Tbi Tests W/codes Chevrolet Camaro II

ELECTRONIC CONTROL MODULE (ECM)

Remove ECM mounting hardware. Disconnect electrical connectors and ground strap. Remove ECM. To install ECM, reverse removal procedure and ensure ground strap is securely attached.

Note. The ECM may be located at right side kick panel, glove compartment area or center console area.

Removal

1. Remove ECM as previously described. Remove sheet metal screw holding access cover closed and remove access cover. Using a small flat tip screwdriver, place blade at PROM carrier reference end between edge of opening in case and underside of protruding lip of carrier. Apply prying force and force side of carrier up as far as possible. Repeat procedure on other reference end lip.
2. Using prying force explained in step 1), force opposite end of carrier up as far as possible. Grasp carrier with thumb and forefinger. Gently rock carrier from side to side while applying upward force and remove PROM.

Scheme 227

1. Before installing new PROM, be sure part number agrees with removed PROM. Ensure molded "half-round" depression of PROM is at same end as "squared-off" symmetrical end of carrier and that PROM is centered in carrier. NOTE: If PROM is installed backwards and ignition is turned on, PROM will be destroyed and must be replaced. (Scheme 227): Replacing PROM in Electronic Control Module (ECM)
2. Position carrier squarely over PROM socket with "squared-off" symmetrical end of carrier aligned with small notch in socket. Press down firmly on top of carrier and press down on body of PROM with narrow blunt tool. Squarely seat PROM in socket by alternately pressing down on either end of PROM.
3. Replace access cover and reinstall ECM. Reconnect electrical connectors and start engine. Enter diagnostics and check for trouble code "51". If trouble code "51" does not appear, PROM is correctly installed.
4. If code "51" does appear, PROM is not fully seated, is installed backwards, has bent pins, or is defective. Remove ECM and fully seat PROM. If pins are bent, remove PROM, straighten pins and reinstall PROM. If pins break or crack during straightening process, replace PROM. If PROM is installed backwards, replace PROM.

Raise and support vehicle (if required). Disconnect electrical connector at harness. Spray threads of oxygen sensor with penetrating oil and allow to soak for 5 minutes. Carefully remove oxygen sensor.

Note. Do not attempt to reinstall an oxygen sensor. Reinstallation of a sensor without special glass bead thread coating may require complete replacement of exhaust system.

THROTTLE POSITION SENSOR (TPS)

Removal and installation require removal of carburetor or throttle body unit.

MAP/BARO Or Vacuum Sensor Location. (Location May Also Be In Passenger Compartment.). Scheme 228

HIGH GEAR SWITCH

Removal and installation requires disassembly of transmission.

Note. Removal and installation of any solenoids, switches or sensors not listed is accomplished by disconnecting the wiring harness and removing or detaching the device. To install, reverse removal procedure.

BASIC TEST PROCEDURES

Diagnosis of the CCC system is done in the following order

1. Ensure that all engine systems NOT related to the CCC are fully operational. Do not proceed with testing unless you are sure all other problems have been fixed.
2. Enter diagnostic mode and record trouble codes flashed by "CHECK ENGINE" light. Exit diagnostic mode.
3. Distinguish between "hard" or "intermittent" trouble codes.
4. If trouble codes were displayed, go to Diagnostic Circuit Check chart. Follow instructions given there.
5. If no trouble codes were recorded, go to Drive Complaint Sheet and follow instructions given there.
6. After any repairs are made, perform System Performance Check. Clear any trouble codes.

Note. The following paragraphs explain the procedures involved in performing the steps outlined above.

The ECM stores component failure information for CCC system under a related trouble code which can be recalled for diagnosis and repair. When recalled, these codes will be displayed by flashes of "CHECK ENGINE" lamp. Codes are displayed starting with lowest numbered code. Only codes in which a related malfunction has occurred will be displayed.

Note. Example of trouble codes is as follows: "FLASH", "FLASH", "FLASH", pause, "FLASH", "FLASH" followed by a longer pause identifies trouble code "32". First series of flashes indicates first digit of trouble code; second series of flashes indicates second digit of trouble code.

Scheme 229

1. Turn ignition on (engine off). "CHECK ENGINE" lamp should glow. Locate Assembly Line Data Link (ALDL) connector attached to ECM wiring harness under instrument panel. Insert spade lug terminal across "TEST" terminal and "GROUND" terminal. (Scheme 229) (Scheme 229): ALDL Connector Terminal Locations
2. "CHECK ENGINE" lamp should flash code "12". Code "12" consists of "FLASH", pause, "FLASH", "FLASH" followed by a longer pause. Trouble code "12" will be repeated 2 more times, then if any trouble codes are stored in ECM memory, they will be displayed in same manner.
3. Trouble codes will be displayed from lowest to highest numbered code (3 times each) and be repeated as long as the "TEST" terminal of ALDL connector is grounded.

CLEARING TROUBLE CODES

To clear memory of trouble codes, turn ignition on and ground "TEST" lead at ALDL connector. Turn ignition off and remove ECM fuse from fuse block for 10 seconds. Remove "TEST" lead ground.

EXITING DIAGNOSTIC MODE

To exit diagnostic mode, turn ignition off and remove spade lug terminal from ALDL connector.

Note. The terms "enter diagnostics" and "exit diagnostics" will be used periodically throughout this section. Follow the procedure for entering diagnostic mode when instructed to "enter diagnostics". Follow the procedure for exiting diagnostic mode when instructed to "exit diagnostics".

FAILURE CODE DETERMINATION

During any diagnostic procedure, "hard failure" codes MUST be distinguished from "intermittent failure" codes. Diagnostic charts CANNOT be used to analyze "intermittent failure" codes, except as noted under Diagnostic Procedure. To determine "hard failure" codes and "intermittent failure" codes, proceed as follows

1) Turn ignition on and enter diagnostics. Read and record all stored trouble codes. Exit diagnostics and clear trouble codes.

Note. Trouble codes will be recorded on "T" cars only with engine running. Turning ignition off after any trouble codes have been set will erase all codes.

1. Apply parking brake and place transmission in neutral (man. trans.) or "P" (auto. trans.). Block drive wheels. Start engine. "CHECK ENGINE" lamp should go out. Run warm engine at specified curb idle for 2 minutes and note "CHECK ENGINE" light. NOTE: Grounding "TEST" terminal with engine running will force engine to operate in closed loop mode if engine is warm and oxygen sensor is hot. If "CHECK ENGINE" lamp does not glow while in closed loop, CCC system is operating properly.
2. If "CHECK ENGINE" lamp comes on, enter diagnostics, read and record trouble codes. This will reveal "hard failure" codes. Codes "13", "15", "24", "35", "44", "45" and "55" may require road test to reset "hard failure" after trouble codes were cleared.
3. If "CHECK ENGINE" lamp does not come on, all stored trouble codes were "intermittent failures", except as noted under Diagnostic Procedure.

Note. Trouble code "15" malfunction will only display after 5 minutes of engine operation. Trouble code "12" will display only during time of no reference pulses received by ECM; it will never be stored as a malfunction.

BASIC DIAGNOSTIC PROCEDURES

The CCC system should be considered as a possible source of trouble on engine performance, fuel economy and exhaust emission complaints ONLY after normal checks (which apply to a vehicle without CCC) have been performed.

Diagnosis of CCC system consists of 3 types of initial checks: Diagnostic Circuit Check, Driver Complaint Check and Field Service Mode Check. Any of these checks may lead to a chart for locating source of problem or indicate no problem on that check and refer to another check.

If there is no trouble in CCC system, all 3 checks will result in that conclusion. The checks and their procedures are as follows

Note. If vehicle exhibits performance problems and no codes are set, refer to the Field Service Mode Check. Components recorded by trouble codes generally do not cause performance problems when no codes are stored in ECM memory.

DIAGNOSTIC CIRCUIT CHECK DESCRIPTION

1. If complaint is "CHECK ENGINE" lamp related, this check will lead to most likely problem area, if malfunction exists. Enter diagnostics and record stored trouble codes. Begin diagnosis with lowest numbered code which is displayed and refer to appropriate trouble code chart.
2. If code "51" is displayed, refer to PROM removal and installation in this article for diagnosis of this code. If codes "54" or "55" are displayed with another code, always refer to diagnostic chart for code "54" or "55" first, then proceed to next lowest numbered code. (Scheme 231)

Note. Any time codes "51", "54" or "55" are displayed with another code, start with "50-series" code first, then proceed to lowest numbered code.

DRIVER COMPLAINT CHECK DESCRIPTION

1. If complaint is not "CHECK ENGINE" lamp related, this check will lead to most likely problem area. However, first make checks that would normally be made for the complaint on a vehicle without CCC system.
2. Follow instructions in diagnostic chart and repair malfunction. After repair, perform Field Service Mode Check.

FIELD SERVICE MODE CHECK DESCRIPTION

1. This test confirms proper operation of fuel system and verifies Closed Loop operation. Clear codes and perform this test after any repair is completed.
2. When performing this check, always engage parking brake and block DRIVE wheels. Parking brake on front-wheel drive models does not hold drive wheels.
3. On some engines, the oxygen sensor will cool off after only a short period of time while engine is idling. This will cause engine to go into open loop. To restore closed loop mode, run engine at part throttle several minutes and accelerate from idle to part throttle several times. (Scheme 233)

Note. Although there are many charts connected with CCC diagnosis, only 2 charts are needed to prove the system is operating properly. Normally, only 3 charts are necessary to find a problem, if one exists.

DIAGNOSTIC TOOLS

1. The CCC system does not require special tools for diagnosis. A dwell meter, tachometer, test light, ohmmeter, digital voltmeter with 10 megohms impedance (minimum), vacuum pump, vacuum gauge and 6 jumper wires 6" long (1 wire with female connectors at both ends; 1 wire with male connectors at both ends; 4 wires with male and female connectors at opposite ends) are only tools necessary for diagnosis.
2. A test light, rather than a voltmeter, must be used when indicated by diagnostic chart.
3. A dwell meter is used to measure the time that mixture control solenoid is on or off. This gives an indication of how the system is working and how rich or lean the mixture is. The dwell meter is set for 6-cylinder scale on ALL engines, regardless of how many cylinders the engine has.
4. Dwell meter is connected to Green connector located near the carburetor. This connector will not be connected to any circuit EXCEPT when you are testing with the dwell meter. Do not allow terminal wire to come in contact with any ground source, including rubber hoses. NOTE: If engine operation seems to change when dwell meter is connected to Green wire, remove dwell meter and use another type. A few brands are not compatible with CCC system.
5. When engine is at operating temperature and idling, dwell meter needle will move up and down on scale, between 10-50°. This indicates "Closed Loop" operation. If the needle does not move, "Open Loop" operation is indicated.

Location of CCC System Components. Scheme 230

TROUBLE CODE ID CHART

ECM TROUBLE CODE IDENTIFICATION

DIAGNOSTIC CIRCUIT CHECK

1. If complaint is "CHECK ENGINE" lamp related, this check will lead to most likely problem area, if malfunction exists. Enter diagnostics and record stored trouble codes. Begin diagnosis with lowest numbered code which is displayed and refer to appropriate trouble code chart.
2. If code "51" is displayed, refer to PROM removal and installation in this article for diagnosis of this code. If codes "54" or "55" are displayed with another code, always refer to diagnostic chart for code "54" or "55" first, then proceed to next lowest numbered code. (Scheme 231)

Note. Any time codes "51", "54" or "55" are displayed with another code, start with "50-series" code first, then proceed to lowest numbered code.

Diagnostic Circuit Check Flow Chart. Scheme 231

Diagnostic Circuit Check Flow Chart. Scheme 232

FIELD SERVICE MODE CHECK

1. This test confirms proper operation of fuel system and verifies Closed Loop operation. Clear codes and perform this test after any repair is completed.
2. When performing this check, always engage parking brake and block DRIVE wheels. Parking brake on front-wheel drive models does not hold drive wheels.
3. On some engines, the oxygen sensor will cool off after only a short period of time while engine is idling. This will cause engine to go into open loop. To restore closed loop mode, run engine at part throttle several minutes and accelerate from idle to part throttle several times. (Scheme 233)

Note. Although there are many charts connected with CCC diagnosis, only 2 charts are needed to prove the system is operating properly. Normally, only 3 charts are necessary to find a problem, if one exists.

Field Service Mode Check Flow Chart. Scheme 233

Field Service Mode Check Flow Chart. Scheme 234

Note. Open Loop at idle only may be caused by a cold oxygen sensor after a period of idling. If this is the cause, running engine at 2000-3000 RPM for one minute should warm it up and give closed loop operation at idle.

INTERMITTENT "CHECK ENGINE" LIGHT OR STORED CODES

Note. DO NOT use diagnostic charts for intermittent problems. The fault must be present to locate the problem. If the fault is intermittent, use of the charts may result in the replacement of non-defective parts.

Most intermittent problems are caused by faulty electrical connectors or wiring. Diagnosis must include a careful visual and physical inspection of the indicated circuit wiring and connectors. Check the following

1. Check for poor mating of the connector halves or terminals not fully seated in connector body.
2. Check for improperly formed or damaged terminals. All connector terminals in the affected circuit should be re-formed to increase contact tension.
3. Check that all HEI distributor EST wires are routed away from distributor, ignition coil, secondary wires and alternator.
4. Check circuit No. 419 ("CHECK ENGINE" light circuit) for a short to ground.
5. Check circuit No. 451 (diagnostic connector to ECM) for a short to ground.
6. Check circuits No. 450 and 450R for an ECM ground at engine block attachment.
7. Check for electrical interference caused by a defective relay, ECM driven solenoid, or a switch causing a sharp electrical surge. The problem will occur when the defective component is operated.
8. Check for improper installation of electrical options.
9. Check for open A/C clutch diode.

1. 2) If the complaint is stalling, rough or improper idle speed, see Chart 11, (Scheme 253).
2. 3) If the engine cranks, but will not run, see Chart 4 or 4A, (Scheme 233) or 8.
3. 4) If the complaint is hard starting, poor performance, driveability or poor fuel economy, see CHART 7, POOR PERFORMANCE (NO STORED CODES) in this article.
4. 5) If the complaint is detonation (spark knock), see Chart 10 ESC Performance (if applicable), (Scheme 252), or chart 8, (Scheme 243).
5. 6) If driver complains of poor performance with A/C on, problem is with the A/C system. Refer to appropriate article in the AIR CONDITIONING section.

Following any repairs or adjustments, always clear codes and confirm closed loop operation and "CHECK ENGINE" light.

Chart 2: No "CHECK ENGINE" Light Flow Chart. Scheme 235

CHART 2: NO "CHECK ENGINE" LIGHT FLOW CHART. Scheme 236

Chart 3: No Code 12 Displayed Flow Chart. Scheme 237

Chart 3: No Code 12 Displayed Flow Chart. Scheme 238

Chart 4: Engine Cranks But Won't Run Flow Chart (4-Cyl). Scheme 239

Chart 4: Engine Cranks But Won't Run Flow Chart (4-Cyl) (1 Of 2). Scheme 240

Chart 4: Engine Cranks But Won't Run Flow Chart (4-Cyl) (2 Of 2). Scheme 241

Chart 4A: Engine Cranks But Won't Run Flow Chart (V8). Scheme 242

Chart 4A: Engine Cranks But Won't Run Flow Chart 1 Of 2 (V8). Scheme 243

Chart 4A: Engine Cranks But Won't Run Flow Chart 2 Of 2 (V8). Scheme 244

Fuel Injection Schematic For Charts 4 & 5 (1.8L & 2.5L). Scheme 245

Fuel Injection Schematic For Charts 4 & 5 (2.0L). Scheme 246

Chart 5: Fuel System Diagnosis Flow Chart 1 of 2 (4-Cyl). Scheme 247

Chart 5: Fuel System Diagnosis Flow Chart 2 of 2 (4-Cyl). Scheme 248

Chart 5: Fuel System Diagnosis Flow Chart 1 Of 2 (4-Cyl). Scheme 249

Chart 5: Fuel System Diagnosis Flow Chart 2 Of 2 (4-Cyl). Scheme 250

Chart 5A: Fuel System Diagnosis Flow Chart (1 of 4) (V8). Scheme 251

Chart 5A: Fuel System Diagnosis Flow Chart (2 of 4) (V8). Scheme 252

Chart 5A: Fuel System Diagnosis Flow Chart (3 of 4) (V8). Scheme 253

Chart 5A: Fuel System Diagnosis Flow Chart (4 of 4) (V8). Scheme 254

Chart 6: HEI Check W/Integral Ign Coil Flow Chart. Scheme 255

Chart 6: HEI Check W/Integral Ign Coil Flow Chart. Scheme 256

Chart 6A: HEI Check W/Remote Ign Coil Flow Chart. Scheme 257

Chart 6A: HEI Check W/Remote Ign Coil Flow Chart. Scheme 258

Hesitates, Sluggish, Sags Or Poor Mileage

Check the following

1. Fuel pressure should be a steady 9-13 psi at all speed ranges.
2. Base timing.
3. MAP hose, visually check for leaks or restrictions.
4. TPS sensor, visually check for sticking or binding.
5. EFI injector(s); with injector harness disconnected, check for fuel leakage while cranking.
6. EFI balance adjustment on V8.
7. A/C compressor clutch control.
8. TCC. See Chart 8E.
9. Check for open HEI ground, circuit 453.
10. Fan control circuit, chart 8A.

Cuts Out Or Stalls

Check the following

1. Intermittent open or short to ground in circuit 416, 5 volt reference, circuit 430, HEI reference, Circuit 120, fuel pump circuit, circuits 467 and 468, injector drive circuits (Chart 4A) and circuits 441, 442, 443 and 444, ICA drive circuits.
2. Check for restricted fuel filter. Fuel pressure should be 9-13 psi at all speed ranges.

Surges

Check the following

1. Intermittent open or short to ground in circuit 420 and 422 (TCC), circuit 424, (HEI bypass), circuit 423 (EST).
2. EGR, See Chart 8.

Hard Starting Hot Or Cold

Check the following

1. Fuel pump relay. Disconnect oil pressure switch. If engine cranks but won't start go to Chart 5 or 5A test point 1
2. Visually check TPS sensor for sticking or binding.
3. Fuel pressure should be 9-13 psi at all speed ranges. Fuel pressure leak down should be gradual after ignition is OFF on 2.5L engine. An instant drop in pressure indicates a leaking in-tank fuel pump coupling hose or check valve.
4. TBI injector(s). With injector harness disconnected, check for fuel leakage while cranking.
5. Crank circuit, see Chart 9B.
6. High resistance in coolant sensor circuit.

CHART 8: EGR CHECK (2.0L & 5.0L)

Note. Make a physical inspection of hoses and electrical connections.

Chart 8: EGR Check Flow Chart (2.0L & 5.0L). Scheme 259

Chart 8: EGR Check Flow Chart (2.0L & 5.0L). Scheme 260

Chart 8A: Cooling Fan Control Circuit With A/C Flow Chart (1.8L & 2.5L). Scheme 261

CHART 8A: COOLING FAN CONTROL CIRCUIT WITH A/C FLOW CHART (1.8L & 2.5L). Scheme 262

WITH ELECTRIC DIVERT AND SWITCHING VALVE

Note. Check vacuum hose condition and connection. Repair as necessary. On some applications, some air may divert above 2000 RPM.

Chart 8B: Air Management W/Elect Divert & Switching Valve Flow Chart (2.0L & 5.0L). Scheme 263

Chart 8B: Air Management W/Elect Divert & Switching Valve Flow Chart 1 Of 2 (2.0L & 5.0L). Scheme 264

Chart 8B: Air Management W/Elect Divert & Switching Valve Flow Chart 2 Of 2 (2.0L & 5.0L). Scheme 265

CHART 8C: PULSAIR SOLENOID CHECK (2.0L)

Note. Remove air cleaner to gain access to pulsair solenoid hose. Make physical check of hose and connections.

Chart 8C: Pulsair Solenoid Flow Chart (2.0L). Scheme 266

Chart 8C: Pulsair Solenoid Flow Chart (2.0L). Scheme 267

Chart 8D: Canister Purge Valve Flow Chart (2.0L & 5.0L). Scheme 268

Chart 8D: Canister Purge Valve Flow Chart (2.0L & 5.0L). Scheme 269

CHART 8E: TCC ELECTRICAL DIAGNOSIS

Note. Mechanical checks, such as linkage, oil level, etc. should be performed before using this chart.

Chart 8E: TCC Electrical Diagnosis Flow Chart. Scheme 270

Chart 8E: TCC Electrical Diagnosis Flow Chart 1 Of 2. Scheme 271

Chart 8E: TCC Electrical Diagnosis Flow Chart 2 Of 2. Scheme 272

Chart 8F: Hood Louvre Solenoid Flow Chart (5.0L). Scheme 273

Chart 8F: Hood Louvre Solenoid Flow Chart (5.0L). Scheme 274

Chart 9A: Park/Neutral Switch Flow Chart. Scheme 275

Chart 9A: Park/Neutral Switch Flow Chart. Scheme 276

Chart 9B: Crank Signal Flow Chart. Scheme 277

Chart 9B: Crank Signal Flow Chart. Scheme 278

ENGINE KNOCK, POOR PERFORMANCE OR ECONOMY - NO CODE 43

Note. This chart should only be used after all other causes of spark knock have been checked, timing EGR, MAP, engine temperature or excessive engine noise, ect.

Chart 10: ESC System Check Flow Chart. Scheme 279

Chart 10: ESC System Check Flow Chart. Scheme 280

Chart 11: Idle Air Control Flow Chart. Scheme 281

Chart 11: Idle Air Control Flow Chart. Scheme 282

Code 13: Open Oxygen (O2) Sensor Circuit Flow Chart. Scheme 283

Code 13: Open Oxygen (O2) Sensor Circuit Flow Chart. Scheme 284

Code 14: Coolant Temp Sensor Signal Volt Lo Flow Chart. Scheme 285

Code 14: Coolant Temp Sensor Signal Volt Lo Flow Chart. Scheme 286

Code 15: Coolant Temp Sensor Signal Volt Hi Flow Chart. Scheme 287

Code 15: Coolant Temp Sensor Signal Volt Hi Flow Chart. Scheme 288

Code 21: TPS Signal Voltage High Flow Chart. Scheme 289

Code 21: TPS Signal Voltage High Flow Chart. Scheme 290

Code 22: TPS Signal Voltage Low Flow Chart. Scheme 291

Code 22: TPS Signal Voltage Low Flow Chart. Scheme 292

Code 24: Vehicle Speed Sensor Flow Chart (1.8L & 2.5L). Scheme 293

Code 24: Vehicle Speed Sensor Flow Chart (1.8L & 2.5L). Scheme 294

Code 24: Vehicle Speed Sensor Flow Chart (2.0L & 5.0L). Scheme 295

Code 24: Vehicle Speed Sensor Flow Chart (2.0L & 5.0L). Scheme 296

Code 33: MAP Sensor Signal Volt Hi Flow Chart. Scheme 297

CODE 33: MAP SENSOR SIGNAL VOLT HI FLOW CHART. Scheme 298

Code 34: MAP Sensor Signal Volt Lo Flow Chart. Scheme 299

Code 34: MAP Sensor Signal Volt Lo Flow Chart. Scheme 300

Code 42: Electronic Spark Timing (EST) Flow Chart. Scheme 301

Code 42: Electronic Spark Timing (EST) Flow Chart. Scheme 302

Code 43: ESC Voltage at ECM Lo Flow Chart. Scheme 303

Code 43: ESC Voltage At ECM Lo Flow Chart. Scheme 304

Code 44: Lean Exhaust Indication Flow Chart. Scheme 305

Code 44: Lean Exhaust Indication Flow Chart. Scheme 306

Code 45: Rich Exhaust Indication Flow Chart. Scheme 307

Code 45: Rich Exhaust Indication Flow Chart. Scheme 308

CODE 51: PROM ERROR

PROM is either installed incorrectly, defective, or the wrong part number. Check for proper installation and application. If installed properly, but code 51 is still present, PROM is defective and must be replaced.

CODE 55: ELECTRONIC CONTROL MODULE

If a Code 55 is displayed, replace the ECM.

CHART C1 - ECM REPLACEMENT CHECK CHART

In order to reduce incidents of repeat ECM failure, a revised ECM diagnostic procedure is available. Beginning in 1982, most ECMs are equipped with Integrated Circuits (IC) in place of separate transistors to operate various controlled components.

These ICs, called Quad-Drivers (QDR), have 4 separate outputs, meaning that each QDR can operate up to 4 different components. An inoperative QDR can result in ECM output becoming open or shorted to ground. Often, all 4 outputs of a QDR will fail, even if just one QDR circuit is faulty.

Refer to the following tables to determine which ECMs contain QDRs. Since this procedure is not applicable to ECMs which do not contain QDRs, those ECMs are not listed.

Performing the diagnostic flow chart will identify an inoperative QDR. Once the circuit is identified, it must be repaired to eliminate repeat ECM failure. This diagnostic procedure must be used when "Replace ECM" is the conclusion of any procedure.

ECM QDR IDENTIFICATION (TBI/PFI)

ECM QDR IDENTIFICATION (CARBURETED)

ECM QDR IDENTIFICATION (PFI)

ECM QDR IDENTIFICATION (TBI)

ECM QDR IDENTIFICATION (TBI)

Scheme 309

EFE (Vacuum Servo) Check Flow Chart. Scheme 310

EFE (Vacuum Servo) Check Flow Chart. Scheme 311

EFE (Vacuum Servo) Check Flow Chart. Scheme 312

EFE (Vacuum Servo) Check Flow Chart. Scheme 313

EFI (Exc. 5.0L) System Wiring Diagram. Scheme 314

EFI (5.0L) System Wiring Diagram (Camaro & Firebird Only). Scheme 315