Ccc Tests W/o Codes (trouble Shooting) Chevrolet Camaro II

DESCRIPTION

Note. Most Computer Command Control (CCC) problems are the result of mechanical breakdowns, poor electrical connections or damaged vacuum hoses. Before considering the CCC system as a possible cause of problems, ignition high tension wires, fuel supply, electrical connections and vacuum hoses should be checked. Failure to do so may result in lost diagnostic time.

The Computer Command Control (CCC) system used on these vehicles monitors as many as 19 engine/vehicle functions. This system controls engine operation, lowers exhaust emissions and maintains good fuel economy and driveability. The Electronic Control Module (ECM) is the "brain" of the CCC system. The ECM controls as many as 12 engine related systems and constantly adjusts engine operation.

The CCC system is primarily an emission control system, designed to maintain a 14.7:1 air/fuel ratio under all operating conditions. When the ideal air/fuel ratio is maintained, the catalytic converter can control oxides of nitrogen (NOx), hydrocarbon (HC) and carbon monoxide (CO) emissions.

Schematic of Computer Command Control System. Scheme 59

ECM OPERATING CONDITIONS SENSED

1. A/C "ON" or "OFF"
2. Engine Coolant Temperature
3. Ambient Temperature
4. Barometric Press. (BARO)
5. Brake "ON" or "OFF"
6. Cruise Control "ON" or "OFF"
7. Differential Press. (Eng. Vacuum)
8. Distributor Reference
9. Crankshaft Position
10. Engine Speed
11. EGR Vacuum
12. Engine Cranking
13. Engine Detonation (ESC)
14. Exhaust Oxygen (O2)
15. Manifold Absolute Press. (MAP)
16. Mass Air Flow (MAF)
17. Manifold Air Temperature (MAT)
18. Park/Neutral Sw. Position (P/N)
19. System Voltage
20. Throttle Position (TPS)
21. Transmission Gear Position
22. Vehicle Speed (VSS)

ECM SYSTEMS CONTROLLED

1. A/C
2. Air Management
3. Canister Purge
4. Diagnostics
5. Check Eng. Light
6. Data Output (ALCL)
7. Diagnostic Test Terminal (ALCL)
8. Early Fuel Evaporation (EFE)
9. Electric Fuel Pump
10. Electronic Fuel Inj.(TBI & Port)
11. Electronic Spark Control (ESC)
12. Electronic Spark Timing (EST)
13. Engine Cooling Fan
14. Exhaust Gas Recirculation (EGR)
15. Fuel Control (M/C solenoid)
16. Hood Louvre
17. Idle Air Control (IAC)
18. Idle Speed (ISC. ILC ISS)
19. Torque Converter Clutch (TCC)
20. Turbo Wastegate

HOW TO USE THIS SECTION

This portion of the article is used only AFTER you have checked that

1. The On-Car Diagnostics are working.
2. The ECM and "SERVICE ENGINE SOON" light are operating.
3. There are no trouble codes stored, or only intermittent ones.
4. The fuel control system is operating properly, by performing the System Performance Check. Refer to appropriate TESTS W/ CODES article in this section.
5. A careful visual check found no obvious problems.

Verify the customer complaint, and locate the correct symptom below. Check the items indicated under that symptom. These procedures will normally lead you to a component system on the vehicle, such as EGR, EST, TCC, etc. These are covered in the Component System charts. These charts are listed with a "C" before the number of the chart (C2A, for example).

Symptom Definition

"CHECK ENGINE" light comes on at all times, but does not stay on. A stored code may or may not exist.

Possible Cause & Correction

1. Check for poor mating of one connector to another. Terminals may not be fully seated. Check for improperly formed or damaged terminals. Check wire to terminal connections.
2. Check for poor connection from ignition coil to ground or arcing at spark plug wires or plugs.
3. Check wire from "CHECK ENGINE" light to ECM for short to ground.
4. Check for loss of the trouble code memory. To check this: On EFI engines, disconnect TPS and run engine at idle until "CHECK ENGINE" light comes on. Code 22 should be stored and retained in memory when ignitions turned off. On carbureted engines, ground dwell lead for 10 seconds with "test" lead left ungrounded. Code 23 should be stored and retained in memory after ignition is turned "OFF". If not, ECM is faulty.
5. Check for electrical system interference caused by a defective relay or an ECM driven solenoid or switch. They can cause a sharp electrical surge. This type of problem will normally occur when faulty component is operated.
6. Check for improper installation of electrical accessories such as auxiliary lights or 2-way radios.
7. Make sure that EST wires are kept away from spark plug wires, distributor wires, distributor housing, ignition coil and generator. Make sure that ground wire from ECM to distributor is connected to a good ground.
8. Check for open diodes across air conditioner compressor clutch.

This is defined as engine cranks properly, but does not start. Engine may fire a few times.

1. Perform "Diagnostic Circuit Check".
2. Make sure proper starting procedure is being used.
3. Visual Check: Vacuum hoses for splits, kinks and proper connections, as shown on the Vehicle Emission Control Information label. Ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs.
4. Remove air cleaner and check carburetor choke valve, vacuum break(s), linkage and unloader operation. See FUEL SYSTEMS Section. Choke valve should move smoothly and be closed when cold; open when hot.
5. Check for presence of fuel by noting carburetor accelerator pump operation. Look for gas squirt in carburetor bore while quickly opening throttle lever. If no squirt, check for: fuel in tank, carburetor fuel inlet filter dirty or clogged, fuel pump capacity, and float needle for proper operation. If there is a pump squirt, crank engine and check for flooding. If engine is not flooding check ignition system. See CHART C- 4.
6. Remove spark plugs, check and replace as necessary.
7. Remove distributor cap and check for moisture, dust cracks, burns, and arcing to coil mounting screws.
8. Try to turn distributor shaft by hand, drive pin may be broken.
9. After starting engine, perform "System Performance Check".
10. In very cold temperatures, check that the oil is the proper viscosity and that the crankcase oil is not contaminated with gasoline.

Engine cranks, but does not start for a long time. Eventually, engine does run. If the engine starts but immediately dies (as soon as key is released from start position. See "No Start - Engine Cranks OK".

1. Perform both the "Diagnostic Circuit Check" and the "System Performance Check". Be sure the driver is using the proper starting procedure.
2. Visually check: Vacuum hoses for splits, kinks and proper connections, as shown on the Vehicle Emission Control Information label. Ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. Air leaks at carburetor mounting and intake manifold. Wires for pinches, cuts and proper connections.
3. Check the choke valve, throttle and fast idle cam for sticking. Replace any malfunctioning parts. If caused by foreign material and gum, clean with non-oil base solvent.
4. Check choke and vacuum break operation adjustment.
5. Check EGR valve system for faulty operation that could cause valve to stick open.
6. Check float level using external float gauge. Adjust float to specification if required.
7. Check carburetor fuel inlet filter, replace if required.
8. Check ignition system. See CHART C-4.
9. Check distributor for: worn shaft, bare and shorted wires, pick-up coil resistance and connections, loose ignition coil ground, and moisture in distributor cap.
10. Remove spark plugs: check for wet plugs, wear, improper gap, burned electrodes or heavy deposits. Repair or replace as necessary.
11. Check ignition timing and adjust if necessary.

Engine cranks, but does not start for a long time. Eventually, engine does run. If the engine starts but immediately dies (as soon as key is released from start position), see "No Start - Engine Cranks OK".

1. Perform both the "Diagnostic Circuit Check" and the "System Performance Check". Be sure the driver is using the proper starting procedure.
2. Visually check: Vacuum hoses for splits, kinks and proper connections, as shown on the Vehicle Emission Control Information label. Ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. Wires for pinches, cuts, and proper connections.
3. Check the choke valve, throttle and fast idle cam for sticking. Replace any malfunctioning parts. If caused by foreign material and gum, clean with non-oil base solvent.
4. Check choke and vacuum break operation adjustment.
5. Check EGR valve system for faulty operation that could cause valve to stick open.
6. Check float level using external float gauge. Adjust float to specification if required.
7. Check carburetor fuel inlet filter, replace if required.
8. Check for obvious overheating problems.
9. Check EFE valve or electric heater if applicable. EFE valve should be "OPEN", heater should be "OFF". See CHARTS C-9C & D (If applicable).
10. Check ignition system. See CHART C-4 (If applicable).
11. Check distributor for: worn shaft, bare and shorted wires, pick-up coil resistance and connections, loose ignition coil ground, and moisture in distributor cap.
12. Remove spark plugs; check for wet plugs, wear, improper gap, burned electrodes or heavy deposits. Repair or replace as necessary.
13. Check ignition timing and adjust if necessary.

This condition is with engine at room or outside temperature, within three minutes after start. 1) Stalls after brief idle; 2) dies as soon as any load is placed on engine (such as A/C turned "ON"or transmission engaged); or 3) Dies on initial driveaway. If symptom is present Cold and Hot, go to symptom "Stall After Start - Hot."

1. Perform both the "Diagnostic Circuit Check" and the "System Performance Check".
2. Visually check vacuum hoses for splits, kinks and proper connections, as shown on the Vehicle Emission Control Information label.
3. Make sure hot air tube is connected to air cleaner.
4. Check for proper operation of THERMAC.
5. Check the hose valve, throttle and fast idle cam for sticking. Replace any malfunctioning parts. If caused by foreign material and gum, clean with non-oil base solvent.
6. With engine "OFF" check all choke adjustments, including vacuum breaks and TVS if used.
7. Check carburetor accelerator pump operation.
8. Check fast idle speed and curb idle speed if applicable.
9. Check EFE valve, or electric heater for proper operation. EFE valve should be "CLOSED" cold, electric heater should be "ON" cold. See CHART C-9C and (if applicable) CHART C-9D in the «FEEDBACK CARBURETOR TESTS W/CODES»(ref-95493) article.
10. Check choke and vacuum break operation adjustment.
11. Check EGR valve system for sticky operation that could cause valve to stick open.
12. Check ignition timing and adjust if necessary.
13. Check for poor or contaminated gasoline.

This condition is with engine at room or outside temperature, within three minutes after start. 1) Stalls after brief idle; 2) Dies as soon as any load is placed on engine (such as A/C turned "ON" or transmission engaged); or 3) Dies on initial driveway.

1. Perform both the "Diagnostic Circuit Check" and the "System Performance Check".
2. Visually check vacuum hoses for splits, kinks and proper connections, as shown on the Vehicle Emission Control Information label.
3. Make sure hot air tube is connected to air cleaner.
4. Check for proper operation of THERMAC.
5. Check the choke valve, throttle and fast idle cam for sticking. Replace any malfunctioning parts. If caused by foreign material and gum, clean with non-oil base solvent.
6. With engine "OFF" check all choke adjustments, including vacuum breaks and TVS if used.
7. Check carburetor accelerator pump operation.
8. Check fast idle speed and curb idle speed if applicable.
9. Check EFE valve, or electric heater for proper operation. EFE valve should be "OPEN", electric heater should be "ON". See CHART C-9C and (if applicable) CHART C-9D in the «FEEDBACK CARBURETOR TESTS W/CODES»(ref-95493) article.
10. Check choke and vacuum break operation adjustment.
11. Check EGR valve system for faulty operation that could cause valve to stick open.
12. Check ignition timing and adjust if necessary.
13. Check for poor or contaminated gasoline.

This is defined as a momentary lack of response as the accelerator is pushed down. It can occur at all car speeds. Usually, it is most severe when first trying to make car move. Occasionally, this condition may cause car to stall.

1. Perform both the "Diagnostic Circuit Check" and the "System Performance Check".
2. Visually check: Vacuum hoses for splits, kinks and proper connections, as shown on the Vehicle Emission Control Information label. Ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. Wires for pinches, cuts, and proper connections.
3. Make sure hot air tube is connected to air cleaner.
4. Check for proper operation of THERMAC.
5. Check float level using external float gauge. Adjust float to specification if required.
6. With engine "OFF" check all choke adjustments, including vacuum breaks and TVS if used.
7. Check carburetor accelerator pump operation.
8. Check fast idle speed and curb idle speed if applicable.
9. Check EFE valve, or electric heater for proper operation. EFE valve should be "CLOSED", electric heater should be "ON". See CHART C-9C and (if applicable) CHART C-9D in the «FEEDBACK CARBURETOR TESTS W/CODES»(ref-95493) article.
10. Check vacuum hose to MAP sensor for leaks, restrictions and proper connections (should be manifold vacuum).
11. Check EGR valve operation.
12. Check TPS adjustment.
13. Check canister purge system.
14. Check for open ignition coil ground and for intermittent ECM ground.
15. Check engine ignition timing.
16. Poor or contaminated gasoline.

This portion of the article is used only AFTER you have checked that

1. The On-Car Diagnostics are working.
2. The ECM and "SERVICE ENGINE SOON" light are operating.
3. There are no trouble codes stored, or only intermittent ones.
4. The fuel control system is operating properly, by performing the Field Service Mode Check. Refer to appropriate TESTS W/ CODES article in this section.
5. A careful visual check found no obvious problems.

Verify the customer complaint, and locate the correct symptom below. Check the items indicated under that symptom. These procedures will normally lead you to a component system on the vehicle, such as EGR, EST, TCC, etc. These are covered in the Component System charts. These charts are listed with a "C" before the number of the chart (C2A, for example).

FUEL SYSTEM PRESSURE TEST (EFI MODELS ONLY)

Note. Trouble shooting and diagnosis of the fuel system should begin with determining fuel injection system pressure. Before performing any test on the fuel system, pressure must be released from the system.

1. Remove "FUEL PUMP" fuse from fuse block. Crank engine. Engine will start and run until fuel supply remaining in fuel lines is used. Engage the starter again for about 3 seconds to ensure that all fuel is out of lines.
2. Remove air cleaner and plug thermal vacuum port on throttle body. Remove steel fuel line from between front and rear throttle body units. When removing fuel line, always use 2 wrenches. Install fuel pressure gauge (J-29658 or equivalent) between throttle body units.
3. Reinstall "FUEL PUMP" fuse in in fuse block. Start engine and observe fuel pressure reading. If fuel pressure is not between 9 and 13 psi (.6-.9 kg/cm 2 ), proceed to Fuel System Diagnosis chart. If fuel pressure is okay, proceed to step 4).
4. Depressurize fuel system as described in step 1). Remove fuel pressure gauge and reinstall steel fuel line between throttle bodies. Reinstall "FUEL PUMP" fuse in fuse block. Start engine and watch for fuel system leaks. Remove plug from throttle body thermal vacuum port and reinstall air cleaner.

"CHECK ENGINE" light comes on at all times, but does not stay on. A stored code may or may not exist.

1. Check for poor mating of one connector to another. Terminals may not be fully seated. Check for improperly formed or damaged terminals. Check wire to terminal connections.
2. Check for poor connection from ignition coil to ground or arcing at spark plug wires or plugs.
3. Check wire from "CHECK ENGINE" light to ECM for short to ground.
4. Check for loss of the trouble code memory. To check this: On EFI engines, disconnect TPS and run engine at idle until "CHECK ENGINE" light comes on. Code 22 should be stored and retained in memory when ignitions turned off. On carbureted engines, ground dwell lead for 10 seconds with "test" lead left ungrounded. Code 23 should be stored and retained in memory after ignition is turned "OFF". If not, ECM is faulty.
5. Check for electrical system interference caused by a defective relay or an ECM driven solenoid or switch. They can cause a sharp electrical surge. This type of problem will normally occur when faulty component is operated.
6. Check for improper installation of electrical accessories such as auxiliary lights or 2-way radios.
7. Make sure that EST wires are kept away from spark plug wires, distributor wires, distributor housing, ignition coil and generator. Make sure that ground wire from ECM to distributor is connected to a good ground.
8. Check for open diodes across air conditioner compressor clutch.

NO START - ENGINE CRANKS OK (EFI MODELS ONLY)

Note. For NO START condition, see Chart "A" tests in appropriate GENERAL MOTORS COMPUTERIZED ENGINE CONTROLS article.

Engine cranks okay but does not start for a long time. Engine eventually starts and runs okay.

1. Check fuel pump relay. To do this, disconnect oil pressure switch. If engine starts, relay is okay. If engine does not start, proceed to Fuel System Diagnosis chart.
2. Check that TPS is not sticking or binding.
3. Check for a leaking injector. To do this, disconnect injector electrical connector at injector. Crank engine and watch for fuel leakage.
4. Check that resistance of coolant sensor circuit or coolant sensor is not too high. See chart for CODE 15.
5. Check ignition system for a worn distributor shaft, bare or shorted wires, incorrect pick-up coil resistance, loose ignition coil ground or moisture in distributor cap.
6. Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes or heavy carbon deposits.
7. Check for correct fuel pressure of 9-13 psi in all speed ranges.
8. A faulty in-tank fuel pump check valve will allow the fuel in the lines to drain back to the tank after the engine is topped. To check this condition: Turn ignition "OFF", disconnect fuel pressure line at the fuel rail, remove the filler cap, and connect a radiator test pump and apply 13 psi pressure. If pressure will hold for 60 seconds, the check valve is okay.

Engine starts okay but dies after brief idle, dies as soon as any load is placed on engine (such as turning on air conditioner or engaging transmission), or on initial driveaway.

1. Make sure that hot air tube is connected to air cleaner.
2. Check for proper operation of thermostatic air cleaner.
3. Check for proper operation of idle air control (IAC) system. See CHART 11: IDLE AIR CONTROL in appropriate TBI TESTS W/CODES article (2.0L "J" Body vehicle only).
4. Check PCV valve for proper operation. See appropriate PCV SYSTEM article.
5. If stall occurs when air conditioner is turned on, check for air conditioner clutch signal to ECM terminal. Voltage at A/C terminal of ECM should be battery voltage when air conditioner compressor clutch is engaged.
6. Check for an overcharged air conditioner system.
7. Check for plugged or restricted fuel lines.
8. Check for a weak spark from ignition coil.