Engine Controls - Remove/install/overhaul Chevrolet Cab & Chassis K3500

INTRODUCTION

Removal, overhaul and installation procedures are covered in this article. If component removal and installation is primarily an unbolt and bolt-on procedure, only a torque specification may be furnished.

ON-VEHICLE ADJUSTMENTS

Note. For adjustments, see appropriate ADJUSTMENTS article in the ENGINE PERFORMANCE section below.

1. «ADJUSTMENTS - GASOLINE»(/chevrolet/cab-chassis-k3500/1989-2000/remont/adjustments/#engine-controls-adjustments-gasoline)
2. «ADJUSTMENTS - 6.5L DIESEL»(/chevrolet/cab-chassis-k3500/1989-2000/remont/adjustments/#engine-controls-adjustments-65l-diesel)

POWERTRAIN CONTROL MODULE (PCM)

Note. All vehicles are equipped with either an Electronic Control Module (ECM), Powertrain Control Module (PCM) or Vehicle Control Module (VCM). Unless specifically stated, references to PCM also apply to ECM and VCM equipped vehicles.

CONTROL UNIT

STATIC CHARGE (VOLTS)

Servicing PCM While Using 3M Anti-Static Mat. Scheme 1

Note. Before replacing PCM, carefully inspect all wiring and control components. Ensure ignition switch is in OFF position when connecting or disconnecting PCM connector.

Removal

Disconnect negative battery cable. Unplug connectors from PCM. (Scheme 1) Remove PCM from vehicle. Remove PROM and CALPAC (if equipped) or MEM-CAL from PCM. See CALPAC, MEM-CAL, or PROGRAMMABLE READ-ONLY MEMORY (PROM).

Installation

Install PROM and CALPAC (if equipped) or MEM-CAL in NEW PCM. See CALPAC , MEM-CAL , or PROGRAMMABLE READ-ONLY MEMORY (PROM) . Install PCM into vehicle. Connect electrical connectors to PCM. Install access panels. Reconnect negative battery cable.

Removal & Installation

Some PCM's use a CALPAC as well as a PROM. (Scheme 2) The CALPAC must also be removed from old PCM and installed in new one. Removal and replacement procedures for CALPAC are same as for PROM. See PROGRAMMABLE READ-ONLY MEMORY (PROM). If units are installed improperly, grounding diagnostic test lead will set Code 52.

Scheme 2

Disconnect negative battery cable. Remove PCM from vehicle. See REMOVAL under CONTROL UNIT . Using 2 fingers, push retaining clips back from MEM-CAL. At the same time, grasp it at both ends and lift out of socket. DO NOT remove MEM-CAL cover.

1. Carefully align MEM-CAL pins with PCM pin holes. DO NOT press in middle of MEM-CAL. Push downward evenly on ends of MEM-CAL until retaining clips on ends of MEM-CAL snap into place.
2. Install PCM. Reconnect negative battery cable. Turn ignition on and ground DLC terminal "B". Code 12 should be flashed at least 4 times. If Code 12 is not flashed at least 4 times, other codes are present. If Code(s) 51 or 52 are present, or if CHECK ENGINE light stays on constantly with code(s) present, MEM-CAL is not fully seated, or is defective.

1. Remove PCM from vehicle. See REMOVAL under «CONTROL UNIT»(/chevrolet/cab-chassis-k3500/1989-2000/remont/removal-installation/#engine-controls-removeinstalloverhaul__control-unit) . Position PCM so bottom cover is facing upward. Remove slide-off PROM access cover by depressing locking tab.
2. Using PROM removal tool, grasp PROM at narrow ends. Gently rock PROM from end to end while pulling up. If installing new PROM, remove old PROM from PROM carrier.

Note. Note reference notch locations in PROM, carrier and PCM for reassembly reference.

1. Ensure new PROM has same service number as old one. Place NEW PROM in PROM carrier, and position squarely over PCM PROM socket. Press on PROM carrier until PROM is firmly seated in PCM. NOTE: Ensure reference notches in PCM and PROM are properly aligned. If PROM is installed backwards and ignition is turned on, PROM will be destroyed.
2. Install PROM access cover on PCM. Install PCM in vehicle. See INSTALLATION under «CONTROL UNIT»(/chevrolet/cab-chassis-k3500/1989-2000/remont/removal-installation/#engine-controls-removeinstalloverhaul__control-unit) . Start engine, and ground DLC terminal "B". Watch for trouble Code 51 or 52.
3. If this occurs, PROM is not fully seated in PCM, installed backwards, has bent pins, or is defective. If bent pins are cracked while straightening, replace PROM. If PROM is installed backwards or is defective, replace PROM.

ELECTRONIC SPARK CONTROL (ESC) MODULE

Note. On models equipped with external ESC module, ESC is located on bracket behind distributor, mounted to firewall.

Turn ignition off. Remove bracket-to-firewall screws. Rotate bracket to access ESC module. Disconnect ESC module harness connector. Remove ESC mounting screws and remove ESC. To install, reverse removal procedure.

FUEL SYSTEM PRESSURE RELIEF (TBI)

Disconnect battery. Set parking brake and block drive wheels. Fuel pressure is relieved and drops to zero when ignition is turned off. To minimize risk of fire and personal injury, cover area to be disconnected with a shop rag.

FUEL PUMP

Note. When installing sending unit, DO NOT fold or twist strainer. This will restrict fuel flow.

Removal & Installation (All Models)

1. Relieve fuel system pressure. See «FUEL SYSTEM PRESSURE RELIEF (TBI)»(/chevrolet/cab-chassis-k3500/1989-2000/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-system-pressure-relief-tbi) under FUEL SYSTEM (GASOLINE). Disconnect negative battery cable. Raise vehicle and remove fuel tank. Remove sender unit and pump by turning cam lock counterclockwise using Tool (J-36608 or J-24187).
2. Remove fuel pump from sending unit by pulling pump up into attaching hose while pulling outward from the bottom support. DO NOT damage rubber insulator or strainer. To install, reverse removal procedure.

Removal (TBI)

Remove air cleaner and related ducting. Remove Idle Air Control (IAC) electrical connector. Unscrew IAC motor. Replace if necessary.

1. Inspect gasket or "O" ring for damage. Replace if necessary. Measure distance from IAC contact flange to tip of pintle. Distance should not exceed 1 1/8" (28 mm). If valve is extended too far, damage to valve will result during installation.
2. To set IAC pintle length on new IAC, use finger pressure to slowly retract pintle. Lubricate NEW "O" ring with ATF and install NEW gasket. Install IAC motor on throttle body. Tighten IAC valve to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/cab-chassis-k3500/1989-2000/remont/removal-installation/#engine-controls-removeinstalloverhaul) . CAUTION: DO NOT extend or retract pintle if IAC has been in service, or damage to worm gear will result.
3. Connect electrical lead to IAC motor and install air cleaner. Start engine and allow it to reach normal operating temperature. Drive vehicle. It may be necessary to reset idle speed. To reset, disconnect battery cable for 10 seconds and reconnect. Cycle ignition on with engine off for 5 seconds. Turn ignition off for 10 seconds and restart vehicle. Proper idle will be initialized.

THROTTLE BODY (TBI)

Note. Identification number is stamped on throttle body near throttle shaft. Identification number must be used for ordering replacement components.

Identification

An 8-digit unit identification number is stamped on throttle body assembly. Number is stamped vertically on front of throttle body, at Throttle Position (TP) sensor side. Letter codes are stamped on throttle body at external tube locations to identify vacuum hose connections.

1. Disconnect air cleaner (THERMAC) hose from engine vacuum fitting (if equipped). Remove air cleaner, adapter and gasket. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (TBI)»(/chevrolet/cab-chassis-k3500/1989-2000/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-system-pressure-relief-tbi) under FUEL SYSTEM (GASOLINE).
2. Disconnect electrical leads at IAC motor, throttle position sensor, and fuel injector(s). Disconnect fuel lines from throttle body. Discard fuel line "O" rings. Disconnect grommet with wires from throttle body.
3. Disconnect throttle linkage, return spring and cruise control linkage (if equipped). Label and disconnect all vacuum hoses from throttle body. Remove throttle body mount bolts/nut. Remove throttle body.

Note. Disassembling throttle body unit for immersion in cleaning solvent requires removal of throttle body cover or fuel meter assembly, TP sensor, IAC assembly and governor assembly (if equipped). Throttle valve screws are staked in position and should NOT be removed.

Disassembly (Throttle Body Cover Model 220)

1. Place throttle body on Holding Fixture (J-9789-118 or BT-30-15) to prevent damage to throttle valve. Remove cover-to-throttle body screws (note location of 2 short screws). Remove throttle body cover. (Scheme 3) Throttle body cover and pressure regulator are serviced as an assembly. DO NOT remove pressure regulator-to-cover screws.
2. Remove TP sensor, IAC, fuel injectors, fuel filter, rubber parts, and diaphragms. Clean all remaining (metal) parts in a cold immersion-type cleaner such as Carbon X (X-55). Blow dry with compressed air. Inspect mating surfaces for damage which may prevent gasket sealing. Repair or replace faulty components.

Disassembly (Fuel Meter Assembly Model 295)

1. Place throttle body on Holding Fixture (J-9789-118 or BT-30-15) to prevent damage to throttle valve. Remove cover-to-throttle body screws (note location of 2 short screws). Remove throttle body cover. (Scheme 3) If fuel pressure regulator cover is removed, regulator diaphragm must be replaced to prevent fuel leaks.
2. Remove TP sensor, IAC, pressure regulator assembly, fuel injectors, fuel filter, rubber parts, and diaphragms. Clean all remaining (metal) parts in a cold immersion-type cleaner such as Carbon X (X-55). Blow dry with compressed air. Inspect mating surfaces for damage which may prevent gasket sealing. Repair or replace faulty components.

Reassembly (Fuel Meter Assembly)

1. Install NEW dust seal into recess of throttle body. Install fuel outlet passage gasket on cover. Install throttle body cover gasket on throttle body. Install TP sensor, IAC, fuel injectors, injectors and diaphragms.
2. On TBI 295, install pressure regulator assembly. On all models, apply locking thread compound to cover attaching screws. Install cover screws and lock washers. Tighten screws. Connect electrical lead to fuel injectors, and install air cleaner.

To install, reverse removal procedure. Ensure throttle body and intake manifold sealing surfaces are clean. Use NEW throttle body gasket and fuel line "O" rings. Check fuel system for leaks by turning ignition on, but DO NOT start engine.

Scheme 3

Scheme 4

1. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (TBI)»(/chevrolet/cab-chassis-k3500/1989-2000/remont/removal-installation/#engine-controls-removeinstalloverhaul__fuel-system-pressure-relief-tbi) under FUEL SYSTEM (GASOLINE). Remove throttle body cover, leaving cover gasket in place. Using screwdriver and fulcrum, pry injector out. (Scheme 5) Remove small "O" ring from nozzle end of injector.
2. Carefully rotate injector fuel filter back and forth to remove fuel filter from base of injector. Remove and discard throttle body cover gasket. Remove large "O" ring and steel back-up washer from top counterbore of throttle body injector cavity.

1. Install fuel filter on nozzle end of fuel injector. Ensure large end of filter faces injector so filter covers raised rib at base of injector. Lubricate small "O" ring with Automatic Transmission Fluid (ATF), and push "O" ring on nozzle end of injector until it presses against injector filter.
2. Install steel back-up washer in top counterbore of throttle body injector cavity. Lubricate large "O" ring with ATF, and install "O" ring directly over back-up washer. Ensure "O" ring is seated properly in cavity, and is flush with top of throttle body casting. CAUTION: Install back-up washer and large "O" ring before installing injector. Improper seating of "O" ring will cause fuel leak.
3. Install "O" ring on injector. Install injector into cavity by aligning raised lug on injector base with cast-in notch of throttle body cavity. Push down on injector until fully seated. Install throttle body cover.

Scheme 5

1. Disconnect negative battery terminal. On "G" series, remove engine cover. On all models, disconnect air cleaner at valve cover. Remove crankcase vent bracket.
2. Loosen vacuum pump hold-down clamp. Rotate pump to access intake manifold bolts. Remove injection line clips and intake manifold. Install Protective Covers (J-29664-1) in intake ports.
3. Remove injection line clips. On "G" series, raise vehicle (for left bank). On all models, disconnect and cap injection lines at injector nozzles. Remove lines at pump. Tag injector lines for reassembly reference. Cap all openings.

Remove caps and install injection lines. Ensure lines are properly positioned. (Scheme 6) Reverse removal procedure to complete installation. Start engine and check for leaks.

Scheme 6

Fuel filter is mounted on rear of intake manifold, under air cleaner or on rear firewall. Remove fuel tank cap to release pressure or vacuum in tank. Remove filter element nut. Remove filter element by lifting straight out of filter housing. (Scheme 7) It is not necessary to drain fuel from filter housing when changing filter element.

Scheme 7

1. Ensure mating surface between filter element assembly and filter housing is clean. Install NEW filter element by aligning widest key slot located under element assembly cap with widest key in filter housing assembly.
2. Tighten element nut by hand. Bleed air from fuel manager/filter. To bleed air, open air bleed valve on top of fuel manager/filter assembly. Connect a hose to air bleed valve and place other end of hose in a container.
3. Disconnect fuel injection pump shutoff solenoid wire. Crank engine for 10-15 seconds. Allow starter to cool down for one minute between cranking intervals. Repeat procedure until clear fuel is observed at the air bleed hose.
4. Close air bleed. Connect injection pump shutoff solenoid wire and reinstall fuel filler cap. Start engine and allow to idle for 5 minutes. Check fuel manager/filter for leaks.

Removal & Installation (Electric)

1. Disconnect negative battery terminal. Disconnect electrical wiring from fuel pump and fuel pump support bracket.
2. Disconnect fuel lines from fuel pump. Remove support bracket screws and remove support bracket from fuel lines. Remove fuel pump and bracket from frame rail. To install, reverse removal procedure. Check for fuel leak at fuel line fittings.

Removal & Installation (Mechanical)

Disconnect fuel lines from fuel pump. Remove mounting screws and remove fuel pump from block. To install, reverse removal procedure. Check for fuel leak at fuel line fittings.

Left Side

1. Disconnect negative battery cables.
2. Using Glow Plug Remover & Installer (J-39083), disconnect glow plug lead wires.
3. Remove glow plug from cylinders No. 1, 3, 5 and 7.

Right Side

1. Raise and support vehicle.
2. Remove right wheel.
3. Remove splash shield from right front wheelwell.
4. Remove lead wire from glow plug in cylinder No. 2.
5. Remove lead wires for glow plugs in cylinders No. 4 and 6 at harness connectors.
6. Remove heat shroud from glow plug in cylinder No. 4.
7. Remove heat shroud from cylinder No. 6. Slide shrouds back far enough to allow access for unplugging the wires at cylinders No. 4 and 6 glow plugs. Use Glow Plug Remover & Installer (J-39083) to disconnect glow plug wires.
8. Remove glow plugs from cylinders No. 2, 4 and 6.
9. Disconnect lead wire at glow plug from cylinder No. 8 by reaching from underneath the vehicle.
10. Remove glow plug from cylinder No. 8.

Installation (Both Sides)

Install glow plug(s). Tighten glow plug to 13 ft. lbs. (N.m). Reconnect harness connector. Reinstall battery negative cable.

1. Disconnect negative battery cable. Remove intake manifold assembly. Install Protective Covers (J-29664-1) in intake ports. Remove fuel injection lines. Disconnect wiring, fuel return line, fuel supply line, and fuel injection lines at pump. Cap all openings.
2. Remove A/C hose retainer bracket (if equipped). Remove oil filler tube and vent hose assembly. Remove grommet. Scribe or paint alignment mark on front cover and injection pump flange.
3. Rotate engine to remove injection pump-to-drive gear retaining bolts accessible through oil filler neck hole. Remove the injection pump mounting nuts. Remove injection pump and gasket. (Scheme 8)

1. Install NEW injection pump gasket. Align locating pin on injection pump hub with slot in injection pump driven gear. At the same time, align injection pump timing marks. Ensure cylinder No. 1 is set at TDC.
2. Attach injection pump to front cover. Ensure alignment marks made during removal are aligned. Tighten nuts. Attach pump to drive gear and tighten bolts. Reverse removal procedure to complete installation. Check injection pump timing. See INJECTION PUMP TIMING (DIESEL) in appropriate «ADJUSTMENTS - 6.5L DIESEL»(/chevrolet/cab-chassis-k3500/1989-2000/remont/adjustments/#engine-controls-adjustments-65l-diesel) article in the ENGINE PERFORMANCE section below.

Scheme 8

Disconnect negative battery cables. Disconnect fuel line clip. Remove fuel return line. Remove fuel injection line. Cap all openings. Using Injector Socket (J-29873), remove injector nozzle(s). Place socket on 1 3/16" (30 mm) hex flats of injector body to prevent damaging injector nozzle.

Remove caps from injector nozzles and fuel lines. Install injector nozzle(s). Install fuel line. Install fuel return line and fuel line clip. Connect battery terminals. Start engine and check for leaks.

PURGING FUEL SYSTEM

1. Park vehicle on a level surface. Place drain pan under drain hose to collect fuel. Open drain valve 3-4 turns. With fuel tank cap installed, use air nozzle and apply 3-5 psi (.21-.35 kg/cm 2 ) through fuel return hose at injection pump.
2. Contaminated fuel will be forced out of tank via filter drain hose. Continue to drain fuel until clear fuel is observed. Entire fuel tank may have to be drained. Close drain valve. Install fuel return hose.

Note. If vehicle is equipped with dual tanks, perform purging procedure on each tank.

WATER-IN-FUEL WARNING LIGHT

1. Fuel filter should be drained every 5000 miles, or when WATER-IN-FUEL warning light comes on. Diesel fuel can damage asphalt and painted surfaces. Always place a drain pan under drain hose to collect fuel.
2. Stop vehicle and turn engine off. Apply parking brake. Remove fuel tank cap. Open water drain valve 2-3 turns. Start and allow engine to idle for 2 minutes or until clear fuel is observed. Turn engine off and close water drain valve.
3. Install fuel tank cap. If WATER-IN-FUEL warning light comes on after driving a short distance, or if engine runs rough or stalls, a large amount of water may be present in fuel tank. Purge fuel system. See «PURGING FUEL SYSTEM»(/chevrolet/cab-chassis-k3500/1989-2000/remont/removal-installation/#engine-controls-removeinstalloverhaul__purging-fuel-system) under FUEL SYSTEM (DIESEL).

1. Disconnect negative battery terminal. On TBI models, remove air cleaner assembly. Remove upper intake manifold assembly.
2. On all models, disconnect electrical connectors to distributor. Remove distributor cap and move out of the way. Remove distributor hold-down bolt and hold-down clamp. Note position of rotor. Pull up slightly on distributor until rotor stops turning counterclockwise and again note position of rotor. Remove distributor from engine.

Disassembly & Reassembly

1. Disassembly procedure is not available from manufacturer. (Scheme 9)for exploded views of distributors.
2. When reassembling, ensure pick-up assembly arm is correctly installed on pin. If not, arm can float and cause ignition timing to vary. To prevent corrosion, lubricate terminals with petroleum jelly before installation.
3. To prevent heat damage, coat bottom of module and module rest pad in distributor housing with silicone grease. Before installing roll pin in driven gear, ensure timing mark on roll pin and rotor tip align. (Scheme 9)

Scheme 9

1. To install, reverse removal procedure. To ensure correct timing of distributor, install with rotor correctly positioned as it was before distributor was removed.
2. If engine was cranked after distributor was removed, remove No. 1 spark plug. Place finger over No. 1 cylinder spark plug hole. Crank engine slowly until compression is felt. Align timing mark on pulley to "0" on engine timing indicator. Turn rotor to point to cylinder No. 1 spark plug tower on distributor cap. Complete distributor installation. Start engine and check ignition timing.

1. Remove air cleaner assembly. Disconnect electrical lead from TP sensor. Remove attaching screws, lock washers, retainers, and TP sensor.
2. To install, reverse removal procedure. Adjust TP sensor to specification. See «ADJUSTMENTS - GASOLINE»(/chevrolet/cab-chassis-k3500/1989-2000/remont/adjustments/#engine-controls-adjustments-gasoline) article in the ENGINE PERFORMANCE section below. When replacing a TP sensor, ensure correct part number is used. Use Loctite on TP sensor attaching screws.

OXYGEN SENSOR

1. Oxygen sensor is mounted in the exhaust pipe, below exhaust manifold. Ensure sensor is free of contaminants. DO NOT use cleaning solvents of any type. Sensor may be difficult to remove when engine temperature is less than 120°F (48°C). Excessive removal force may damage threads in exhaust manifold or pipe.
2. Disconnect negative battery terminal. Disconnect electrical connector from oxygen sensor. Carefully remove oxygen sensor from exhaust pipe.

1. Whenever oxygen sensor is removed, coat threads with anti-seize compound before reinstalling. New oxygen sensors already have this compound applied to threads.
2. Install oxygen sensor in exhaust pipe and tighten sensor to 30 ft. lbs. (41 N.m). Reconnect electrical connector to oxygen sensor. Reconnect negative battery terminal.

TURBOCHARGER

Note. Turbocharger overhaul information is not available from manufacturer.

Removal & Installation (6.5L Diesel)

1. Remove air intake duct between air cleaner and turbocharger. Remove Crankcase Depression Regulator (CDR) valve vent tube bracket on top of turbocharger.
2. Remove CDR valve and vent tube from air intake duct. Remove oil feed line at top of turbocharger, outlet to intake duct rubber connector and loosen exhaust pipe-to-turbocharger exhaust outlet elbow clamp.
3. Remove oil drain tube from turbocharger. Remove turbocharger-to-exhaust manifold nuts. Remove turbocharger assembly.
4. To install, reverse removal procedure. Ensure no foreign objects are present in intake and exhaust passages to turbocharger. Use a high temperature Anti-Seize Compound (GM 1052771) on all threaded fasteners. Fill oil feed hole at top of turbocharger with clean engine oil and manually rotate compressor wheel/shaft. This will pre-lube turbocharger shaft bearings.
5. Disconnect injection pump fuel shutoff connector (top of injector pump or at harness connector). Crank engine for not longer than 15 seconds. DO NOT let engine start. Complete installation of components. Tighten retaining bolts and nuts. See the appropriate «TORQUE SPECIFICATIONS»(/chevrolet/cab-chassis-k3500/1989-2000/remont/removal-installation/#engine-controls-removeinstalloverhaul) . Start engine and operate at low idle for 3 minutes. Check for oil leak at turbocharger fittings.

1. Remove turbocharger heat shield. Remove retaining pin or clip to wastegate actuator rod. Remove vacuum hose to actuator, and remove bolts securing actuator to turbocharger unit.
2. Remove wastegate actuator from turbocharger unit. To install, reverse removal procedure.

TORQUE SPECIFICATIONS (GASOLINE)

TORQUE SPECIFICATIONS (GASOLINE)

TORQUE SPECIFICATIONS (DIESEL)

TORQUE SPECIFICATIONS (DIESEL)

See also:
• ADJUSTMENTS - GASOLINE
• ADJUSTMENTS - 6.5L DIESEL
• CALPAC
• CONTROL UNIT
• FUEL SYSTEM PRESSURE RELIEF (TBI)
• PURGING FUEL SYSTEM