Engine Controls - System/component Tests - 5.9l Diesel Dodge Pickup R2500

INTRODUCTION

Before testing separate components or systems, perform procedures in appropriate BASIC TESTING - 5.9L DIESEL article. Since many computer-controlled and monitored components set a diagnostic trouble code if they malfunction, also perform procedures in appropriate TESTS W/CODES - 5.9L article.

Note. Testing individual components does not isolate short or open circuits. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate shorted or open wiring harness.

INTAKE MANIFOLD AIR HEATER SYSTEM

See INTAKE MANIFOLD AIR HEATER SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS.

INTERCOOLER

Cleaning and inspection procedures for the intercooler is the only information available. See INTERCOOLER under AIR INDUCTION SYSTEM in REMOVE/INSTALL/OVERHAUL - DIESEL article.

TURBOCHARGER

Note. Manufacturer does not recommend turbocharger disassembly. Turbocharger overhaul should be performed only by an authorized repair facility.

Turbocharger Boost Pressure

Turbocharger boost pressure testing information is not available.

POWERTRAIN CONTROL MODULE (PCM)

The PCM is located at passenger's side rear corner of engine compartment, on the firewall. The PCM power and ground circuits may be checked by performing specified No Trouble Code (NTC) test. See TEST NTC-11A CHECKING PCM POWER & GROUND CIRCUITS in TESTS W/CODES - 5.9L article.

Battery Temperature Sensor

1. Battery temperature sensor is snapped into the battery tray, below driver's side battery. Disconnect wiring harness at battery temperature sensor.
2. Using ohmmeter, check resistance between electrical terminals on battery temperature sensor. Resistance should be 9000-11,000 ohms at 75-80°F (25-27°C). Replace battery temperature sensor if resistance is not within specification.
3. If problem exists in battery temperature sensor or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in the PCM. See appropriate «TESTS W/CODES - 5.9L»(/dodge/pickup-r2500/1997-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-59l-gas-diesel) article.

Engine Coolant Temperature Sensor (Calif. Models With EGR)

1. Engine coolant temperature sensor is located on driver's side of engine, behind fuel filter/water separator, just below intake manifold. (Scheme 200)
2. Disconnect wiring harness electrical connector for engine coolant temperature sensor from engine wiring harness. Wiring harness electrical connector is located near top of fuel filter/water separator.
3. Using ohmmeter, check resistance between electrical terminals on wiring harness electrical connector for engine coolant temperature sensor. Replace engine coolant temperature sensor if resistance is not within specification in relation to engine coolant temperature. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE table.
4. If problem exists in engine coolant temperature sensor or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in the PCM. See appropriate «TESTS W/CODES - 5.9L»(/dodge/pickup-r2500/1997-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-59l-gas-diesel) article.

ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE

Scheme 200

Engine Speed Sensor

Engine speed sensor may also be referred to as Crankshaft Position (CKP) sensor. Engine speed sensor is located on front of timing gear cover, just above vibration damper. If problem exists in engine speed sensor, a Diagnostic Trouble Code (DTC) will be stored in the PCM. See appropriate TESTS W/CODES - 5.9L article.

Fuel Heater Temperature Sensor

See FUEL DELIVERY under FUEL SYSTEM.

Intake Manifold Air Temperature Sensor

1. Intake manifold air temperature sensor is located on intake manifold, behind intake manifold air heater. (Scheme 205)
2. Disconnect electrical connector from intake manifold air temperature sensor. Using ohmmeter, check resistance between electrical terminals on intake manifold air temperature sensor. Resistance should be within specification in relation to the air temperature. See INTAKE MANIFOLD AIR TEMPERATURE SENSOR RESISTANCE table. Replace intake manifold air temperature sensor if resistance is not within specification.
3. To check wiring harness, use ohmmeter to check resistance on wires between intake air temperature sensor and Powertrain Control Module (PCM). The PCM is located at passenger's side rear corner of engine compartment, on the firewall.
4. Using ohmmeter, check resistance on Black/Red wire between intake air temperature sensor and terminal A15 (Black/Red wire) on Black 32-pin PCM connector. Check resistance on Black/Light Blue wire between intake air temperature sensor and terminal A4 (Black/Light Blue wire) on Black 32-pin PCM connector. Resistance should be one ohm or less. Repair wiring if resistance is more than one ohm.
5. If problem exists in intake air temperature sensor or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in the PCM. See appropriate «TESTS W/CODES - 5.9L»(/dodge/pickup-r2500/1997-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-59l-gas-diesel) article.

INTAKE MANIFOLD AIR TEMPERATURE SENSOR RESISTANCE

Throttle Position Sensor (A/T Models & M/T Models With EGR)

For testing and adjustment of throttle position sensor, see THROTTLE POSITION SENSOR ADJUSTMENT under THROTTLE POSITION SENSOR in appropriate ADJUSTMENTS - 5.9L DIESEL article.

Transmission Governor Pressure Sensor (A/T Models)

See TRANSMISSION under MISCELLANEOUS CONTROLS.

Transmission Speed Sensor (A/T Models)

See TRANSMISSION under MISCELLANEOUS CONTROLS.

Transmission Temperature Sensor (A/T Models)

See TRANSMISSION under MISCELLANEOUS CONTROLS.

Vehicle Speed Sensor

Vehicle speed sensor is mounted on transmission extension housing (2WD) or transfer case (4WD). If problem exists in vehicle speed sensor or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM. See appropriate TESTS W/CODES - 5.9L article.

Water-In-Fuel (WIF) Sensor

Water-in-fuel sensor is located in bottom of fuel filter/water separator. (Scheme 205) Testing information is not available.

A/C Switch

Testing information is not available.

Brake Switch

1. Remove lower panel for access to brake switch. Brake switch is located on bracket, near top of brake pedal.
2. Disconnect electrical connector from brake switch. Pull plunger on brake switch fully outward. (Scheme 201)
3. Using ohmmeter, check for continuity between terminals No. 5 and 6 on brake switch. (Scheme 201) Continuity should exist. If continuity exists, go to next step. If continuity does not exist, replace brake switch.
4. Push plunger on brake switch fully inward. Using ohmmeter, check for continuity between terminals No. 1 and 2, and 3 and 4 on brake switch. (Scheme 201) Continuity should exist. If continuity does not exist, replace brake switch.

Scheme 201

Park/Neutral Switch (A/T Models)

See TRANSMISSION under MISCELLANEOUS CONTROLS.

Transmission Overdrive Switch (A/T Models)

See TRANSMISSION under MISCELLANEOUS CONTROLS.

A/C Clutch Relay

A/C clutch relay may also be referred to as A/C relay. A/C clutch relay is located in power distribution center at driv-her's side front corner of engine compartment, near the battery. If problem exists in A/C clutch relay or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM. See TESTS W/CODES - 5.9L article.

Auto Shutdown (ASD) Relay

ASD relay is located in power distribution center at driver's side front corner of engine compartment, near the battery. If problem exists in ASD relay or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM. See TESTS W/CODES - 5.9L article.

Fuel Heater Relay & Fuel Shutdown Solenoid Relay

Fuel heater relay and fuel shutdown solenoid relay are located in the engine compartment, next to the brake master cylinder. (Scheme 202) Individual component testing is not available. Consult wiring diagram for relay testing. See wiring diagram in WIRING DIAGRAMS - 5.9L - DIESEL article.

Scheme 202

Intake Manifold Air Heater Relays

1. Intake manifold air heater relays may also be referred to as intake air heater relays. Intake manifold air heater relays are mounted on inner wheelwell, below driver's side battery. (Scheme 203)
2. Disconnect negative battery cables. Note location of wiring on intake manifold air heater relays for reassembly reference. Disconnect all electrical connectors and cables from intake manifold air heater relays.
3. Connect ohmmeter between large terminals of intake manifold air heater relay to check for continuity. Momentarily apply battery voltage and ground to relay trigger wire terminals (small terminals) on intake manifold air heater relay.
4. Intake manifold air heater relay should click and ohmmeter should indicate continuity between the large terminals. If operation is not as specified, replace intake manifold air heater relay. Test remaining intake manifold air heater relay. Remove ohmmeter. Reconnect all electrical connectors and negative battery cables.

Scheme 203

Transmission Relay (A/T Models)

Transmission relay may be referred to as transmission control relay. Transmission relay is located in power distribution center at driver's side front corner of engine compartment, near the battery. If problem exists in transmission relay or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM. See appropriate TESTS W/CODES - 5.9L article.

EGR Valve Vacuum Regulator Solenoid (Calif. Models Only)

See EMISSION SYSTEMS & SUB-SYSTEMS.

Fuel Shutdown Solenoid (Preliminary Check)

1. Ensure ignition switch is in OFF position. Check that lever pin on fuel shutdown solenoid is extended downward and pump lever is in SHUTDOWN position. (Scheme 204)
2. Turn ignition switch to START position while noting if lever pin and pump lever move upward to the RUN position. (Scheme 204) Release ignition switch from START position to the ON position. Ensure lever pin and pump lever remain in the RUN position.
3. If solenoid operates as specified, solenoid and wiring are okay. If solenoid does not operate as specified, go to appropriate procedure as follows, depending solenoid lever pin operation.

Fuel Shutdown Solenoid Does Not Operate (Lever Pin Does Not Move Upward At All)

1. Disconnect electrical connector at fuel shutdown solenoid. While holding ignition switch in START position, use voltmeter to check voltage at Red/Violet wire terminal on wiring harness side of electrical connector. Red/Violet wire goes to fuel shutdown solenoid relay. Battery voltage should exist.
2. If battery voltage exists, replace fuel shutdown solenoid. See FUEL SHUTDOWN SOLENOID under FUEL SYSTEM in «REMOVE/INSTALL/OVERHAUL - 5.9L»(/dodge/pickup-r2500/1997-1998/remont/removal-installation/#engine-controls-component-removeinstalloverhaul-59l) article.
3. If battery voltage does not exist, check fuel shutdown solenoid relay and wiring circuit. Fuel shutdown solenoid relay is located in engine compartment, next to the brake master cylinder. (Scheme 202) Consult wiring diagram for relay and wiring circuit testing. See appropriate wiring diagram in «WIRING DIAGRAMS - 5.9L - DIESEL»(/dodge/pickup-r2500/1997-1998/remont/wiring-diagrams-engine-performance/#wiring-diagrams-59l-engine-diesel) article.
4. If fuel shutdown solenoid relay is okay, check for open circuit on Red/Violet wire between fuel shutdown solenoid relay and fuel shutdown solenoid, and for open wiring circuit to fuel solenoid shutdown relay from battery and starter motor. See appropriate wiring diagram in «WIRING DIAGRAMS - 5.9L - DIESEL»(/dodge/pickup-r2500/1997-1998/remont/wiring-diagrams-engine-performance/#wiring-diagrams-59l-engine-diesel) article.

Fuel Shutdown Solenoid Operates Only With Ignition Switch In START Position (Lever Pin Moves Upward But Does Not Stay Up)

1. Disconnect electrical connector at fuel shutdown solenoid. Turn ignition switch to ON position.
2. Using voltmeter, check voltage at Light Green/Black wire terminal on wiring harness side of electrical connector. This is the wire from ignition switch and fuse No. 9 (10-amp) to the fuel shutdown solenoid. Fuse No. 9 is located in fuse block on end of instrument panel, at driv-er's door opening.
3. If battery voltage exists, replace fuel shutdown solenoid. See FUEL SHUTDOWN SOLENOID under FUEL SYSTEM in «REMOVE/INSTALL/OVERHAUL - DIESEL»(/dodge/pickup-r2500/1997-1998/remont/removal-installation/#engine-controls-component-removeinstalloverhaul-59l-diesel) article.
4. If battery voltage does not exist, repair open circuit on Light Green/Black wire between ignition switch and fuel shutdown solenoid. See wiring diagram in «WIRING DIAGRAMS - 5.9L - DIESEL»(/dodge/pickup-r2500/1997-1998/remont/wiring-diagrams-engine-performance/#wiring-diagrams-59l-engine-diesel) article.

Transmission Overdrive Solenoid (A/T Models)

See TRANSMISSION under MISCELLANEOUS CONTROLS.

Transmission Torque Converter Clutch Solenoid (A/T Models)

See TRANSMISSION under MISCELLANEOUS CONTROLS.

Scheme 204

Scheme 205

Fuel Filter/Water Separator

1. A restricted fuel filter/water separator may cause engine starting problems, prevent engine from accelerating, low power, or Blue or White exhaust smoke.
2. When ignition switch is first turned to ON position, Water-In-Fuel (WIF) warning light on instrument panel should come on for 2 seconds to perform bulb and wiring circuit test and then go off.
3. If warning light stays on, water should be drained from fuel filter/water separator. To drain water from fuel filter/water separator, with engine off, place drain pan below drain tube at fuel filter/water separator. (Scheme 205)
4. Rotate handle on drain valve forward, toward front of vehicle to drain water from fuel filter/water separator. Drain valve is located at top of fuel filter/water separator. (Scheme 205)
5. If no water exists and a clean flow of diesel fuel exists, close drain valve. Go to next step. If water exists, allow water to drain until clean flow of diesel fuel exists. Close drain valve. Go to next step.
6. Verify fuel filter/water separator has been serviced according to proper service schedule. See SERVICE INTERVALS & SPECIFICATIONS under QUICK-SERVICE in «SPECIFICATIONS - 5.9L»(/dodge/pickup-r2500/1997-1998/remont/specifications/#engine-controls-service-adjustment-specifications-59l) article. Ensure pre-filter was cleaned when fuel filter/water separator was serviced. Pre-filter is located at bottom of fuel heater on driver's side of engine. (Scheme 205) No other testing information is available.

Fuel Heater

1. Malfunctioning fuel heater may cause excessive wax build-up in the fuel filter/water separator during cold ambient temperatures. Wax build-up may cause engine starting problems, prevent engine from accelerating, low power, or Blue or White exhaust smoke.
2. Disconnect electrical connector at fuel heater located on driver's side of engine, just above pre-filter. (Scheme 205) Using ohmmeter, check resistance between electrical terminals on fuel heater.
3. Resistance should be about one ohm when fuel is cold, and about 1000 ohms when fuel is warm. Replace fuel heater if resistance is not within specification.

Note. Fuel heater receives battery voltage from fuel heater relay. Fuel heater relay is located in engine compartment, next to brake master cylinder. (Scheme 202) Consult wiring diagram for relay and wiring circuit testing. See appropriate wiring diagram in WIRING DIAGRAMS - 5.9L - DIESEL article.

1. Disconnect electrical connector at fuel heater. (Scheme 205) Fuel heater temperature sensor is located on fuel heater. (Scheme 205) Using ohmmeter, check for continuity between electrical terminals for fuel heater temperature sensor.
2. If fuel temperature is greater than 80°F (26.7°C), no continuity should exist. If fuel temperature is less than 40°F (4.4°C), continuity should exist. Replace fuel heater temperature sensor if continuity is not as specified.

Note. Defective fuel transfer pump may cause low power and/or hard starting. Check fuel transfer pump output pressure and then fuel transfer pump output volume. Low fuel transfer pump output pressure may also be caused by worn eccentric on engine camshaft.

Fuel Transfer Pump Preliminary Inspection

1. Check for restricted or leaking fuel supply line to fuel transfer pump located on driver's side of engine. (Scheme 205) Repair fuel supply line if restricted or leaking.
2. Check for fuel leaking from weep hole on housing of fuel transfer pump. Replace fuel transfer pump if fuel is leaking from weep hole. Check fuel transfer pump output pressure.

Fuel Transfer Pump Output Pressure

1. Place drain pan below fuel injection pump. Remove banjo bolt, gaskets and disconnect fuel supply line from side of fuel injection pump. (Scheme 206)
2. Using Adapter (6976) and gaskets, reconnect fuel supply line on side of fuel injection pump. (Scheme 206) Install a 0-100 psi fuel pressure gauge on adapter.
3. Start engine and warm engine to normal operating temperature. Record output pressure with engine idling and then at 2500 RPM with no load. Output pressure should be 17-22 psi (117-152 kg/cm 2 ) at idle and 25-30 psi (172-207 kPa) at 2500 RPM with no load.
4. If output pressure is within specification, go to step 11). If output pressure exceeds specification, go to next step. If output pressure is less than specified, go to step 6).
5. High output pressure indicates a restriction. Check that overflow valve is installed on fuel return line on fuel injection, and not on the fuel supply line. Overflow valve is used to secure fuel return line on fuel injection pump. (Scheme 207) If overflow valve is installed in the improper fuel line, reinstall in correct location and recheck output pressure. If overflow valve is installed in correct location, check for fuel line restrictions.
6. Check for dirty or restricted fuel filter/water separator and pre-filter. Fuel filter/water separator and pre-filter are located on driver's side of engine. (Scheme 205) Pre-filter is located at bottom of fuel heater.
7. Change dirty or restricted fuel filter/water separator or pre-filter as necessary and recheck output pressure. If output pressure is now within specification, go to step 11). If output pressure is still less than specified, overflow valve on fuel injection pump may be defective. Overflow valve is used to secure fuel return line on fuel injection pump. (Scheme 207) Go to next step.
8. To determine if overflow valve is defective, carefully pinch fuel return line closed and note output pressure. Fuel return line is located at rear of engine (Scheme 205)
9. If output pressure is still less than specified, go to next step. If output pressure is now within specification, check that overflow valve is installed on fuel return line on fuel injection, and not on the fuel supply line. If overflow valve is installed in correct location, replace overflow valve. If overflow valve is installed in the improper fuel line, reinstall in correct location and recheck output pressure.
10. If output pressure is still less than specified with fuel return line pinched closed, ensure fuel filter/water separator or pre-filter are in good condition. If fuel filter/water separator and pre-filter are okay, replace transfer pump.
11. Shut engine off. Remove test equipment. Reinstall fuel supply line on fuel injection pump. Install and tighten fuel supply banjo bolt to 18 ft. lbs. (24 N.m). Check fuel transfer pump output volume. See FUEL TRANSFER PUMP OUTPUT VOLUME.

Scheme 206

Scheme 207

Fuel Transfer Pump Output Volume

1. Disconnect electrical connector for fuel shutdown solenoid. Fuel shutdown solenoid is located on driver's side of engine. (Scheme 205) This is done to prevent engine from starting, as engine must be cranking to check fuel transfer pump output volume.
2. Connect hand-held Tachometer (3377462) to engine. Remove fuel drain line-to-cylinder head clamp bolt near cylinder No. 5 rocker lever cover to prevent damage to fuel drain line when disconnecting fuel drain line from fuel filter/water separator. Remove banjo bolt and disconnect fuel drain line from fuel inlet line at top of fuel filter/water separator. (Scheme 208)
3. Using Adapter (6836), secure fuel inlet line to top of fuel filter/water separator. (Scheme 208) Connect rubber hose on adapter. Place remaining end of rubber hose in graduated container which measures ounces.
4. Crank engine for 30 seconds while noting engine cranking speed RPM. DO NOT crank engine for more than 30 seconds or starter may be damaged. Note amount of fuel volume obtained.
5. To determine fuel transfer pump output volume specification, use engine cranking speed RPM and fuel volume. (Scheme 209)
6. For example: if engine cranking speed is 250 RPM and fuel volume was 13.6 ounces, fuel transfer pump output volume would be within specification, as this was above the flow line. If engine cranking speed was 250 RPM and fuel volume was 11.9 ounces, this would be an inadequate fuel transfer pump output volume, as this was below the flow line.
7. If fuel transfer pump output volume is less than specified, condition may be caused by a restricted fuel supply inlet line, restricted pre-filter or defective transfer pump. Remove test equipment. Reinstall fuel drain line and electrical connector for fuel shutdown solenoid.

Scheme 208

Scheme 209

Overflow Valve

Overflow valve is used to secure fuel return line on fuel injection pump. (Scheme 207) A sticking check valve in the overflow valve may result in low power. Overflow valve operation may be checked when testing fuel transfer pump output volume. See FUEL TRANSFER PUMP OUTPUT VOLUME under FUEL DELIVERY.

FUEL CONTROL

Note. A leaking fuel injector or high-pressure fuel line may cause a rough idle, Black smoke, poor engine performance, poor fuel economy and fuel knock. Following procedure is for determining if fuel injector is defective.

Fuel Injector

1. Since a leaking high-pressure fuel line may cause the same symptoms, check for leaking high-pressure fuel line before checking fuel injector. To check for a leaking high-pressure fuel line, start engine and allow engine to idle.
2. Inspect high-pressure fuel lines and connections for signs of fuel leakage by placing cardboard over high-pressure fuel line and connection. Note if leak is being detected by fuel being sprayed onto the cardboard. If leak exists, repair leak by tightening high-pressure fuel line nut to 22 ft. lbs. (30 N.m) or replacing high-pressure fuel line as necessary. If high-pressure fuel line is replaced, bleed air from fuel system. See FUEL LINE BLEEDING under FUEL SYSTEM in appropriate «REMOVE/INSTALL/OVERHAUL - DIESEL»(/dodge/pickup-r2500/1997-1998/remont/removal-installation/#engine-controls-component-removeinstalloverhaul-59l-diesel) article.
3. To check for defective fuel injector, start engine and allow engine to idle. Loosen high-pressure fuel line nut at fuel injector and listen for a decrease in engine speed. Tighten high-pressure fuel line nut to 22 ft. lbs. (30 N.m).
4. If fuel injector is operating properly, engine idle speed should decrease when high-pressure fuel line nut is loosened. Repeat procedure on each fuel injector.
5. If a fuel injector is suspected to be faulty, fuel injector should be removed and tested with a diesel fuel injector tester. Replace fuel injector if fuel injector opening pressure is not 3394-3887 psi (23,400-26,800 kPa).

Fuel Shutdown Solenoid

See SOLENOIDS under RELAYS & SOLENOIDS.

EGR System Test

1. Check for Diagnostic Trouble Codes (DTCs) pertaining to EGR system. See appropriate «TESTS W/CODES - 5.9L»(/dodge/pickup-r2500/1997-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-59l-gas-diesel) article. If no DTCs exist pertaining to EGR system, go to next step. If any DTCs exist for EGR system, ensure repair procedures for DTC are performed and then proceed to next step. NOTE: EGR valve operation cannot be checked by applying vacuum to EGR valve with engine idling, as opening of EGR valve will not affect the engine idle speed.
2. Using scan tool, follow scan tool manufacturer's instructions and check operation of EGR valve vacuum regulator solenoid and electrical circuit. If EGR valve vacuum regulator solenoid and electrical circuit is operating properly, go to next step. If EGR valve vacuum regulator solenoid and electrical circuit is not operating properly, repair system as necessary and go to next step.
3. Start engine and allow engine to idle. Check that vacuum exists on inlet side of EGR valve vacuum regulator solenoid. EGR valve vacuum regulator solenoid is located on driver's side of engine, just in front of EGR valve. (Scheme 210)
4. If vacuum exists at inlet side of EGR valve vacuum regulator solenoid, go to next step. If vacuum does not exist at inlet side of EGR valve vacuum regulator solenoid, check vacuum pump operation. See VACUUM PUMP OPERATION.
5. Check operation of EGR valve. See EGR VALVE. If EGR valve operates properly, check operation of EGR valve one-way check valve. See EGR VALVE ONE-WAY CHECK VALVE.

Scheme 210

EGR Valve

1. Remove EGR valve from intake manifold and EGR tube. (Scheme 210)
2. Inspect EGR valve for excessive carbon deposits on head of poppet valve at base opening at end of EGR valve. (Scheme 211) Using flashlight, apply light at poppet valve opening and seat area on EGR valve. Light should not pass through poppet valve opening and seat area.
3. If no excessive carbon deposits exist and light does not pass through poppet valve opening and seat area, go to next step. If excessive carbon deposits exist or light passes through poppet valve opening and seat area, replace EGR valve. DO NOT attempt to clean poppet valve and seat area in EGR valve.
4. To check EGR valve operation, use vacuum pump to slowly apply 10 in. Hg of vacuum on EGR valve and note operation of poppet valve. (Scheme 211)
5. If poppet valve starts to open when 10 in. Hg of vacuum is applied and vacuum holds steady, go to next step. If poppet valve does not start to open when 10 in. Hg of vacuum is applied or vacuum does not hold steady, replace EGR valve.
6. Continue to increase vacuum supply to 20 in. Hg. Poppet valve should be fully open at approximately 20 in. Hg and vacuum should hold steady.
7. If poppet valve is fully open with 20 in. Hg of vacuum applied and vacuum holds steady, go to next step. If poppet valve does not fully open with 20 in. Hg of vacuum applied or vacuum does not hold steady, replace EGR valve.
8. EGR valve is operating properly. If EGR valve is operating properly, but EGR system does not operate, check for restricted passages in EGR tube, exhaust manifold and intake manifold due to excessive carbon deposits. EGR tube fits between intake manifold and exhaust manifold. (Scheme 210)

Scheme 211

EGR Valve Vacuum Regulator Solenoid

1. EGR valve vacuum regulator solenoid is located on driver's side of engine, just in front of EGR valve. (Scheme 210) EGR valve vacuum regulator solenoid controls the vacuum to EGR valve and is controlled by the Powertrain Control Module (PCM).
2. For checking operation of EGR valve vacuum regulator solenoid and electrical circuit, use scan tool and follow scan tool manufacturer's instructions. If EGR valve vacuum regulator solenoid and electrical circuit is not operating properly, repair system as necessary and go to next step.

EGR Valve One-Way Check Valve

1. EGR valve one-way check valve is located between EGR valve and EGR valve vacuum regulator solenoid on driver's side of engine. (Scheme 210)
2. EGR valve one-way check valve allows vacuum to be quickly released from EGR valve. If EGR valve one-way check valve is defective, EGR valve may remain open as vacuum is not released from EGR valve, or EGR valve may not operate, as vacuum supply to EGR valve is being released.
3. Using "T" fitting, install vacuum gauge in vacuum hose between EGR valve and EGR valve vacuum regulator solenoid. EGR valve vacuum regulator solenoid is located on driver's side of engine, just in front of EGR valve. (Scheme 210)
4. Start engine and warm engine to normal operating temperature to allow EGR system operation. Road test vehicle while driving at a steady speed and observing vacuum reading.
5. High vacuum should be obtained when driving at a steady speed. Quickly open the throttle and note vacuum reading. Vacuum should rapidly decrease to no vacuum when throttle is opened.
6. If vacuum does not quickly decrease to no vacuum, go to next step. If vacuum quickly decreases to no vacuum, EGR valve one-way check valve is operating properly. Remove vacuum gauge and reconnect vacuum hose.
7. Using scan tool, follow scan tool manufacturer's instructions and check operation of EGR valve vacuum regulator solenoid and electrical circuit. If EGR valve vacuum regulator solenoid and electrical circuit is operating properly, but vacuum does not decrease to no vacuum, go to next step. If EGR valve vacuum regulator solenoid and electrical circuit is not operating properly, repair system as necessary.
8. Remove vacuum gauge. Disconnect vacuum hoses from both vacuum hose fittings on EGR valve one-way check valve. Install vacuum pump on solenoid side of EGR valve one-way check valve. (Scheme 212) This is the side that goes to EGR valve vacuum regulator solenoid. NOTE: Ensure at least 20 in. Hg of vacuum is applied on EGR valve one-way check valve when testing.
9. Plug EGR valve side of EGR valve one-way check valve. Apply at least 20 in. Hg of vacuum on EGR valve one-way check valve. Vacuum should hold steady and no vacuum leakage should exist. If vacuum holds steady, go to next step. If vacuum does not hold steady, replace EGR valve one-way check valve.
10. Release vacuum. Disconnect vacuum pump from solenoid side of EGR valve one-way check valve. Install vacuum pump on EGR valve side of EGR valve one-way check valve. (Scheme 212)
11. Plug solenoid side of EGR valve one-way check valve. Attempt to apply vacuum to EGR valve one-way check valve. No vacuum should be obtained. If vacuum cannot be obtained, EGR valve one-way check valve is operating properly. If vacuum can be obtained, replace EGR valve one-way check valve. Remove vacuum pump and reconnect all vacuum hoses on EGR valve one-way check valve.

Scheme 212

Vacuum Pump Operation

1. The gear-driven vacuum pump provides vacuum source for operation of EGR system, brake system and various vacuum controlled devices. Vacuum pump is located between power steering pump and gear housing on driver's side of engine. (Scheme 205)
2. Vacuum pump should have a vacuum output of 8.5-25 in. Hg depending engine speed. No other testing information is available.

Intake Manifold Air Heater Preheat/Postheat Cycle

1. Air temperature at intake manifold must be less than 59°F (15°C). Turn ignition on. DO NOT start engine.
2. The WAIT-TO-START light on instrument panel should come on. A click should be heard from at intake manifold air heater relays, indicating preheat cycle has begun. Intake manifold air heater relays are mounted on inner wheelwell, below driver's side battery. (Scheme 203) NOTE: If starter is engaged before preheat cycle is complete, the Powertrain Control Module (PCM) will stop the preheat cycle.
3. Remove rubber cable terminal shields from cable connections on intake manifold air heater. Intake manifold air heater is located between air inlet housing and intake manifold. (Scheme 213)
4. Using voltmeter, check for voltage at both terminals on intake manifold air heater. Battery voltage should exist at both terminals for 10-30 seconds, depending on intake air temperature. See HEAT CYCLE SPECIFICATIONS table.

HEAT CYCLE SPECIFICATIONS

Intake Manifold Air Heater

1. Disconnect negative battery cables. Remove rubber cable terminal shields from cable connections at intake manifold air heater. Intake manifold air heater is located between air inlet housing and intake manifold. (Scheme 213) DO NOT disconnect cables from intake manifold air heater.
2. Using ohmmeter, check resistance between ground and each cable connection. DO NOT use mounting stud for cable on intake manifold air heater when checking resistance. Resistance should be zero ohms.
3. If any resistance exists, check for corroded or dirty electrical connections. Clean and repair cable connections as necessary. Recheck resistance. If resistance still exists, go to next step.
4. Disconnect cable connections from intake manifold air heater. Isolate cables to prevent cables from contacting other components.
5. Using ohmmeter, check resistance between ground and each cable terminal on intake manifold air heater. Resistance should be zero ohms. If any resistance exists, replace intake air manifold heater. Reinstall cable connections and negative battery cables.

Intake Manifold Air Heater Relay

See RELAYS under RELAYS & SOLENOIDS.

See SENSORS under ENGINE SENSORS & SWITCHES.

Scheme 213

MISCELLANEOUS CONTROLS

Note. Although some of the controlled devices listed here are not technically engine performance components, they can affect driveability if they malfunction.

Park/neutral switch is mounted on transmission case, near the shift lever and contains a 3-pin connector. If problem exists in park/neutral switch or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM. See appropriate TESTS W/CODES - 5.9L article.

Transmission governor pressure sensor is located on transmission valve body. If problem exists in transmission governor pressure sensor or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in the PCM. See appropriate TESTS W/CODES - 5.9L article.

Transmission overdrive solenoid may also be referred to as overdrive solenoid or 3-4 solenoid. Transmission overdrive solenoid is located transmission valve body. If problem exists in transmission overdrive solenoid or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM. See appropriate TESTS W/CODES - 5.9L article.

Transmission overdrive switch may be referred to as overdrive/override switch, OD switch or overdrive off switch. Transmission overdrive switch is located on instrument panel. If problem exists in transmission overdrive switch or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in the PCM. See appropriate TESTS W/CODES - 5.9L article.

See RELAYS under RELAYS & SOLENOIDS.

Transmission speed sensor may also be referred to as transmission output shaft speed sensor. Transmission speed sensor is located on overdrive case at rear of transmission. Transmission speed sensor contains a 2-pin Black connector with a Dark Blue/Black wire and a Light Green/Black wire. If problem exists in transmission speed sensor or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM. See appropriate TESTS W/CODES - 5.9L article.

Transmission temperature sensor is incorporated into governor pressure sensor on transmission valve body. If problem exists in transmission temperature sensor or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM. See TESTS W/CODES - 5.9L article.

The transmission Torque Converter Clutch (TCC) solenoid is located on transmission valve body. If problem exists in TCC solenoid or wiring circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM. See appropriate TESTS W/CODES - 5.9L article.

See also:
• BASIC TESTING - 5.9L DIESEL
• TESTS W/CODES - 5.9L
• REMOVE/INSTALL/OVERHAUL - DIESEL
• ADJUSTMENTS - 5.9L DIESEL
• WIRING DIAGRAMS - 5.9L - DIESEL
• REMOVE/INSTALL/OVERHAUL - 5.9L
• SPECIFICATIONS - 5.9L