3.0l v6 Mpfi System Dodge Caravan I

DESCRIPTION

The computerized engine control system used on the 3.0L engine controls ignition timing, air/fuel ratio, emission control devices, cooling fan, charging system, idle speed, and cruise control for proper engine operation.

In order to control these systems, the computer monitors several engine and vehicle operating conditions. The engine conditions monitored include: manifold absolute pressure, throttle position, coolant temperature, charge temperature, exhaust gas oxygen content, and vehicle speed.

Vehicle conditions monitored include vehicle speed and the status (off or on) of several vehicle systems that affect engine load. These include the transaxle neutral/safety, brake light, speed control, and A/C clutch switches.

The Single Module Engine Controller (SMEC) is the "BRAIN" of the system. It is a digital computer with an integral microprocessor. The SMEC processes all sensor inputs and assigns control signals to all output devices to control injector pulse width ("on-off" time), spark advance, idle speed, and other engine functions.

Components of 3.0L Single Module Engine Control System. Scheme 121

OPERATION

The computerized engine control system consists of 11 sub-systems; Fuel Control, Data Sensors and Switches, Single Module Engine Controller (SMEC), Ignition Control, Idle Speed Control, Emission Control, Lock-Up Torque Converter Solenoid, Cooling Fan Control, Charging System Control, Cruise Control, and On-Board Diagnostic System.

FUEL CONTROL

An electric, positive-displacement, roller vane type fuel pump is located in the fuel tank. The fuel pump is an integral part of the fuel gauge sending unit. The fuel pump supplies fuel to the fuel rail. A fuel pressure regulator, mounted downstream of injectors on fuel rail, maintains fuel system pressure at a constant 36 psi (2.5 kg/cm 2 ) pressure. See CANISTER PURGE SOLENOID under EMISSION CONTROL in this article for more information.

Power to the fuel pump is supplied by the SMEC via the Automatic Shutdown (ASD) relay. The SMEC is supplied with an operating signal from the distributor. When the SMEC senses a distributor signal during cranking, it grounds the ASD closing contacts. This completes the circuit for the electric fuel pump, injectors and ignition coil. If the distributor signal is lost for any reason, the ASD relay shuts off this circuit in less than one second; preventing fuel, spark and engine operations.

The electrically pulsed fuel injectors supply fuel to each cylinder. The SMEC provides power to each group of injectors (2 injectors per group). The SMEC determines when to energize each group of injectors, and how long each injector remains open (pulse width) based upon engine operating conditions.

When electrical current is supplied to the injector, an integral armature and pintle valve move a short distance against a spring, opening a small orifice. Fuel supplied to the injector is forced around the pintle valve and through this opening, resulting in a fine spray of fuel in the shape of a hollow cone. The injector pulse width (injector "on" time) determines the amount of fuel entering the engine and, therefore, the air fuel ratio.

Manifold Absolute Pressure (MAP) Sensor

The MAP sensor is located in the engine compartment, mounted on firewall. The MAP sensor monitors manifold vacuum through a vacuum line from the intake plenum to the sensor.

The sensor supplies the SMEC with an electrical signal that indicates manifold pressure conditions and barometric pressure. This information on engine load is combined with data supplied by other sensors to determine correct air/fuel ratio.

Heated Oxygen (O2) Sensor

The oxygen sensor is mounted in the rear exhaust manifold so that it is exposed to exhaust gas flow. The sensor monitors oxygen content of exhaust gases. The oxygen content reacts with the sensor to produce a voltage output signal that is sent to the SMEC.

The O2 sensor is equipped with a heating element that keeps the sensor at a consistent temperature under warm-up and idle conditions. This allows the engine control system to enter "closed loop" mode of operation much earlier, and to remain in "closed loop" during extended idle periods.

If the oxygen content of the exhaust gases is high (lean air/fuel mixture), voltage signal from the sensor to the SMEC is low. As oxygen content decreases (mixture becomes richer), the signal voltage increases.

In this manner, the SMEC is kept constantly informed of air/fuel ratio. It can then alter fuel injector "on" time, in response to these signals, to obtain the best air/fuel ratio under any given condition.

Coolant Temperature Sensor (CTS)

The coolant temperature sensor is a dual thermistor that measures temperature of engine coolant. The coolant temperature sensor is mounted in the thermostat housing. One side of the CTS supplies SMEC with a voltage signal that varies with engine coolant temperature. The other side of the sensor is used to control the electric cooling fan. See COOLING FAN CONTROL under EMISSION CONTROL in this article for more information.

Information provided by this sensor, along with charge temperature sensor information, allows the SMEC to provide slightly richer air/fuel mixtures and higher idle speeds during cold engine operation.

Charge Temperature Sensor

The charge temperature sensor measures the temperature of the incoming air/fuel mixture. The sensor, mounted in the intake manifold, supplies the SMEC with incoming air/fuel mixture temperature information. With this information, the SMEC can alter fuel injector pulse width to change the air/fuel ratio.

Throttle Position Sensor (TPS)

The TPS is a variable resistor that is operated by movement of throttle shaft. It is mounted on the throttle body and senses throttle blade opening angle.

The sensor produces a voltage signal that varies with throttle angle. This signal is transmitted to the SMEC where it is used to adjust air/fuel ratio during acceleration, deceleration, idle and wide open throttle conditions.

Speed Sensor

This sensor informs the SMEC of vehicle speed. This information is used primarily for cruise control and torque converter clutch operation.

Transaxle Neutral Safety Switch

This switch informs the SMEC when the automatic transaxle is in Neutral. Information from this switch is used for spark timing control, torque converter clutch operation, and idle speed control.

SMEC - SINGLE MODULE ENGINE CONTROLLER

The SMEC contains the operating software, and performs calculations and adjustments necessary for engine operation. The SMEC is located at the front of the left fender panel in the engine compartment. (Scheme 122)

The SMEC is a microprocessor-based digital computer, with 60-pin and 14-pin connectors. The SMEC receives input signals from various switches, sensors and other components. Using these signals, the microprocessor computes fuel injector pulse width, spark advance, ignition coil dwell, automatic idle speed actuation, canister purge cycle, cooling fan operation, and alternator output.

The SMEC also contains a diagnostic circuit to test input and output circuits. The diagnostic circuit will store information about any malfunctions as they occur for read-out prior to service. Either the Chrysler Diagnostic Read-Out Box (C-4805) or the flashing "CHECK ENGINE" light may be used in diagnosing and displaying trouble codes. However, the "CHECK ENGINE" light is limited in its diagnostic capabilities.

Location of Single Module Engine Controller (SMEC). Scheme 122

IGNITION CONTROL

The SMEC controls all aspects of ignition system, including spark advance, ignition dwell, and spark timing. During cranking, timing is advanced by the SMEC to provide quick efficient start. During running mode, the SMEC advances and retards ignition timing in accordance with information on coolant temperature, engine RPM, and engine load.

Engine speed and crankshaft position information is received from the distributor. This information is used by the SMEC to control fuel injection, ignition timing, and idle speed. Engine speed and crankshaft position are also used to synchronize the fuel injection timing to ignition timing.

IDLE SPEED CONTROL

Idle speed is controlled by the SMEC through the Automatic Idle Speed (AIS) motor. The AIS is mounted on the throttle body assembly. The SMEC uses sensor input to determine optimum engine idle speed for any idle condition.

The AIS receives control signals from the SMEC to adjust the amount of air allowed through the air by-pass in the throttle body. This by-pass is enlarged or restricted, as an increase or decrease in engine idle speed is required, to meet varying engine operating conditions.

This results in a change in air/fuel ratio that alters the oxygen content of the exhaust gases as detected by the oxygen sensor. The SMEC then changes the amount of fuel introduced into the intake charge to maintain an optimum air/fuel ratio.

The SMEC monitors A/C operation and transaxle lever position. When necessary, the SMEC issues commands to the AIS to increase idle speed under these load conditions. With the air conditioning on and the throttle blade above a specific angle, the A/C cut-out relay prevents the air conditioning clutch from engaging until the throttle blade angle is reduced.

The A/C cut-out relay is wired in series with the A/C cycling clutch switch and A/C low pressure cut-out switch. This relay is normally closed during engine operation.

When the throttle is closed quickly after driving (sudden deceleration), engine stall (die-out) is prevented by increasing engine idle speed. This is an automatic function of the AIS motor through the SMEC.

Canister Purge Solenoid

The canister purge solenoid controls canister purge and fuel pressure. When the SMEC energizes the solenoid, the solenoid closes to block the flow of fuel vapor, and to increase fuel pressure. Depending upon coolant sensor and charge sensor temperatures at start-up, the solenoid will be energized for a specific amount of time that is programed into the SMEC.

Lock-Up Torque Converter Solenoid

The SMEC controls a transaxle-mounted solenoid to allow the torque converter to directly connect the engine to the transaxle. When vehicle speed is high enough, the SMEC energizes the lock-up solenoid and the engine is mechanically linked to the transaxle.

When operating conditions indicate that the transaxle should operate as normal, the solenoid is de-energized. This allows the transaxle to return to normal automatic operation. The transaxle will also return to normal automatic operation when the brake pedal is depressed.

Cooling Fan Control

The electric cooling fan is controlled by the SMEC. Coolant temperature information is sensed by the coolant temperature sensor. The sensor is a dual thermistor that measures temperature of engine coolant. The sensor is mounted in the thermostat housing. One side of the CTS supplies SMEC with a voltage signal that varies with engine coolant temperature. The other side of the sensor is used to control the electric cooling fan.

The cooling fan is controlled in the following manner

1. The fan will not be energized during cranking until engine starts, regardless of coolant temperature.
2. The fan is energized at all times during A/C clutch operation.
3. On vehicles without A/C or when A/C clutch is not energized, fan is energized at vehicle speeds above 40 MPH, only if coolant temperature is 230°F (110°C) or greater, and de-energized when coolant temperature drops below 220°F (104°C). At vehicle speeds below 40 MPH, the fan turns on at 210°F (99°C) and turns off at 200°F (93°C).

Charging System Control

The SMEC monitors battery voltage and charging system voltage. Some circuits are monitored continuously, while other circuits are checked only under specific operating conditions.

If a circuit fails the test sequence, the SMEC will enter "LIMP-IN" mode, will turn on the "CHECK ENGINE" light, and will substitute a value in place of the failed value. The following conditions will cause the SMEC to enter the "LIMP-IN" mode

1. Battery Voltage Sense - If battery voltage signal drops below 4 volts after engine has run for a least one minute. The SMEC will cause the charging system to operate at a fixed rate.
2. Battery Voltage Too High - If battery voltage exceeds the predetermined control voltage by one volt.

The "CHECK ENGINE" light will be turned off, and the charging system will be returned to normal operating condition if the faults correct themselves during that current engine operating cycle.

Cruise Control System

The SMEC monitors vehicle speed, cruise controls switch, and brake switch. When cruise control is activated, the SMEC sends the appropriate command signal to the servo. By monitoring vehicle speed and brake switch, the SMEC can energize and de-energize the servo as required to meet the specific driving condition.

ON-BOARD DIAGNOSTICS OPERATION

The SMEC is equipped with a self-diagnostic system that detects system failures or abnormalities. The self-diagnostic system is divided into 2 categories: faults requiring immediate attention and faults which do not require immediate attention.

Faults requiring immediate attention cause the SMEC to substitute the failed value with a calculated value, to store a trouble code in memory, and to turn on the "CHECK ENGINE" light to alert the driver that service is required. This is the "LIMP-IN" mode of operation. In this mode, driveability characteristics are greatly affected. The following faulty circuits will cause the system to enter the "LIMP-IN" mode

1. MAP Sensor - If MAP sensor signal is too low (below .02 volt), too high (above 4.9 volts), or not changing (no change from start to full throttle condition). The SMEC then uses the TPS signal and engine speed signal to create a substitute MAP signal. Under this condition, the AIS motor is commanded to its minimum position by the SMEC.
2. TPS - If throttle position signal is too low (below .16 volt), or too high (above 4.7 volts). The SMEC then uses MAP sensor signal to crate a substitute throttle position signal.
3. CTS - If coolant temperature signal exceeds 4.96 volts when engine is cold, or below 5.1 volts when engine is warm. The SMEC will set a fixed value of 150°F (66°C). The cooling fan will run continuously in this mode.
4. Battery Voltage - If battery voltage drops below 4 volts, or to 7 1/2-8 1/2 volts after engine has been running for at least one minute. The SMEC will operate the charging system at a fixed rate in this mode.
5. Battery Voltage Too High - If battery voltage exceeds the predetermined control voltage by one volt.

If these faults correct themselves during the engine operating cycle in which they were detached, the "CHECK ENGINE" light will be turned off and the system will return to normal operation. The fault code will remain in memory for diagnostic evaluation. If the fault does not occur after 20-40 engine starts, the code will be cleared from memory.

Faults that do not require immediate attention will cause a trouble code to be stored in memory. During diagnostics, these codes can be evaluated, and appropriate action can be taken. Fault codes will be retained in memory as long as the monitored circuit remains faulty. The code will be erased from memory only if the fault does not appear again within 20-40 engine starts.

As a bulb and system test, the "CHECK ENGINE" light will glow when the ignition switch is turned on and will remain on for 3 seconds.

PRELIMINARY CHECKS

Most driveability problems in the engine control system result from faulty or poor wiring, or loose and/or leaking hose connections. To avoid unnecessary component testing, a visual check should be performed before beginning trouble shooting procedures to help spot these common faults. A preliminary visual check should be made of the following areas

Electrical connections should be checked to ensure connector terminals lock together, and wiring between each connector and wiring harness is not pinched or frayed in such a way as to produce a short to ground condition. Check the following locations to ensure that electrical connections are okay

1. Single Module Engine Controller (SMEC).
2. A/C cut-out relay (if equipped).
3. Starter relay.
4. Cooling fan relay.
5. Distributor.
6. Coolant temperature sensor.
7. Spark plug and coil wires.
8. Throttle position sensor.
9. Manifold absolute pressure sensor.
10. Fuel injector harness and injectors.
11. Charge temperature sensor.
12. Automatic idle speed motor.
13. System ground connection at left side of cylinder head.
14. Engine harness to main harness.
15. Alternator.
16. Battery cables.
17. Battery ground on engine, and engine-to-firewall ground strap.
18. Canister purge solenoid and cruise control vacuum solenoid (if equipped).
19. Ignition coil.
20. Oxygen sensor.
21. Speed sensor.
22. Cooling fan motor.
23. A/C condenser motor, A/C clutch, and A/C damped pressure switch (if equipped).
24. Neutral safety switch.
25. Transaxle lock-up solenoid.
26. In-tank fuel pump.

All hose and vacuum connections should be checked to ensure connectors are fully and firmly seated. Ensure hoses and lines are not pinched, melted, or cut anywhere along the routing. Check the following locations to ensure connections and lines are okay

1. Canister purge EGR vacuum signal lines at throttle body and vacuum lines at tee in canister purge signal line.
2. PCV hose at valve cover and at air intake plenum.
3. EGR signal hose at EGR backpressure valve, hoses at EGR valve, hose between backpressure valve and exhaust supply tube on EGR valve, and hose between backpressure valve and EGR valve.
4. Purge hose and purge signal vacuum line connector at charcoal canister, fuel tank vapor hose at canister, fuel tank vapor hose at pressure relief/roll-over valve, purge signal vacuum line connectors at purge control solenoid, and vacuum line at air intake plenum.
5. Vacuum line connector at MAP sensor and at intake manifold.
6. Hose at power brake booster and filter, and hose at cruise control servo (if equipped), and at air intake plenum.
7. Vacuum line at power brake booster to instrument panel controls for A/C-heating control and vacuum line connector at water valve.
8. Vacuum lines at canister purge solenoid and at fuel pressure regulator (leads into canister purge signal line).

DIAGNOSTIC PROCEDURE

If the "CHECK ENGINE" light comes on, or if certain driveability or engine performance difficulties exist, the probable source of these difficulties lay be determined by enter "On-Board Diagnostics" and recording the trouble codes as they are displayed. Trouble codes may be displayed on the Chrysler Diagnostic Read-Out Box (C,4805) or, to a limited extent, be flashed on the "CHECK ENGINE" light.

Once there codes are known, refer to TROUBLE CODES DESCRIPTION under TESTING & DIAGNOSIS in this article to determine the questionable circuit. Then use the wiring diagram and connector identification charts to locate testing points for each circuit. Test circuits and repair or replace as needed. If the problem is repaired or ceases to exist, the SMEC cancels the trouble code after 20-40 ignition on/off cycles.

Introduction To Diagnostic System

The SMEC has 5 different test modes. Corresponding codes are used for each diagnostic mode. All 5 test modes must be used to properly diagnose the system. The following information explains each test mode, the bodes that correspond to each mode, and the method used to enter the test mode.

Diagnostic Mode

1. The diagnostic test mode is used to determine if there are any fault codes stored in memory. The corresponding code is balled a fault code. Fault codes are 2-digit numbers that identify which circuit is bad.
2. To enter diagnostic mode, attach the Chrysler Diagnostic Read-Out Box (C-4805) to diagnostic connector. The connector is located in the engine compartment near the left strut tower. If diagnostic read-out box is not available, codes may be read off of the "CHECK ENGINE" light.
3. To read codes using the diagnostic read-out box, start engine if possible. Cycle transaxle shift lever and A/C switch (if equipped). Turn engine off. Place "READ/HOLD" button in "READ" position. Turn ignition switch on, off, on, off, on within 5 seconds. Record all 2-digit fault codes. Moving button to "HOLD" position will stop the display of codes momentarily. Move button back to "READ" position to continue display of fault codes.
4. If using "CHECK ENGINE" light to read codes, start engine if possible. Cycle transaxle shift lever and A/C switch (if equipped). Turn engine off. Turn ignition switch on, off, on, off, on within 5 seconds. The "CHECK ENGINE" light will glow for 2 seconds as a bulb check, then flash the fault bodes. Record 2-digit codes by counting flashes of the "CHECK ENGINE" light.
5. The 2-digit codes displayed by the "CHECK ENGINE" light are indicated by a series of flashes. For example, code 23 is displayed as flash, flash, 4-second pause, flash, flash, flash. After a slightly longer pause, any other codes stored are displayed in numerical order. Once the light begins to display trouble codes, it cannot be stopped. If you lose count, it will be necessary to start over.
6. The setting of a specific code is the result of a particular circuit failure. It does not identify the specific component in a circuit. The diagnostic system cannot determine the reason for a failure, only that the fault is due to a particular circuit identified with that code. Therefore, the existence of a particular code denotes the probable area of the malfunction, not necessarily the failed component itself.

Switch Test Mode

1. The switch test mode is used to determine if specific switch inputs are being received by the SMEC.
2. To enter this mode, first ensure all switches that send an input signal to SMEC are turned off. Put system into Diagnostic Mode and wait for code 55 to appear and the "CHECK ENGINE" light to stop blinking.
3. Turn on switches to send input to SMEC. If the SMEC is receiving the switch input, the diagnostic read,out box display will change or the "CHECK ENGINE" light will turn on as the switch is turned on. The display will change again or the light will turn off when the switch is turned to the "OFF" position. The following switches output signals to the SMEC: Brake switch. Gearshift position (Park, Reverse). A/C switch (if equipped). This is valid only when damped pressure switch is closed and blower switch is in "ON" position.

Circuit Actuation Test Mode (ATM)

1. The ATM test lode is used to activate and deactivate specific circuit to determine if they are operational. ATM test codes are the output of this test. ATM codes are 2-digit codes that identify the circuit. The diagnostic read-out box MUST be used for this test. The "CHECK ENGINE" light does not function in this mode.
2. To activate ATM test mode, put system into Diagnostic Mode. Wait for code 55 to appear on diagnostic read-out box display and "CHECK ENGINE" light to stop blinking. Ensure "READ/HOLD button is in "RED" position. Press and hold "ATM" button on diagnostic read-out box until the desired ATM test code is displayed. Release ATM button.
3. The SMEC will turn the selected circuit on and off at 2-second intervals for 5-minute period and then turn the test off. To stop the test before the 5-minute period is complete, turn the ignition switch off.

Sensor Test Mode

1. The senor test mode is used to read the output signal of specific sensors to the SMEC when the engine is not running. Sensors access codes are used to select specific sensors. This mode is also used to clear all fault codes from memory. Sensor codes are 2,digit codes similar to ATM codes. The diagnostic read,out box MUST be used for this test, "CHECK ENGINE" light does not function in this mode.
2. To enter this mode, put system into ATM test mode. Press and hold "ATM" button until the desired sensor access code is displayed. Release button. Love "READ/HOLD" switch to "HOLD" position. NOTE: Since sensor access codes are the same as some ATM test codes, the ATM circuit will turn on before moving the "READ/HOLD" switch to the "HOLD" position.
3. The SMEC will use the diagnostic read,out box to display the output of the selected sensor. Divide all displayed readings except coolant sensor and battery voltage by 00 for actual reading. Multiply coolant sensor readings by 10 for actual readings. Battery voltage readings are actual and no correction is necessary.

Engine Running Test Mode

1. The engine running test mode is used to read the output signal of specific sensor to the SMEC when the engine is running. This test can be performed with the engine idling in Neutral with parking brake applied, or during vehicle road test. Engine running codes are 2-digit codes. The diagnostic read-out box MUST be used for this test; "CHECK ENGINE" light does not function in this mode.
2. To enter this mode, connect diagnostic readout box to diagnostic connector. Ensure "READ/HOLD" button is in "READ" position. Start engine and observe diagnostic readout box display. When the O2 sensor is at operating temperature, the display will reveal if the system is switching rich-lean by alternately displaying "0" and "1" when in closed loop ("0" - Lean, "1"- Rich).
3. When the engine is running in Neutral or Park and the O2 system switching is displayed, the idle motor system can be checked by moving the "READ/HOLD" button to the "HOLD" position. Engine speed should increase to about 1400 RPM.
4. When the engine is running, O2 switching is displayed, and the "READ/HOLD" button is in "READ" position, depress and hold the "ATM" button until the desired engine running test code is displayed. Release "ATM" button. Move "READ/HOLD" button to the "HOLD" position. The SMEC will display the selected sensor output or will operate the engine in a specific mode for system diagnosis.
5. Battery voltage, manifold vacuum and vehicle speed are actual readings and no correction is required. Coolant sensor and engine RPM readings are to be multiplied by 10 for actual readings. All other readings are to be divided by 10 for actual reading.

Note. If using a diagnostic read-out box other than Chrysler Diagnostic Read-Out Box (C-4805), follow manufacturer's instructions on how to connect diagnostic read-out box and obtain codes. Some diagnostic read-out boxes will display information that is not contained in this testing. This information may not be relative to diagnosing a problem. Only information contained in this article should be used during diagnosis.

INDICATOR CODES DESCRIPTION

Indicator codes are 2-digit numbers that will tell you if certain sequences or conditions have occurred.

Code 88

This code implies the "start of diagnostic mode". If this code is not displayed first, trouble codes will be inaccurate.

Code 55

This code signals the "end of diagnostic mode". This code will always appear as the final code after all other trouble codes have been displayed.

Code 0

Indicates oxygen feedback system is lean with engine running.

Code 1

Indicates oxygen feedback system is rich with engine running.

Code 12

Problem with battery feed to SMEC. This circuit is monitored whenever ignition switch is on. Code 12 is stored in memory when SMEC memory has been cleared of codes within last 20-40 engine starts.

CIRCUIT ACTUATION TEST (ATM) CODES DESCRIPTION

Place system in ATM mode of testing. Press and hold "ATM" button on diagnostic read-out box until desired ATM code is displayed. Release button.

Code 01

Entering "01" on diagnostic read-out box activates spark control circuit.

Code 02

Entering "02" on diagnostic read-out box activates fuel injector driver circuits.

Code 03

Entering "03" on diagnostic read-out box activates AIS circuit.

Code 04

Entering "04" in diagnostic read-out box activates cooling fan relay circuit.

Code 05

Entering "05" on diagnostic read-out box activates A/C cut-out relay circuit (if equipped).

Code 06

Entering "06" on diagnostic read-out box activates automatic shutdown relay circuit.

Code 07

Entering "07" on diagnostic read-out box activates canister purge solenoid circuit.

Code 08

Entering "08" on diagnostic read-out box activates cruise control servo circuit (if equipped).

Code 09

Entering "09" on diagnostic read-out box activates alternator field control circuit.

Code 10

Entering "10" on diagnostic read-out box activates lock-up torque converter circuit.

SENSOR TEST CODES DESCRIPTION

Place system in ATM mode of testing. Press and hold "ATM" button on diagnostic read-out box until desired ATM code is displayed. Release button. Move "READ/HOLD" button to "HOLD" position. Some codes are the same as some ATM codes.

Entering "02" on diagnostic read-out box displays current oxygen sensor reading.

Entering "03" on diagnostic read-out box displays current charge temperature reading.

Entering "04" on diagnostic read-out box displays current coolant temperature reading.

Entering "05" on diagnostic read-out box displays current throttle position reading.

Entering "07" on diagnostic read-out box displays current battery voltage reading.

Entering "08" on diagnostic read-out box displays current MAP sensor reading.

Entering "09" on diagnostic read-out box displays current cruise control position (if equipped).

Entering "10" on diagnostic read-out box erases all fault codes in memory. The display will flash zeros for 4 seconds.

ENGINE RUNNING TEST CODES DESCRIPTION

Connect diagnostic read-out box to diagnostic connector. Make sure "READ/HOLD" button is in "READ" position. Start engine and observe diagnostic read-out box display. When the engine is running, O2 switching is displayed, and the "READ/HOLD" button is in "READ" position, depress and hold the "ATM" button until the desired engine running test code is displayed. Release "ATM" button. Move "READ/HOLD" button to the "HOLD" position.

Code 62

Entering "62" on diagnostic read-out box displays current oxygen sensor reading.

Code 63

Entering "63" on diagnostic read-out box displays current charge temperature reading.

Code 64

Entering "64" on diagnostic read-out box displays current coolant temperature reading.

Code 65 & 69

Entering "65 or "69" on diagnostic read-out box displays current throttle position reading.

Code 67

Entering "67" on diagnostic read-out box displays current battery voltage reading.

Code 68

Entering "68" on diagnostic read-out box displays current MAP sensor reading.

Code 71

Entering "71" on diagnostic read-out box displays current vehicle speed reading.

TROUBLE CODES DESCRIPTION

The following list presents the trouble codes that can be stored in SMEC memory, and the system malfunctions which they represent.

Code 11

Problem with distributor circuit. This bode is stored in memory if there has been no distributor signal to SMEC since memory was cleared. This circuit is monitored only during cranking mode.

Code 13

Problem with MAP sensor vacuum circuit. This code is stored in memory if sensor vacuum level does not change between ignition pulses. This circuit is monitored when engine is running at 600-1600 RPM, and the MAP sensor electrical circuit is okay.

Code 14

Problem with MAP sensor electrical circuit. This code is stored in memory if sensor signal is below .02 volt or above 4.9 volts. This circuit is monitored whenever ignition switch is on.

Code 15

Problem with vehicle speed sensor circuit. This code is stored in memory if no speed sensor signal is detected within an 11-second period. This circuit is monitored at engine speeds higher than 1800 RPM, with vacuum less than 10 in. Hg.

Code 16

Problem with battery sensing voltage. This code is stored in memory if battery sensing voltage drops below 4 volts for more than 4 seconds. This circuit is constantly monitored one minute after engine starts.

Code 17

Problem with coolant temperature circuit. This code is stored in memory if engine coolant temperature does not reach 160°F (71°C) within 8 minutes after vehicle reaches speed greater than 28 MPH. This circuit is monitored 12 minutes after engine starts.

Code 21

Problem with O2 sensor circuit. This code is stored in memory if no lean or rich condition is indicated for a 2-minute time period. This circuit is monitored when engine temperature is above 170°F (77°C) and engine speed is above 1500 RPM.

Code 22

Problem with coolant temperature sensor circuit. This code is stored in memory if coolant sensor voltage is above 4.95 volts when engine is cold, or below .51 volt when engine is warm. This circuit is monitored whenever ignition switch is on.

Code 23

Problem with charge temperature sensor circuit. This code is stored in memory if charge temperature sensor voltage is below .04 volt or above 4.96 volts when engine coolant temperature is above 77°F (25°C). This circuit is monitored only during cranking mode.

Code 24

Problem with TPS circuit. This code is stored in memory if throttle position sensor signal is below .16 volt or above 4.7 volts. This circuit is monitored whenever the ignition switch is on.

Code 25

Problem with AIS circuit. This code is stored in memory if proper voltage is not present in AIS circuit. This code will not be stored in memory if an open circuit appears on circuit. This circuit is monitored only when the AIS system is required to control engine speed.

Code 26

Problem with fuel injector driver. This code is stored in memory if the current through any pair of the injector drive circuits does not reach proper peak level. This circuit is monitored only during cranking mode.

Code 27

Problem with fuel control circuit. This code is stored in memory if fuel control circuit interface fails to properly switch. This circuit is monitored whenever the ignition switch is on.

Code 31

Problem with canister purge solenoid circuit. This code is stored in memory if canister purge solenoid does not turn on and off when it should. This circuit is monitored whenever the ignition switch is on.

Code 33

Problem with A/C cut-out relay driver circuit. This code is stored in memory if relay does not turn on and off when it should. This circuit is monitored only when A/C condenser fan relay is energized.

Code 34

Problem with cruise control servo circuit. This code is stored in memory if servo does not turn on and off when it should. This circuit is monitored only when cruise control system is activated, and brake pedal is not applied.

Code 35

Problem in the cooling fan relay circuit. This code is stored in memory if relay does not turn on and off when it should. This circuit is monitored whenever the ignition switch is on.

Code 37

Problem with transaxle lock-up solenoid. This code is stored in memory if solenoid does not turn on and off when it should. This circuit is monitored whenever the ignition switch is on.

Code 41

Problem with charging system. This code is stored in memory if field control fails to properly switch. This circuit is monitored whenever the ignition switch is on.

Code 42

Problem in the ASD relay circuit. This code is stored in memory if relay does not turn on and off when it should. This circuit is monitored whenever the ignition switch is on.

Code 43

Problem in the spark control interface circuit. This code is stored in memory if spark control interface fails to properly switch. This circuit is monitored only during cranking mode.

Code 44

Problem with fused "J2" circuit within SMEC. This code is stored in memory if this circuit is not on the logic board of the SMEC. This circuit is monitored whenever the ignition switch is on.

Code 46

Problem with battery sensing voltage. This code is stored in memory if battery sensing voltage is greater than one volt above desired control voltage for more than 20 seconds. This circuit is monitored whenever engine is running.

Code 47

Problem with battery sensing voltage. This code is stored in memory if battery sensing voltage is less than one volt below desired control voltage for more than 20 seconds. This circuit is monitored whenever engine has been running for more than 6 minutes, engine temperature is above 160°F (71°C), and engine speed is above 1500 RPM.

Code 51

Problem with oxygen feedback system. This code is stored in memory if the oxygen sensor indicates a lean condition for more than 2 minutes. This circuit is monitored during all periods of "closed loop" of operation.

Code 52

Problem with oxygen feedback system. This code is stored in memory if the oxygen sensor indicates a rich condition for more than 2 minutes. This circuit is monitored during all periods of "closed loop" mode of operation.

Code 53

Problem within SMEC. This code is stored in memory if the logic board inside the SMEC fails. This circuit is monitored when the ignition switch is first turned to "ON" position.

Code 54

Problem in distributor synchronization pick-up circuit. This code is stored in memory if there is not a distributor synchronization pick-up signal. This circuit is monitored whenever the engine is running.

ERASING CODES FROM SMEC MEMORY

To erase codes from memory, enter ATM TEST MODE as previously outlined. Move "READ.HOLD" button to "HOLD" position. Diagnostic read-out display will flash alternating zeros. When flashing zero stops and display shows "00", all codes have been erased from memory.

NS-1 TEST - PRELIMINARY TESTS

Note. Before replacing major components, be sure connector pins or cavities are not damaged, preventing proper voltage and resistance readings.

Scheme 123

Scheme 124

Scheme 125

Scheme 126

1. Remove wire from spark plug and insert insulated screwdriver in terminal. Hold screwdriver shaft 1/4" from good engine ground. Crank engine for at least 7 seconds. There should be good spark as long as engine is being cranked. Treat 1-2 sparks as no spark. If there is spark, proceed to step 4). If there is spark for about 5 seconds and then stops and/or engine starts and runs for a few seconds then stalls, perform NS6.
2. If no spark occurred, remove ignition coil wire from distributor cap. Hold coil wire 1/4" from a good engine ground. Crank engine. There should be good spark. Treat 1-2 sparks as no spark. If spark is okay, check distributor cap, rotor and plug wires. Replace defective parts as necessary. If no spark occurred, go to next step.
3. Connect voltmeter between Dark Green/Black wire at injector 4-pin connector and ground. (Scheme 123) Crank engine for at least 7 seconds. If voltage reading is within one volt of cranking voltage during cranking of engine, perform NS3. If voltage reading is zero volts, or cranking voltage for about one second, perform NS9. (Scheme 123): Attaching Voltmeter To Injector 4-Pin Connector
4. If there was good spark in step 1), install Pressure Gauge (C-3292 ) with Adapter (C-4799) in fuel supply hose at throttle body. (Scheme 124) Crank engine for at least 7 seconds. If fuel pressure is at least 30 psi (2.1 kg/cm 2 ), go to next step. If fuel pressure is zero, perform NS2. WARNING: Fuel system is under pressure. Relieve pressure before servicing fuel pump, fuel lines, fuel filter, throttle body, or fuel injector. To relieve pressure, loosen fuel filler cap to release tank pressure. Remove wiring harness connector from any injector and ground one terminal. Connect jumper wire to other terminal of injector and touch positive battery terminal for no longer than 10 SECONDS to release fuel pressure. Perform service and restore components to original condition. (Scheme 124): Fuel Return Line & Fuel Supply Line Identification
5. If fuel pressure was okay in step 4), connect diagnostic read-out box to diagnostic connector in engine compartment. Place system in Sensor Test Mode "05". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Code 88 should be displayed. If Code 88 is not displayed, ensure diagnostic read-out box is operating properly and that there is no open circuit between SMEC and diagnostic connector. If circuit and diagnostic read-out box are okay, replace SMEC. (Scheme 125): Diagnostic Read-Out Box
6. If code 88 was displayed, divide display reading by 10 for actual TPS voltage reading. If reading is.50-1.5 volts, go to step 7. If reading is greater than 1.5 volts, replace throttle position sensor.
7. With diagnostic read-out box connected, connect voltmeter between Dark Green/Black wire at injector 4-pin connector and ground. (Scheme 126) Turn ignition switch to "RUN" position. Place system in ATM Test Mode "02". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. If voltmeter reading is within one volt of battery voltage, go to next step. If voltmeter reading is zero volt, repair Dark Green/Black wire (open circuit to wiring harness splice). (Scheme 126): Attaching Voltmeter To Injector 4-Pin Connector
8. Remove spark plugs. Check spark plug electrodes for wet fuel. If electrodes are wet, clean and reinstall. Try to restart engine. If spark plug electrodes were dry, connect timing device and crank engine. If timing is 0-16 BTDC, remove distributor cap. Crank engine to be sure rotor is turning and is indexed correctly. Check compression and valve timing.
9. If timing was not 0-16 BTDC, set timing to 10 BTDC during cranking. Engine should start. If engine starts, reset timing to specification. If engine does not start, remove distributor cap. Crank engine to be sure rotor is turning and is indexed correctly. Check compression and valve tiling.

Scheme 127

Scheme 128

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Turn ignition switch to "RUN" position. Press "ATM" button on diagnostic read-out box. If fuel pump is running, check all fuel lines for leaks, restrictions, and/or kinks, and check for plugged fuel filter. If all are okay, remove and check fuel pump. (Scheme 127): Diagnostic Read,Out Box
2. If fuel pump is not running, hoist vehicle. Disconnect in-tank fuel pump connector at fuel pump. Using a voltmeter, connect positive lead to Dark Green/Black wire. Connect negative lead to Gray wire. (Scheme 128) Press "ATM" button on diagnostic read-out box. If voltage reading is within one volt of battery voltage, replace fuel pump. (Scheme 128): In-Tank Fuel Pump Connector & Voltmeter
3. If voltage reading is zero, move negative voltmeter lead to good engine ground point and press "ATM" button. If voltage is now okay, repair Gray wire of connector (open circuit). If voltage is still zero volt, repair Dark Green/Black wire (open circuit).

NS-3 TEST - IGNITION FAULT CODE CHECK

Connect diagnostic read-out box to diagnostic connector. Erase fault codes. See ERASING CODES FROM SMEC MEMORY under TESTING & DIAGNOSIS in this article. Crank engine for 5 seconds and turn ignition off. Place system in Diagnostic Mode. See ENTERING ON-BOARD DIAGNOSTICS under TESTING & DIAGNOSIS in this article. Record all codes. If code 88-12-45 is stored, perform NS-4 TEST - AUTO SHUTDOWN RELAY CHECK . If code 88-12-43-55 is stored, perform NS-5 TEST - SPARK CONTROL CIRCUIT CHECK (CHECK FOR CODE 43) .

Diagnostic Read-Out Box. Scheme 129

Scheme 130

Scheme 131

Scheme 132

1. If code 88-12-55 was displayed in NS3, connect diagnostic read-out box to diagnostic connector. Connect analog voltmeter positive lead to ignition coil positive terminal. (Scheme 130) Attach negative lead to ground. Place system in ATM Test Mode "01". See ENTERING ON-BOARD DIAGNOSTICS under TESTING & DIAGNOSIS in this article. If voltmeter reading is within one volt of battery voltage, go to next step. If reading is zero volt, repair open in Dark Green/Black wire to wiring harness splice. (Scheme 130): Attaching Analog Voltmeter To Ignition Coil Positive
2. If voltage in step 1) was within one volt of battery voltage, move voltmeter positive lead to ignition coil negative terminal. (Scheme 131) If voltage reading is pulsating between 00-14 volts or between 5-10 volts, replace ignition coil. If reading is not pulsating, but is above 10 volts, proceed to next step. If reading is pulsating between 0-2 volts, proceed to step 4). (Scheme 131): Attaching Analog Voltmeter To Ignition Coil Negative
3. If voltage in step 2) war not pulsating but reads above 10 volts, turn ignition switch off. Disconnect 14-pin connector from SMEC. Connect ohmmeter leads between negative terminal of ignition coil and cavity No. 12 of SMEC 14-pin connector. (Scheme 132) If continuity is shown, replace SMEC (defective power board). Ensure terminal is not spread apart before replacing SMEC. If no continuity exists, repair Black/Yellow wire from cavity No. 12 to ignition coil (open circuit). (Scheme 132): Ignition Coil To 14-Pin Connector Terminal No. 12
4. If voltage in step 2) was pulsating between 0-2 volts, leave diagnostic read-out box connected, and turn ignition switch off. Disconnect wire from negative terminal of coil. Connect voltmeter positive lead to coil negative terminal and negative lead to ground. Place system in ATM Test Mode "01". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. If voltage reading is greater than 10 volts, go to next step. If voltage reading is 0-2 volts, replace ignition coil.
5. If voltage reading was above 10 volts in step 4), disconnect negative coil wire. Turn ignition off. Disconnect 14-pin connector from SMEC. Connect an ohmmeter between cavity No. 12 of SMEC 14-pin connector and ground. (Scheme 133) If ohmmeter does not show continuity, replace SMEC. If there is continuity, repair Black/Yellow wire of cavity No. 12 (open circuit).

Attaching Ohmmeter To 14-Pin Connector & Ground. Scheme 133

Scheme 134

1. If code 88,12-43-55 was displayed in NS3, leave diagnostic read-out box connected. Turn ignition off. Disconnect ignition coil wire from distributor and position it near good engine ground with 1/4" gap. Disconnect 60-pin connector from SMEC and connect one end of jumper wire to cavity No. 34. (Scheme 134) Turn ignition switch on. Press and hold "ATM" button on diagnostic read-out box. (Scheme 134): 60-Pin Connector Terminal No. 34 Location
2. Touch other end of jumper wire to a good engine ground. (Scheme 134) Make and break this connection several times. If there is a spark at the coil wire each time connection is broken, replace SMEC. Ensure terminal No. 34 of SMEC connector is not spread apart before replacing SMEC.
3. If no spark occurred in step 2), turn ignition off. Remove jumper wire from cavity No. 34. Disconnect SMEC 14,pin connector. Connect ohmmeter leads between cavity No. 34 of 60-pin connector and cavity No. 13 of 14-pin connector. (Scheme 135) If continuity is shown on ohmmeter, replace SMEC. Ensure terminal No. 13 of 14-pin connector is not spread apart, causing a poor connection, before replacing SMEC. If there is no continuity, repair open circuit in wire.

Attaching Ohmmeter Between Terminals No. 34 & 13. Scheme 135

NS-6 TEST - FUEL INJECTOR SYSTEM (CHECK FOR CODES 26 & 27)

Connect diagnostic read-out box to diagnostic connector. Erase fault codes. See ERASING CODES FROM SMEC MEMORY under TESTING & DIAGNOSIS in this article. Crank engine for 5 seconds and turn ignition off (in some instances, engine may start and run for a few seconds and then stall). Place system in Diagnostic Mode. See ENTERING ON-BOARD DIAGNOSTICS under TESTING & DIAGNOSIS in this article. Record codes. If codes 88-12-26-55 are stored, perform NS-7 TEST - FUEL INJECTOR SYSTEM (CODE 26) . If codes 88-12-27-55 are stored, perform NS-11 TEST - DISTRIBUTOR REFERENCE CIRCUIT CHECK (CODE 11) .

Diagnostic Read-Out Box. Scheme 136

Scheme 137

Scheme 138

Scheme 139

Scheme 140

Scheme 141

Scheme 142

Scheme 143

Scheme 144

Scheme 145

Scheme 146

Scheme 147

1. If codes 88-12-26-55 were displayed in NS6, leave diagnostic read-out box connected to diagnostic connector. Remove air intake plenum. Release fuel system pressure: Disconnect electrical connectors from all injectors. Place system in ATM Test Mode "02". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Connect negative lead of voltmeter to ground. Touch positive lead of voltmeter to Dark Green/Black wire of each injector connector.
2. If voltmeter reading is within one volt of battery voltage at each connector, go to next step. If voltmeter reading is zero volt at one or more connectors, repair open circuit in injector harness.
3. If voltmeter reading in step 2) was within one volt of battery voltage, leave equipment connected as in step 1). Connect No. 1 injector electrical connector. Leave connector connected for 10 seconds and listen for clicking sound. If injector clicks, go to step 9). If injector does not click, go to next step. Before proceeding to next step, make sure ATM Test Mode "02" did not time out.
4. Disconnect electrical connector from injector No. 1. Connect No. 6 injector electrical connector. Leave connector connected for 10 seconds and listen for clicking sound. If injector clicks, go to step 8). If injector does not click, go to next step.
5. Disconnect electrical connector from injector No. 6. Connect electrical connector of No. 2 injector to No. 1 injector. Leave connected for 10 seconds and listen for clicking sound. Disconnect injector No. 2 connector from injector No. 1 and connect No. 4 injector electrical connector to injector No. 6. Leave connected for 10 seconds and listen for clicking sound. If injector No. 1 and No. 6 do not click, replace injector No. 1 and No. 6. If one injector clicks and the other does not click, replace only the injector that did not click. If both injectors clicked, go to next step.
6. Turn ignition off. Disconnect 14-pin connector from SMEC. Connect an ohmmeter between cavity No. 5 and ground. (Scheme 137) If continuity is shown on ohmmeter, repair Yellow/White wire in cavity No. 5 of 14-pin connector (short to ground). If continuity is not shown, go to next step. (Scheme 137): 14-Pin Connector Terminal No. 5 To Ground
7. With ignition off and 14-pin connector disconnected from SMEC, connect ohmmeter between terminal No. 5 of 14-pin connector and Yellow/White wire of electrical connector for injector No. 1, and then No. 6. (Scheme 138) If continuity is shown on ohmmeter, replace SMEC (defective power board). Ensure terminal No. 5 of 14-pin connector is not spread apart, causing a poor connection, before replacing SMEC. If continuity is not shown, repair Yellow/White wire in cavity No. 5 of 14-pin connector (open circuit). (Scheme 138): Nos. 1 & 6 Injector Connector To Terminal No. 5
8. Turn ignition off and disconnect electrical connector from injector No. 6. Disconnect 4-pin injector harness connector at engine harness connector. Connect an ohmmeter between Yellow/White wire at injector No. 1 connector and same wire at 4-pin connector. (Scheme 139) If continuity is shown on ohmmeter, replace injector No. 1. If continuity is not shown, repair Yellow/White wire (open circuit). (Scheme 139): No. 1 Injector Connector To Injector Harness 4-Pin Connector
9. Ensure diagnostic read-out box is still connected to diagnostic connector, air intake plenum is removed, all electrical connectors are disconnected from injectors except No. 1, and system is in ATM Test Mode "02". Disconnect electrical connector from injector No. 1. Connect electrical connector of injector No. 6 to injector No. 6. Leave connected for 10 seconds and listen for clicking sound. If injector No. 6 clicks, go to step 11). If injector does not click, go to next step.
10. Turn ignition off. Disconnect electrical connector from injector No. 6. Disconnect 4-pin injector harness connector at engine harness connector. Connect an ohmmeter between Yellow/White wire at injector No. 6 connector and same wire at 4-pin connector. (Scheme 140) If continuity is shown on ohmmeter, replace injector No. 6. If continuity is not shown, repair Yellow/White wire (open circuit). (Scheme 140): No. 6 Injector Connector To Injector Harness 4-Pin Connector
11. Disconnect electrical connector from injector No. 6. Connect electrical connector of injector No. 2 to injector No. 2. Leave connected for 10 seconds and listen for clicking sound. If injector clicks, go to step 17). If injector does not click, go to next step. Before proceeding to next step, make sure ATM Test Mode "02" did not time out.
12. Disconnect electrical connector from injector No. 2. Connect electrical connector of injector No. 3 to injector No. 3. Leave connected for 10 seconds and listen for clicking sound. If injector clicks, go to step 16). If injector does not click, go to next step.
13. Disconnect electrical connector from injector No. 3. Connect electrical connector of No. 1 injector to No. 2 injector. Leave connected for 10 seconds and listen for clicking sound. Disconnect injector No. 1 connector from injector No. 2 and connect No. 1 injector electrical connector to injector No. 3. Leave connected for 10 seconds and listen for clicking sound. If injector No. 2 and No. 3 do not click, replace injector No. 2 and No. 3. If one injector clicks and the other does not click, replace only the injector that did not click. If both injectors clicked, go to next step.
14. Turn ignition off. Disconnect 14-pin connector from SMEC. Connect an ohmmeter between terminal No. 10 of 14-pin connector and ground. (Scheme 141) If continuity is shown on ohmmeter, repair Tan wire in terminal No. 10 of 14-pin connector (short to ground). If continuity is not shown, go to next step. (Scheme 141): 14-Pin Connector Terminal No. 10 To Ground
15. With ignition off and 14-pin connector disconnected from SMEC, connect ohmmeter between cavity No. 10 of 14-pin connector and Tan wire of electrical connector for injector No. 2, and then No. 3. (Scheme 142) If continuity is shown on ohmmeter, replace SMEC (defective power board). Ensure terminal No. 10 of 14-pin connector is not spread apart, causing a poor connection, before replacing SMEC. If continuity is not shown, repair Tan wire in cavity No. 10 of 14-pin connector (open circuit). (Scheme 142): No. 2 & 3 Injector Connector To 14-Pin Connector
16. Turn ignition off and disconnect electrical connector from injector No. 3. Disconnect 4-pin injector harness connector at engine harness connector. Connect an ohmmeter between Tan wire at injector No. 2 connector and same wire at 4-pin connector. (Scheme 143) If continuity is shown on ohmmeter, replace injector No. 2. If continuity is not shown, repair Tan wire (open circuit). (Scheme 143): No. 2 Injector Connector To Injector Harness 4-Pin Connector
17. Ensure diagnostic read-out box is still connected to diagnostic connector, air intake plenum is removed, all electrical connectors are disconnected from injectors except No. 2, and system is in ATM Test Mode "02". Disconnect electrical connector from injector No. 2. Connect electrical connector of injector No. 3 to injector No. 3. Leave connected for 10 seconds and listen for clicking sound. If injector No. 3 clicks, go to step 19). If injector does not click, go to next step.
18. Turn ignition off. Disconnect electrical connector from injector No. 3. Disconnect 4-pin injector harness connector at engine harness connector. Connect an ohmmeter between Tan wire at injector No. 3 connector and same wire at 4-pin connector. (Scheme 144) If continuity is shown on ohmmeter, replace injector No. 3. If continuity is not shown, repair Tan wire (open circuit). (Scheme 144): No. 3 Injector Connector To Injector Harness 4-Pin Connector
19. Disconnect electrical connector from injector No. 3. Connect electrical connector of injector No. 4 to injector No. 4. Leave connected for 10 seconds and listen for clicking sound. If injector clicks, go to step 25). If injector does not click, go to next step. Before proceeding to next step, make sure ATM Test Mode "02" did not time out.
20. Disconnect electrical connector from injector No. 4. Connect electrical connector of injector No. 5 to injector No. 5. Leave connected for 10 seconds and listen for clicking sound. If injector clicks, go to step 24). If injector does not click, go to next step.
21. Disconnect electrical connector from injector No. 5. Connect electrical connector of No. 6 injector to No. 4 injector. Leave connected for 10 seconds and listen for clicking sound. Disconnect injector No. 6 connector from injector No. 4 and connect No. 6 injector electrical connector to injector No. 5. Leave connected for 10 seconds and listen for clicking sound. If injector No. 4 and No. 5 do not click, replace injector No. 4 and No. 5. If one injector clicks and the other does not click, replace only the injector that did not click. If both injectors clicked, go to next step.
22. Turn ignition off. Disconnect 14-pin connector from SMEC. Connect an ohmmeter between cavity No. 9 and ground. (Scheme 145) If continuity is shown on ohmmeter, repair White wire in cavity No. 9 of 14-pin connector (short to ground). If continuity is not shown, go to next step. (Scheme 145): 14-Pin Connector Terminal No. 9 To Ground
23. Turn ignition off. Disconnect 14-pin connector from SMEC. Connect ohmmeter between cavity No. 9 of 14-pin connector and White wire of electrical connector for injector No. 4, and then No. 5. (Scheme 146) If continuity is shown on ohmmeter, replace SMEC (defective power board). Ensure terminal No. 9 of 14-pin connector is not spread apart, causing a poor connection, before replacing SMEC. If continuity is not shown, repair White wire in cavity No. 9 of 14-pin connector (open circuit). (Scheme 146): No. 4 & 5 Injector Connector To 14-Pin Connector
24. Turn ignition off and disconnect electrical connector from injector No. 5. Disconnect 4-pin injector harness connector at engine harness connector. Connect an ohmmeter between White wire at injector No. 4 connector and same wire at 4-pin connector. (Scheme 147) If continuity is shown on ohmmeter, replace injector No. 4. If continuity is not shown, repair White wire (open circuit). (Scheme 147): No. 4 Injector Connector To Injector Harness 4-Pin Connector
25. Turn ignition off. Disconnect electrical connector from injector No. 4. Disconnect 4-pin injector harness connector at engine harness connector. Connect an ohmmeter between White wire at injector No. 5 connector and same wire at 4-pin connector. (Scheme 148) If continuity is shown on ohmmeter, replace injector No. 5. If continuity is not shown, repair White wire (open circuit).

No. 5 Injector Connector To Injector Harness 4-Pin Connector. Scheme 148

Scheme 149

Scheme 150

Scheme 151

1. If codes 88-12-27-55 were displayed in NS6, leave diagnostic read-out box connected to diagnostic connector. Turn ignition off and disconnect 60-pin connector from SMEC. Connect one end of jumper wire to terminal No. 33 of 60-pin connector. (Scheme 149) Turn ignition on. Press "ATM" button on diagnostic read-out box, and touch other end of jumper wire to battery positive post. If injector No. 4 and No. 5 click, go to step 3). If injector No. 4 and No. 5 do not click, go to next step. (Scheme 149): 60-Pin Connector Terminal No. 33
2. With 60-pin connector disconnected, turn ignition off. Disconnect 14-pin connector from SMEC. Connect an ohmmeter between cavity No. 33 of 60-pin connector and cavity No. 8 of 14-pin connector. (Scheme 150) If continuity is shown on ohmmeter, replace SMEC (defective power board). Ensure terminal No. 8 of 14-pin connector is not spread apart, causing a poor connection, before replacing SMEC. If no continuity is shown on ohmmeter, repair Violet/Yellow wire between 14-pin and 60-pin connectors (open circuit). (Scheme 150): 60-Pin Terminal No. 33 To 14-Pin Terminal No. 8
3. Remove SMEC from vehicle and remove cover. Disconnect 2-pin connector located between logic board and power board. Connect 14-pin connector to power board. Connect one end of jumper wire to male terminal of 2-pin connector of power board. (Scheme 151) Turn ignition on. Press "ATM" button on diagnostic read-out box and touch other end of jumper wire to battery positive post. If injector No. 2 and No. 3 click, go to next step. If injector No. 2 and No. 3 do not click, replace SMEC (defective power board). (Scheme 151): SMEC Power Board Internal Connector Male Terminal
4. Move jumper wire to female terminal of 2-pin connector of power board. (Scheme 152) Press and hold "ATM" button on diagnostic read-out box and touch other end of jumper wire to battery positive post. If injector No. 1 and No. 6 click, replace SMEC (defective logic board). If injector No. 1 and No. 6 do not click, replace SMEC (defective power board).

SMEC Power Board Internal Connector Female Terminal. Scheme 152

NS-9 TEST - CHECKING SYSTEM FOR CODE

1. Connect diagnostic read-out box to diagnostic connector. Erase fault codes. See «ERASING CODES FROM SMEC MEMORY»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__erasing-codes-from-smec-memory) under TESTING & DIAGNOSIS in this article. Crank engine for 7 seconds. Turn ignition switch to "RUN" position for 5 seconds prior to turning ignition off. Place system in Diagnostic Mode. See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Record all codes.
2. If codes 88-11-12-55 are stored, perform «NS-11 TEST - DISTRIBUTOR REFERENCE CIRCUIT CHECK (CODE 11)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) . If codes 88-42-55 are stored, perform «NS-12 TEST - CHECKING AUTO SHUTDOWN RELAY (CODE 42)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) . If codes 88-12-14-22-24-55 or 88-12-14-22-23-24-55 are stored, repair wire in cavity No. 4 of SMEC 60-pin connector (open circuit). If there is no code 88 or 00 displayed, perform «NS-10 TEST - SYSTEM POWER CIRCUIT CHECKS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) .

Diagnostic Read-Out Box. Scheme 153

Scheme 154

Scheme 155

Scheme 156

Scheme 157

Scheme 158

1. Turn ignition off. Disconnect throttle position sensor connector. Turn ignition on. Connect voltmeter between Violet/White wire at throttle position sensor (TPS) connector and ground. (Scheme 154) If voltmeter reading is at least 4.5 volts. Go to next step. If zero volt is indicated, proceed to step 3). (Scheme 154): Attaching Voltmeter To TPS Connector & Ground
2. If voltage was at least 4.5 volts in step 1), disconnect 60-pin connector from SMEC. Connect negative ohmmeter lead to system ground eyelet. Touch positive ohmmeter lead to terminal No. 15, and then terminal No. 16 of 60-pin connector. (Scheme 155) If ohmmeter shows continuity with less than.5 ohm resistance in both circuits, replace SMEC (defective logic board). If there is no continuity, repair wiring to cavity No. 15 and/or No. 16 (open circuit). If wiring is okay, replace SMEC. If ohmmeter is showing more than.5 ohm resistance at one or both cavities, repair ground circuit (high resistance to system ground eyelet). (Scheme 155): 60-Pin Terminal Nos. 15 & 16 To Ground
3. Disconnect MAP sensor connector. Connect voltmeter between ground and Violet/White wire at throttle position sensor connector. If voltmeter reading is at least 4.5 volts, replace MAP sensor. If zero volt is indicated, proceed to next step.
4. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect negative voltmeter lead to ground. Turn ignition on. Touch positive voltmeter lead to terminal No. 52 of 60-pin connector. (Scheme 156) If voltmeter reading is at least 8 volts, replace SMEC (defective logic board). Ensure terminal No. 52 of 60-pin connector is not spread apart, causing a poor connection, before replacing SMEC. If voltmeter reads zero volt, go to next step. (Scheme 156): 60-Pin Terminal No. 52 To Ground
5. Disconnect distributor pick-up harness connector. Touch positive voltmeter lead to cavity No. 52 of 60-pin connector. If voltmeter reading is at least 8 volts, replace distributor pick-up. If voltmeter reads zero volt, go to next step.
6. Turn ignition off. Using an ohmmeter, touch one lead to cavity No. 52 of 60-pin connector and touch other lead to Orange wire terminal of distributor harness connector. (Scheme 157) If ohmmeter shows continuity, go to next step. If ohmmeter does not show continuity, repair Orange wire at cavity No. 52 of 60-pin connector (open circuit). (Scheme 157): 60-Pin Terminal No. 52 To Distributor Connector
7. With ignition off, disconnect 14-pin connector from SMEC. Connect negative voltmeter lead to ground. Turn ignition on. Touch positive voltmeter lead to Terminal No. 4 of 14-pin connector. (Scheme 158) If voltmeter reading is within one volt of battery voltage, go to next step. If voltmeter reading is not within one volt of battery voltage, repair Blue wire at cavity No. 4 of 14-pin connector (open circuit). (Scheme 158): 14-Pin Terminal No. 4 To Ground
8. Turn ignition off. Connect negative ohmmeter lead to system ground eyelet. Connect positive ohmmeter lead to Terminal No. 6 and then No. 7 of 14-pin connector. (Scheme 159) If ohmmeter shows continuity with less than.5 ohm resistance in both circuits, replace SMEC (defective logic board). If there is no continuity, repair wiring to cavity No. 6 and/or No. 7 (open circuit). If wiring is okay, replace SMEC. If ohmmeter is showing more than.5 ohm resistance at one or both cavities, repair ground circuit (high resistance to system ground eyelet).

Ground To 14-Pin Terminal Nos. 6 & 7. Scheme 159

Scheme 160

Scheme 161

Scheme 162

1. Turn ignition off. Disconnect distributor pick-up coil connector. Remove coil wire from distributor and place it near good engine ground with 1/4" gap. Turn ignition switch to "RUN" position. Connect jumper wire between Gray wire and Black/Light Blue wire of distributor harness connector. (Scheme 160) Make and break this connection several times while watching for sparks at coil wire. If there is spark at the coil wire, go to next step. If there is not spark at coil wire, go to step 4). (Scheme 160): Distributor Harness Connector Jumper Wire Installation
2. Connect voltmeter between Orange wire of distributor harness connector and good ground. (Scheme 161) If voltmeter reading is at least 7 volts, go to next step. If voltmeter reading is zero volt, repair Orange wire of distributor harness connector (open circuit). (Scheme 161): Distributor Harness Connector (Orange Wire) To Ground
3. Turn ignition off. Remove distributor cap and crank engine while watching rotor. If rotor turns as engine cranks, replace distributor pick-up coil. Ensure terminals of distributor harness connector are not spread apart, causing a poor connection, before replacing pick-up coil. If rotor does not turn as engine is cranked, repair as required.
4. With ignition switch in "RUN" position, distributor pick-up connector disconnected, and coil wire placed near good engine ground, connect jumper wire between Gray wire of distributor harness connector and good engine ground. If there is spark at coil wire, repair Black/Light Blue wire of distributor harness connector (open circuit). If there is no spark at coil wire, go to next step. (Scheme 162): Distributor Harness Connector (Grey Wire) To Ground
5. Disconnect 60-pin connector from SMEC. Connect ohmmeter between terminal No. 47 of 60-pin connector and Gray wire of distributor harness connector. (Scheme 163) If ohmmeter registers continuity, replace SMEC (defective logic board). Ensure terminals of cavity No. 47 in connector are not spread apart, causing a poor connection, before replacing SMEC. If ohmmeter does not register continuity, repair Gray wire in cavity No. 47 in 60-pin connector (open circuit).

60-Pin Terminal No. 47 To Grey Distributor Wire. Scheme 163

Scheme 164

Scheme 165

Scheme 166

Scheme 167

Scheme 168

1. Connect diagnostic read-out box to diagnostic connector. Connect voltmeter to Dark Blue/Yellow wire of ASD relay 3-pin connector and ground. (Scheme 164) Place system in ATM Test Mode "06". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. (Diagnostic read-out box may go directly from indication code 55 to ATM Test "01" and continue to cycle through all ATM tests without depressing "ATM" button.) If voltmeter pulsates between 0-12 volts while system is in ATM Test Mode "06", go to next step. If voltmeter reading is within one volt of battery voltage and system cannot be placed in ATM Test Mode "06", go to step 6). If voltmeter reading is steady zero to one volt and system cannot be place in ATM Test Mode "06", go to step 4). (Scheme 164): Attaching Voltmeter To Dark Blue/Yellow Wire & Ground
2. Connect voltmeter between Red wire in ASD relay 3-pin connector and ground. (Scheme 165) If voltmeter reading is within one volt of battery voltage, go to next step. If voltmeter reading is zero volt, repair Red wire in 3-pin connector (open circuit). (Scheme 165): Attaching Voltmeter To Red Wire & Ground
3. Turn ignition off. Connect one end of jumper wire to Dark Green/Black wire in ASD relay 3-pin connector. Touch other end of jumper wire to Red wire in ASD relay 3-pin connector. (Scheme 166) If fuel pump runs, replace ASD relay. If fuel pump does not run, repair Dark Green/Black wire of 3-pin connector. (Scheme 166): Installing Jumper Wire To ASD Relay Connector
4. Connect negative lead of a voltmeter to ground. Turn ignition off. Disconnect single wire connector from ASD relay. Connect positive voltmeter lead to Dark Blue/White wire of ASD relay single connector. (Scheme 167) Turn ignition on. If voltmeter reading is within one volt of battery voltage, replace ASD relay. If voltmeter reading is zero volt, go to next step. (Scheme 167): ASD Single Connector To Ground
5. Turn ignition off. Disconnect 14-pin connector from SMEC. Connect ohmmeter between cavity No. 3 of 14-pin connector and Dark Blue/White wire of ASD relay single wire connector. (Scheme 168) If ohmmeter does not show continuity, repair Dark Blue/White wire at cavity No. 3 of 14-pin connector (open circuit). If ohmmeter does show continuity, replace SMEC (defective power board). Ensure terminals of cavity No. 3 are not spread apart, causing a poor connection, before replacing SMEC. (Scheme 168): ASD Relay Connector To 14-Pin Terminal No. 3
6. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 58 of 60-pin connector and ground. (Scheme 169) Turn ignition on. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminals of cavity No. 58 are not spread apart, causing a poor connection, before replacing SMEC. If voltmeter reading is zero volt, repair Dark Blue/Yellow wire at cavity No. 58 (open circuit).

60-Pin Terminal No. 58 To Ground. Scheme 169

DRIVEABILITY TROUBLE CODE-TO-TEST MENU

DR TROUBLE CODE-TO-TEST MENU

Scheme 170

Scheme 171

Scheme 172

Scheme 173

Scheme 174

Scheme 175

Scheme 176

Scheme 177

Scheme 178

Scheme 179

1. Connect diagnostic read-nut box to diagnostic connector. Turn ignition on-off-on-off-on within 5 seconds. Record all trouble codes. If codes 15-17-21-33-51-52 are displayed, proceed to appropriate test. Refer to «DR TROUBLE CODE-TO-TEST MENU»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). (Scheme 170): Diagnostic Read-Out Box
2. Turn ignition off. Erase fault codes. See «ERASING CODES FROM SMEC MEMORY»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__erasing-codes-from-smec-memory) under TESTING & DIAGNOSIS in this article. Without depressing accelerator, start engine. Let engine run for 5 minutes. Raise engine speed to 2000 RPM for 10 seconds and then return to idle. Cycle transaxle gear selector (auto. trans.). Turn A/C on and off (if equipped). Stop engine.
3. Turn ignition on-off-on-off-on within 5 seconds. Record all codes. If same code appears before and after codes were cleared, the problem still exists. Proceed to the appropriate test. Refer to «DR TROUBLE CODE-TO-TEST MENU»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If a code does not reappear after engine is started, problem no longer exists, but was intermittent. Using wiring diagram as a guide, check for loose or corroded wiring connections in the circuit. Go to step 28).
4. All codes will open by displaying codes 88 then 12. These will be followed by the indicated trouble code. Diagnosis will end with code 55. Only indicated codes will be used in majority of the driveability tests.
5. If code 88-12-55 is displayed (no fault codes stored), go to step 5). If codes 88-12-13-55, 88-12-14-55, 88-12-13-14-55 are displayed (MAP sensor problem), go to «DR-2 TEST - MAP SENSOR CKT (CODES 13 AND/OR 14)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If code 88-12-15-55 is displayed (speed sensor problem), go to «DR-3 TEST - SPEED SENSOR CIRCUIT (CODE 15)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system).
6. If code 88-12-17-55 is displayed (engine running too cool), check engine cooling system for a possible bad thermostat.
7. If code 88-12-21-55 is displayed (oxygen sensor problem), go to «DR-4 TEST - OXYGEN SENSOR CIRCUIT (CODE 21)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If codes 88-12-22-55 or 88-12-17-22-55 are displayed (engine coolant sensor problem), go to «DR-5 TEST - COOLANT TEMPERATURE SENSOR CIRCUIT (CODE 22)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If code 88-12-23-55 is displayed (charge temperature sensor problem), go to «DR-6 TEST - CHARGE TEMPERATURE SENSOR (CODE 23)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system).
8. If code 88-12-24-55 is displayed (throttle position sensor problem), go to «DR-7 TEST - THROTTLE POSITION SENSOR (TPS) CIRCUIT (CODE 24)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If code 88-12-25-55 is displayed (AIS motor problem), go to «DR-8 TEST - AUTOMATIC IDLE SPEED CKT (CODE 25)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If code 88-12-31-55 is displayed (canister purge solenoid problem), go to «DR-9 TEST - CANISTER PURGE SOLENOID CIRCUIT (CODE 31)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system).
9. On A/C equipped vehicles, if code 88-12-33-55 is displayed (A/C cut-out relay problem), place system in ATM Test Mode "05". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. (Code 33 will be displayed if A/C condenser fan does not turn on when A/C button is pressed. DO NOT proceed with test unless fan turns on.) Place A/C button in "ON" position. If A/C cut-out relay is clicking, disregard code 33. If relay is not clicking, go to «DR-10 TEST - A/C CUT-OUT RELAY CIRCUIT (CODE 33)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system).
10. If code 88-12-35-55 is displayed (cooling fan relay problem), go to «DR-11 TEST - COOLING FAN RELAY CIRCUIT (CODE 35)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If code 88-12-37-55 is displayed (transaxle lock-up solenoid problem), go to «DR-12 TEST - LOCK-UP TORQUE CONVERTER SOLENOID CKT (CODE 37)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system).
11. If code 88-12-42-55 is displayed (auto shutdown relay problem), repair Dark Green/Black wire in cavity No. 10 of SMEC 60-pin connector (open circuit).
12. If code 88-12-44-55 is displayed (fused "J2" problem), go to «DR-13 TEST - FUSED "J2" CIRCUIT TO SMEC (CODE 44)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__dr-13-test-fused-j2-circuit). If codes 88-12-51-55 or 88-12-52-55 are displayed (oxygen feedback system locked at lean or rich indication), go to «DR-16 TEST - WARM ENGINE SENSOR CALIBRATION CHECK»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__dr-16-test-warm-engine-sensor).
13. If code 88-12-53-55 is displayed (SMEC problem), replace SMEC. If code 88-12-54-55 is displayed (distributor synchronization pick-up circuit problem), go to «DR-14 TEST - DISTRIBUTOR SYNCHRONIZATION PICK-UP (CODE 54)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system).
14. With diagnostic read-out box connected to diagnostic connector, enter ATM Test Mode "04". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. If cooling fan is not turning on and off, check if fan relay is clicking. If relay is not clicking, replace relay. If relay is clicking, repair wiring to cooling fan motor.
15. If cooling fan turned on and off every 2 seconds in step 14), press and hold "ATM" button until Test Mode "05" (A/C equipped) or Test Mode "07" (non-A/C equipped) is displayed. With system in Test Mode "05", A/C cut-out relay should be clicking every 2 seconds. Press A/C button on. (A/C compressor clutch will also cycle every 2 seconds and A/C condenser fan will run continuously.) If A/C cut-out relay is not clicking, replace relay. If relay is clicking, press and hold "ATM" button until Test Mode "07" is displayed.
16. With Test Mode "07" displayed, canister purge solenoid should be clicking. If canister purge solenoid is not clicking, replace solenoid. If canister purge solenoid is clicking, press and hold "ATM" button until Test Mode "10" is displayed.
17. With system in Test Mode "10", transaxle lock-up solenoid should be clicking. If lock-up solenoid is not clicking, replace solenoid. If solenoid is clicking, place system in Switch Test Mode. See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Press down brake pedal, move gear selector from Park to Reverse, and press A/C button (if equipped). If diagnostic read-out box display changes (does not matter what it changes to, just ensure display changes), go to step 22). If display does not change when brake switch is activated, go to next step for vehicles without cruise control, or step 19) on vehicles with cruise control. If display does not change when gear selector is moved from Park to Reverse, go to step 20). If display does not change when A/C button is activated (if equipped), go to step 21).
18. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 29 of 60-pin connector and ground. (Scheme 171) Turn ignition to "RUN" position. Press down on brake pedal. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal No. 29 of 60-pin connector is not spread apart before replacing SMEC. If voltmeter reading is zero volt, check wire at cavity No. 29 for open circuit to brake switch, check for bad brake switch, and/or check voltage supply circuit to brake switch. (Scheme 171): 60-Pin Terminal No. 29 To Ground (Voltmeter)
19. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect an ohmmeter between cavity No. 29 of 60-pin connector and ground. (Scheme 172) Press down on brake pedal and then release. If ohmmeter shows no continuity when pedal is depressed and continuity when released, replace SMEC. Ensure terminal No. 29 of 60-pin connector is not spread apart before replacing SMEC. If ohmmeter does not read as indicated, check wire at cavity No. 29 for open circuit to brake switch, check for bad brake switch, and/or check for open circuit to taillights. (Scheme 172): 60-Pin Terminal No. 29 To Ground (Ohmmeter)
20. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect an ohmmeter between cavity No. 30 of 60-pin connector and ground. (Scheme 173) Disconnect battery quick disconnect. Turn ignition to "RUN" position. Place gear selector in Park, Reverse, Neutral, and Drive and observe ohmmeter display in each position. If ohmmeter shows continuity in all gear positions, check wire at cavity No. 30 for short to ground and check for bad neutral safety switch. If ohmmeter shows no continuity in all gear positions, repair wire at cavity No. 30 (open circuit to neutral safety switch). If ohmmeter reads continuity in Park and Neutral and no continuity in Reverse and Drive (disregard resistance value, ensure there is continuity), replace SMEC. Ensure terminal No. 30 of 60-pin connector is not spread apart before replacing SMEC. (Scheme 173): 60-Pin Terminal No. 30 To Ground (Ohmmeter)
21. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 45 of 60-pin connector and ground. (Scheme 174) Turn ignition to "RUN" position, press A/C button "ON" and then "OFF". If voltmeter reading is zero to one volt when A/C button is "ON" and within one volt of battery voltage when A/C button is "OFF", replace SMEC. Ensure terminal No. 45 of 60-pin connector is not spread apart before replacing SMEC. If voltmeter does not display as indicated, repair wire at cavity No. 45 (open or short to wiring harness splice). (Scheme 174): 60-Pin Terminal No. 45 To Ground (Voltmeter)
22. With diagnostic read-out box connected to diagnostic connector, place "READ/HOLD" button in "READ" position. Connect tachometer to engine. Start engine. Disconnect coolant sensor electrical connector. Move "READ/HOLD" button to "HOLD" position. If engine speed increases to about 1500 RPM, go to step 26). If engine speed does not increase, go to next step.
23. With diagnostic read-out box connected to diagnostic connector, turn ignition off. Disconnect Automatic Idle Speed (AIS) motor electrical connector. Connect a digital voltmeter between terminal Nos. 1 and 4 of AIS connector. (Scheme 175) Set voltmeter to "A/C VOLTAGE" position. Place system in ATM Test Mode "03". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. If voltmeter pulsates between zero and 12 volts every 2 seconds, go to next step. If voltmeter does not pulsate, go to step 25). (Scheme 175): AIS Motor Connector Terminal Nos. 1 To 4
24. Move digital voltmeter connectors between terminal No. 2 and No. 3 of AIS connector. (Scheme 176) If voltmeter pulsates between zero and 12 volts every 2 seconds, replace AIS motor. Check terminals in connector for damage and proper connection before replacing AIS motor. If voltmeter does not pulsate, go to step 26). (Scheme 176): AIS Motor Connector Terminal Nos. 2 To 3
25. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect ohmmeter between cavity No. 19 and No. 20 of 60-pin connector. (Scheme 177) If ohmmeter displays continuity, repair wire in cavity No. 19 or No. 20 (open circuit to AIS motor connector). If ohmmeter displays continuity, replace SMEC. Ensure terminal No. 19 and No. 20 of 60-pin connector are not spread apart before replacing SMEC. (Scheme 177): 60-Pin Terminal Nos. 19 To 20
26. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect ohmmeter between cavity No. 17 and No. 18 of 60-pin connector. (Scheme 178) If ohmmeter is not showing continuity, repair wire in cavity No. 17 or No. 18 (open circuit to AIS motor connector). If ohmmeter displays continuity, replace SMEC. Ensure terminal No. 17 and No. 18 of 60-pin connector are not spread apart before replacing SMEC. (Scheme 178): 60-Pin Terminal Nos. 17 To 18
27. Turn ignition off. Disconnect 14-pin and 60-pin connectors from SMEC. Connect negative lead of digital ohmmeter to system ground eyelet on cylinder head. Connect positive lead to cavity No. 2, No. 6, and No. 7 of 14-pin connector and to cavity No. 5, No. 15, and No. 16 of 60-pin connector. (Scheme 179) If ohmmeter reading shows continuity with less than.50 ohm resistance at all cavities, perform «DR-15 TEST - COLD ENGINE SENSOR CALIBRATION CHECK»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__dr-15-test-cold-engine-sensor) if coldm problem, or «DR-16 TEST - WARM ENGINE SENSOR CALIBRATION CHECK»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__dr-16-test-warm-engine-sensor) if warm problem. If ohmmeter does not show continuity at one or more cavities, repair affected wire (open circuit to wiring harness connector). If ohmmeter reading shows more than.50 ohm resistance at one or more cavities, repair affected wire (high resistance to system ground eyelet). (Scheme 179): 60-Pin & 14-Pin Identification
28. The majority of intermittent failures are caused by wiring and connections. The only way to find them is to try to duplicate the problem. Since the SMEC can remember where they are, the ATM and Sensor Test Modes can be used in an attempt to locate them.
29. If a fault code does not reappear in the PRELIMINARY DR1 after the engine is started, use the following procedures to try to locate the intermittent problem. If the following fault codes do not reappear, match the ATM Test Mode to the code first indicated using the following chart: FAULT CODE-TO-ATM TEST MODE MENU Fault Code ATM Test Mode 25 03 26 02 27 02 31 07 35 04 37 10 42 06 43 01
30. Once in the correct test mode, wiggle all the connectors and wires in the circuit. When bad connection or wire is located, the ATM test will be interrupted. If the following fault codes do not reappear, match the Sensor Test Mode to the code first indicated using the following chart. Then go to step 31). SENSOR TEST NO. MODE CHART Fault Code Sensor Test Mode 14 (1) 08 22 04 23 03 24 05 (1) When checking MAP sensor circuit, apply 10 in. Hg vacuum to the MAP sensor before testing.
31. Once in the correct test mode, wiggle all the connectors and wires in the circuit. When bad connection or wire is located, diagnostic read-out box display will change.

Scheme 180

Scheme 181

Scheme 182

Scheme 183

1. Turn ignition off. Tee a vacuum gauge into vacuum line at MAP sensor. (Scheme 180) Start engine and observe gaffe with engine idling. Observe gauge while snapping throttle open and closed. If gauge reads manifold vacuum with engine idling, and immediately drops to zero when throttle is snapped open and closed, go to next step. If vacuum is zero at idle, repair vacuum supply line to throttle body. If vacuum drops slowly to zero when throttle is snapped open and closed, repair restriction in vacuum supply line to MAP sensor. (Scheme 180): Installing Vacuum Gauge to Vacuum Line at MAP Sensor
2. Stop engine and turn ignition off. Connect diagnostic read-out box to diagnostic connector in engine compartment. Disconnect MAP sensor connector. (Scheme 181) Place system in Sensor Test Mode "08". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Divide diagnostic read-out box display by 10 to get actual voltage. If diagnostic read-out box display is 4 volts, go to next step. If diagnostic read-out box display is zero volt, replace SMEC. Check wire in cavity No. 1 of 60-pin connector for short to ground before replacing SMEC. (Scheme 181): Disconnecting MAP Sensor Connector
3. Connect a jumper wire between Dark Green/Red wire and Black/Light Blue wire of MAP sensor harness connector. (Scheme 182) If diagnostic read-out box display is zero volt, proceed to step 5). If diagnostic read-out box display is not zero volt, go to next step. (Scheme 182): Connecting Jumper Wire To MAP Sensor Harness Connector
4. Connect one end of jumper wire to negative battery terminal. Connect other end of jumper wire to Dark Green/Red wire in MAP sensor harness connector. (Scheme 183) If diagnostic read-out box display is zero volt, repair Black/Light Blue wire in MAP sensor connector (open circuit to wiring harness splice). If diagnostic read-out box display is 5 volts, repair Dark Green/Red wire in MAP sensor harness connector (open circuit to SMEC). (Scheme 183): Battery & MAP Sensor Harness Connector Test
5. Connect a digital voltmeter to Violet/White wire of MAP sensor harness connector (Scheme 184) If voltmeter reading is at least 4 volts, check MAP sensor harness connector terminals to ensure they are not damaged, causing a poor connection. If terminals are okay, replace MAP sensor. If voltmeter reading is zero volt, repair Violet/White wire (open circuit to wiring harness splice).

Attaching Digital Voltmeter To MAP Sensor Harness Connector. Scheme 184

Scheme 185

Scheme 186

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Start engine. Disconnect speed sensor connector. Place system in Engine Running Test Mode "71". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Connect a jumper wire between terminals if speed sensor harness connector. (Scheme 185) Make and break this connection. If display on diagnostic read-out box changes as connection is made and broken, replace speed sensor. If display does not change, go to next step. (Scheme 185): Installing Jumper To Speed Sensor Connector
2. Turn engine off. Disconnect 60-pin connector from SMEC. Connect an ohmmeter between cavity No. 48 of 60-pin connector and White/Orange wire at speed sensor harness connector. (Scheme 186) If ohmmeter shows continuity, go to next step. If ohmmeter shows no continuity, repair wire in cavity No. 48 of 60-pin connector (open circuit to speed sensor harness connector). (Scheme 186): 60-Pin Terminal No. 48 & White/Orange Wire
3. Move ohmmeter leads to cavity No. 4 of 60-pin connector and Black wire of speed sensor harness connector. (Scheme 187) If ohmmeter shows continuity, replace SMEC. Ensure terminal is not spread apart before replacing SMEC. If ohmmeter is not showing continuity, repair Black wire of speed sensor harness connector (open circuit to wiring harness splice).

60-Pin Terminal No. 4 & Black Wire. Scheme 187

Scheme 188

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Turn ignition off. Disconnect oxygen sensor connector. (Scheme 188) Place system in Sensor Test Mode "02". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Divide diagnostic read-out box display by 10 to get actual voltage. If display on diagnostic read-out box is at least.40 volt, go to next step. If display on diagnostic read-out box is zero, replace SMEC (defective logic board). Check wire in cavity No. 23 of 60-pin connector for short to ground before replacing SMEC. (Scheme 188): Heated Oxygen Sensor 3-Pin Connector
2. Connect one end of jumper wire to Black wire in harness end of oxygen sensor 3-pin connector (end wire, not wire in middle). (Scheme 189) Touch other end of jumper wire to battery positive post. If display on diagnostic read-out box is at least 5 volts, replace oxygen sensor. If display on diagnostic read-out box is.40 volt, repair Black wire of oxygen sensor connector (open circuit to SMEC).

Installing Jumper To O2 Sensor Harness Connector & Battery. Scheme 189

Scheme 190

Scheme 191

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Turn ignition off. Disconnect connector from coolant sensor. (Scheme 190) Place system in Sensor Test Mode "04". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Multiply diagnostic read-out box display by 10 to get actual temperature. If display reads "00°", go to next step. If display reads "260°", ensure wire to cavity No. 3 of SMEC 60-pin connector is not shorted to ground. If wiring is okay, replace SMEC. (Scheme 190): CTS Connector Location
2. Connect jumper wire between terminals of coolant sensor connector. (Scheme 191) If display reads "260°", replace coolant sensor. If display reads "00°", go to next step. (Scheme 191): Installing Jumper To CTS Connector
3. Connect one end of jumper wire to negative battery terminal. Connect other end of jumper wire to Tan/White wire terminal of coolant sensor harness connector. (Scheme 192) If display reads "260°", repair Black/Light Blue wire of coolant sensor harness connector (open circuit to wiring harness splice). If display reads "00°", repair Tan/White wire of coolant sensor harness connector (open circuit to SMEC).

Jumper CTS Tan/White Wire To Ground. Scheme 192

Scheme 193

Scheme 194

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Disconnect charge temperature sensor connector. (Scheme 193) Place system in Sensor Test Mode "03". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Multiply display readings by 10 for actual readings. If display on diagnostic read-out box reads 5 volts, go to next step. If display on diagnostic read-out box is zero volt, or reads zero volt and then increases, ensure wiring to cavity No. 21 of 60-pin connector is not shorted to ground. If wiring is okay, replace SMEC. (Scheme 193): Charge Temperature Sensor Connector Location
2. Connect jumper wire between terminals of charge temperature sensor harness connector. (Scheme 194) If display on diagnostic read-out box reads zero volt, replace charge temperature sensor. If display reads 5 volts, go to next step. (Scheme 194): Jumper Charge Temperature Sensor Connector Terminals
3. Connect one end of jumper wire to negative battery terminal. Connect other end of jumper wire to Black/Red wire terminal of charge temperature sensor. (Scheme 204) If display on diagnostic read-out box is zero volt, repair Black/Light Blue wire of charge temperature sensor connector (open circuit to wiring harness splice). If display reads 5 volts, repair Black/Red wire of charge temperature sensor connector (open circuit to SMEC).

Jumper Black/Red Wire To Ground. Scheme 195

Scheme 196

Scheme 197

Scheme 198

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Disconnect throttle position sensor connector. Place system in Sensor Test Mode "05". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Divide display readings by 10 for actual readings. If display on diagnostic read-out box reads 5 volts, go to next step. If display on diagnostic read-out box is zero volt, ensure wiring to cavity No. 22 of 60-pin connector is not shorted to ground. If wiring is okay, replace SMEC. (Scheme 196): TPS Connector Location
2. Connect jumper wire between Orange/Dark Blue wire and Black/Light Blue wire of throttle position sensor harness connector. (Scheme 197) If display on diagnostic read-out box reads zero volt, go to step 4). If display reads 5 volts, go to next step. (Scheme 197): Jumper TPS Connector Orange/Dark Blue To Black/Light Blue Wire
3. Connect one end of jumper wire to negative battery terminal. Connect other end of jumper wire to Orange/Dark Blue wire terminal of throttle position sensor. (Scheme 198) If display on diagnostic read-out box is zero volt, repair Black/Light Blue wire of throttle position sensor connector (open circuit to wiring harness splice). If display reads 5 volts, repair Orange/Dark Blue wire of throttle position sensor connector (open circuit to SMEC). (Scheme 198): Jumper TPS Connector Orange/Dark Blue To Ground
4. Connect digital voltmeter between Violet/White wire of throttle position sensor harness connector and ground. (Scheme 199) If voltmeter reading is at least 4 volts, replace throttle position sensor. If voltmeter reads zero volt, repair Violet/White wire (open circuit to wiring harness splice).

Installing Digital Voltmeter To TPS Connector. Scheme 199

Scheme 200

Scheme 201

1. Turn ignition off. Disconnect 60-pin connector at SMEC. Connect an ohmmeter between cavity No. 17 and cavity No. 18 of 60-pin connector. (Scheme 200) If there is resistance (amount of resistance is not important, should be some resistance), go to next step. If ohmmeter reading is zero resistance go to step 3). (Scheme 200): 60-Pin Terminal Nos. 17 & 18
2. Connect ohmmeter between cavity No. 19 and cavity No. 20 of 60-pin connector. (Scheme 201) If there is resistance (amount of resistance is not important, should be some resistance), replace SMEC (defective logic board). If ohmmeter reading is zero resistance go to next step. (Scheme 201): 60-Pin Terminal Nos. 19 & 20
3. With ohmmeter connected as explained in step 1) or step 2), disconnect Automatic Idle Speed (AIS) motor connector. If ohmmeter shows an open circuit, replace AIS motor. If ohmmeter shows zero resistance, repair wiring to AIS motor (short to each other in harness).

Scheme 202

Scheme 203

Scheme 204

1. Connect voltmeter between Pink/White wire of canister purge solenoid connector and ground. (Scheme 202) Turn ignition switch to "RUN" position. If voltmeter reads within one volt of battery voltage, go to next step. If voltmeter reads between zero to one volt, go to step 3). (Scheme 202): Canister Purge Solenoid Connector Location
2. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect voltmeter between terminal No. 54 of 60-pin connector and ground. (Scheme 203) Turn ignition switch to "RUN" position. If voltmeter is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 54 is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reads zero volt, repair wire in cavity No. 54 of 60-pin connector (open circuit to canister purge solenoid). (Scheme 203): 60-Pin Terminal No. 54
3. Attach voltmeter between Pink/White wire of canister purge solenoid connector and ground. (Scheme 204) Disconnect 60-pin connector at SMEC. Turn ignition switch to "RUN" position. If voltmeter reads within one volt of battery voltage, replace SMEC (defective logic board). If voltmeter reads zero volt, go to next step. (Scheme 204): Canister Purge Solenoid Connector Location
4. With ignition switch in "RUN" position, connect voltmeter between Dark Blue wire of canister purge solenoid harness connector and ground. If voltmeter reads within one volt of battery voltage, replace canister purge solenoid. If voltmeter reads zero volt, repair Dark Blue wire of canister purge solenoid harness connector (open circuit to wiring harness splice).

Scheme 205

Scheme 206

Scheme 207

1. Connect voltmeter between Dark Blue/Orange wire of A/C cut-out relay single connector and ground. (Scheme 205) Turn ignition switch to "RUN" position. Press A/C button "ON". If voltmeter reads within one volt of battery voltage, go to next step. If voltmeter reads zero to one volt, go to step 3). (Scheme 205): A/C Cut-Out Relay Single Connector
2. With A/C button "ON", turn ignition switch off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 56 of 60-pin connector and ground. (Scheme 206) Turn ignition switch to "RUN" position. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 56 is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reads zero volt, repair wire in cavity No. 56 (open circuit to A/C cut-out relay). Check diode in wire for integrity before repairing wire. (Scheme 206): 60-Pin Terminal No. 56
3. With voltmeter connected between Dark Blue/Orange wire of A/C cut-out relay single connector and ground, turn ignition switch off. (Scheme 207) Press A/C button "ON". Disconnect 60-pin connector from SMEC. Turn ignition switch to "RUN" position. If voltmeter reads within one volt of battery voltage, replace SMEC (defective logic board). If voltmeter reads zero volt, go to next step. (Scheme 207): A/C Cut-Out Relay Single Connector
4. With ignition switch in "RUN" position, turn A/C button "ON". Connect voltmeter between Dark Green wire of A/C cut-out relay 3-pin connector and ground. (Scheme 208) If voltmeter reads within one volt of battery voltage, replace A/C cut-out relay. If voltmeter reads zero volt, repair Dark Green wire to A/C condenser fan relay 3-pin connector (open circuit).

A/C Cut-Out Relay Connector Identification. Scheme 208

Scheme 209

Scheme 210

Scheme 211

1. Connect voltmeter between Dark Blue/Pink wire of cooling fan single connector and ground. (Scheme 209) If voltmeter reading is within one volt of battery voltage, go to next step. If voltmeter reading is zero to one volt, go to step 3). (Scheme 209): Cooling Fan Relay Terminal Identification
2. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 57 of 60-pin connector and ground. (Scheme 210) If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 57 is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reading is zero volt, repair wire in cavity No. 57 (open circuit to cooling fan relay). (Scheme 210): 60-Pin Terminal No. 57
3. With voltmeter connected between Dark Blue/Pink wire of cooling fan single connector and ground, turn ignition off. (Scheme 211) Disconnect 60-pin connector from SMEC. Turn ignition to "RUN" position. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). If voltmeter reading is zero volt, go to next step. (Scheme 211): Cooling Fan Relay Terminal Identification
4. With ignition switch in "RUN" position, connect voltmeter between Dark Blue wire of cooling fan relay 3-pin connector and ground. (Scheme 212) If voltmeter reads within one volt of battery voltage, replace cooling fan relay. If voltmeter reading is zero volt, repair Dark Blue wire of 3-pin connector (open circuit to wiring harness splice).

Cooling Fan Relay Connector Identification. Scheme 212

Scheme 213

Scheme 214

1. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 55 of 60-pin connector and ground. (Scheme 213) Turn ignition switch to "RUN" position. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 55 is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reading is zero volt, go to next step. (Scheme 213): 60-Pin Terminal No. 55 To Ground
2. With equipment connected as in step 1), disconnect lock-up solenoid connector at transaxle. Connect a jumper wire between Dark Blue wire and Orange/Black wire terminals of lock-up solenoid connector. (Scheme 214) If voltmeter reading is within one volt of battery voltage, replace lock-up solenoid. If voltmeter reading is zero volt, go to next step. (Scheme 214): Installing Jumper Wire On Lock-Up Solenoid Connector
3. Remove jumper wire from lock-up solenoid connector and connect voltmeter between Dark Blue wire of connector and ground. (Scheme 215) If voltage reading is within one volt of battery voltage, repair Orange/Black wire of solenoid connector (open circuit to SMEC). If voltmeter reading is zero volt, repair Dark Blue wire of connector (open circuit to wiring harness splice).

Transaxle Lock-Up Voltage Check. Scheme 215

DR-13 TEST - FUSED "J2" CIRCUIT TO SMEC (CODE 44)

Turn ignition off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 12 of 60-pin connector and ground. (Scheme 216) Turn ignition switch to "RUN" position. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 12 is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reading is zero volt, repair Dark Blue/White wire of cavity No. 12 (open circuit to ASD relay single connector).

60-Pin Terminal No. 12 To Ground. Scheme 216

Scheme 217

1. Turn ignition off. Disconnect distributor electrical connector. Connect voltmeter between Tan/Yellow wire of distributor harness connector and ground. (Scheme 217) Turn ignition switch to "RUN" position. If voltmeter reading is at least 4 volts, replace distributor pick-up assembly. If voltmeter reading is zero volt, go to next step. (Scheme 217): Distributor Harness Connector Identification
2. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect ohmmeter between cavity No. 49 of 60-pin connector and Tan/Yellow wire of distributor harness connector. (Scheme 218) If ohmmeter registers continuity, replace SMEC (defective logic board). Ensure terminal in cavity No. 49 is not damaged, causing a poor connection, before replacing SMEC. If ohmmeter does not register continuity, repair Tan/Yellow wire in cavity No. 49 (open circuit to distributor harness connector).

60-Pin Terminal No. 49 To Distributor Connector. Scheme 218

DR-15 TEST - COLD ENGINE SENSOR CALIBRATION CHECK

Note. The following test must begin with a COLD engine. Allow engine to sit at least 7 hours without being started.

Scheme 219

Scheme 220

1. Connect diagnostic read-out box to diagnostic connector. Start engine. Place system in Engine Running Test Mode "64". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. (Scheme 219): Diagnostic Read-Out Box
2. Coolant Temperature Sensor - Multiply display reading by 10 to get correct temperature. If display on diagnostic read-out box is within 10 degrees of ambient temperature, go to next step. If display is not within 10 degrees of ambient temperature, replace coolant temperature sensor.
3. Throttle Position Sensor (TPS) - Turn ignition off. Allow engine to cool to "cold engine" condition. Place system in Sensor Test Mode "05". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Divide diagnostic read-out box display by 10 to get actual reading. If display on diagnostic read-out box shows.5-1.5 volts when throttle is completely closed (throttle cables are not holding throttle open), shows uninterrupted change of voltage as throttle opening is varied (between closed and open throttle), and shows at least 3.5 volts when throttle is at wide open throttle, go to next step. If voltage readings are not as indicated, replace throttle position sensor.
4. With diagnostic read-out box connected to diagnostic connector, start engine. Place system in Engine Running Test Mode "5". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Slowly increase engine speed to 2000 RPM while observing diagnostic read-out box display. Divide diagnostic read-out box display by 10 to get actual reading. If voltage reading increases as engine speed increases, go to next step. If voltage reading does not increase as engine speed increases, replace throttle position sensor.
5. With diagnostic read-out box connected to diagnostic connector, run engine at idle. Place system in Engine Running Test Mode "69". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Divide diagnostic read-out box display by 10 to get actual reading. If voltage reading is between zero and.10 volt, go to next step. If voltage reading is greater than.10 volt, replace the TPS.
6. MAP Sensor - Connect diagnostic read-out box to diagnostic connector. Tee a vacuum gauge into MAP sensor vacuum line. (Scheme 220) Start engine. Place system in Engine Running Test Mode "68". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. If vacuum displayed on diagnostic read-out box is within one in. Hg vacuum of reading shown on vacuum gauge, proceed to step 9). If display is not within one in. Hg vacuum of vacuum gauge reading, go to next step. (Scheme 220): Installing Vacuum Gauge
7. Ensure engine is cold before performing this step, and diagnostic read-out box is connected to diagnostic connector. Place system in Sensor Test Mode "08". Divide display readings by 10 for actual readings. Disconnect vacuum hose from MAP sensor. Connect a vacuum pump to MAP sensor. Apply 5 in. Hg vacuum and record voltage displayed on diagnostic read-out box.
8. Slowly apply up to 20 in. Hg vacuum while observing diagnostic read-out box display. Record voltage reading at 20 in. Hg vacuum. Subtract voltage reading at 20 in. Hg vacuum from voltage reading at 5 in. Hg vacuum. If diagnostic read-out box showed an uninterrupted change of voltage between 5-20 in. Hg vacuum and the voltage difference between the 2 readings is 2.3-2.9 volts, repair vacuum line to MAP sensor for a restriction. If diagnostic read-out box showed an uninterrupted change of voltage between 5-20 in. Hg vacuum and the voltage difference between the 2 readings IS NOT 2.3-2.9 volts, replace MAP sensor.
9. Charge Temperature Sensor - Ensure engine is cold before performing this step. Connect diagnostic read-out box to diagnostic connector. Start engine. Place system in Engine Running Test Mode "63". Divide display readings by 10 for actual readings. If diagnostic read-out box display reads 3-5 volts, go to next step. If reading is not 3-5 volts, replace charge temperature sensor.
10. Fouled Spark Plugs - Remove spark plugs. If spark plugs are dry, perform «DR-17 TEST - EGR SYSTEM CHECK»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If spark plugs are wet with fuel, clean and reinstall. Check for gasoline in crankcase. Change oil and filter if required.

DR-16 TEST - WARM ENGINE SENSOR CALIBRATION CHECK

Note. The following test must begin with a WARM engine. Allow engine to reach normal operating temperature.

Scheme 221

Scheme 222

1. Connect diagnostic read-out box to diagnostic connector. Start engine. Place system in Engine Running Test Mode "64". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. (Scheme 221): Diagnostic Read-Out Box
2. Coolant Temperature Sensor - Multiply display reading by 10 to get correct temperature. If display on diagnostic read-out box is between 180-250 degrees, go to next step. If display is not 180-250 degrees, replace coolant temperature sensor.
3. Throttle Position Sensor - Turn ignition off. Place system in Sensor Test Mode "05". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Divide diagnostic read-out box display by 10 to get actual reading. If display on diagnostic read-out box shows.5-1.5 volts when throttle is completely closed (throttle cables are not holding throttle open), shows uninterrupted change of voltage as throttle opening is varied (between closed and open throttle), and shows at least 3 volts when throttle is at wide open throttle, go to next step. If voltage readings are not as indicated, replace throttle position sensor.
4. With diagnostic read-out box connected to diagnostic connector, start engine. Place system in Engine Running Test Mode "65". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Slowly increase engine speed to 2000 RPM while observing diagnostic read-out box display. Divide diagnostic read-out box display by 10 to get actual reading. If voltage reading increases as engine speed increases, go to next step. If voltage reading does not increase as engine speed increases, replace throttle position sensor.
5. With diagnostic read-out box connected to diagnostic connector, run engine at idle. Place system in Engine Running Test Mode "69". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Divide diagnostic read-out box display by 10 to get actual reading. If voltage reading is between zero and.10 volt, go to next step. If voltage reading is greater than.10 volt, replace throttle position sensor.
6. MAP Sensor - Connect diagnostic read-out box to diagnostic connector. Tee a vacuum gauge into MAP sensor vacuum line. (Scheme 222) Start engine. Place system in Engine Running Test Mode "69". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. If vacuum displayed on diagnostic read-out box is within one in. Hg vacuum of reading shown on vacuum gauge, proceed to step 9). If display is not within one in. Hg vacuum of vacuum gauge reading, go to next step. (Scheme 222): Installing Vacuum Gauge
7. Ensure engine is warm before performing this step, and diagnostic read-out box is connected to diagnostic connector. Place system in Sensor Test Mode "08". Divide display readings by 10 for actual readings. Disconnect vacuum hose from MAP sensor. Connect a vacuum pump to MAP sensor. Apply 5 in. Hg vacuum and record voltage displayed on diagnostic read-out box.
8. Slowly apply up to 20 in. Hg vacuum while observing diagnostic read-out box display. Record voltage reading at 20 in. Hg vacuum. Subtract voltage reading at 20 in. Hg vacuum from voltage reading at 5 in. Hg vacuum. If diagnostic read-out box showed an uninterrupted change of voltage between 5-20 in. Hg vacuum and the voltage difference between the 2 readings is 2.3-2.9 volts, repair vacuum line to MAP sensor for a restriction. If diagnostic read-out box showed an uninterrupted change of voltage between 5-20 in. Hg vacuum and the voltage difference between the 2 readings IS NOT 2.3-2.9 volts, replace MAP sensor.
9. Charge Temperature Sensor - Ensure engine is warm before performing this step. Connect diagnostic read-out box to diagnostic connector. Start engine. Place system in Engine Running Test Mode "63". Divide display readings by 10 for actual readings. If diagnostic read-out box display reads 1-4 volts, perform «DR-17 TEST - EGR SYSTEM CHECK»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If reading is not 1-4 volts, replace charge temperature sensor.

Scheme 223

Scheme 224

Scheme 225

1. Disconnect vacuum line at EGR backpressure valve that comes from throttle body assembly, and connect vacuum gauge. (Scheme 223) Start engine. Raise engine speed to 2000 RPM. If vacuum gauge reading is at least 5 in. Hg vacuum, record reading and go to next step. If vacuum gauge does not register vacuum, or reading is below 5 in. Hg, repair vacuum line as required. (Scheme 223): EGR Backpressure Valve
2. With engine running, disconnect vacuum gauge from vacuum line. Reconnect vacuum line to backpressure valve. Disconnect vacuum line from EGR valve and connect vacuum gauge to line. (Scheme 224) Raise engine speed to 2000 RPM. If vacuum reading is the same, or nearly the same as reading recorded in step 1), go to next step. If vacuum reading is not the same, nor nearly the same as reading recorded in step 1), replace EGR/backpressure valve assembly. (Scheme 224): EGR Valve & Backpressure Valve
3. With vacuum line disconnected from EGR valve and engine running, connect auxiliary vacuum supply to EGR valve. (Scheme 225) Disconnect AIS motor electrical connector. With engine running at idle speed, slowly apply vacuum to EGR valve. If engine speed begins to drop when applied vacuum is 2.5-3.5 in. Hg, go to next step. If engine speed does not drop when vacuum is applied, replace EGR/backpressure valve assembly. After removing assembly, ensure supply tube to manifold is not plugged before replacing EGR/backpressure valve assembly. (Scheme 225): Connecting Auxiliary Vacuum Supply
4. Vacuum line disconnected from EGR valve and engine running at idle. Auxiliary vacuum supply connected to EGR valve. (Scheme 226) Reconnect AIS motor electrical connector. Slowly apply 10 in. Hg vacuum to EGR valve. If vacuum holds, without bleeding down, for 10 seconds, perform DR18. If vacuum does not hold, or bleeds down before 10 seconds elapse, replace the EGR/backpressure valve assembly.

EGR Valve & Backpressure Valve. Scheme 226

DR-18 TEST - SECONDARY IGNITION SYSTEM CHECK

Connect engine analyzer to engine. Start engine and allow engine speed to stabilize for 2 minutes. Following equipment manufacturer's instructions, test secondary ignition system. Ensure ignition coil output is checked during this test. If secondary ignition system is okay, perform DR-19 TEST - BASIC IGNITION TIMING CHECK . If secondary ignition system does not test okay, repair as required.

DR-19 TEST - BASIC IGNITION TIMING CHECK

1. Connect tachometer and powered timing light to engine. Start and run engine until normal operating temperature is obtained. Disconnect coolant temperature sensor and do not reconnect. (Scheme 227) "CHECK ENGINE" light MUST come on. If basic timing is within 2 degrees of specification shown on emission label, go to next step. If basic timing is not within specification, adjust timing.
2. With tachometer and powered timing light connected to engine, remove air cleaner, if required. With engine at normal operating temperature, reconnect coolant temperature sensor connector. "CHECK ENGINE" light MUST go out. Raise engine speed to 2000 RPM. If timing is 26-34° BTDC (timing is okay), perform «DR-20 TEST - CHECKING FUEL SUPPLY & RETURN SYSTEM»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__dr-20-test-checking-fuel-supply). If timing is not 26-34° BTDC, replace SMEC (defective logic board).

Coolant Temperature Sensor Connector Location. Scheme 227

DR-20 TEST - CHECKING FUEL SUPPLY & RETURN SYSTEM

Scheme 228

Scheme 229

Scheme 230

1. Connect diagnostic read-out box to diagnostic connector. Install Pressure Gauge (C-3292 ) with Adapter (C-4799 ) in fuel supply line at throttle body. (Scheme 228) Turn ignition switch to "RUN" position. Press "ATM" button on diagnostic read-out box. If fuel pressure is 35-37 psi, perform «DR21»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__dr-21-test-oxygen-sensor-operational). If fuel pressure is below 35 psi, record pressure and go to next step. If fuel pressure is above 37 psi, go to step 4). (Scheme 228): Fuel Supply & Return Line Identification
2. Turn ignition off. Release fuel system pressure. Remove pressure gauge and adapter. Reinstall hose to throttle body. Tee pressure gauge into line before fuel filter. (Scheme 229) Turn ignition switch to "RUN" position. Press "ATM" button. If fuel pressure is 5 psi higher than recorded in step 1), replace fuel filter. If fuel pressure is still below 35 psi, go to next step. (Scheme 229): Install Pressure Gauge To Fuel Filter Inlet
3. Turn ignition off. Release fuel pressure. Remove pressure gauge. Tee pressure gauge into line after fuel filter. (Scheme 230) Turn ignition switch to "RUN" position. Press "ATM" button. VERY GENTLY squeeze fuel return line at fuel rail and IMMEDIATELY release line. If fuel pressure increases above operating pressure, replace pressure regulator. If fuel pressure does not increase, replace in-tank fuel pump. Before replacing pump, look for contamination in fuel tank that may be plugging pump filter. Also ensure electrical connections are not corroded. (Scheme 230): Install Pressure Gauge To Fuel Filter Outlet
4. Turn ignition off. Remove fuel return hose (small one) from fuel rail. (Scheme 231) Connect 3 foot length of fuel hose to throttle body and place other end into large receptacle (2 gallon minimum). Turn ignition switch to "RUN" position. Press "ATM" button. DO NOT hold button for more than 10 seconds. If fuel pressure reading is 35-37 psi, check fuel return lines for kinks or restrictions, including return line check valve located inside fuel tank. If fuel pressure reading is above 37 psi, replace pressure regulator.

Fuel Return Hose Identification. Scheme 231

DR-21 TEST - OXYGEN SENSOR OPERATIONAL CHECK

Connect diagnostic read-out box to diagnostic connector. Make sure "READ/HOLD" button is in "READ" position. Start engine and wait 2 minutes. Move "READ/HOLD" button to "HOLD" position to increase engine speed. If display on diagnostic read-out box is switching between "0" and "1", or stays on "1", perform DR22 . If display on diagnostic read-out box reads "0", check for grounded oxygen sensor wire, and/or plugged fuel injectors.

Diagnostic Read-Out Box. Scheme 232

DR-22 TEST - CHECKING THROTTLE BODY MINIMUM AIRFLOW

Connect diagnostic read-out box to diagnostic connector. Connect tachometer to engine. Disconnect hose from PCV valve and install Orifice (C-5004 ) into PCV vacuum supply hose. (Scheme 233) Start engine and allow to run until cooling fan cycles on and then off. With cooling fan NOT running, place system in Engine Running Test Mode "70". See ENTERING ON-BOARD DIAGNOSTICS under TESTING & DIAGNOSIS in this article. If tachometer registers 850-1050 RPM (725-925 RPM on vehicles with less than 300 miles), perform DR23. If tachometer reading is not within specifications, replace throttle body.

Disconnecting PCV & Installing Orifice. Scheme 233

DR-23 TEST - NON-ENGINE CONTROL RELATED PROBLEMS

At this point in driveability testing procedures, all engine control systems have been determined to be operating properly. Therefore, engine control system devices are not the cause of the driveability problem. Check the following items as possible causes of driveability problem

1. Engine vacuum MUST be at least 13 in. Hg in Neutral.
2. Valve timing must be set to specifications.
3. Engine compression must be within specifications.
4. Engine exhaust system must be free of restrictions.
5. Engine PCV system must flow freely.
6. Ensure engine drive sprockets (camshaft and crankshaft) are properly installed, meshed and timed.
7. Torque converter stall speed must be within specifications.
8. Power brake booster must not have any internal vacuum leaks.
9. Fuel must not be contaminated (high alcohol and water content).
10. Crossed fuel injector control wires (wrong wire connected to injector) may cause rough idle.

Any one or more of these conditions can cause a driveability related problem. They must be considered as possible causes.

TROUBLE CODE-TO-TEST MENU

CH TROUBLE CODE-TO-TEST MENU

Scheme 234

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Turn ignition on-off-on-off-on within 5 seconds. Record all codes. Erase fault codes. See «ERASING CODES FROM SMEC MEMORY»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__erasing-codes-from-smec-memory) under TESTING & DIAGNOSIS in this article. Start engine and allow to idle for 7 minutes. Raise engine speed above 1500 RPM for 30 seconds. Stop engine. Turn ignition on-off-on-off-on within 5 seconds. Record all codes. (Scheme 234): Diagnostic Read-Out Box
2. If same code(s) were stored before and after memory was cleared, problem still exists. If a code does not reappear after engine is started, problem no longer exists, but was intermittent. Go to step 5). If code 88-12-55 is stored (no codes stored), proceed to «CH-2 TEST - CHECKING BATTERY TEMPERATURE SENSOR CALIBRATION»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system__ch-2-test-checking-battery-temperature). If code 88-11-12-16-55 is stored, proceed to CHARGING SYSTEM TEST NO. 3. If codes 88-12-41-46-55 or 88-12-46-55 are stored, proceed to «CH-4 TEST - ALTERNATOR OUTPUT HIGH (CODE 46 OR CODES 41-46)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). 3) If codes 88-12-41-55, 88-12-41-47-55, or 88-12-47-55 are stored, proceed to «CH-5 TEST - ALTERNATOR OUTPUT LOW (CODE 41, 41/47 OR CODE 47)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If there is no code 88, ensure diagnostic read-out box is operating properly and that there is not an open circuit between SMEC and diagnostic connector. 4) The majority of intermittent failures are caused by wiring and connectors. The only way to locate intermittents is to try to duplicate the problem. Because the SMEC can remember where the fault is located, the ATM and Sensor Test modes can be used to try to locate the intermittents. 5) If code 41 does not reappear after clearing memory, enter ATM Test Mode "09" on diagnostic read-out box. See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Connect voltmeter to field control wire terminal of alternator and watch pulsations of meter. Once in correct test mode, wiggle all connectors and wires in the circuit. When bad connection or wire is located, ATM Test Mode "09" will be interrupted. 6) If code 16 does not reappear after clearing memory, enter Sensor Test Mode "07" on diagnostic read-out box. See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Once in correct test mode, wiggle all connectors and wires in the circuit. When bad connection or wire is located, diagnostic read-out box display will change.

CH-2 TEST - CHECKING BATTERY TEMPERATURE SENSOR CALIBRATION

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Place system in Engine Running Test Mode "61". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Divide display reading by 10 for actual reading. If diagnostic read-out box display is .2-3.0 volts, go to next step. If diagnostic read-out box display is not .2-3.0 volts, replace SMEC (defective logic board). 2) With diagnostic read-out box connected to diagnostic connector, place system in Engine Running Test Mode "67". Display reading is actual reading. If diagnostic read-out box display is 13-15 volts, check battery and also check for battery drain-down condition. If display reading is not 13-15 volts, check alternator.

Diagnostic Read-Out Box. Scheme 235

CH-3 TEST - BATTERY VOLTAGE SENSING CIRCUIT (CODE 16)

Turn ignition switch off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 41 of 60-pin connector and ground. (Scheme 236) If voltmeter reads within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 41 is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reading is zero volt, repair Red wire in cavity No. 41 of 60-pin connector (open circuit to wiring harness splice).

60-Pin Terminal No. 41 To Ground. Scheme 236

Scheme 237

Scheme 238

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Turn ignition off. Disconnect 14-pin connector from SMEC. Separate connector into 2 parts. Reconnect the part containing cavity No. 1 through cavity No. 7 to SMEC. Connect positive lead of ANALOG voltmeter to cavity No. 14 and negative lead to cavity No. 11. (Scheme 237) Place system in ATM Test Mode "09". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. If voltmeter is pulsating between zero and 12 volts, replace SMEC (defective power board). If voltmeter reads zero volt, go to next step. (Scheme 237): Checking 14-Pin Terminal Nos. 14 To 11
2. With test equipment connected as in step 1), turn ignition switch to "RUN" position. Move negative lead of ANALOG voltmeter from cavity No. 11 to negative battery terminal. (Scheme 238) If voltmeter reads within one volt of battery voltage, go to next step. If voltmeter reads zero to one volt, repair alternator field circuit (short to ground). (Scheme 238): 14-Pin Terminal No. 14 To Negative Battery Terminal
3. With part of 14-pin connector containing cavity No. 8 through cavity No. 14 disconnected from SMEC, turn ignition off. Disconnect 60-pin connector from SMEC connector. Connect an ohmmeter between cavity No. 14 of 60-pin connector and ground. (Scheme 239) If ohmmeter does not register continuity, replace SMEC (defective logic board). If ohmmeter registers continuity, repair Dark Green/Orange wire in cavity No. 14 of 60-pin connector (short to ground).

60-Pin Terminal No. 14 To Ground. Scheme 239

Scheme 240

Scheme 241

Scheme 242

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Connect negative lead of voltmeter to negative battery terminal. Place system in ATM Test Mode "09". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Touch positive lead of voltmeter to each alternator field terminal. (Scheme 240): Diagnostic Read-Out Box
2. If voltmeter reads zero volt at both alternator field terminals, repair "J2" circuit to alternator field (open circuit to wiring harness splice). If voltmeter reads battery voltage at one alternator field terminal and is pulsating between zero and battery voltage at other terminal, check for loose alternator drive belt, check alternator, and check battery. If voltmeter reads battery voltage at both alternator field terminals, go to next step.
3. With diagnostic read-out box connected to diagnostic connector, turn ignition off. Disconnect 14-pin connector from SMEC. Connect voltmeter between cavity No. 14 of 14-pin connector and ground. (Scheme 241) Turn ignition switch to "RUN" position. If voltmeter reads within one volt of battery voltage, go to next step. If voltmeter reads zero volt, repair Dark Green wire in cavity No. 14 of 14-pin connector (open circuit to alternator). (Scheme 241): 14-Pin Terminal No. 14 To Ground
4. With diagnostic read-out box connected to diagnostic connector and 14-pin connector disconnected from SMEC, turn ignition off. Disconnect 14-pin connector from SMEC. Separate connector into 2 parts. Reconnect the part containing cavity No. 1 through cavity No. 7 to SMEC. Connect positive lead of ANALOG voltmeter to cavity No. 14 and negative lead to cavity No. 11. (Scheme 242) (Scheme 242): 14-Pin Terminal Nos. 14 To 11
5. Place system in ATM Test Mode "09". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. If voltmeter is pulsating between zero and 12 volts, replace SMEC (defective power board). Ensure terminal in cavity No. 11 and cavity No. 14 of 14-pin connector are not damaged, causing a poor connection, before replacing SMEC. If voltmeter reads zero volt, go to next step. 6) Turn ignition off. Disconnect 60-pin connector from SMEC. Connect an ohmmeter between cavity No. 11 of 14-pin connector and cavity No. 14 of 60-pin connector. (Scheme 243) If ohmmeter registers continuity, replace SMEC (defective logic board). Ensure terminal in cavity No. 14 of 60-pin connector is not damaged, causing a poor connection, before replacing SMEC. If ohmmeter does not register continuity, repair Dark Green/Orange wire in 60-pin connector (open circuit to 14-pin connector).

14-Pin Terminal No. 11 To 60-Pin Terminal No. 14. Scheme 243

Scheme 244

Scheme 245

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Place system in Diagnostic Test Mode. See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Record all codes. If codes 88-55 or 88-12-55 are displayed (no codes stored), go to next step. If codes 88-34-55 or 88-12-34-55 are displayed, proceed to «CCS-2 TEST - CRUISE CONTROL SERVO CHECK (CODE 34)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If codes 88-15-55 or 88-12-15-55 are displayed, perform «DR-3 TEST - SPEED SENSOR CIRCUIT (CODE 15)»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). (Scheme 244): Diagnostic Read-Out Box
2. Connect diagnostic read-out box to diagnostic connector in engine compartment. Place system in Sensor Test Mode "09". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Ensure cruise control switch is in "OFF" position. While observing diagnostic read-out box display, move cruise control "ON/OFF" switch to "ON" position. Press "SET" button, and then "RESUME" button. Record display readings. (Scheme 245): Cruise Control Switch Positions
3. If display reads "00" with "ON/OFF" switch in "ON" position, "10" when "SET" button is pressed, and "01" when "RESUME" button is pressed, cruise control switch is okay. Proceed to «CCS-3 TEST - CRUISE CONTROL SERVO GROUND CIRCUIT CHECK»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). 4) If display reads "blank" with "ON/OFF" switch in "ON" position, "blank" when "SET" button is pressed, and "blank" when "RESUME" button is pressed, proceed to «CCS-4 TEST - CRUISE CONTROL SYSTEM POWER SUPPLY CHECK»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). If display reads "blank" with "ON/OFF" switch in "ON" position, "10" when "SET" button is pressed, and "10" when "RESUME" button is pressed, proceed to «CCS-5 TEST - CRUISE CONTROL SYSTEM SET FUNCTION CHECK»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system). 5) If display reads "00" with "ON/OFF" switch in "ON" position, "00" when "SET" button is pressed, and "00" when "RESUME" button is pressed, proceed to «CCS-6 TEST - CRUISE CONTROL SYSTEM RESUME CIRCUIT CHECK»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system).

Scheme 246

Scheme 247

Scheme 248

Scheme 249

Scheme 250

Scheme 251

1. Connect diagnostic read-out box to engine harness connector. Connect voltmeter between Tan/Red wire in cruise control servo harness connector and ground. (Scheme 246) Place system in ATM Test Mode "08". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Set cruise control "ON/OFF" switch to "ON" position. (Scheme 246): Cruise Control Servo Voltage Check
2. If voltmeter is pulsating between 0-12 volts, vacuum solenoid is okay, go to next step. If voltmeter reading is within one volt of battery voltage, proceed to step 6). If voltmeter reading is between zero and one volt, proceed to step 7).
3. Turn ignition off. Connect voltmeter between Light Green/Red wire in cruise control servo harness connector and ground. If voltmeter reading is within one volt of battery voltage, proceed to next step. If voltmeter reading is between zero and one volt, proceed to step 5).
4. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 60 of 60-pin connector and ground. (Scheme 247) Turn ignition switch to "RUN" position. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 14 of 60-pin connector is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reading is between zero and one volt, repair wire in cavity No. 60 of 60-pin connector (open circuit to cruise control servo connector). (Scheme 247): 60-Pin Terminal No. 60 To Ground
5. Connect voltmeter between Light Green/Red wire of cruise control servo harness and ground. (Scheme 248) Disconnect 60-pin connector from SMEC. Turn ignition to "RUN" position. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). If voltmeter reading is between zero and one volt, repair wire in cavity No. 60 of 60-pin connector (short to ground from logic board to cruise control servo connector). (Scheme 248): Cruise Control Servo Voltage Check
6. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect voltmeter between cavity No. 53 of 60-pin connector and ground. (Scheme 249) Turn ignition switch to "RUN" position. If voltmeter reading is within one volt of battery voltage, replace SMEC. Ensure terminal in cavity No. 14 of 60-pin connector is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reading is between zero and one volt, repair wire in cavity No. 53 of 60-pin connector (open circuit to cruise control servo connector). (Scheme 249): 60-Pin Terminal No. 53 To Ground
7. Connect voltmeter between Tan/Red wire of cruise control servo harness connector and ground. (Scheme 250) Disconnect 60-pin connector from SMEC. Turn ignition switch to "RUN" position. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). If voltmeter reading is between zero and one volt, go to next step. (Scheme 250): Cruise Control Servo Voltage Check
8. Turn ignition off. Connect voltmeter between Dark Blue/Red wire of cruise control harness connector and ground. Turn ignition switch to "RUN" position. If voltmeter reading is within one volt of battery voltage, replace cruise control servo. If voltmeter reading is between zero and one volt, go to next step. 9) Place cruise control "ON/OFF" switch in "ON" position. Turn ignition switch to "RUN" position. Connect voltmeter between Dark Blue/Red wire of brake switch harness connector and ground. (Scheme 251) If voltmeter reading is within one volt of battery voltage, repair Dark Blue/Red wire (open circuit to cruise control servo). If voltmeter reading is between zero and one volt, go to next step. (Scheme 251): Brake Switch Harness Connector To Ground
9. Place cruise control "ON/OFF" switch in "ON" position. Turn ignition switch to "RUN" position. Connect voltmeter between Yellow/Red wire of brake switch harness connector and ground. If voltmeter reading is within one volt of battery voltage, replace brake switch. If voltmeter reading is zero volt, repair Yellow/Red wire (open circuit to wiring harness splice).

Scheme 252

Scheme 253

Scheme 254

Scheme 255

Scheme 256

1. Turn ignition off. Disconnect cruise control servo electrical connector. Connect an ohmmeter between Black wire in cruise control servo harness connector and ground. (Scheme 252) If ohmmeter is not showing continuity, repair Black wire (open circuit to wiring harness splice). If ohmmeter is showing continuity, reconnect electrical connector and go to next step. (Scheme 252): Cruise Control Servo Connector To Ground
2. Connect diagnostic read-out box to diagnostic connector in engine compartment. Place system in Switch Test Mode. See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Press brake pedal down. If display on diagnostic read-out box changes as pedal is depressed (not important what the reading is, just that display changes), go to step 4). If display on diagnostic read-out box does not change as pedal is depressed, go to next step. (Scheme 253): Diagnostic Read-Out Box
3. Turn ignition switch off. Disconnect 60-pin connector from SMEC. Connect an ohmmeter between cavity No. 29 of 60-pin connector and ground. (Scheme 254) Depress brake pedal, and then release. If ohmmeter does not register continuity when brake pedal is depressed and does register continuity when pedal is released, replace SMEC (defective logic board). Ensure terminal in cavity No. 29 of 60-pin connector is not damaged, causing a poor connection, before replacing SMEC. If ohmmeter does not register as indicated, check wire at cavity No. 29 of 60-pin connector (open circuit to stoplight ground eyelet). (Scheme 254): 60-Pin Terminal No. 29 To Ground
4. With diagnostic read-out box connected to diagnostic connector in engine compartment, place system in Switch Test Mode. See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Place gear selector lever in Park, Reverse, Neutral, and Drive while observing diagnostic read-out box display. If display on diagnostic read-out box changes as gear selector lever is moved from Park to Reverse, Reverse to Neutral, Neutral to Drive, and Drive to Park (not important what the reading is, just that display changes), go to step 6). If display on diagnostic read-out box does not change when gear selector lever is moved, go to next step.
5. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect an ohmmeter between cavity No. 30 of 60-pin connector and ground. (Scheme 255) Disconnect battery quick disconnect. Turn ignition switch to "RUN" position. While observing ohmmeter, place gear selector in Park, Reverse, Neutral, and Drive. If ohmmeter shows continuity in all gear selector positions, check wire in cavity No. 30 (short to ground), and check for bad neutral safety switch. If ohmmeter shows no continuity in all gear selector positions, repair wire in cavity No. 30 (open circuit to neutral safety switch). (Scheme 255): 60-Pin Terminal No. 30 To Ground & Battery Quick Disconnect
6. Reconnect cruise control servo electrical connector. Connect diagnostic read-out box to diagnostic connector in engine compartment. Disconnect cruise control servo vacuum supply hose from power brake booster and connect an auxiliary vacuum supply. (Scheme 256) Place system in ATM Test Mode "08". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Continuously apply vacuum to cruise control servo. (Scheme 256): Connecting Auxiliary Vacuum Supply
7. If throttle is opening and closing as cruise control system is turning on and off (vacuum continuously applied), check vacuum supply to cruise control servo. Also check speed sensor operation by entering Engine Running Test Mode "71". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. MPH on diagnostic read-out box display must be stable at all times. If not, replace speed sensor. If throttle is not opening and closing as cruise control system is turning on and off (vacuum continuously applied), replace cruise control servo. Before replacing servo, ensure cruise control cable is properly adjusted, or is not broken. Also ensure there are no leaks or restrictions in vacuum supply hose to servo.

Scheme 257

Scheme 258

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Place system in Sensor Test Mode "09". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Place cruise control "ON/OFF" switch in "ON" position. Connect jumper wire between Dark Blue/White wire and Yellow/Red wire of cruise control switch harness connector, without disconnecting electrical connector. (Scheme 257) If diagnostic read-out box display is "00", replace cruise control switch. If diagnostic read-out box display is blank, go to next step. (Scheme 257): Installing Jumper Wire With Connector Connected
2. Turn ignition off. Connect negative lead of voltmeter to ground and positive voltmeter lead to Dark Blue/White wire of cruise control switch harness connector, without disconnecting electrical connector. (Scheme 258) Turn ignition on. If voltmeter reading is within one volt of battery voltage, go to next step. If voltmeter reading is zero volt, repair Dark Blue/White wire (open circuit to fuse block). (Scheme 258): Checking Voltage
3. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect negative voltmeter lead to ground and positive voltmeter lead to cavity No. 8 of 60-pin connector. (Scheme 259) DO NOT disconnect cruise control switch connector. Turn ignition on. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 8 of 60-pin connector is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reading is zero volt, repair Yellow/Red wire in cavity No. 8 of 60-pin connector (open circuit to cruise control switch).

60-Pin Terminal No. 8 To Ground. Scheme 259

Scheme 260

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Place system in Sensor Test Mode "09". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Move cruise control "ON/OFF" switch to "ON" position. Connect jumper wire between Dark Blue/White wire and Brown/Red wire of cruise control switch harness connector, without disconnecting connector. (Scheme 260) If diagnostic read-out box display is "00", replace cruise control switch. If diagnostic read-out box display is "10", go to next step. (Scheme 260): Installing Jumper Wire To Harness Connector (Connected)
2. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect negative lead of voltmeter to ground and positive voltmeter lead to cavity No. 9 of 60-pin connector. (Scheme 261) DO NOT disconnect cruise control switch electrical connector. Turn ignition on. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 9 of 60-pin connector is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reading is zero volt, repair Brown/Red wire in cavity No. 9 of 60-pin connector (open circuit to cruise control switch).

60-Pin Terminal No. 9 To Ground. Scheme 261

Scheme 262

1. Connect diagnostic read-out box to diagnostic connector in engine compartment. Place system in Sensor Test Mode "09". See «ENTERING ON-BOARD DIAGNOSTICS»(/dodge/caravan/i-1984-1990/remont/testing-diagnostics/#30l-v6-mpfi-system) under TESTING & DIAGNOSIS in this article. Move cruise control "ON/OFF" switch to "ON" position. Connect jumper wire between Dark Blue/White wire and White wire of cruise control switch harness connector, without disconnecting harness. (Scheme 262) If "01" is displayed on diagnostic read-out box, replace cruise control switch. If "00" is displayed on diagnostic read-out box, go to next step. (Scheme 262): Installing Jumper To Harness Connector (Connected)
2. Turn ignition off. Disconnect 60-pin connector from SMEC. Connect negative lead of voltmeter to ground and positive voltmeter lead to cavity No. 7 of 60-pin connector. (Scheme 263) DO NOT disconnect cruise control switch electrical connector. Turn ignition on. Press "RESUME" on cruise control switch. If voltmeter reading is within one volt of battery voltage, replace SMEC (defective logic board). Ensure terminal in cavity No. 7 of 60-pin connector is not damaged, causing a poor connection, before replacing SMEC. If voltmeter reading is zero volt, repair White wire in cavity No. 7 of 60-pin connector (open circuit to cruise control switch).

60-Pin Terminal No. 7 To Ground. Scheme 263

Caravan, Mini Ram Van & Voyager 3.0L Wiring Diagram. Scheme 264

See also:
• CANISTER PURGE SOLENOID
• EMISSION CONTROL
• ERASING CODES FROM SMEC MEMORY
• DR-13 TEST - FUSED "J2" CIRCUIT TO SMEC (CODE 44)
• DR-16 TEST - WARM ENGINE SENSOR CALIBRATION CHECK
• DR-15 TEST - COLD ENGINE SENSOR CALIBRATION CHECK
• DR-19 TEST - BASIC IGNITION TIMING CHECK
• DR-20 TEST - CHECKING FUEL SUPPLY & RETURN SYSTEM
• DR21
• DR22
• CH-2 TEST - CHECKING BATTERY TEMPERATURE SENSOR CALIBRATION