Engine Controls - Basic Testing - Diesel Dodge Cab & Chassis R3500

INTRODUCTION

Note. For complete no-start testing, see NO-START TESTS in SELF-DIAGNOSTICS - PICKUP article.

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is verifying the customer's complaint with a test drive under the conditions the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns or poor electrical connections. Before condemning the computerized system, perform each test listed in this article.

Two different module systems are used for powertrain control of diesel engine. The Engine Control Module (ECM), located on left side of engine, is used to control the fuel system. (Scheme 8) The Fuel Pump Control Module (FPCM) located on pump, is a separate component of ECM.

The Powertrain Control Module (PCM), located at right rear of engine compartment, is used for charging system, transmission and speed control functions. CCD Bus circuits connect the various vehicle control modules. These circuits are connected between ECM and PCM to allow communication between modules.

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

1. Check Water-In-Fuel (WIF) sensor electrical connector for corrosion, damaged terminals or wiring and tight fit on engine wiring harness. WIF sensor is located in bottom of fuel filter/water separator. (Scheme 8)
2. Check for water in fuel filter/water separator by placing drain pan below drain tube at fuel filter/water separator. (Scheme 8)
3. With engine not running, rotate handle on drain valve forward, toward front of vehicle to OPEN position. Drain valve is located near top of fuel filter/water separator. (Scheme 8) Drain water from fuel filter/water separator.
4. If no water exists and a clean flow of diesel fuel exists, rotate handle on drain valve back to CLOSE position. Go to next step. If water exists, allow water to drain until clean flow of diesel fuel exists. Rotate handle on drain valve back to CLOSE position. Go to next step.
5. Verify fuel filter/water separator has been serviced according to proper service schedule. See SERVICE & ADJUSTMENT SPECIFICATIONS - TRUCKS article.
6. Check color of Filter Minder. Filter Minder is located on top cover on air filter housing, just above air filter. DO NOT remove air filter from air filter housing for inspection. If Yellow disc in Filter Minder has reached Red zone, remove and inspect air filter. (Scheme 9) If air filter is dirty, replace air filter and reset Filter Minder by pressing rubber button on top of Filter Minder. NOTE: The Yellow disc in Filter Minder may reach Red zone if air intake is restricted or air filter has become wet during heavy rain or snow. If air filter has become wet, allow air filter to dry during normal engine operation and reset Filter Minder by pressing rubber button on top of Filter Minder.
7. Ensure intercooler inlet and outlet duct clamps are tight and front of intercooler is not restricted with dirt. (Scheme 10)
8. Ensure connections on both batteries are tight and not corroded. Ensure the three 32-pin connectors are fully engaged on Powertrain Control Module (PCM). PCM is located on firewall at passenger's side rear corner of engine compartment.
9. Check for loose, defective or corroded connections at intake manifold air temperature sensor. (Scheme 11)
10. Ensure electrical connections on intake manifold air heater relays and intake manifold air heater are tight and not corroded. Intake manifold air heater relays are mounted on inner wheelwell, below driver's side battery. (Scheme 12) Intake manifold air heater is located between air inlet housing and intake manifold cover. (Scheme 13) NOTE: Restricted low-pressure fuel lines from fuel tank to fuel transfer pump, fuel heater and fuel filter/water separator may cause starting problems and prevent engine from accelerating. Restricted high-pressure fuel lines from fuel injection pump to fuel injector may cause starting problems, poor engine performance and excessive Black smoke.
11. Check all fuel supply and returns lines for damage, kinking or leakage. Check throttle linkage for binding. Check for a stretched or disconnected throttle return spring.
12. Ensure all ground connections are tight and free of corrosion. Ensure accessory drive belt is not damaged or slipping. Check for loose or defective electrical connection on Crankshaft Position (CKP) sensor. (Scheme 8)
13. On A/T models, ensure all electrical connectors are clean and properly connected to electrical plugs on transmission case. On all models, check for loose or defective electrical connections on starter and starter solenoid.

Compression

Manufacturer does not provide information for checking compression.

AIR IN FUEL SYSTEM

Note. Air in the fuel system may cause hard starting, rough running, excessive smoke, poor engine performance, engine misfire, poor fuel economy and fuel knock. Air may enter fuel system whenever fuel supply lines, fuel filter/water separator, fuel injection pump, fuel injectors or high-pressure fuel lines are removed or disconnected.

1. Inspect all low-pressure fuel lines from fuel tank to fuel transfer pump, fuel heater and fuel filter/water separator for signs of leakage. Inspect all high-pressure fuel lines for signs of leakage. See «FUEL INJECTOR & HIGH-PRESSURE FUEL LINES»(/dodge/cab-chassis-r3500/1996-2002/remont/testing-diagnostics/#engine-controls-basic-testing-diesel__fuel-injector-high-pressure-fuel-lines) under FUEL SYSTEM.
2. After repairing fuel leak, bleed air from fuel system. See FUEL LINE BLEEDING under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - TRUCKS - DIESEL article.

FUEL HEATER

1. Fuel heater is located in fuel filter/water separator. (Scheme 8) Fuel heater uses a fuel heater temperature sensor for controlling operation of the fuel heater.
2. A defective fuel heater may cause excessive wax build-up in the fuel filter/water separator during cold ambient temperatures. Wax build-up may cause hard starting, prevent engine from accelerating, low power, Blue smoke or White smoke. For testing of fuel heater and fuel heater temperature sensor, see SYSTEM & COMPONENT TESTING - TRUCKS - DIESEL article.

FUEL HEATER RELAY

Ensure fuel heater relay, located in power distribution center is installed correctly and that terminals are not corroded. For fuel heater relay testing, see SYSTEM & COMPONENT TESTING - TRUCKS - DIESEL article.

FUEL FILTER/WATER SEPARATOR

Note. A blocked or restricted fuel filter/water separator may cause starting problems, prevent engine from accelerating, low power or White smoke. If an excessive amount of water collects in filter/separator in a short period of time, it may be necessary to drain and clean fuel tank.

1. When ignition switch is first turned to ON position, WATER-IN-FUEL (WIF) warning light should come on for 2 seconds to perform bulb and wiring circuit test and then go off. WATER-IN-FUEL (WIF) warning light is located on instrument panel, just below the tachometer.
2. If WATER-IN-FUEL (WIF) warning light stays on, water should be drained from fuel filter/water separator. To drain water from fuel filter/water separator, ensure engine is not running. Place drain pan below drain tube at fuel filter/water separator. (Scheme 8)
3. Rotate handle on drain valve forward, toward front of vehicle to OPEN position. Drain valve is located near top of fuel filter/water separator. (Scheme 8)
4. Allow water to drain until clean flow of diesel fuel exists. Rotate handle on drain valve back to CLOSE position.

FUEL TRANSFER PUMP

Note. A defective fuel transfer pump may cause low power, hard starting and White smoke. Check fuel transfer pump output pressure (cranking and starting), pressure drop and fuel supply.

Fuel Transfer Pump Preliminary Inspection

1. Check for restricted or leaking fuel supply line to fuel transfer pump or fuel return line located on driver's side of engine. (Scheme 8) Repair fuel supply line or fuel return line if restricted or leaking.
2. Check for fuel leaking from fuel transfer pump. Replace fuel transfer pump if fuel is leaking. Check fuel transfer pump output pressure.

Scheme 14

1. Clean area around filter fitting plugs, then remove plugs. (Scheme 14) Install Test Fittings (AVU1-2). Install Fuel Pressure Test Gauge (6828) at inlet port. (Scheme 14) To prevent engine starting, remove fuel injection pump relay, located in power distribution center.
2. Turn ignition switch to START position. Inlet pressure should be 5-7 psi. Install fuel injection pump relay. Start engine. Inlet pressure should be 10 psi. Using a scan tool, clear DTC. DTC may set when relay is removed. Check pressure drop.

Pressure Drop Test

Turn engine off. Move pressure gauge from inlet port to outlet port. (Scheme 14) Start engine. Outlet pressure should not be more 5 psi (0.4 kg/cm 2 ) less than inlet pressure. If pressure drop is more than 5 psi (0.4 kg/cm 2 ), replace fuel filter and retest pressure. If pressure drop is less than 5 psi (0.4 kg/cm 2 ), check for fuel supply restriction.

Fuel Supply Restriction Test

Note. Due to very small vacuum specifications, use a scan tool and Periphal Expansion Port (PEP) module with 0-15 psi transducer to perform following test.

Ensure transfer pump pressure is okay. Disconnect fuel supply line at fuel transfer pump inlet. Remove plastic clip from pump inlet and install in end of fuel supply line. Install 3/8" Adapter Hose (6631) between fuel supply line and pump inlet. Install transducer from PEP module to "T" fitting on adapter. Connect scan tool to module. Start engine. Check vacuum reading with engine at full throttle with no load. If vacuum reading is less than 6 in. Hg, check for fuel supply air leaks. If vacuum reading is 6 in. Hg or more, check fuel line for damage, dents and kinks. Repair as necessary. If no problem is found, remove fuel module from fuel tank and check for obstructions. Repair as necessary.

Fuel Supply Air Leak Test

Note. A 3 ' section of 1/4 " I.D. clear tubing and a 1/8 " NPT fitting are required for the following test.

Clean area around filter inlet fitting plug, then remove plug. (Scheme 14) Install 1/8 " NPT fitting with 1/4 " nipple fitting in test port. Attach clear hose with a clamp to fitting. Place other end of hose in a fuel container. Turn ignition switch to START position, then release to RUN position without starting engine. Fuel transfer pump should run for 25 seconds. After hose has been purged, watch for any air bubbles in hose. If no bubbles exist, system is okay. If bubbles exist, check fuel line, fittings and fuel module in tank. Repair as necessary.

OVERFLOW VALVE

1. Fuel transfer pump delivers more fuel to fuel injection pump than needed. Surplus fuel is routed back to fuel tank by overflow valve. Overflow valve is used to secure fuel return line to side of fuel injection pump. (Scheme 8) A sticking check valve in the overflow valve may result in low power. Pressure release is set at 14 psi. (1.0 kg/cm 2 ). If outlet valve is stuck closed, a DTC may set.
2. Clean area around outlet valve and fuel return line. Remove valve from pump and fitting. Using regulated air pressure, test valve by blowing into valve inlet. Valve should open at 14-16 psi. (1.0-1.1 kg/cm 2 ). If valve does not open, replace valve. Reduce air pressure to 10 psi. (0.7 kg/cm 2 ). Valve should close. If valve does not close, replace valve. Using NEW gaskets, install valve through banjo fitting into fuel injection pump. Tighten valve to 24 ft. lbs. (30 N.m).

FUEL INJECTOR & HIGH-PRESSURE FUEL LINES

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. Since a leaking high-pressure fuel line may cause the same symptoms, check for leaking high-pressure fuel line before checking fuel injector.

1. To determine which injector or line is malfuntioning, start engine and check each cylinder output using scan tool. If scan tool is not available, start engine and engine allow to idle. Loosen high-pressure fuel line nut at each fuel injector in turn and listen for a decrease in engine speed. Tighten high-pressure fuel line nut to 30 ft. lbs. (40 N.m). Go to next step.
2. To check for a leaking high-pressure fuel line, start engine and allow engine to idle. 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 30 ft. lbs. (40 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 REMOVAL, OVERHAUL & INSTALLATION - TRUCKS - DIESEL article. If no leaks are found, go to next step.
3. Remove suspect injector. See FUEL INJECTOR under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - TRUCKS - DIESEL article. Test injector with a diesel fuel injector tester. Follow tester instructions. Replace fuel injector if fuel injector opening (pop) pressure is not 4250-4750 psi (299-334 kg/cm 2 ). Replace injector if any leaks are noted at 291 psi (20 kg/cm 2 ) less than opening (pop) pressure. Inspect injector for burrs, cracks, wear and plugging. Check spray pattern. If any problems are noted, replace injector.

FUEL INJECTION PUMP TIMING

Improper fuel injection pump timing may result in low power, excessive smoke and poor fuel economy. To check fuel injection pump timing, see FUEL INJECTION PUMP TIMING in ADJUSTMENTS - TRUCKS - DIESEL article.

INTAKE MANIFOLD AIR HEATER

Note. Intake manifold air heater is used to heat incoming air before entering each cylinder. Warming of incoming air aids in engine starting and improved driveability during cold ambient temperatures. Engine Control Module (ECM) uses input signals from various sensors for controlling intake manifold air heater relays.

SUMMARY

If no faults were found while performing basic diagnostic procedures, proceed to SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article. If no diagnostic trouble codes are found in self-diagnostics, proceed to TROUBLE SHOOTING - NO CODES - DIESEL article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

See also:
• NO-START TESTS
• FUEL INJECTOR & HIGH-PRESSURE FUEL LINES