2.8l VIN [s] Pfi "c" Charts Chevrolet Camaro III рестайлинг

DIAGNOSTIC CIRCUIT CHECK - TESTING

The Diagnostic Circuit Check is an organized approach for identifying fuel injection problems using the Assembly Line Data Link (ALDL). This communication link can provide diagnostic information for display on any "Scan" tester designed for this purpose. If the "Scan" tester is not operating, check tester on another vehicle. If okay, the cigar lighter socket should be checked for 12 volts and a good ground. With the ignition on, if the "Scan" tester reads "NO DATA" or "NO ALDL", check the serial data wire for an open or short to ground. Also check for an open diagnostic "test" terminal "B". Refer to appropriate CHART A1 schematic for circuit wiring reference. Refer to the appropriate PORT FUEL INJECTION - SCAN DATA SPECIFICATIONS table in the CCC EFI TESTS W/O CODES article for "SCAN DATA" tables.

Diagnostic Circuit Check Flow Chart. Scheme 321

Diagnostic Circuit Check Flow Chart. Scheme 322

CHART C1: ECM QUAD-DRIVER CHECK (2.8L F BODY)

To energize controlled devices, the ECM uses integrated circuits called "QuaD-Drivers" in place of separate transistors. Each QuaD-Driver has 4 separate circuits that can be turned on or off independently. The ECM used on this vehicle (part No. 1227302) does not have fault protection, therefore, a single faulty circuit many times causes all 4 QuaD-Driver circuits to fail. Because of increased current flow, 2 QuaD-Drivers are used to drive the Torque Converter Clutch (TCC) solenoid. A faulty circuit is the largest cause of a failed QuaD-Driver, therefore, this check should be performed whenever instructed to "Replace ECM" or whenever ECM exhibits characteristics of a damaged QuaD-Driver, such as the following

1. "SERVICE ENGINE SOON" light on, with no stored codes.
2. Engine will not start and/or ECM will not flash Code 12.
3. Flickering, intermittent or dim "SERVICE ENGINE SOON" light.
4. Output, such as the TCC, is inoperative or constantly "on".
5. Engine misfires, surges or stalls.
6. "Scan" tester is erratic or inoperative.

ECM NO. 1227170 QUAD-DRIVER CIRCUIT IDENTIFICATION

ECM NO. 1227302 QUAD-DRIVER CIRCUIT IDENTIFICATION

Chart C1: ECM Quad-Driver Check Schematic. Scheme 323

Chart C1: ECM QuaD-Driver Check Flow Chart. Scheme 324

Note. Use this check procedure only after other diagnostic charts have determined that there was an ECM failure.

Chart C1: ECM QuaD-Driver Check Flow Chart. Scheme 325

CHART C1A: PARK/NEUTRAL SWITCH

The park/neutral switch contacts are a part of the neutral start switch. Contacts are closed to ground in Park or Neutral. The ECM applies and monitors a 12-volt signal on circuit No. 434 and senses a closed switch when voltage drops to less than one volt. If circuit No. 434 indicates park/neutral switch is grounded while in Drive, the EGR system would be inoperative, resulting in possible detonation. If circuit No. 434 indicates Drive (open), a dip in idle may exist when gear selector is moved to Drive.

Note. Test numbers refer to test numbers on diagnostic chart.

1. Checks for a switch closed to ground in Park.
2. Checks for an open switch in Drive.
3. To test for an intermittent or misadjusted switch in Drive, be sure "Scan" tester indicates Drive, even while wiggling shifter.

Chart C1A: Park/Neutral Switch Schematic. Scheme 326

Chart C1A: Park/Neutral Switch Flow Chart. Scheme 327

Chart C1A: Park/Neutral Switch Flow Chart. Scheme 328

CHART C1E: PSPS CHECK

The Power Steering Pressure Switch (PSPS) is a normally open switch that closes when P/S pressure goes high, such as on a full turn in either direction. When the P/S switch closes, it turns the A/C relay off and sends a signal to the ECM. The ECM uses this signal for idle control.

1. A pressure switch that will not close, or an open in circuits No. 901 or 450 may cause the engine to stop when power steering loads are high.
2. A switch that will not open, or a circuit No. 901 shorted to ground, may affect idle quality and will cause the A/C relay to dEenergize. NOTE: Test numbers refer to test numbers on diagnostic chart.

1. Different makes of "Scan" testers may display the status of this switch in different ways. Refer to "Scan" tester operating manual to determine how this input is indicated.
2. Checks to determine if circuit No. 901 is shorted to ground.
3. This should simulate a closed switch.

Chart C1E: P/S Pressure Switch Schematic. Scheme 329

Chart C1E: P/S Pressure Switch Check Flow Chart. Scheme 330

Chart C1E: P/S Pressure Switch Check Flow Chart. Scheme 331

CHART C2A: INJECTOR BALANCE TEST

The injector balance test is used to pulse the injector for a precise amount of time, spraying a measured amount of fuel in the intake manifold. As each injector is pulsed, a drop in fuel rail pressure occurs. This pressure drop can be recorded and compared to other injectors. An injector that has a pressure drop of 1.5 psi (.11 kg/cm 2 ) or more, greater than or less than other injectors, should be considered faulty.

Note. Allow engine to cool down to avoid irregular readings due to "Hot Soak" fuel boiling. In order to prevent flooding, the INJECTOR BALANCE TEST should not be repeated more than once, without starting and running engine.

1. With ignition off, connect Fuel Pressure Gauge (J-34730-1) to pressure tap. Unplug harness connector at all injectors. Connect Injector Tester (J-34730-3) to one of the injectors. On turbocharged engines, use adapter harness supplied with injector tester to pulse injectors that are not accessible.
2. Follow manufacturer's instructions for use of the adapter harness. Ignition should be turned off for at least 10 seconds to complete ECM shutdown cycle.
3. Turn ignition on. Fuel pump should run at least 2 seconds after ignition is turned on. Bleed air from gauge and hose to ensure accurate gauge reading. Repeat this procedure until all air is bled from system. Turn ignition off for at least 10 seconds.
4. Turn ignition on again to bring fuel pressure to maximum. Record initial pressure reading. Energize tester one time and note pressure drop at lowest point.
5. Disregard any slight pressure drop after low point is reached. Subtracting second pressure reading from initial reading indicates amount of injector pressure drop.
6. Repeat step 4) on each injector and compare amount of pressure drop. Recheck injectors that do not read within pressure drop range. Replace injector(s) that fail second check.
7. If injectors are all okay, plug in harness connectors and review appropriate symptoms in TROUBLE SHOOTING in THEORY & OPERATION section of this article.

Chart C2A: Injector Balance Test. Scheme 332

CHART C2C: IDLE AIR CONTROL 2.8L F BODY

The ECM will control engine idle speed by moving the Idle Air Control (IAC) valve to control airflow around the throttle plate. It does this by sending voltage pulses to the proper motor winding for each internal IAC motor. This will cause the motor shaft and valve to move in or out of the motor a given distance for each pulse received. The IAC position is measured in counts. Zero counts is a fully extended valve (no airflow), 255 counts is a fully retracted valve (maximum airflow).

Note. Test numbers refer to test numbers on diagnostic chart.

1. Continue with test even if engine will not idle. If idle is too low, "Scan" tester will display 80 or more counts. If idle is high, it will display zero counts. Occasionally, an erratic or unstable idle may occur. Engine speed may vary 200 RPM or more up or down. If this condition exists, disconnect IAC motor. If the condition is unchanged, the IAC is not at fault. There is a system problem. Proceed to DIAGNOSTIC AIDS.
2. When the engine was stopped, the IAC valve retracted to a fixed "Park" position for increased airflow and idle speed during the next engine start. A "Scan" tester will display 40 or more counts.
3. Be sure to disconnect the IAC valve prior to this test. The test light will confirm the ECM signals by a steady or flashing light on all circuits.
4. There is a remote possibilty that one of the circuits is shorted to voltage which would have been indicated by a steady light. Disconnect ECM and turn the ignition on. Probe terminals to check for this condition.

DIAGNOSTIC AIDS

Engine idle speed can be adversly affected by the following

1. If ECM thinks the vehicle is always in Neutral, idle will not be controlled to the specified Drive RPM.
2. Leaking injectors will cause fuel imbalance and poor idle quality due to different air/fuel ratios in each cylinder. See appropriate CHART A7.
3. Vacuum or crankcase leaks can affect idle.
4. When the throttle shaft or TPS is binding or sticking in an open throttle position, the ECM does not know the vehicle has stopped and does not control idle.
5. Check AIR management system for intermittent air to ports while in "closed loop".
6. Inspect electrical and mechanical operation of EGR valve.
7. Faulty battery cables can result in voltage variations. The ECM will try to compensate, resulting in erratic idle speeds.
8. The ECM compensates for A/C compressor loads on engine. Loss of the A/C signal would be most apparent in Neutral.
9. Contaminated fuel can adversely affect idle.
10. Perform injector balance test. See CHART C2A.

Chart C2C: Idle Air Control Schematic (2.8L F/Y Body). Scheme 333

Chart C2C: Idle Air Control Flow Chart. Scheme 334

Chart C2C: Idle Air Control Flow Chart. Scheme 335

CHART C3: CANISTER PURGE CHECK

Canister purge is controlled by a solenoid that allows manifold vacuum to purge the canister when dEenergized. The ECM supplies a ground on circuit No. 428 to energize the solenoid.

Note. Test numbers refer to test numbers on diagnostic chart.

1. This test checks to see if the solenoid is open or closed. The solenoid is normally energized in this step. It should be closed.
2. This test checks for a complete circuit. Normally there is ignition voltage on circuit No. 39 and the ECM provides a ground on circuit No. 428.
3. Completes functional check by grounding ALDL "test" terminal. This should normally dEenergize the solenoid and allow the vacuum to drop. On 2.8L F body models, if circuit No. 428 is shorted to ground or ECM is faulty, perform CHART C1, ECM QUAD-DRIVER CHECK

Chart C3: Canister Purge Schematic. Scheme 336

Chart C3: Canister Purge Check Flow Chart. Scheme 337

Chart C3: Canister Purge Check Flow Chart. Scheme 338

CHART C4: IGNITION SYSTEM CHECK (W/HEI)

Note. Test numbers refer to test numbers on diagnostic chart.

1. 1) This test checks 2 wires, to ensure that an open is not present in a spark plug wire.
2. 1A) If spark occurs with EST connector disconnected, pick-up coil output is too low for EST operation.
3. 2) A spark indicates the problem must be the distributor cap or rotor.
4. 3) There should be battery voltage at terminal "C" and at the "+" terminal. Low voltage would indicate an open or a high resistance circuit from the distributor to the coil or ignition switch. If terminal "C" voltage was low, but "+" terminal voltage is 10 volts or more, check circuit from terminal "C" to ignition coil for open or check ignition coil primary winding for open.
5. 4) This test checks for a shorted module or grounded circuit from the ignition coil to the module. The distributor module should be turned off, so normal voltage should be about 12 volts. If the module is turned on, the voltage would be low, but should be greater than one volt. This could cause the ignition coil to fail from excessive heat. With an open ignition coil primary winding, a small amount of voltage will leak through the module from the battery to the tachometer terminal.
6. 5) Applying 1.5-8 volts to module terminal "P" should turn the module on and the tachometer terminal voltage should drop to about 7-9 volts. This test will determine whether the module or coil is faulty or if the pick-up coil is not generating the proper signal to turn the module on. This test can be performed by using a DC battery with a rating of 1.5-8 volts. The use of the test light is mainly to allow the terminal "P" to be probed more easily. Some digital volt/ohmmeters can also be used to trigger the module by selecting the ohms scale, usually in the "diode" position. In this position, the meter may have a voltage across the terminals which can be used to trigger the module. The voltage in the "ohm" position can be checked by using a second meter or by checking the manufacturer's specification of the tester being used.
7. 6) This should turn off the module and cause a spark. If no spark occurs, the fault is most likely in the ignition coil because most module problems would have been found before this point in the procedure. Use a module tester to determine which is at fault.

Chart C4: Ignition System W/HEI Schematic. Scheme 339

Chart C4: Ignition System Check W/HEI Flow Chart. Scheme 340

Chart C4: Ignition System Check W/HEI Flow Chart (1 Of 2). Scheme 341

Chart C4: Ignition System Check W/HEI Flow Chart (2 Of 2). Scheme 342

CHART C6A: ELECT. AIR DIVERT (M/T) 2.8L F BODY

This system uses a single bed converter. Air management is controlled by an air control valve (divert valve). When grounded by the ECM, the solenoid causes the valve to direct air to the exhaust ports. When dEenergized, air diverts to the atmosphere. Air will go to the ports, provided the valve has a ground to the ECM and good manifold vacuum.

Note. Test numbers refer to test numbers on diagnostic chart.

1. This is a system performance test. When vehicle goes to "closed loop", air will switch from the ports to divert.
2. Tests for a grounded electric diverter circuit. Normally, light will be off.
3. Checks for an open control circuit. Grounding ALDL "test" terminal will energize the solenoid if ECM and circuits are okay. In this test, if test light is on, circuits are okay. Fault is in valve connections or valve.

Note. Quad-Driver check CHART C1 applies to 2.8L F body only. QuaD-Drivers on other models are protected internally.

Chart C6A: Elect. Air Divert (M/T) Schematic. Scheme 343

Chart C6A: Electric Air Divert (M/T) Flow Chart. Scheme 344

Chart C6A: Electric Air Divert (M/T) Flow Chart. Scheme 345

CHART C7: EGR CHECK 2.8L F BODY

The EGR valve is controlled by a normally closed solenoid (allows vacuum to pass when energized). The ECM energizes the solenoid to turn the EGR on and monitors vacuum to the EGR with the EGR diagnostic switch. Code 32 will detect a faulty solenoid, vacuum switch or vacuum supply. This chart checks for plugged EGR passages, a sticking EGR valve, or a stuck open solenoid.

Note. Test numbers refer to test numbers on diagnostic chart.

1. With the ignition on and engine stopped, the solenoid should not be energized and vacuum should not pass to the EGR valve.
2. Grounding the ALDL "test" terminal will energize the solenoid and allow vacuum to pass the valve.
3. Checks for plugged EGR passages. If passages are plugged, the engine may have severe detonation on acceleration.
4. The EGR solenoid will not be energized in Park or Neutral. This will determine if park/neutral switch input is being received by ECM.

Chart C7: EGR Check Schematic. Scheme 346

Chart C7: EGR Check Flow Chart. Scheme 347

Chart C7: EGR Check Flow Chart. Scheme 348

CHART C8A: TORQUE CONVERTER CLUTCH (TCC) 440-T4 TRANS, 2.8L F BODY (1 OF 2)

The purpose of the Torque Converter Clutch (TCC) feature is to eliminate the power loss of the torque converter stage when the vehicle is in a cruise condition. When the solenoid coil is activated, the TCC is applied through a mechanical coupling from the engine to transmission. When transmission solenoid is dEenergized, TCC is released, which allows torque converter to operate in a conventional manner (fluidic coupling between engine and transmission).

Note. Test numbers refer to test numbers on diagnostic chart.

1. When a test light is connected from ALDL terminal "F" to ground, a test light on indicates battery voltage is okay and the TCC solenoid is disengaged.
2. When the ALDL "test" terminal is grounded, the ECM should energize the TCC solenoid and the test light should go out. On 2.8L F body models, if circuit No. 422 is faulty or ECM is faulty, perform CHART C1, ECM QUAD-DRIVER CHECK.

A "Scan" tester only indicates when the ECM has turned on the TCC driver (grounded circuit No. 422). This does not confirm that the TCC has engaged. To determine if TCC is functioning properly, observe engine RPM. RPM should decrease when the "Scan" tester indicates the TCC driver has turned on. The switches will not prevent TCC from functioning, but will affect TCC lock and unlock points. If the 4th gear switch circuit is always open, the TCC may engage as soon as sufficient oil pressure is reached.

Chart C8A: TCC 440-T4 Schematic. Scheme 349

Chart C8A: TCC 440-T4 Flow Chart (1 Of 2, 2.8L F Body). Scheme 350

Chart C8A: TCC 440-T4 Flow Chart (1 Of 2, 2.8L F Body). Scheme 351

CHART C8A: TCC 440-T4 TRANS, 2.8L F BODY (2 OF 2)

Note. Test numbers refer to test numbers on diagnostic chart.

1. Unless the switch or circuit No. 446 is open, the "Scan" tester should display "NO" or "OFF", indicating the transmission is not in 4th gear. The 4th gear switch should only be open while in 4th gear.
2. This test determines if the ECM and wiring are okay. Grounding circuit No. 446 should cause the "Scan" tester to display "NO" or "OFF", indicating the transmission is not in 4th gear.
3. Checks the operation of the 4th gear switch. When the transmission shifts into 4th gear, the switch should open and the "Scan" tester should display "YES" or "ON".
4. Disconnecting the TCC connector simulates an open switch to determine if circuit No. 446 is shorted to ground or the problem is in the transmission.

A road test may be necessary to verify the problem. If the "Scan" tester indicates TCC is turning on and off erratically, check the status of the 4th gear switch to be sure it is not changing under a steady throttle position. If the switch is changing, check connections and wire routing carefully. If the 4th gear switch is always open, the TCC may engage as soon as sufficient oil pressure is reached.

Chart C8A: TCC 440-T4 Flow Chart (2 Of 2, 2.8L F Body). Scheme 352

Note. Checks made in this chart will not prevent the TCC from working, but will affect engagement or disengagement points.

Chart C8A: TCC 440-T4 Flow Chart (2 Of 2, 2.8L F Body). Scheme 353

CHART C8C: SHIFT LIGHT INDICATOR M/T

The shift light indicates the best transmission shift point for maximum fuel economy. The light is controlled by the ECM and is turned on by grounding circuit No. 456. To control the shift light, the ECM uses calculations involving the CTS, TPS, VSS and ignition module reference (RPM). These calculations determine when the shift light should be turned on.

Note. Test numbers refer to test numbers on diagnostic chart.

1. This test should not turn on the shift light. If the light is on, there is a short to ground in circuit No. 456 wiring or a fault in the ECM.
2. When the ALDL "test" terminal is grounded, the ECM should ground circuit No. 456 and the shift light should come on.
3. This checks the shift light circuit up to the ECM connector. If the shift light illuminates, the ECM connector is faulty or the ECM does not have the ability to ground the circuit.

Chart C8C: Shift Indicator M/T Schematic. Scheme 354

Chart C8C: Shift Light Indicator M/T Flow Chart. Scheme 355

Chart C8C: Shift Light Indicator M/T. Scheme 356

CHART C10: A/C CLUTCH CONTROL

The ECM control of the A/C clutch improves idle quality and performance by delaying clutch application about .4 second until idle air rate is increased. The ECM also causes the A/C clutch to release with high power steering loads, during Wide Open Throttle (WOT) and during overheat conditions. The ECM also smooths cycling of the compressor by providing aD-Ditional fuel at the instant clutch is applied. Voltage is supplied to the A/C clutch control relay on circuit No. 59 by the A/C select switch. Through the high pressure cut-out switch, this same voltage is supplied as a signal to ECM pin "B8". After a time delay of about a 1/2 second the ECM will ground terminal "A2" (circuit No. 905) and close the A/C relay contacts. When the relay is energized by battery voltage from circuit No. 59, a signal is sent to the A/C clutch through the A/C clutch relay and circuit No. 959.

Note. Test numbers refer to test numbers on diagnostic chart.

1. The ECM will only energize the A/C relay when the engine is running. This test will determine if the relay or circuit No. 905 is faulty.
2. In order for the clutch to properly be engaged, the pressure cycling switch must be closed to provide 12 volts to the relay. Also, the high pressure switch must be closed, so the A/C request (12 volts) will be present at the ECM.
3. Determines if the signal is reaching the ECM on circuit No. 59 from the A/C control panel. Signal should only be present when the A/C mode or defrost mode has been selected.
4. A short to ground in any part of the A/C request circuit could be the cause of the blown fuse.
5. With the ignition on and the diagnostic terminal grounded, the ECM should be grounding circuit No. 905, which should cause the test light to be on.

If problem is insufficient cooling, this may be caused by an inoperative cooling fan. The engine cooling fan should turn on when A/C is on and A/C head pressure exceeds about 233 psi (16.4 kg/cm 2 ). See CHART C12 for diagnosing the cooling fan.

Chart C10: A/C Clutch Control Schematic. Scheme 357

Chart C10: A/C Clutch Control Flow Chart. Scheme 358

Chart C10: A/C Clutch Control Flow Chart (1 Of 2). Scheme 359

Chart C10: A/C Clutch Control Flow Chart (2 Of 2). Scheme 360

COOLING FAN CIRCUIT, 2.8L F BODY (1 OF 2)

The electric cooling fan is controlled by the ECM based on inputs from the coolant temperature sensor, the A/C fan control switch, and vehicle speed sensor. The ECM controls the fan by grounding circuit No. 335, which energizes the fan control relay. Battery voltage is then supplied to the fan motor.

The ECM grounds circuit No. 335, when coolant temperature is greater than about 225°F (107°C), or when A/C has been turned on. This will cause the fan control switch to open with high A/C pressure, about 200 psi (13.8 kg/cm 2 ). Once the ECM turns the relay on, it will keep it on for a minimum of 30 seconds, or until vehicle speed exceeds 70 MPH. Also, if Code 14 or 15 sets, or the ECM is in throttle body back-up, the fan will run at all times. On vehicles not equipped with A/C, circuit No. 732 is jumpered to ground so that the fan does not run at all times.

Note. Test numbers refer to test numbers on diagnostic chart.

1. With the diagnostic "test" terminal grounded, the cooling fan control driver will close, which should energize the fan control relay.
2. If the A/C fan control switch or circuit is open, the fan would run whenever the engine is running.
3. With the A/C clutch engaged, the A/C fan control switch should open when A/C high pressure exceeds about 200 psi (13.8 kg/cm 2 ). This signal should cause the ECM to energize the fan control relay.

If the problem is overheating, it must be determined if the overheating was due to an actual boilover, or the hot light or the temperature gauge indicating overheating. If the gauge or light indicates overheating, but no boilover is detected, the gauge circuit should be checked. The gauge accuracy can also be checked by comparing the coolant sensor reading using the "Scan" tester and comparing its reading with the gauge reading. If the engine is actually overheating and the gauge indicates overheating, but the cooling fan is not coming on, the coolant sensor has probably shifted out of calibration and should be replaced. If the engine is overheating and the cooling fan is on, the cooling system should be checked.

Chart C12: Cooling Fan Schematic. Scheme 361

Chart C12: Cooling Fan Flow Chart (1 Of 2, 2.8L F Body). Scheme 362

Chart C12: Cooling Fan Flow Chart (1 Of 2, 2.8L F Body) (1 Of 2). Scheme 363

Chart C12: Cooling Fan Flow Chart (1 Of 2, 2.8L F Body) (2 Of 2). Scheme 364

COOLING FAN CIRCUIT, 2.8L F BODY (2 OF 2)

Note. Test numbers refer to test numbers on diagnostic chart.

1. There should be 12 volts available to both terminals "E" and "D" when the ignition is on.
2. This test checks the ability of the ECM to ground circuit No. 335. The "SERVICE ENGINE SOON" light should also be flashing at this point. If it isn't flashing, see CHART A2.
3. By jumpering "A" and "E" together, the relay is being by-passed. Cooling fan motor should be on.

Chart C12: Cooling Fan Flow Chart (2 Of 2, 2.8L F Body). Scheme 365

Chart C12: Cooling Fan Flow Chart (2 Of 2, 2.8L F Body). Scheme 366

Scheme 367

Scheme 368

Scheme 369

Wiring Diagram (F Body 2.8L VIN S). Scheme 370