Shield) Shield Ground Circuit
85 Data Line (Transmission Module) Input/Output Signal
86 Data Line (Transmission Module) Input/Output Signal
87 Diagnostic Initiation Line (RxD) (10) 12 Volts (Battery Voltage Input)
88 Diagnostic Data Line (TxD) (10) Input/Output Signal
(1) Pin assignments not listed are not used (blank).
(2) In case of defect, check CHECK ENGINE light function.
(3) No DME functions if voltage is not present.
(4) No DME functions when master relay is off. Connect jumper wire between terminals No. 30 and 87.
(5) Duty cycle depends on engine speed and load.
(6) Output signal to A/C relay only at speed of 5 MPH and engine at full load.
(7) Only activated during programming.
(8) With A/C system on.
(9) Voltage signal input to control unit will vary depending on throttle position.
(10) With diagnostic socket cover closed.
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