Electronic Control Modules - Service Information: Overview RAM Pickup 2500

DESCRIPTION

The primary on-board communication network between microprocessor-based electronic control modules in this vehicle is the Controller Area Network (CAN) data bus system. A data bus network minimizes redundant wiring connections; and, at the same time, reduces wire harness complexity, sensor current loads and controller hardware by allowing each sensing device to be connected to only one module (also referred to as a node). Each node reads, then broadcasts its sensor data over the bus for use by all other nodes requiring that data. Each node ignores the messages on the bus that it cannot use.

The CAN bus is a two-wire multiplex system. Multiplexing is any system that enables the transmission of multiple messages over a single channel or circuit. The CAN bus is used for communication between most vehicle nodes. However, in addition to the CAN bus network, certain nodes may also be equipped with a Local Interface Network (LIN) data bus. The LIN data bus is a single wire low-speed (9.6 Kbps) serial link bus used to provide direct communication between a LIN master module and certain switch or sensor inputs.

There are actually three separate CAN bus systems used in the vehicle. They are designated: the CAN-Interior (also known as CAN Interior High Speed/IHS), the CAN-C and the Diagnostic CAN-C. The CAN-Interior and CAN-C systems provide on-board communication between all nodes in the vehicle. The CAN-C is the faster of the two systems providing near real-time communication (500 Kbps). The CAN-C is used typically for communications between more critical nodes, while the slower (125 Kbps) CAN-Interior system is used for communications between less critical nodes.

The added speed of the CAN data bus is many times faster than previous data bus systems. This added speed facilitates the addition of more electronic control modules or nodes and the incorporation of many new electrical and electronic features in the vehicle.

The Diagnostic CAN-C bus is also capable of 500 Kbps communication, and is sometimes informally referred to as the CAN-D system to differentiate it from the other high speed CAN-C bus. The Diagnostic CAN-C is used exclusively for the transmission of diagnostic information between the Totally Integrated Power Module/Central GateWay (TIPM or TIPMCGW) and a diagnostic scan tool connected to the industry-standard 16-way Data Link Connector (DLC) located beneath the instrument panel on the driver side of the vehicle.

The TIPM is located in the engine compartment near the battery. The central CAN gateway or hub module integral to the TIPM is connected to all three CAN buses. This gateway physically and electrically isolates the CAN buses from each other and coordinates the bi-directional transfer of messages between them.

OPERATION

The Controller Area Network (CAN) data bus allows all electronic modules or nodes connected to the bus to share information with each other. Regardless of whether a message originates from a module on the lower speed CAN-Interior (also known as CAN Interior High Speed/IHS) bus or on the higher speed CAN-C or CAN-D bus, the message structure and layout is similar, which allows the Totally Integrated Power Module/Central GateWay (TIPM or TIPMCGW) to process and transfer messages between the CAN buses. The TIPM also stores a Diagnostic Trouble Code (DTC) for certain bus network faults.

All modules (also referred to as nodes) transmit and receive messages over one of these buses. Data exchange between nodes is achieved by serial transmission of encoded data messages. Each node can both send and receive serial data simultaneously. Each digital bit of a CAN bus message is carried over the bus as a voltage differential between the two bus circuits which, when strung together, form a message. Each node uses arbitration to sort the message priority if two competing messages are attempting to be broadcast at the same time.

The Cluster (also known as the Cabin Compartment Node/CCN) is the Local Interface Network (LIN) master module in this vehicle and it gathers information from the compass module, the instrument panel switch bank, the Steering Control Module (SCM), and the Heated Seat Module (HSM) through the LIN data bus. There is also LIN bus communication between the individual Tire Pressure Monitor (TPM) transponders and the Wireless Ignition Node (WIN). Both the EMIC and the WIN either act directly upon the information received through the LIN data bus, relay the information to other nodes in the vehicle using electronic messages placed on the CAN bus, or both.

The voltage network used to transmit messages requires biasing and termination. Each module on the CAN bus network provides its own biasing and termination. There are two types of nodes used in the CAN bus network. On the CAN-C or the IHS bus, a dominant node has a 120 ohm termination resistance while a non-dominant (or recessive) node has about a 2500 to 3000 ohm (2.5 to 3.0 kilohm) termination resistance. The dominant nodes on the CAN-C bus are the WIN and the Powertrain Control Module (PCM). The dominant nodes on the IHS bus are the Cluster and the TIPM.

The termination resistance of two dominant nodes is combined in parallel to provide a total of about 60 ohms. This resistance value may vary somewhat by application, depending upon the number of non-dominant nodes on the bus. On the CAN-D bus (or Diagnostic CAN-C) all of the 60 ohm termination resistance is present in the Central GateWay (TIPMCGW).

Note. All measurement of termination resistance is done with the vehicle battery disconnected.

The communication protocol being used for the CAN data bus is a non-proprietary, open standard adopted from the Bosch CAN Specification 2.0b. The CAN-C is the faster of the two primary buses in the CAN bus system, providing near real-time communication (500 Kbps).

The CAN bus nodes are connected in parallel to the two-wire bus using a twisted pair, where the wires are wrapped around each other to provide shielding from unwanted electromagnetic induction, thus preventing interference with the relatively low voltage signals being carried through them. The twisted pairs have between 33 and 50 twists per meter (yard). While the CAN bus is operating (active), one of the bus wires will carry a higher voltage and is referred to as the CAN High or CAN bus (+) wire, while the other bus wire will carry a lower voltage and is referred to as the CAN Low or CAN bus (-) wire. Refer to the CAN BUS VOLTAGES Chart below.

In order to minimize the potential effects of Ignition-OFF Draw (IOD), the CAN-Interior network employs a sleep strategy. However, a network sleep strategy should not be confused with the sleep strategy of the individual nodes on that network, as they may differ. For example: The CAN-C bus network is awake only when the ignition switch is in the ON or START positions; however, the TIPM, which is on the CAN-C bus, may still be awake with the ignition switch in the ACCESSORY or UNLOCK positions. The integrated circuitry of an individual node may be capable of processing certain sensor inputs and outputs without the need to utilize network resources.

The CAN-Interior bus network remains active until all nodes on that network are ready for sleep. This is determined by the network using tokens in a manner similar to polling. When the last node that is active on the network is ready for sleep, and it has already received a token indicating that all other nodes on the bus are ready for sleep, it broadcasts a bus sleep acknowledgment message that causes the network to sleep. Once the CAN-Interior bus network is asleep, any node on the bus can awaken it by transmitting a message on the network. The TIPM will keep either the CAN-Interior or the CAN-C bus awake for a timed interval after it receives a diagnostic message for that bus over the Diagnostic CAN-C bus.

In the CAN system, available options are configured into the TIPM at the assembly plant, but additional options can be added in the field using the diagnostic scan tool. The configuration settings are stored in non-volatile memory. The TIPM also has two 64-bit registers, which track each of the as-built and currently responding nodes on the CAN-Interior and CAN-C buses. The TIPM stores a Diagnostic Trouble Code (DTC) in one of two caches for any detected active or stored faults in the order in which they occur. One cache stores powertrain (P-Code), chassis (C-Code) and body (B-Code) DTCs, while the second cache is dedicated to storing network (U-Code) DTCs.

If there are intermittent or active faults in the CAN network, a diagnostic scan tool connected to the Diagnostic CAN-C bus through the 16-way Data Link Connector (DLC) may only be able to communicate with the TIPM. To aid in CAN network diagnosis, the TIPM will provide CAN-Interior and CAN-C network status information to the scan tool using certain diagnostic signals. In addition, the transceiver in each node on the CAN-C bus will identify a bus off hardware failure , while the transceiver in each node on the CAN-Interior bus will identify a general bus hardware failure . The transceivers for some CAN-Interior nodes will also identify certain failures for both CAN-Interior bus signal wires.

Scheme 11

The Data Link Connector (DLC) (3) is a 16-way molded plastic connector insulator on a dedicated take out of the instrument panel wire harness. This connector is located at the lower edge of the instrument panel, outboard of the steering column. The connector insulator is retained by integral snap features within a rectangular cutout in the lower instrument panel reinforcement (2), just below the lower edge of the instrument panel steering column opening cover (1).

The Data Link Connector (DLC) is an industry-standard 16-way connector that permits the connection of a diagnostic scan tool to the Controller Area Network (CAN) data bus for interfacing with, configuring, and retrieving Diagnostic Trouble Code (DTC) data from the electronic modules that reside on the data bus network of the vehicle.

Scheme 12

The Antilock Brake Module (ABM) (2) is mounted to the Hydraulic Control Unit (HCU) (3) and operates the ABS system.

The ABM voltage source is through the ignition switch in the RUN position. The ABM contains a self check program that illuminates the ABS warning light when a system fault is detected. Faults are stored in a diagnostic program memory and are accessible with the scan tool. ABS faults remain in memory until cleared, or until after the vehicle is started approximately 50 times. Stored faults are not erased if the battery is disconnected.

Note. If the ABM is being replaced with a new ABM is must be reprogrammed with the use of a scan tool.

The microprocessor-based electronic front door control modules (also known as a Driver Door Module/DDM, a Passenger Door Module/PDM or Front Door Multiplex/MUX Modules) contain logic circuits that monitor various hard wired low current, multiplexed inputs from the power window, power lock, power mirror and memory switches on their respective door. They also receive Controller Area Network (CAN) Interior High Speed (IHS) data bus electronic message-based external inputs from the opposing front door control module as well as from other electronic modules in the vehicle. The front door control modules also monitor hard wired power window motor Hall effect sensors and memory mirror position sensor inputs.

In addition, the front door control module on the driver side front door receives electronic message inputs from the driver side front door switch module over the Local Interface Network (LIN) data bus network. The program logic within the front door control module allows the microprocessor to prioritize all of these inputs and determine the tasks it needs to perform. These tasks are then completed either by controlling hard wired outputs to the various motors, actuators or lamps on its own or the rear doors, or by sending electronic message requests over the CAN-IHS bus to the appropriate electronic module in the vehicle.

The front door control modules are powered by a fused B(+) circuit and are grounded at all times so that they can operate regardless of the ignition switch position. Both driver and passenger door control modules provide active and stored Diagnostic Trouble Codes (DTC) through On-Board Diagnostics (OBD) and communicate with a diagnostic scan tool using the CAN data bus.

The hard wired inputs and outputs of the front door control module may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the electronic controls and communication between modules and other devices that provide some features of the power window, power lock, memory, interior lighting or exterior lighting system features the front door control modules provide. The most reliable, efficient and accurate means to diagnose the front door control modules or the electronic controls and communication related to operation of these systems requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

The Drivetrain Control Module (DTCM) controls the 4X4 transfer case shift functions via the actuation of a shift motor and utilizing the feedback of a mode sensor assembly. Communication is handled through the CAN bus. The user selectable transfer case modes include the following: 2WD, 4WD AUTO, 4WD LOCK, 4WD LOW, and Neutral (selections vary with the specific transfer case).

The DTCM is located in the passenger footwell, below the HVAC blower.

During normal operation of an active transfer case the Drive Train Control Module (DTCM) control module learns and remembers the Clutch Engagement Point (Kiss Point), the position in the motor actuator's travel where torque begins to be transferred to the front wheels. The position is read out using the encoder as a 0 to 5 volt signal. This information is written into the module's EEPROM area at Ignition OFF. Over time the clutch pack wears and the Kiss Point changes in one direction (going from a lower voltage to a higher value).

Normal Operation

This mode is achieved by the ignition being switched in the RUN position, which powers up the 5V regulator and generates the appropriate RESET for the microprocessor. This mode also includes any required power-up system checks.

The Heated Seat Module (HSM) is used to control the functions of the following systems

1. Vented Seats - Two vented seats can be controlled by the HSM, refer to «Operation»(ref-457814-S26949181222012030200000) .
2. Heated Seats - Up to four heated seats can be controlled by the HSM, refer to «Operation»(ref-457815-S39644608362012030200000) .
3. Heated Steering Wheel . Refer to «Operation»(ref-457814-S26949181222012030200000) .

Note. The HSM will configure itself depending on what components are installed on the vehicle. This allows for one module to be used for every component combinations available.

The HSM will only be on with the engine running. Therefore the heated seats, vented seats, and heated steering wheel will only operate with the engine running. Seat heating and seat venting are independent systems; however, they can not be actuated at the same time. Turning the vented seats on when the heated seat are already on will turn off the heated seats and vice versa. The heated steering wheel on the other hand can be on at the same time as either the heated seats or the cooled seats.

Note. The Integrated Trailer Brake Module (ITBM) does not control the trailer lights or the vehicle lights.

Automatic Braking

The Integrated Trailer Brake Module (ITBM) is powered with an ignition ON voltage source and has a single ground connection. The ITBM communicates on the CAN Bus for vehicle speed signal, Electronic Stability Control (ESC) active signal and the VIN information. There is also a hard wired brake switch input into the ITBM. The ITBM uses this information along with an internal accelerometer to determine how much braking to apply to the trailer brakes. The output is a Pulse Width Modulated (PWM) circuit for control of trailer braking intensity during stops. The ratio between vehicle braking and trailer braking is adjusted by the user with the plus/minus (±) switch on the face of the module. The ITBM is used to control the trailer brakes based on the deceleration reading of the vehicle and will send the output to control the trailer brakes only when a trailer connection is recognized. If a trailer is not connected to the vehicle, the ITBM output will be disabled.

Manual Trailer Braking

In addition to automatic trailer braking, the user can manually apply the trailer brakes prior to or without the vehicle brakes by sliding the ITBM manual sliding brake lever/switch to the right at any time. In this circumstance the accelerometer and other trailer braking inputs are ignored and trailer braking intensity is controlled by the user.

Scheme 13

Scheme 14

Scheme 15

Scheme 16

1. Disconnect and isolate the battery negative cable.
2. Remove the steering column opening cover retaining screws (2).
3. Using a trim stick, remove the steering column opening cover (1) from the instrument panel and position aside.
4. Using a trim stick, from the notch on the bottom, remove the left instrument panel side cover (1).
5. From under the instrument panel, disconnect the integrated trailer brake module (ITBM) electrical connectors (1). NOTE: One screw on the right front of the ITBM not shown in illustration.
6. Remove the three ITBM retainer screws (1). NOTE: There is a retainer clip on each side of the ITBM near the bottom.
7. Using a trim stick, remove the ITBM (1) from the IP.

The Memory Seat Module (MSM), also referred to as Memory Module (MM) receives battery current through a 25 amp Maxi Fuse in the Totally Integrated Power Module (TIPM) so that the memory system remains operational, regardless of the ignition switch position. When the driver memory switch button is pushed, a resistance signal is sent to the MSM via the Controller Area Network (CAN) bus circuit. The MSM is responsible for the 12v battery feed and ground path to the power seat adjuster motor and other memory system components.

The MSM receives memory set/position switch input through the CAN bus circuit. The MSM also receives hard wired input from the hall effect sensors, mounted on each of the driver power seat adjuster motors, the driver side view mirror motor, and adjustable pedals. The programmed software in the module allows it to know where the seat and adjustable pedals are located in its designed travel by a pulse count generated from the hall effect sensors. This way, when the memory switch is depressed the module will power these components until the correct preset location is achieved. The module will prevent the seat memory recall function from being initiated, if the transmission gear selector lever is not in the Park position, or if the vehicle is moving. These inputs are monitored over the Controller Area Network (CAN) bus circuit by the MSM.

A memory setting is saved by pressing the "set" button, then pressing either the memory "1" or "2" button within 5 seconds of pressing the "set" button.

A memory setting is recalled by pressing either the memory "1" or "2" button, or by pressing the unlock button on a "linked" FOBIK transmitter.

For driver safety, memorized settings can not be recalled if the transmission is in a position other than Park.

The MSM performs the following functions

1. Positions the driver power seat (vertical, horizontal, and recliner positions).
2. Positions the power adjustable pedals.
3. Sends the memory save or recall (number 1 or number 2) command over the CAN data bus circuit to the other memory system components, radio station presets and power mirror positions.
4. Provides for the easy entry/exit feature.

When a memory button is pressed (number 1 or number 2) on the memory switch, it provides resistive signal/input to the MSM. The MSM will then position the memory system components to the preprogramming location/setting. FOBIK Transmitter button is pressed, depending on which transmitter (number 1 or number 2), the WIN/SKIM Receiver sends the recall request and FOBIK number (number 1 or number 2) data message. This FOBIK transmitter function depends on if the MSM is programmed to trigger the recall (linked FOBIKs).

A FOBIK is "linked" to a memory setting by pressing the "set" button and then pressing either the memory "1" or "2" button within 5 seconds of pressing the set button, then by pressing the "lock" button on the selected FOBIK.

The memory system "Easy Entry and Exit" feature provides the driver with more room to enter or exit the vehicle. When the seat is in a memorized position, it will move rearward 55 millimeters or to the end of its travel, whichever occurs first, when the key is removed from the ignition switch lock cylinder. This is a customer programmable feature in the EVIC. The seat will return to the memory position when the driver turns the vehicle's ignition switch out of the LOCK position.

The memory system "learns" the seat and adjustable pedal motor maximum end positions when the motor reaches the limit of travel in any direction and stalls. Subsequently, movement will stop just short of that position to avoid extra stress on the motors and mechanisms. If the system learned a maximum position as a result of an obstruction, as for instance if a large object was placed on the floor behind the seat, the system can relearn the "true" maximum position through manually operating the power seat after the obstruction is removed.

Note. It is normal for the power accessories contained in the memory system to stop at the maximum "learned" position and then continue to the "true" maximum position when the control switch is released and then applied in the same direction a second time.

Certain functions and features of the memory system rely upon resources shared with other electronic modules in the vehicle over the Controller Area Network (CAN) bus. The CAN bus allows the sharing of sensor information. This helps to reduce wire harness complexity, internal controller hardware, and component sensor current loads. At the same time, this system provides increased reliability, enhanced diagnostics, and allows the addition of many new feature capabilities. For diagnosis of these electronic modules or of the CAN bus, the use of a scan tool and the proper diagnostic information are needed.

PICK UP MODELS

Scheme 17

The oxygen sensor module (1) is located under the vehicle. It is bolted to the outer side of right frame rail (4).

PICK UP MODELS

Two different six-wire Oxygen (O2) sensors are used. These sensors are titled 1/1 upstream, and 1/2 downstream. A separate O2 sensor module (1) is also used.

The engine aftertreatment system monitors the O2 content in the diesel engine exhaust. The Powertrain Control Module (PCM) monitors the exhaust gases for oxygen content and varies the rich/lean fuel mixture of the intake air fuel mixture to adjust the system. This diagnostic monitors the status message broadcast by the O2 Sensor Module (1) for the upstream O2 sensor's internal heater circuit. The PCM will set the fault if it receives a Failure Mode Indicator (FMI) message from the O2 Sensor Module. The PCM will illuminate the MIL lamp immediately when the diagnostic runs and fails. The PCM will turn off the MIL lamp diagnostic runs and passes in four consecutive drive cycles.

MODES OF OPERATION

As input signals to the Powertrain Control Module (PCM) change, the PCM adjusts its response to the output devices. For example, the PCM must calculate different injector pulse width and ignition timing for idle than it does for wide open throttle (WOT).

The PCM will operate in two different modes: Open Loop and Closed Loop .

During Open Loop modes, the PCM receives input signals and responds only according to preset PCM programming. Input from the oxygen (O2S) sensors is not monitored during Open Loop modes.

During Closed Loop modes, the PCM will monitor the oxygen (O2S) sensors input. This input indicates to the PCM whether or not the calculated injector pulse width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-1 part fuel. By monitoring the exhaust oxygen content through the O2S sensor, the PCM can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined with low emission engine performance.

The fuel injection system has the following modes of operation

1. Ignition switch ON
2. Engine start-up (crank)
3. Engine warm-up
4. Idle
5. Cruise
6. Acceleration
7. Deceleration
8. Wide open throttle (WOT)
9. Ignition switch OFF

The ignition switch On, engine start-up (crank), engine warm-up, acceleration, deceleration and wide open throttle modes are Open Loop modes. The idle and cruise modes, (with the engine at operating temperature) are Closed Loop modes.

PCM OPERATION

The PCM operates the fuel system. The PCM is a pre-programmed, triple microprocessor digital computer. It regulates ignition timing, air-fuel ratio, emission control devices, charging system, certain transmission features, speed control, air conditioning compressor clutch engagement and idle speed. The PCM can adapt its programming to meet changing operating conditions.

The PCM receives input signals from various switches and sensors. Based on these inputs, the PCM regulates various engine and vehicle operations through different system components. These components are referred to as Powertrain Control Module (PCM) Outputs. The sensors and switches that provide inputs to the PCM are considered Powertrain Control Module (PCM) Inputs.

The PCM adjusts ignition timing based upon inputs it receives from sensors that react to: engine rpm, manifold absolute pressure, engine coolant temperature, throttle position, transmission gear selection (automatic transmission), vehicle speed, power steering pump pressure, and the brake switch.

The PCM adjusts idle speed based on inputs it receives from sensors that react to: throttle position, vehicle speed, transmission gear selection, engine coolant temperature and from inputs it receives from the air conditioning clutch switch and brake switch.

Based on inputs that it receives, the PCM adjusts ignition coil dwell. The PCM also adjusts the generator charge rate through control of the generator field and provides speed control operation.

Note. PCM Inputs

1. ABS module (if equipped)
2. A/C request (if equipped with factory A/C)
3. A/C select (if equipped with factory A/C)
4. A/C pressure transducer
5. Auto shutdown (ASD) sense
6. Battery temperature sensor
7. Battery voltage
8. Brake switch
9. CAN C BUS (+) circuits
10. CAN C BUS (-) circuits
11. Camshaft position sensor signal
12. Crankshaft position sensor
13. Data link connection for a scan tool
14. EATX module (if equipped)
15. Engine coolant temperature sensor
16. Fuel level
17. Generator (battery voltage) output
18. Ignition circuit sense (ignition switch in on/off/crank/run position)
19. Intake manifold air temperature sensor
20. Knock sensors (2 on 3.7L engine)
21. Leak detection pump (switch) sense (if equipped)
22. Manifold absolute pressure (MAP) sensor
23. Oil pressure
24. Oxygen sensors
25. Park/neutral switch (auto. trans. only)
26. Power ground
27. Power steering pressure switch (if equipped)
28. Sensor return
29. Signal ground
30. Speed control multiplexed single wire input
31. Throttle position sensor
32. Transfer case switch (4WD range position)
33. Vehicle speed signal

Note. PCM Outputs

1. A/C clutch relay
2. Auto shutdown (ASD) relay
3. CAN C BUS (+/-) circuits for: speedometer, voltmeter, fuel gauge, oil pressure gauge/lamp, engine temp. gauge and speed control warn. lamp
4. Data link connection for diagnostic scan tool
5. EGR valve control solenoid (if equipped)
6. EVAP canister purge solenoid
7. Five volt sensor supply (primary)
8. Five volt sensor supply (secondary)
9. Fuel injectors
10. Fuel pump relay
11. Generator field driver (-)
12. Generator field driver (+)
13. Idle air control (IAC) motor
14. Ignition coil(s)
15. Leak detection pump (if equipped)
16. Malfunction indicator lamp (Check engine lamp).
17. Oxygen sensor heater relays
18. Oxygen sensors (pulse width modulated)
19. Radiator cooling fan relay (pulse width modulated)
20. Speed control vacuum solenoid
21. Speed control vent solenoid
22. Tachometer (if equipped).
23. Transmission convertor clutch circuit.

The Powertrain Control Module (PCM) is used to control the functions of the engine and transmission. The PCM is bolted to the left side of the engine below the intake manifold.

The main function of the Powertrain Control Module (PCM) is to electrically control the fuel system. The PCM also controls the functions of transmission.

The PCM can adapt its programming to meet changing operating conditions.

The PCM receives input signals from various switches and sensors. Based on these inputs, the PCM regulates various engine and vehicle operations through different system components. These components are referred to as PCM Outputs. The sensors and switches that provide inputs to the PCM are considered PCM Inputs.

Note. PCM Inputs

1. Accelerator Pedal Position Sensor (APPS) Signals No. 1 and No. 2
2. AC system pressure
3. Auto shutdown (ASD) sense
4. Battery voltage
5. Brake switch
6. Camshaft Position Sensor (CMP)
7. Crankshaft Position Sensor (CKP)
8. Data link connection for a scan tool
9. EGR Air Flow Control
10. EGR Valve
11. Engine Coolant Temperature (ECT) sensor
12. Exhaust Gas Temperature sensor
13. EATX module (if equipped)
14. Fuel level
15. Fuel pressure sensor
16. Fan speed (engine cooling fan)
17. Generator (battery voltage) output
18. Governor pressure (Auto. trans.)
19. Ground circuits
20. Inlet air temperature sensor/pressure sensor
21. Intake air temperature sensor/MAP sensor
22. CAN C BUS (+) circuits
23. CAN C BUS (-) circuits
24. Key switch (ignition)
25. Oil Pressure switch
26. Overdrive switch (automatic transmission only)
27. Park/neutral switch (auto. trans. only)
28. Power ground
29. SCI datalink bus (+) circuits
30. SCI datalink bus (-) circuits
31. Sensor return
32. Signal ground
33. Speed control multiplexed single wire input
34. Transfer case switch (4WD range position)
35. Transmission governor psi (automatic transmission only)
36. Transmission OSS (automatic transmission only)
37. Transmission oil pressure (automatic transmission only)
38. Transmission oil temperature (automatic transmission only)
39. Transmission throttle valve position (automatic transmission only)
40. Vehicle speed signal
41. Water-In-Fuel (WIF) sensor

Note. PCM Outputs

After inputs are received by the PCM, certain sensors, switches and components are controlled or regulated by the PCM. These are considered PCM Outputs. These outputs are for

1. A/C clutch relay
2. Auto shutdown (ASD) relay
3. Data link connection for diagnostic scan tool
4. EGR air flow control
5. EGR valve
6. Fan clutch PWM
7. Five volt sensor supply (primary)
8. Five volt sensor supply (secondary)
9. Fuel control actuator
10. Fuel injector driver circuits
11. Fuel transfer (lift) pump
12. Generator field driver (-)
13. Generator field driver (+)
14. Governor pressure (VFS solenoid)
15. Intake manifold air heater relays No. 1 and No. 2 control circuits
16. CAN C BUS (+/-) circuits for: speedometer, voltmeter, fuel gauge, oil pressure gauge/lamp, engine temp. gauge and speed control warn. lamp
17. Malfunction indicator lamp (Check engine lamp). Driven through J1850 circuits.
18. Oil pressure switch/warning lamp (databus)
19. Overdrive/3 - 4 shift solenoid (automatic transmission only)
20. SC source
21. SCI datalink bus (+) circuits
22. SCI datalink bus (-) circuits
23. Speed control vacuum solenoid
24. Speed control vent solenoid
25. Tachometer (if equipped). Driven through J1850 circuits.
26. TCC solenoid (automatic transmission only)
27. Transmission battery relay (automatic transmission only)
28. Transmission throttle valve actuator (automatic transmission only)
29. Transmission governor solenoid (automatic transmission only)
30. Wait-to-start warning lamp (databus)
31. Turbo wastegate solenoid
32. Water-In-Fuel (WIF) warning lamp (databus)

The microprocessor-based Steering Control Module (SCM) utilizes integrated circuitry to monitor hard wired analog and multiplexed inputs from the individual switches within the multi-function switch. In response to those inputs, the internal circuitry of the SCM allows it to transmit electronic message outputs to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) over the Local Interface Network (LIN) data bus.

In response to those LIN messages the internal circuitry and programming of the EMIC, which is also the LIN master module in the vehicle, allow it to control and integrate many electronic functions and features of the vehicle through both hard wired outputs and the transmission of electronic message outputs to other electronic modules in the vehicle over the Controller Area Network (CAN) data bus. Refer to COMMUNICATION , Description .

The SCM is connected to both a fused B(+) circuit and a fused ignition switch output (run-start) circuit. It receives a path to ground at all times. These connections allow it to remain functional regardless of the ignition switch position. Any input to the SCM that controls a vehicle system function that does not require that the ignition switch be in the ON position such as flashing the high beam headlamps, prompts the SCM to wake up and transmit on the LIN data bus.

The hard wired circuits between components related to the SCM may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the SCM or the electronic controls or communication between modules and other devices that provide some features of the SCM. The most reliable, efficient, and accurate means to diagnose the SCM or the electronic controls and communication related to SCM operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

Following are brief descriptions of the systems that the WIN controls.