ELECTRONIC CONTROL MODULE (ECM)
Note. All vehicle are equipped with either an Electronic Control Module (ECM), Powertrain Control Module (PCM) or Vehicle Control Module (VCM). Unless specifically stated, references to ECM also apply to PCM and VCM equipped vehicles.
CONTROL UNIT
| CAUTION | When certain materials rub together, a transfer of electrons from one material to another may occur under special conditions. This causes electrostatic charge (static electricity) build up in one of the materials. When any conducting material comes in contact with the charged material, electrostatic discharge occurs, transferring electrons to the third material. Electronic components used in control systems are designed to carry very low voltages; a 30-volt charge created by static electricity can cause a total or degrading failure in ECM or other electronic components containing integrated circuits. Before servicing ECM, ground yourself, and ground the work area to discharge stored electricity. |
| Movement | 10-20% (1) | 65-90% (1) |
|---|---|---|
| Walking Across Carpet | 35,000 | 1500 |
| Handling Clear Plastic Bag | 20,000 | 1200 |
| Sliding Across Velour Seat | 15,000 | 400 |
| Walking Across Tile/Vinyl | 12,000 | 50 |
| Handling Vinyl Envelope | 7000 | 600 |
| (1) Relative Humidity | ||
| (1) | Relative Humidity |
STATIC CHARGE (VOLTS)
| CAUTION | DO NOT remove ECM from packaging until ready to install. Ground static-proof package BEFORE opening. DO NOT touch electrical terminals of components unless properly grounded. DO NOT lay electrical components on car seat, carpeting or dashboard. Use electrostatic protection mat and ground strap whenever possible. (Scheme 14) |
Servicing ECM While Using 3M Anti-Static Mat. Scheme 14
Note. Before replacing ECM, carefully inspect all wiring and control components. Ensure ignition switch is in OFF position when connecting or disconnecting ECM connector.
ELECTRONIC SPARK CONTROL (ESC) MODULE
Note. On models equipped with external ESC module, ESC is located on bracket behind distributor, mounted to firewall.
FUEL SYSTEM PRESSURE RELIEF (CPI)
- Disconnect negative battery cable. Loosen fuel filler cap to relieve fuel tank vapor pressure. Install Fuel Pressure Gauge(J-34730-1) to fuel pressure connection.
- Wrap shop towel around pressure connection when installing fuel pressure gauge to absorb fuel leakage. Place gauge bleed hose in container. Open bleed valve to bleed fuel pressure.
FUEL SYSTEM PRESSURE RELIEF (PFI)
Fuel system is under pressure. Fuel pressure may be relieved by 2 different methods.
Method 1
Disconnect fuel pump electrical connector. Start engine and allow to run until it stops. Operate starter for 3 seconds to relieve remaining fuel from fuel lines.
Method 2
Install Fuel Pressure Gauge (J-34730-1) on fuel pressure connection. Wrap shop towel around pressure connection when installing fuel pressure gauge to absorb fuel leakage. Place gauge bleed hose in container. Open bleed valve to bleed fuel pressure.
TBI Unit Model 700
Place transmission gear selector in Park (Neutral on M/T). Set parking brake and block drive wheels. Loosen fuel filler cap to relieve tank pressure. Disconnect 3-terminal electrical connector at fuel tank. Start engine and allow to run until engine stalls. Crank engine for 3 seconds to relieve any residual pressure left in fuel lines. Fuel lines are now safe for servicing.
TBI Unit Model 220
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.
THROTTLE BODY (PFI)
Note. Identification number is stamped on throttle body near throttle shaft. Identification number must be used for ordering replacement components.
PURGING FUEL SYSTEM
- 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.
- 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
- 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.
- 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.
- 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 under FUEL SYSTEM (DIESEL).
DISTRIBUTOR
Note. 3.8L engines are equipped with Distributorless Ignition System (DIS).
OXYGEN SENSOR
| CAUTION | Oxygen sensor is equipped with a permanent pigtail, which must be protected to prevent damage when removing sensor. |
TURBOCHARGER
Note. Turbocharger overhaul information is not available from manufacturer.
CHARGE AIR SYSTEM BLEEDING (4.3L)
- Open petcock on charge air cooler radiator. Fill charge air cooler radiator with a 56/44 mixture of coolant and distilled water. When coolant flows out of drain hole, close petcock.
- Add coolant mixture to air charge cooler until full. Remove charge air cooler pump relay located near coil assembly. Turn ignition on. Install jumper wire between charge air cooler relay terminals "A" and "B" to operate charge air cooler pump.
- While pump is operating, add coolant mixture to system until system is full. Install charge air cooler pressure cap.