Файл: 92FWD_14.pdf

14 - 118 FUEL SYSTEMS

Fig. 2 Ignition Coil Electrical Connection

Fig. 3 Electrical Connector Canister Purge Solenoid

Fig. 4 Map Sensor Electrical and Vacuum Connec-

tions

(8)Verify hoses are securely attached to the vapor canister (Fig. 5).

(9)Verify the engine ground strap is attached at the engine and dash panel (Fig. 6).

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Fig. 5 Vapor Canister

Fig. 6 Oxygen Sensor Connector

(10)Ensure the heated oxygen sensor connector is connected to the harness connector (Fig. 6).

(11)Verify the distributor connector is connected to the harness connector (Fig. 7).

Fig. 7 Distributor Connector

Fig. 9 Oil Pressure Sending Unit Electrical Connec-

tion

(16)Check hose connections at throttle body (Fig.

10).

(17)Check throttle body electrical connections (Fig.

10).

(18)Check PCV hose connections (Fig. 11).

Fig. 12 EGR System Vacuum Hose Connections

(19)If equipped, check EGR system vacuum hose connections (Fig. 12).

(20)If equipped, check EGR tube to intake plenum connections (Fig. 12).

Fig. 13 Power Brake Booster and Speed Control

Vacuum Hose Connections (Without Anti-lock

Brakes)

Fig. 14 Speed Control Vacuum Hose Connection

(With Anti-lock Brakes)

(24)Inspect engine harness to main harness connections.

(25)Check all automatic transmission electrical connections (Fig. 15).

(26)Check the distance sensor electrical connection (Fig. 16).

(27)Inspect the engine controller 60-way electrical connector for damage or spread terminals. Verify the 60-way connector is fully inserted into the socket of the engine controller. Ensure wires are not stretched or pulled out of the connector (Figs. 17, 18, and 19).

Fig. 16 Distance Sensor Electrical Connector

Fig. 17 Engine ControllerÐAA Body

(28)Check the air conditioning, starter, ASD, fuel pump and radiator fan relay connections (Figs. 20, 21, and 22).

(29)Check battery cable connections.

(30)Check hose and electrical connections at fuel pump. Ensure connector is making contact with terminals on pump.

Fig. 18 Engine ControllerÐAC Body

Fig. 19 Engine ControllerÐAG and AJ Bodies

ON BOARD DIAGNOSTICS

The engine controller has been programmed to monitor many different circuits of the fuel injection system. If a problem is sensed with a monitored circuit often enough to indicate an actual problem, the controller stores a fault. If the problem is repaired or ceases to exist, the engine controller cancels the Fault Code after 51 vehicle key on/off cycles.

Certain criteria must be met for a fault code to be entered into engine controller memory. The criteria may be a specific range of engine RPM, engine temperature, and/or input voltage to the engine controller.

It is possible a fault code for a monitored circuit may not be entered into memory even though a malfunction has occurred. This may happen because one of the fault code criteria for the circuit has not been met. For example, assume one of the fault code criteria for the MAP sensor circuit is the engine must be operating between 750 and 2000 RPM. If the MAP sensor output circuit shorts to ground when engine RPM is above 2400 RPM (resulting in a 0 volt input to the engine controller) a fault code will not be

Fig. 20 Relay IdentificationÐAA Body

Fig. 21 Relay IdentificationÐAC Body

entered into memory. This is because the condition does not occur within the specified RPM range.

There are several operating conditions that the engine controller does not monitor and set fault codes for. Refer to Monitored Circuits and Non-Monitored Circuits in this section.

Stored fault codes can be displayed either by cycling the ignition key On - Off - On - Off - On, or through use of the Diagnostic Readout Box II (DRB II). The DRB II connects to the diagnostic connector in the vehicle (Fig. 17, Fig. 18 or Fig. 19).

MONITORED CIRCUITS

The engine controller can detect certain fault conditions in the fuel injection system.

Fig. 22 Relay IdentificationÐAG and AJ Bodies

Open or Shorted Circuit - The engine controller can determine if the sensor output (input to controller) is within proper range. Also, the controller can determine if the circuit is open or shorted.

Output Device Current Flow - The engine controller senses whether the output devices are hooked up. If there is a problem with the circuit, the controller senses whether the circuit is open, shorted to ground, or shorted high.

Oxygen Sensor - The engine controller can determine if the oxygen sensor is switching between rich and lean once the system has entered closed loop. Refer to Modes of Operation in this section for an explanation of closed loop operation.

NON-MONITORED CIRCUITS

The engine controller does not monitor the following circuits, systems and conditions that could have malfunctions that result in driveability problems. Fault codes may not be displayed for these conditions. However, problems with these systems may cause fault codes to be displayed for other systems. For example, a fuel pressure problem will not register a fault directly, but could cause a rich or lean condition. This could cause an oxygen sensor fault to be stored in the engine controller.

Fuel Pressure - Fuel pressure is controlled by the vacuum assisted fuel pressure regulator. The engine controller cannot detect a clogged fuel pump inlet filter, clogged in-line fuel filter, or a pinched fuel supply or return line. However, these could result in a rich or lean condition causing an oxygen sensor fault.

Secondary Ignition Circuit - The engine controller cannot detect an inoperative ignition coil, fouled or worn spark plugs, ignition cross firing, or open spark plug cables.

Engine Timing - The engine controller cannot detect an incorrectly indexed timing chain, camshaft sprocket and crankshaft sprocket. The engine controller also cannot detect an incorrectly indexed distribu-

tor. However, these could result in a rich or lean condition causing an oxygen sensor fault to be stored in the engine controller.

Cylinder Compression - The engine controller cannot detect uneven, low, or high engine cylinder compression.

Exhaust System - The engine controller cannot detect a plugged, restricted or leaking exhaust system.

Fuel Injector Malfunctions - The engine controller cannot determine if the fuel injector is clogged, the pintle is sticking or the wrong injector is installed. However, these could result in a rich or lean condition causing an oxygen sensor fault to be stored in the engine controller.

Excessive Oil Consumption - Although the engine controller monitors exhaust stream oxygen content when the system is in closed loop, it cannot determine excessive oil consumption.

Throttle Body Air Flow - The engine controller cannot detect a clogged or restricted air cleaner inlet or filter element.

Evaporative System - The engine controller will not detect a restricted, plugged or loaded evaporative purge canister.

Vacuum Assist - Leaks or restrictions in the vacuum circuits of vacuum assisted engine control system devices are not monitored by the engine controller. However, these could result in a MAP sensor fault being stored in the engine controller.

Engine Controller System Ground - The engine controller cannot determine a poor system ground. However, a fault code may be generated as a result of this condition.

Engine Controller Connector Engagement - The engine controller cannot determine spread or damaged connector pins. However, a fault code may be generated as a result of this condition.

HIGH AND LOW LIMITS

The engine controller compares input signal voltages from each input device with established high and low limits that are programmed into it for that device. If the input voltage is not within specifications, and other fault code criteria are met, a fault code will be stored in memory. Other fault code criteria might include engine RPM limits or input voltages from other sensors or switches that must be present before a fault condition can be verified.

FAULT CODE DESCRIPTION

When a fault code appears, it indicates that the Engine Controller has recognized an abnormal condition in the system. Fault codes can be obtained from the Check Engine lamp on the Instrument Panel or from the Diagnostic Readout Box II (DRBII). Fault codes indicate the results of a failure but do not identify the failed component directly.