Engine Controls - System/component Tests - Diesel Dodge Cab & Chassis Dakota

INTRODUCTION

Note. In mid-year, an intercooler was installed in front of the radiator. (Scheme 286) Note if the vehicle contains an intercooler before servicing engine components. Service procedures may vary on models with intercooler.

Scheme 286

TURBOCHARGERS

Note. The following items listed in INITIAL CHECKS can cause excessive smoke, low manifold pressure and loss of power.

Initial Checks

1. Check air intake for clogged air cleaner. Check for loose connections or cracks on suction (intake) side of turbocharger. Check for damage to compressor blades causing an imbalance and resulting in bearing failure.
2. Check for pressurized air leaking from loose connections and cracks in crossover tube from turbocharger to intake manifold cover on non-intercooled models. On intercooled models, check for air leaks at intercooler and intercooler ducts from turbocharger to intercooler and from intercooler to air inlet on intake manifold cover on intercooled models.
3. On all models, a soapy solution may be used to check for pressurized air leaks at intake manifold cover, crossover tube or intercooler and connections.
4. Check for exhaust leaks at exhaust manifold and turbocharger. Check for exhaust pipe restrictions and restricted or damaged turbocharger oil return line.
5. To verify a bearing failure or damaged compressor, remove intake and exhaust piping, and check for compressor or turbine wheel-to-housing contact. Compressor or turbine wheel must rotate freely. Measure shaft end play and radial clearance. See «SHAFT END PLAY & RADIAL CLEARANCE»(/dodge/cab-chassis-dakota/1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-diesel__shaft-end-play-radial-clearance) .

Boost Pressure

Boost pressure testing information is not available from manufacturer.

Shaft End Play & Radial Clearance

Shaft end play and radial clearance can be checked to determine if turbocharger repairs are required. Using a dial indicator, check shaft end play and radial clearance. (Scheme 287) Turbocharger must be repaired if clearances are not within specification. See TURBOCHARGER SPECIFICATIONS table.

TURBOCHARGER SPECIFICATIONS

Scheme 287

AIR TEMPERATURE SWITCH (INTERCOOLED)

1. Air temperature switch is located in the intake manifold cover. (Scheme 290) Air temperature switch is used for controlling KSB valve.
2. Air temperature switch is open when intake manifold air temperature is more than 60°F (16°C) and fully closed when temperature is less than 54°F (12°C). When air temperature switch is closed, voltage is applied to KSB valve. Not other information is available from manufacturer.

CHARGE AIR TEMPERATURE SENSOR

See CHARGE AIR TEMPERATURE SENSOR under EMISSION SYSTEMS & SUB-SYSTEMS.

COOLANT TEMPERATURE SWITCH (INTERCOOLED WITH A/T)

1. Coolant temperature switch is located in the cylinder head, below intake manifold, near air temperature switch. (Scheme 290) Coolant temperature switch opens when coolant temperature is less than 60°F (16°C).
2. When coolant temperature switch opens, transmission will not shift into overdrive. Transmission will downshift if it is in overdrive when coolant temperature switch opens. No other information is available from manufacturer.

PARK/NEUTRAL SWITCH (INTERCOOLED WITH A/T)

1. The park/neutral switch is located on side of transmission, near shift linkage. Remove electrical connector from park/neutral switch.
2. Using ohmmeter, check continuity between center terminal of park/neutral switch and transmission case. Continuity should exist when transmission is in Park or Neutral.
3. Place transmission in Reverse. Check for continuity between the outer terminals of park/neutral switch. Continuity should exist in Reverse only. Continuity should not exist between outer terminals and transmission case. Replace park/neutral switch if defective.

THERMISTOR (NON-INTERCOOLED)

Thermistor is used for controlling the intake manifold heater system. See THERMISTOR under INTAKE MANIFOLD HEATER SYSTEM (NON-INTERCOOLED MODELS) under EMISSION SYSTEMS & SUB-SYSTEMS.

THROTTLE POSITION SENSOR (INTERCOOLED WITH A/T)

1. Before checking TPS, ensure cable rod is adjusted so control lever contacts low-speed screw when in idle position.
2. Ensure control lever moves over center position and rests against breakover spring when in full throttle position. If adjustment is required, see THROTTLE LINKAGE in D - DIESEL ADJUSTMENTS article in ENGINE PERFORMANCE section.
3. Connect negative probe of voltmeter to ground. Turn ignition on. Backprobe center wire terminal at TPS electrical connector. With control lever contacting low-speed screw (idle position), voltage should be at least one volt. If voltage is not at least one volt, adjust TPS to obtain correct voltage using 10 mm wrench. (Scheme 288)
4. Open throttle to full throttle position. Backprobe center wire terminal at TPS electrical connector. Voltage should be at least 2.25 volts higher than voltage obtained with throttle in idle position. If voltage is not at least 2.25 volts more than idle position voltage, adjust TPS to obtain correct voltage. Replace TPS if it cannot be adjusted.

WATER-IN-FUEL SENSOR

1. Water-in-fuel sensor is located in bottom of fuel/water separator filter. (Scheme 289) The water-in-fuel sensor sends an input signal to SBEC (intercooled models) or air heater controller (non-intercooled models) when water exists in fuel/water separator filter.
2. SBEC or air heater controller will then turn on the WATER-IN-FUEL light on the message center in the cab. No other information is available from manufacturer.

VEHICLE SPEED SENSOR (INTERCOOLED MODELS)

Vehicle speed sensor is mounted on rear of transmission. No other information is available from manufacturer.

Scheme 288

Scheme 289

Non-Intercooled Models

Air heater controller is located in left rear corner of engine compartment, on driver's side of dash panel, near bulkhead wiring connector. No other information is available from manufacturer.

Intercooled Models

SBEC is located on left front corner of engine compartment, near horns on left fender. No other information is available from manufacturer.

Fuel Heater

1. Fuel heater is located between fuel/water separator filter and filter adapter on cylinder head. (Scheme 289) Voltage to operate fuel heater is provided from ignition switch.
2. A minimum of 7 volts is required for fuel heater operation. Fuel heater will operate when temperature is approximately 43°F (6°C) and shut off at approximately 53°F (13°C). Fuel heater resistance is 2.5-3.0 ohms. No other information is available from manufacturer.

Fuel Injector

1. To determine which fuel injector is defective, operate engine and loosen high-pressure fuel line nut at fuel injector. CAUTION: Carefully loosen high-pressure fuel line nut. Fuel is under excessive pressure and will spray out around fuel line nut.
2. Listen for a change in engine RPM. If engine RPM decreases, fuel injector is operating properly. If engine RPM stays the same, fuel injector or engine components are defective. Ensure all high-pressure fuel line nuts are tightened to 18 ft. lbs. (24 N.m).

Fuel Lift Pump

1. Fuel lift pump is located on left rear side of engine. (Scheme 289) To check lift pump vacuum, disconnect fuel supply line at fuel lift pump. Install vacuum gauge on a fitting between fuel supply line and fuel lift pump.
2. Operate engine at approximately 1500 RPM for 30 seconds, and note vacuum reading. If vacuum reading exceeds 3.75 in. Hg, check for restriction in fuel/water separator filter or fuel supply line.
3. Check fuel lift pump output pressure and volume at cranking speed. Replace fuel lift pump if not within specification. See «FUEL LIFT PUMP SPECIFICATIONS»(/dodge/cab-chassis-dakota/1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-diesel) table. FUEL LIFT PUMP SPECIFICATIONS Application Output Pump Pressure 3 psi minimum (.2 kg/cm 2 ) Volume Within 30 Seconds.7 qts. (.6L) CAUTION: Defective fuel lift pump can create low engine power and long cranking periods. Hand lever must be in upward position to provide proper engine operation.

SHUTOFF SOLENOID VALVE

1. Shutoff solenoid valve is located on rear side of fuel injection pump. (Scheme 289) Using voltmeter, ensure at least 10 volts exists at shutoff solenoid valve.
2. If at least 10 volts exists, remove shutoff solenoid valve from fuel injection pump. CAUTION: DO NOT attach power supply to shutoff solenoid valve with plunger removed, or valve assembly will be damaged.
3. Remove plunger and spring from fuel injection pump. Reinstall shutoff solenoid valve with electrical connector disconnected. If engine starts, replace shutoff solenoid valve. NOTE: Engine must be shut off using manual shutdown lever when plunger and spring are removed. (Scheme 289)
4. If engine does not start, shutoff solenoid valve is not the problem, fuel system or engine should be checked for proper operation. Reinstall plunger, spring and shutoff solenoid valve. Tighten shutoff solenoid valve to 32 ft. lbs. (43 N.m).

INTAKE MANIFOLD HEATER SYSTEM (INTERCOOLED MODELS)

Note. Intake manifold heater will operate when intake manifold air temperature is less than 59°F (15°C).

Charge air temperature sensor is located in intake manifold cover. (Scheme 290) Charge air temperature sensor monitors intake manifold air temperature and sends signal to Single Board Engine Controller (SBEC). SBEC controls intake manifold heater. No other information is available from manufacturer.

Scheme 290

INTAKE MANIFOLD HEATER

1. Disconnect electrical leads from intake manifold heater. Intake manifold heater is located between air inlet housing and intake manifold. Isolate electrical leads from contacting other components.
2. Using ohmmeter, measure continuity to ground from each terminal on intake manifold heater. Replace intake manifold heater if continuity exists.

Scheme 291

1. Intake manifold heater relays are mounted on the inner wheelwell. (Scheme 291) Intake manifold heater relays are energized by SBEC depending on intake manifold air temperature monitored by the charge air temperature sensor.
2. Intake manifold heater relays are not energized during engine cranking. A clicking sound will be heard when relays are energized. No other information is available from manufacturer. CAUTION: Intake manifold heater relays should not be cycled (ignition turned off and then on) more than once within 15 minutes. Wait 15 minutes before turning ignition on. NOTE: During preheat/postheat cycle, if intake manifold air temperature is less than 59°F (15°C), intake manifold heater will preheat before engine starts. For normal preheat/postheat cycle operating ranges, see «HEAT CYCLE SPECIFICATIONS (INTERCOOLED)»(/dodge/cab-chassis-dakota/1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-diesel) table.

PREHEAT/POSTHEAT CYCLE

1. With intake manifold air temperature less than 60°F (16°C), turn ignition on. The WAIT-TO-START light on the message center in the cab should come on. A "click" sound should be heard at intake heater relays to indicate preheat cycle.
2. Using voltmeter, check for battery voltage at both terminals on intake manifold heater. Intake manifold heater is located between air inlet housing and intake manifold.
3. Voltage should exist at intake manifold heater terminals for 10-20 seconds. Preheat cycle should operate for specified amount of time depending on intake manifold temperature. See «HEAT CYCLE SPECIFICATIONS (INTERCOOLED)»(/dodge/cab-chassis-dakota/1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-diesel) table. HEAT CYCLE SPECIFICATIONS (INTERCOOLED) Intake Manifold Air Temperature °F (°C) Preheat Cycle Engine Off Postheat Cycle Engine On Above 59 (15) 0 Seconds No 18 (-8) to 59 (15) 10 Seconds Yes 1 (-17) to 16 (-9) 15 Seconds Yes -15 (-26) to 0 (-18) 17.5 Seconds Yes Below -15 (-26) 20 Seconds Yes

INTAKE MANIFOLD HEATER SYSTEM (NON-INTERCOOLED MODELS)

Note. Intake manifold heater will operate when intake manifold air temperature is below 59°F (15°C).

Thermistor

1. Thermistor is located in intake manifold cover. (Scheme 289) Thermistor monitors intake manifold air temperature and sends signal to air heater controller.
2. Disconnect electrical connector from thermistor. Turn ignition on. The WAIT-TO-START light on the message center in the cab should come on. A "click" sound should be heard at intake heater relays to indicate preheat cycle. Intake manifold heater relays are mounted on the inner wheelwell. (Scheme 291)
3. The WAIT-TO-START light should remain on for 20 seconds. After 20 seconds, the WAIT-TO-START light should turn off and intake heater relays should shut off.
4. After another 20 seconds, the WAIT-TO-START light should start to flash. This indicates an open circuit because electrical connector is disconnected from thermistor.
5. Using voltmeter, check for voltage between ground and KSB valve. The KSB valve is located on side of the fuel injection pump. (Scheme 289) No voltage should exist at the KSB valve. Reconnect electrical connector on thermistor.

1. Disconnect electrical leads from intake manifold heater. Isolate electrical leads from contacting other components. Intake manifold heater is located between crossover tube from turbocharger and the intake manifold.
2. Using ohmmeter, measure continuity to ground from each terminal on intake manifold heater. Replace intake manifold heater if continuity exists.

Intake Manifold Heater Relays

1. Intake manifold heater relays are mounted on the inner wheelwell. (Scheme 291) Intake manifold heater relays are energized by the air heater controller depending on intake manifold air temperature monitored by the thermistor.
2. Intake manifold heater relays are not energized during engine cranking. A clicking sound will be heard when relays are energized. CAUTION: Intake manifold heater relays should not be cycled (ignition turned off then on) more than once within 15 minutes. Wait 15 minutes before turning ignition on. NOTE: During preheat/postheat cycle, if intake manifold air temperature is less than 59°F (15°C), intake manifold heater will preheat before engine starts. For normal preheat/postheat cycle operating ranges, see «HEAT CYCLE SPECIFICATIONS (NON-INTERCOOLED)»(/dodge/cab-chassis-dakota/1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-diesel) table.

1. With intake manifold air temperature less than 59°F (15°C), turn ignition on. The WAIT-TO-START light on the message center in the cab should come on. A "click" sound should be heard at intake heater relays to indicate preheat cycle.
2. Using voltmeter, check for battery voltage at both terminals on intake manifold heater. Intake manifold heater is located between crossover tube from turbocharger and intake manifold.
3. Voltage should exist at intake manifold heater terminals for 10-20 seconds. Preheat cycle should operate for specified amount of time depending on intake manifold temperature. See «HEAT CYCLE SPECIFICATIONS (NON-INTERCOOLED)»(/dodge/cab-chassis-dakota/1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-diesel) table.
4. Using voltmeter, check for voltage between ground and KSB valve. The KSB valve is located on side of the fuel injection pump. (Scheme 289) No voltage should exist at the KSB valve. HEAT CYCLE SPECIFICATIONS (NON-INTERCOOLED) Intake Manifold Air Temperature °F (°C) Preheat Cycle Engine Off Postheat Cycle Engine On Above 59 (15) 0 Seconds No 15 (-9) to 59 (15) 10 Seconds Yes 0 (-18) to 15 (-9) 15 Seconds Yes -15 (-26) to 0 (-18) 17.5 Seconds Yes Below -15 (-26) 20 Seconds Yes

Intercooled

1. KSB valve is located on side of the fuel injection pump. (Scheme 289) KSB valve wiring circuit contains 3-ohm resistor and air temperature switch. Air temperature switch is located in the intake manifold cover. (Scheme 290)
2. Air temperature switch is open when intake manifold air temperature is more than 60°F (16°C) and fully closed when temperature is less than 54°F (12°C). The KSB valve should "click" when 10 volts is applied to KSB valve when air temperature switch is fully closed. CAUTION: DO NOT apply 12 volts to KSB valve. Wiring circuit contains a 3-ohm resistor to decrease voltage to KSB valve to 10 volts.

Non-Intercooled

1. The KSB valve is located on side of the fuel injection pump. (Scheme 289)
2. The KSB valve is activated by air heater controller when thermistor determines that intake manifold air temperature is more than 59°F (15°C). Thermistor is located in intake manifold cover. (Scheme 289)

1. Coolant temperature switch is located in the cylinder head, below intake manifold, near air temperature switch. (Scheme 290)
2. Coolant temperature switch opens when coolant temperature is less than 60°F (16°C).
3. When coolant temperature switch opens, transmission will not shift into overdrive. Transmission will downshift if it was in overdrive when coolant temperature switch opens. No other information is available from manufacturer.

TRANSMISSION OVERDRIVE OVERRIDE SWITCH (INTERCOOLED WITH A/T)

1. Switch is mounted in instrument panel. The switch is normally closed. If switch is depressed and switch opens, transmission will not go into overdrive.
2. Transmission will downshift if transmission is in overdrive and switch is depressed. No other information is available from manufacturer.

Scheme 292

Scheme 293

1. Transmission thermoswitch is located in transmission-to-radiator oil cooler line. Transmission thermoswitch opens when transmission fluid temperature is more than 273°F (134°C) and closes at 240°F (116°C).
2. If transmission is in overdrive and thermoswitch opens, transmission will downshift. Once switch closes, SBEC will send a signal to transmission to shift into overdrive. No other information is available from manufacturer. (Scheme 292): Intake Heater System Wiring Diagram (Non-Intercooled Models) (Scheme 293): Intake Heater System Wiring Diagram (Intercooled Models)

See also:
• INITIAL CHECKS
• SHAFT END PLAY & RADIAL CLEARANCE
• TURBOCHARGER SPECIFICATIONS
• THERMISTOR