Engine Control System - Basic Engine Testing Cadillac DeVille Concours I final

INTRODUCTION

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is verifying the customer's complaint with a test drive under the conditions during which the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article.

Note. Unless otherwise instructed in test procedures, perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance.

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. If necessary, see appropriate VACUUM DIAGRAMS article to verify routing and connections. Inspect air induction system for possible vacuum leaks.

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. For compression specifications, see appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.

Exhaust System Backpressure

Before replacing any components, check exhaust system for restrictions. Use a vacuum gauge or a low-pressure (0-5 psi) gauge to check exhaust system.

If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Partially open throttle and hold steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction. If using a low pressure gauge, connect gauge in one of the following manners

1. Check At AIR Check Valve Remove AIR check valve. Install backpressure tester in place of AIR check valve.
2. Check At Oxygen Sensor Remove oxygen sensor. Install backpressure tester in place of oxygen sensor. After test is completed, coat oxygen sensor threads with anti-seize compound before installation.

Diagnosis

1. Start engine and allow it to reach normal operating temperature. Increase engine speed to 2000-2500 RPM and note gauge. If reading exceeds 1.25 psi (.09 kg/cm 2 ), exhaust system is restricted.
2. Check exhaust system for collapsed pipe, heat distress and possible internal muffler failure. If none of these conditions exist, check for restricted catalytic converter. Replace as necessary.

NO START DIAGNOSIS

Note. Some vehicles are equipped with anti-theft systems (VATS or PASS-Key(R)) which will not allow vehicle to be started if improper starting procedures or improperly coded ignition keys are used. Both fuel injection and cranking systems will be disabled. Loss of fuel enable signal from anti-theft decoder module should set a diagnostic trouble code in PCM memory.

Note. For terminal and circuit identification, see appropriate wiring diagram in WIRING DIAGRAMS article.

1. Definition No-start is defined as engine cranks properly, but does not start. Engine may fire a few times.

NO START - ENGINE CRANKS OKAY (1.9L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

Diagnostic Procedure

1. Install scan tool. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. Check for stuck Throttle Position (TP) sensor. Ensure Engine Coolant Temperature (ECT) sensor value reads close to ambient temperature. Check for fuel injector Diagnostic Trouble Codes (DTCs). If fuel injector DTCs are present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If fuel injector DTCs are not present, go to next step.
2. If DTC P1635 is present, diagnose DTC first. See appropriate SELF-DIAGNOSTICS article. If DTC P1635 is not present, go to next step.
3. If any Ignition Control (IC) related DTC is present, diagnose DTC first. See appropriate SELF-DIAGNOSTICS article. If DTC is not present, go to next step.
4. If an EGR related DTC is present, diagnose DTC first. See appropriate SELF-DIAGNOSTICS article. If EGR DTC is not present, go to next step.
5. Using scan tool, monitor engine RPM (7X CKP reference pulse) while cranking engine. If RPM is detected, go to next step. If RPM is not detected, go to step 15.
6. If scan tool 7X counter reads more than 100 counts, go to next step. If scan tool 7X counter reads 100 counts or less, go to step 10.
7. Check for spark at cylinders No. 2 and 4. If spark is present, check for fouled spark plugs. If spark plugs are okay, go to step 11. If spark is not present, go to next step.
8. Check EIS fuse (10-amp), located in underhood fuse block, or voltage to fuse with ignition on. (Scheme 1) If fuse is okay and voltage is present, go to next step. If fuse is faulty or voltage is not present, replace fuse or repair circuit.
9. Disconnect Electronic Ignition (EI) module harness connector. Turn ignition on. Using a test light, check for voltage between ground and terminal "A" at EI module harness connector. (Scheme 1) If voltage is present, check EI module connector tightness. If connector is okay, EI module is faulty. If voltage is not present, repair open in Pink wire (circuit No. 1039) between EI module and instrument panel fuse block.
10. Check for spark at plug wires of cylinders No. 2 and 4. If spark is present at both wires, go to next step. If spark is not present at either plug wire, check for 12 volts and ground to EI module. (Scheme 1) Repair as necessary. If spark is present at only one plug wire, check spark at opposing cylinder. If spark is present at opposing cylinder, replace spark plug wire. If spark is not present at opposing cylinder, replace EI module.
11. Reconnect EI module harness connector. Install Fuel Pressure Gauge (SA9127E). Turn ignition on. Fuel pressure reading should be 38-44 psi (2.7-3.1 kg/cm 2 ). If fuel pressure is as specified, see appropriate TROUBLE SHOOTING - NO CODES article. If fuel pressure is not as specified, go to next step.
12. Turn ignition off. Using a test light connected to ground, probe FUEL PUMP fuse (10-amp), located in instrument panel fuse block. (Scheme 2) Turn ignition on. Test light should illuminate for 2 seconds, and then turn off. If test light illuminates and turns off after about 2 seconds, check for open in fuel pump circuit (Gray wire) or ground circuit (Black wire). If circuits are okay, check fuel pump. If test light does not illuminate, go to next step.
13. Turn ignition off. Repeat test with test light inserted in instrument panel fuse block probe hole. (Scheme 2) If test light does not illuminate, check for open or short to ground in Dark Green/White wire between fuel pump relay and PCM. If circuit is okay, check PCM connector tightness or for faulty PCM. If test light illuminates, go to next step.
14. Remove fuel pump relay. Using a test light connected to ground, probe Red wire terminal of fuel pump relay connector (relay socket) in instrument panel fuse block. (Scheme 2) If test light illuminates, check fuel pump relay connector tightness. Check for faulty fuel pump relay ground or for faulty fuel pump relay. If test light does not illuminate, check for faulty I/P BATT fuse (30-amp), located in underhood fuse block. If fuse is okay, repair open in Red wire between fuel pump relay and underhood fuse block.
15. Turn ignition off. Disconnect PCM connector J3. (Scheme 1) Using DVOM, measure resistance between PCM connector J3, terminals D13 (7X ref hi circuit) and D14 (7X ref lo circuit). Resistance should be 700-900 ohms. If resistance is as specified, go to next step. If resistance is not as specified, go to step 17.
16. Set DVOM to AC scale. Connect DVOM between PCM connector J3, terminals D13 (7X ref hi circuit) and D14 (7X ref lo circuit). (Scheme 1) Crank engine. DVOM should display 200 millivolts. If voltage is as specified, check PCM connector tightness. If voltage is not as specified, replace Crankshaft Position (CKP) sensor.
17. Check for continuity in 7X ref hi circuit (Yellow wire) and 7X ref lo circuit (Purple wire). (Scheme 1) Repair as necessary. If continuity is present, check circuits for short to ground or voltage. Repair as necessary. If circuits are okay, go to next step.
18. Remove Crankshaft Position (CKP) sensor. Measure CKP sensor resistance. Resistance should be 700-900 ohms. If resistance is not as specified, replace CKP sensor. If resistance is as specified, go to next step.
19. Check if CKP sensor is still magnetized. If sensor is not magnetized, replace CKP sensor. If sensor is magnetized, check for poor or intermittent connection at sensor connector. Repair as necessary.

Scheme 1

Scheme 2

NO START - ENGINE CRANKS OKAY (2.2L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

General Inspection

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

Ignition System

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Using scan tool, check for Diagnostic Trouble Codes (DTCs). If DTC P0601, P0602, P1621 or P1629 is present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
3. Check PCM ground connection at engine block. If ground connection is okay, go to next step. If ground connection is faulty, go to step 5 .
4. Check F/P-INJ and IGN fuses (20-amp), located in instrument panel fuse block. If fuses are okay, go to step 6 . If fuses are faulty, go to step 7 .
5. Repair PCM ground connection. After repairs, go to step 43 .
6. Check fuel level and add fuel if necessary. If fuel level is okay, go to step 8 . If fuel level was low and needed to be added, go to step 43 .
7. Check for short to ground in appropriate circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. Replace faulty fuse. After repairs, go to step 43 .
8. Install scan tool. Turn ignition on, leaving engine off. Ensure throttle is closed. Monitor Throttle Position (TP) sensor voltage. If TP sensor voltage is less than one volt, go to next step. If TP sensor voltage is not less than one volt, go to DTC P0123. See appropriate SELF-DIAGNOSTICS article.
9. Using scan tool, monitor Engine Coolant Temperature (ECT) sensor and Intake Air Temperature (IAT) sensor values. If sensor values are about the same, go to next step. If sensor values are not about the same, go to DTC P0118. See appropriate SELF-DIAGNOSTICS article.
10. Using scan tool, ensure MAP sensor voltage is greater than 4 volts with ignition on. Crank engine. If serial data is lost while cranking engine, or if MAP sensor voltage is not greater than 4 volts, go to step 13 . If MAP sensor value is greater than 4 volts and serial data was not lost during cranking, go to next step.
11. Using scan tool, ensure MAP sensor voltage is greater than 4 volts with ignition on. Crank engine. If MAP sensor voltage changes while cranking engine, go to next step. If MAP sensor voltage is not greater than 4 volts, or does not change while cranking engine, diagnose MAP sensor. See appropriate SYSTEM & COMPONENT TESTING article.
12. Using scan tool, check Crankshaft Position (CKP) sensor activity while cranking engine. If CKP ACTIVITY COUNTER increments while cranking, go to step 14 . If CKP ACTIVITY COUNTER does not increment, go to step 24 .
13. Repair voltage loss to PCM from ignition switch. After repairs, go to step 43 .
14. Turn ignition off. Disconnect 2-pin Ignition Control Module (ICM) harness connector. Check ICM ground circuit for an open or short to power. See appropriate wiring diagram in WIRING DIAGRAMS article. If ground circuit is okay, go to next step. If ground circuit is not okay, repair as necessary and go to step 43 .
15. Reconnect ICM harness connector. Install Spark Tester (J-26792) to cylinder No. 1, leaving other spark plug wires connected to spark plugs. Crank engine and check for spark. Repeat procedure for remaining cylinders. If spark is present at all wires, go to step 39 . If spark is not present at all wires, go to step 27 .
16. Turn ignition off. Disconnect 6-pin Ignition Control Module (ICM) harness connector. Connect DVOM between ICM harness connector CKP sensor ground terminal and CKP sensor signal terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Check combined CKP sensor and harness resistance. Resistance should be 700-1300 ohms. If resistance is as specified, go to step 18 . If resistance is not as specified, go to next step.
17. Remove CKP sensor. Using DVOM, check CKP sensor resistance. Resistance should be 700-1300 ohms. If resistance is as specified, go to step 20 . If resistance is not as specified, go to step 21 .
18. Set DVOM to AC scale. Connect DVOM between ICM connector CKP sensor ground terminal and CKP sensor signal terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Crank engine. Voltage reading should be greater than 200 millivolts. If voltage reading is as specified, go to next step. If voltage reading is not as specified, go to step 23 .
19. Check CKP sensor signal circuit for a short to power. See appropriate wiring diagram in WIRING DIAGRAMS article. If CKP sensor signal circuit is okay, go to next step. If CKP sensor signal circuit is not okay, repair as necessary and go to step 43 .
20. Check CKP sensor signal circuit for a short to ground. See appropriate wiring diagram in WIRING DIAGRAMS article. If CKP sensor signal circuit is okay, go to next step. If CKP sensor signal circuit is not okay, repair as necessary and go to step 43 .
21. Using a test light connected to ICM connector 7X reference signal terminal, touch battery ground terminal, and then battery positive terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Monitor CKP ACTIVITY COUNTER increment on scan tool. If CKP ACTIVITY COUNTER increments as test light is touched to battery positive, go to step 31 . If CKP ACTIVITY COUNTER does not increment, go to step 25 .
22. Repair open or short in CKP sensor wiring harness. After repairs, go to step 43 .
23. Replace CKP sensor. After replacing CKP sensor, go to step 43 .
24. Turn ignition off. Disconnect 2-pin Ignition Control Module (ICM) harness connector. Turn ignition on. Using a test light connected to ground, probe ICM harness connector ignition positive voltage terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 16 . If test light does not illuminate, go to step 26 .
25. Check CKP sensor 7X reference signal circuit for an open or short. See appropriate wiring diagram in WIRING DIAGRAMS article. If CKP sensor 7X reference signal circuit is okay, go to step 33 . If CKP sensor 7X reference signal circuit is not okay, repair as necessary and go to step 43 .
26. Repair faulty ICM ignition positive voltage circuit. After repairs, go to step 43 .
27. Turn ignition off. Disconnect Powertrain Control Module (PCM) harness connectors. Connect spark tester to spark plug wire that did not show spark. Turn ignition on. Using a test light connected to battery positive, momentarily touch affected ignition control circuit with test light. A spark should jump across spark tester. If a spark jumps across tester, go to step 33 . If a spark does not jump across tester, go to step 34 .
28. Measure resistance of spark plug wire that would not produce spark with spark tester. If resistance is less than 30,000 ohms, go to next step. If resistance is greater than 30,000 ohms, go to step 37 .
29. Check secondary resistance of ignition coil that did not produce a spark. Resistance should be 5000-8000 ohms. If resistance is not as specified, go to step 38 . If resistance is as specified, go to next step.
30. Reconnect ICM and PCM harness connectors. Using a test light, backprobe ignition coil terminals at ICM harness connector. Crank engine and observe test light. If test light flashes, go to step 38 . If test light does not flash, go to next step.
31. Check ICM harness connectors for poor connections. If connections are okay, go to next step. If connections are not okay, repair as necessary and go to step 43 .
32. Replace ICM. After replacing ICM, go to step 43 .
33. Check for faulty PCM harness connectors or connections. If connectors and connections are okay, go to step 36 . If connectors and connections are faulty, go to step 35 .
34. Check ignition control circuit of faulty cylinder for an open or short. If ignition control circuit is okay, go to step 28 . If ignition control circuit is not okay, repair as necessary and go to step 43 .
35. Repair harness connectors or connections. After repairs, go to step 43 .
36. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to step 43 .
37. Replace faulty spark plug wires. After repairs, go to step 43 .
38. Replace faulty ignition coils. After repairs, go to step 43 .
39. Disconnect all fuel injector harness connectors. Connect injector test light to injectors No. 1, 2, 3 and 4 (one at a time). Crank engine and observe injector test light. If test light flashed on all tests, go to next step. If test light did not flash on all tests, go to step 42 .
40. Install fuel pressure gauge. Turn ignition on and note fuel pressure after 2 seconds. Fuel pressure should be 41-47 psi (2.9-3.3 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to «FUEL SYSTEM ELECTRICAL CIRCUIT»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-electrical-circuit) .
41. Check for fouled spark plugs. If spark plugs are okay, check for water in fuel system. Check for basic engine problem (low compression, etc.). Ensure spark plugs are of resistor type. Check fuel pump operation with scan tool. If spark plugs are fouled, replace as necessary and go to step 43 .
42. Repair open in fuel pump and injector ignition feed circuit. After repairs, go to next step.
43. Using scan tool, clear DTC(s). Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
44. Allow engine to reach normal operating temperature. Check for DTCs. If DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.

Fuel System Electrical Circuit

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Ensure F/P-INJ fuse (20-amp), located in instrument panel fuse block is okay. If fuse is okay, go to next step. If fuse is faulty, go to step 20 .
3. Install scan tool. Turn ignition on. Using scan tool, command fuel pump relay on. If fuel pump operates, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) . If fuel pump does not operate, go to next step.
4. Remove fuel pump relay. Using a fused jumper wire, jumper fuel pump relay ignition feed terminal and fuel pump feed terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. If fuel pump operates, go to next step. If fuel pump does not operate, go to step 6 .
5. Using a test light connected to ground, probe fuel pump relay control terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Using scan tool, command fuel pump on. If test light illuminates, go to step 7 . If test light does not illuminate, go to step 8 .
6. Using a test light connected to ground, probe fuel pump relay ignition feed terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 10 .
7. Using a test light connected to battery positive, probe fuel pump relay ground terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 11 . If test light does not illuminate, go to step 12 .
8. Check for an open or short to ground in fuel pump relay control circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 13 .
9. Reinstall fuel pump relay. Disconnect fuel pump harness connector at fuel pump. Using a test light connected to ground, probe fuel pump harness connector feed terminal (body side). Using scan tool, command fuel pump on. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
10. Repair open in ignition feed circuit to fuel pump relay. After repairs, go to step 25 .
11. Check for poor connection at fuel pump relay. Repair as necessary. If connection is okay, replace fuel pump relay. After repairs, go to step 25 .
12. Repair open in ground circuit to fuel pump relay. After repairs, go to step 25 .
13. Check connections and terminals to PCM. Repair as necessary. After repairs, go to step 25 . If connections and terminals are okay, go to step 16 .
14. Using a test light connected to battery positive, probe fuel pump ground terminal (body side). If test light illuminates, go to step 17 . If test light does not illuminate, go to step 18 .
15. Repair open in fuel pump feed circuit. After repairs, go to step 25 .
16. Turn ignition off. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to step 25 .
17. Check for an open in fuel pump feed circuit and ground circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 19 .
18. Repair open in fuel pump ground circuit. After repairs, go to step 25 .
19. Replace fuel pump. After repairs, go to step 25 .
20. Turn ignition off. Disconnect fuel pump harness connector at fuel pump. Remove fuel pump relay. Using a test light connected to battery positive, probe fuel pump feed terminal. If test light illuminates, go to next step. If test light does not illuminate, go to step 22 .
21. Repair short to ground in fuel pump feed circuit and/or fuel injector feed circuit. After repairs, go to step 25 .
22. Using a test light connected to battery positive, probe fuel pump relay ignition feed terminal. If test light illuminates, go to next step. If test light does not illuminate, go to step 24 .
23. Repair short to ground in fuel pump relay ignition feed circuit. After repairs, go to step 25 .
24. Check for short to ground in fuel pump feed circuit. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step 19 .
25. Reinstall fuel pump relay. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
26. Allow engine to reach normal operating temperature. Using scan tool, check for DTCs. If DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.

NO START - ENGINE CRANKS OKAY (2.4L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Check secondary boots for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Check for Diagnostic Trouble Codes (DTCs). If DTC P0601, P0602 or P1629 is present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
3. Check PCM ground connection at engine block. If ground connection is okay, go to next step. If ground connection is faulty, go to step 5 .
4. Check fuel pump, injector and ignition fuses, located in underhood fuse block. If fuses are okay, go to step 6 . If fuses are faulty, go to step 7 .
5. Repair PCM ground connection. After repairs, go to step 37 .
6. Check fuel level in tank and add if necessary. If fuel level is okay, go to step 8 . If fuel level was low and needed to be added, go to step 37 .
7. Check for short to ground in fuel pump and injector ignition feed circuits. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. Replace faulty fuse(s). After repairs, go to step 37 .
8. Install scan tool. Turn ignition on with engine off. Ensure throttle is closed. Observe TP sensor voltage. If TP sensor voltage is less than one volt, go to next step. If TP sensor voltage is not less than one volt, go to DTC P0123. See appropriate SELF-DIAGNOSTICS article.
9. Using scan tool, monitor Engine Coolant Temperature (ECT) sensor and Intake Air Temperature (IAT) sensor values. Both values should be about the same. If values are the same, go to next step. If values are not the same, go to DTC P0117 or P0118. See appropriate SELF-DIAGNOSTICS article.
10. Using scan tool, observe MAP sensor voltage while cranking engine. If serial data is lost while cranking engine, go to step 13 . If serial date is not lost while cranking engine, go to next step.
11. Check MAP sensor value with ignition on and engine cranking. If MAP sensor voltage is greater than 4 volts, and then changes while cranking engine, go to next step. If MAP sensor voltage is not greater than 4 volts, or does not change while cranking engine, diagnose MAP sensor. See appropriate SYSTEM & COMPONENT TESTING article.
12. Using scan tool, check Crankshaft Position (CKP) sensor activity while cranking engine. If CKP ACTIVITY COUNTER increments while cranking, go to step 28 . If CKP ACTIVITY COUNTER does not increment, go to step 14 .
13. Repair voltage loss to PCM from ignition switch. After repairs, go to step 37 .
14. Turn ignition off. Disconnect 11-pin Ignition Control Module (ICM) harness connector. Turn ignition on with engine off. Connect DVOM between ICM ground and ignition feed terminals. See appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage is present, go to next step. If battery voltage is not present, go to step 16 .
15. Connect DVOM between ICM connector CKP sensor ground terminal and CKP sensor signal terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Measure combined CKP sensor and harness resistance. Resistance should be 500-900 ohms. If resistance is as specified, go to step 19 . If resistance is not as specified, go to step 18 .
16. Repair open in ground circuit or ignition feed circuit to ICM. After repairs, go to step 37 .
17. Check CKP sensor signal circuit for a short to ground. If CKP sensor signal circuit is okay, go to step 23 . If CKP sensor signal circuit is not okay, repair as necessary and go to step 37 .
18. Turn ignition off. Remove CKP sensor. Using DVOM, measure CKP sensor resistance. Resistance should be 500-900 ohms. If resistance is as specified, go to step 22 . If resistance is not as specified, go to step 23 .
19. Set DVOM to AC scale. Connect DVOM between ICM harness connector CKP sensor ground terminal and CKP sensor signal terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Crank engine. If voltage reading is greater than 200 millivolts, go to next step. If voltage reading is not as specified, go to step 17 .
20. Check for a short to power in CKP sensor signal circuit. If CKP sensor signal circuit is okay, go to next step. If CKP sensor signal circuit is not okay, repair as necessary and go to step 37 .
21. Using a test light connected to ICM harness connector 7X reference signal terminal, touch battery negative terminal, and then battery positive terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Monitor CKP ACTIVITY COUNTER on scan tool. If CKP ACTIVITY COUNTER increments as test light is touched to battery positive, go to step 24 . If CKP ACTIVITY COUNTER does not increment, go to step 25 .
22. Repair poor connection, open or short in CKP sensor. After repairs, go to step 37 .
23. Replace CKP sensor. After replacing CKP sensor, go to step 37 .
24. Inspect ICM harness connector. Check for clean and tight connections. Repair as necessary. After repairs, go to step 37 . If connector is okay, go to step 26 .
25. Check CKP activity (7X reference) circuit for an open or short. Repair as necessary. After repairs, go to step 37 . If circuit is okay, go to step 27 .
26. Replace ICM. After replacing ICM, go to step 37 .
27. Turn ignition off. Check for poor connection at PCM. Repair as necessary. If connection is okay, replace PCM. Perform PCM relearn procedures. After replacing PCM, go to step 37 .
28. Disconnect all fuel injector harness connectors. Install injector test light on injector No. 1 harness connector. Crank engine and observe injector test light. If test light flashes, go to next step. If test light does not flash, go to step «FUEL SYSTEM ELECTRICAL CIRCUIT»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) .
29. Remove ignition coil and ignition control module assembly. Install Spark Plug Jumper (J-36012-A) between coil and ignition control module. Remove spark plug boot from companion cylinder of ignition coil housing and install jumper wire from spark plug boot connector of ignition housing to ground (cylinders No. 1-4 and 2-3). Using Spark Tester (J-26792), check for spark on all 4 wires (one at a time). If spark jumps spark tester on all 4 wires, go to next step. If spark does not jump on all 4 wires, go to step 32 .
30. Install fuel pressure gauge. Turn ignition on with engine off. If engine is equipped with an EGR valve, fuel pressure should be 41-47 psi (2.9-3.3 kg/cm 2 ). If engine is not equipped with an EGR valve, fuel pressure should be 52-58 psi (3.7-4.1 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) .
31. Check for fouled spark plugs. Replace as necessary. If spark plugs were fouled, go to step 37 . If spark plugs were okay, check for water in fuel system. Check for basic engine problem (low compression). Ensure spark plugs are of resistor type. Check fuel pump operation with scan tool.
32. Turn ignition off. Disconnect Powertrain Control Module (PCM) harness connectors. Turn ignition on. Using a test light connected to battery positive, momentarily touch affected ignition control circuit with test light. A spark should jump across spark tester. If a spark jumps across tester, go to step 27 . If a spark does not jump across tester, go to next step.
33. Turn ignition off. Disconnect spark plug jumper wires and remove ignition coil housing. Reconnect PCM harness connectors. Disconnect ignition coil harness connector at ICM. Connect an additional test light between battery positive and ICM control terminal for ignition coil(s) that did not spark. Crank engine and observe test light. If test light flashes, go to next step. If test light does not flash, go to step 36 .
34. Check for faulty ignition coil harness connector or open in ignition coil. Repair as necessary. After repairs, go to step 37 . If ignition coils and harness connectors are okay, go to next step.
35. Replace ignition coil that did not produce a spark. After repairs, go to step 37 .
36. Check for an open or short in ignition control circuit. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step 24 .
37. Reconnect all components. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
38. Allow engine to reach normal operating temperature. Check for DTCs. If DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Check fuel pump relay fuse, located in underhood relay block. If fuse is okay, go to next step. If fuse is faulty, go to step 20 .
3. Install scan tool. Turn ignition on. Using scan tool, command fuel pump relay on. If fuel pump operates, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) . If fuel pump does not operate, go to next step.
4. Remove fuel pump relay. Using a fused jumper wire, jumper fuel pump relay ignition feed terminal and fuel pump feed terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. If fuel pump operates, go to next step. If fuel pump does not operate, go to step 6 .
5. Using a test light connected to ground, probe fuel pump relay control terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. Using scan tool, command fuel pump on. If test light illuminates, go to step 7 . If test light does not illuminate, go to step 8 .
6. Using a test light connected to ground, probe fuel pump relay ignition feed terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 10 .
7. Using a test light connected to battery positive, probe fuel pump relay ground terminal. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 11 . If test light does not illuminate, go to step 12 .
8. Check for an open or short to ground in fuel pump relay control circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 13 .
9. Reinstall fuel pump relay. Disconnect fuel pump harness connector at fuel pump. Using a test light connected to ground, probe fuel pump harness connector feed terminal (body side). Using scan tool, command fuel pump on. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
10. Repair open in ignition feed circuit to fuel pump relay. After repairs, go to step 25 .
11. Check for poor connections at fuel pump relay. Repair as necessary. If connections are okay, replace fuel pump relay. After replacing fuel pump relay, go to step 25 .
12. Repair open in ground circuit to fuel pump relay. After repairs, go to step 25 .
13. Check connections and terminals at PCM. Repair as necessary. After repairs, go to step 25 . If connections and terminals are okay, go to step 16 .
14. Using a test light connected to battery positive, probe fuel pump ground terminal (body side). If test light illuminates, go to step 17 . If test light does not illuminate, go to step 18 .
15. Repair open in fuel pump feed circuit. After repairs, go to step 25 .
16. Turn ignition off. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to step 25 .
17. Check for an open in fuel pump feed circuit and ground circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 19 .
18. Repair open in fuel pump ground circuit. After repairs, go to step 25 .
19. Replace fuel pump. After replacing fuel pump, go to step 25 .
20. Disconnect fuel pump harness connector at fuel pump. Remove fuel pump relay. Turn ignition off. Using a test light connected to battery positive, probe fuel pump feed terminal. If test light illuminates, go to next step. If test light does not illuminate, go to step 22 .
21. Repair short to ground in fuel pump circuit. After repairs, go to step 25 .
22. Using a test light connected to battery positive, probe fuel pump relay ignition feed terminal. If test light illuminates, go to next step. If test light does not illuminate, go to step 24 .
23. Repair short to ground in fuel pump relay ignition feed circuit. After repairs, go to step 25 .
24. Check for short to ground in fuel pump feed circuit. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step 19 .
25. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
26. Allow engine to reach normal operating temperature. Check for DTCs. If DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.

NO START - ENGINE CRANKS OKAY (3.0L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, check for Diagnostic Trouble Codes (DTCs). If DTC P0100, P0230, P0335, P0560, P0601, P0602, P0604, P1460, P1501, P1502 or P1503 is present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
3. Using scan tool, check engine coolant temperature. Engine coolant temperature reading on scan tool should be close to actual engine temperature. If coolant temperature reading is as specified, go to next step. If scanned coolant temperature is not close to actual engine temperature reading, go to DTC P0115. See appropriate SELF-DIAGNOSTICS article.
4. Using scan tool, check TP NORMALIZED. If TP NORMALIZED is greater than 15 percent, go to DTC P1221. See appropriate SELF-DIAGNOSTICS article. If TP NORMALIZED is not greater than 15 percent, go to next step.
5. Using Spark Tester (J-26792), check for spark at either wire on each coil while cranking engine. If spark is present at each coil, go to next step. If spark is not present at one or more coils, diagnose ignition system. See «BASIC IGNITION SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) .
6. Disconnect main injector harness connector at rear of intake manifold. Check for poor terminal connection. Repair as necessary. After repairs, go to step 14 . If harness connector is okay, go to next step.
7. Using a test light connected to ground, probe main injector harness connector (ECM side) switched battery voltage circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
8. Using a fused jumper wire, connect switched battery voltage circuit of main injector harness connectors together. Using a test light connected to ground, probe main injector harness connector (injector side) injector control circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
9. Crank engine for about 2 seconds, and then release key without turning ignition off. Fuel pump should operate and continue operating for about 2 seconds after engine stops cranking. If fuel pump operates as specified, go to next step. If fuel pump does not operate as specified, go to «FUEL SYSTEM ELECTRICAL CIRCUIT»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) .
10. Turn ignition off. Install fuel pressure gauge. Turn ignition on with engine off, for 5 seconds. Fuel pressure should be 46-59 psi (3.2-4.1 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to «FUEL SYSTEM ELECTRICAL CIRCUIT»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) .
11. Check for fouled spark plugs. Check for leak in air duct between Mass Airflow (MAF) sensor and throttle body. Check for faulty MAF sensor. To check MAF sensor, disconnect MAF sensor, and then attempt to start engine. If engine starts and idles, MAF sensor is faulty. After repairs, go to step 14 . If spark plugs, air duct and MAF sensor are okay, see appropriate SELF-DIAGNOSTICS article.
12. Repair open or high resistance in main injector harness connector switched battery voltage circuit. After repairs, go to step 14 .
13. Repair main injector harness. After repairs, go to next step.
14. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
15. Allow engine to reach normal operating temperature. Using scan tool, check for DTCs. If any DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
16. If any additional DTCs are present during On-Board Diagnostic (OBD) System Check, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Install scan tool. Turn ignition on. Using scan tool, command fuel pump relay on and off while observing scan tool display. If scan tool display reads ON and OFF as commanded, go to next step. If scan tool display is not as specified, go to step 9 .
3. Inspect fuses V3 and No. 18. If a fuse is faulty, go to step 13 . If fuses are okay, go to next step.
4. Turn ignition off. Remove fuel pump relay. Using a fused jumper wire, connect fuel pump relay battery feed circuit and fuel pump feed circuit together at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on. If fuel pump operates for about 2 seconds, go to step 14 . If fuel pump does not run, go to next step.
5. Using a test light connected to ground, probe fuel pump relay battery feed circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 15 .
6. Using a test light connected to battery positive, probe fuel pump feed circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 16 .
7. Turn ignition off. Raise and support vehicle. Disconnect fuel pump harness connector. Turn ignition on. Using a test light connected to battery positive, probe fuel pump feed circuit at fuel pump relay connector. If test light illuminates, go to step 17 . If test light does not illuminate, go to next step.
8. Using a test light connected to battery positive, probe ground circuit at fuel pump harness connector (vehicle harness side). If test light illuminates, go to step 18 . If test light does not illuminate, go to step 19 .
9. Disconnect ECM harness connector. Remove fuel pump relay. Using a test light connected to battery positive, probe fuel pump relay control circuit at fuel pump relay connector. If test light illuminates, go to step 20 . If test light does not illuminate, go to next step.
10. Using DVOM, check for continuity in fuel pump relay control circuit between fuel pump relay and ECM. If continuity is present, go to next step. If continuity is not present, go to step 21 .
11. Disconnect fuel pump relay. Using test light connected to ground, probe fuel pump relay ignition feed circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on. If test light illuminates, go to step 22 . If test light does not illuminate, go to next step.
12. Check engine control power relay feed circuit for an open or short to ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. After repairs, go to step 24 . If circuit is okay, go to «POWER RELAY CIRCUIT (CATERA)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__power-relay-circuit-catera) under ENGINE CONTROLS CIRCUIT CHECKS.
13. Inspect circuit related to faulty fuse. Repair as necessary. Replace fuse and go to step 24 .
14. Replace fuel pump relay. Go to step 24 .
15. Repair open in battery positive circuit. Go to step 24 .
16. Repair open in fuel pump power feed circuit from fuel pump relay. Go to step 24 .
17. Repair short to ground in fuel pump power feed circuit. Go to step 24 .
18. Replace fuel pump. Go to step 24 .
19. Repair open in fuel pump ground circuit. Go to step 24 .
20. Repair short to ground in fuel pump relay control circuit. Go to step 24 .
21. Repair open in fuel pump relay control circuit. Go to step 24 .
22. Check for poor connections at ECM. Repair as necessary. After repairs, go to step 24 . If connections are okay, go to next step.
23. Turn ignition off. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to next step.
24. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
25. Allow engine to reach normal operating temperature. Check for DTCs. If DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
26. If any additional DTCs were noted during powertrain OBD system check that have not been diagnosed, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If no other DTCs are present, system is okay.

NO START - ENGINE CRANKS OKAY (3.1L & 3.4L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank. After fault is isolated and repairs are completed, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, select FAILED SINCE CODE CLEAR function. If Diagnostic Trouble Code (DTC) P0101, P0123, P0201-P0206, P0230, P0601, P0602, P1200, P1374, P1626, P1629, P1630 or P1631 is present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
3. Turn ignition on with engine off. Using scan tool, monitor Manifold Absolute Pressure (MAP) sensor. If MAP sensor value is less than 65 kPa, go to step 27 . If MAP sensor value is not as specified, go to next step.
4. Turn ignition off. Disconnect MAP sensor harness connector. Attempt to start engine. If engine starts and continues to run, go to step 27 . If engine does not start, go to next step.
5. Turn ignition off. Reconnect MAP sensor harness connector. Install fuel pressure gauge. Turn ignition on and observe fuel pressure. Fuel pressure should be 41-47 psi (2.9-3.3 kg/cm 2 ). If fuel pressure is as specified, go to step 7 . If fuel pressure is not as specified, go to next step.
6. If fuel pressure is present, but not as specified, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) . If fuel pressure is not present, go to «FUEL SYSTEM ELECTRICAL CIRCUIT (EXCEPT GRAND PRIX)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-electrical-circuit-except-grand) or «FUEL SYSTEM ELECTRICAL CIRCUIT (GRAND PRIX)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-electrical-circuit-grand-prix) .
7. Turn ignition off. Disconnect 10-pin fuel injector harness connector. Using a test light connected to battery positive, probe each injector driver circuit while cranking engine. If test light flashes, go to next step. If test light does not flash, go to step 9 .
8. Remove fuel injection fuse from underhood fuse block. Install Spark Tester (J-26792) to cylinders No. 2, 4 and 6 (one at a time). Connect the spark plug wire of companion cylinder to ground. Crank engine and observe spark tester. If spark is present, go to step 19 . If spark is not present, go to step 11 .
9. Check fuel injector feed circuit fuse. If fuse is faulty, check for a short to ground in injector feed circuit, or shorted injector. Repair as necessary. If circuit and injector are okay, go to next step.
10. Check for open in fuel injector feed and driver circuits. Repair as necessary. If circuits are okay, go to step 31 .
11. Check fuse to Ignition Control Module (ICM) ignition feed circuit. If fuse is faulty, check for short to ground in ICM feed circuit or short to voltage in IC control circuit. Repair as necessary. If fuse is okay, go to next step.
12. Check for open in ICM feed and ground circuits. Repair as necessary. If circuits are okay, go to next step.
13. Disconnect 2-pin 7X Crankshaft Position (CKP) sensor harness connector from ICM. Connect DVOM between CKP sensor harness connector terminals. Set DVOM to AC scale. Crank engine and observe DVOM. If voltage is about 2 volts, go to step 15 . If voltage is not as specified, go to next step.
14. Turn ignition off. Check 7X CKP sensor circuit for an open or short to voltage or ground. Check for poor 7X CKP sensor connection. Repair as necessary. If circuit is okay, go to step 28 .
15. Check for poor ICM connection. Repair as necessary. If connection is okay, go to next step.
16. Remove and inspect ignition coil that did not produce a spark. Check for cracks or carbon tracking. Replace as necessary. If ignition coil(s) are okay, go to next step.
17. Measure secondary resistance of ignition coil that did not produce a spark. Resistance should be 5000-7000 ohms. If resistance is not as specified, replace ignition coil. If resistance is as specified, go to next step.
18. Connect a test light across affected ICM primary terminals. Crank engine and observe test light. If test light flashes while cranking engine, go to step 29 . If test light does not flash, go to step 30 .
19. Check spark plug wires for cylinders No. 2, 4 and 6. Check for carbon tracking or damaged insulation. Replace as necessary. If wire(s) are okay, go to next step.
20. Measure spark plug wire resistance of cylinders No. 2, 4 and 6. Resistance should be 7000 ohms (3.1L), or 600 ohms per foot (3.4L). If resistance is not as specified, replace wire(s). If wire(s) are okay, go to next step.
21. Remove spark plugs from cylinders No. 2, 4 and 6. Check spark plug electrodes for excessive fouling. If excessive fouling is present, go to step 26 . If excessive fouling is not present, go to next step.
22. Check spark plug wires for cylinders No. 1, 3 and 5. Check for carbon tracking or damaged insulation. Replace as necessary. If wire(s) are okay, go to next step.
23. Measure spark plug wire resistance of cylinders No. 1, 3 and 5. Resistance should be 7000 ohms (3.1L), or 600 ohms per foot (3.4L). If resistance is not as specified, replace wire(s). If wire(s) are okay, go to next step.
24. Remove spark plugs from cylinders No. 1, 3 and 5. Check spark plug electrodes for excessive fouling. If excessive fouling is present, go to step 26 . If excessive fouling is not present, go to next step.
25. Test fuel for contamination. If fuel is contaminated, clean fuel system. If fuel is not contaminated, check for poor or damaged PCM harness connector, for faulty engine coolant temperature sensor, or mass airflow miscalculated due to faulty TP sensor or MAP sensor. See appropriate SYSTEM & COMPONENT TESTING article.
26. Check for engine mechanical problem. Check for bent push rods, faulty camshaft, leaking or sticky valves or rings, excessive valve deposits, loose or worn rocker arms, weak valve springs, incorrect valve timing or leaking head gasket. Repair as necessary.
27. Replace MAP sensor.
28. Replace 7X CKP sensor.
29. Replace ignition coil(s) associated with cylinder that did not produce a spark.
30. Replace ICM.
31. Replace PCM. Perform PCM relearn procedures.

Fuel System Electrical Circuit (Except Grand Prix)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition off. Install fuel pressure gauge. Remove fuel pump relay. Using a fused jumper wire, jumper fuel pump feed circuit at fuel pump relay connector to battery positive. See appropriate wiring diagram in WIRING DIAGRAMS article. Fuel pressure should be 41-47 psi (2.9-3.3 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 10 .
3. Disconnect jumper wire from fuel pump relay connector. Connect test light between ignition feed circuit and ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on. If test light illuminates, go to next step. If test light does not illuminate, go to step 9 .
4. Turn ignition off. Connect test light between fuel pump relay driver circuit and ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on. Test light should illuminate for about 2 seconds. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
5. Turn ignition off. Disconnect PCM harness connectors. Using a test light connected to battery positive, probe fuel pump relay driver circuit at PCM harness connector. If test light illuminates, go to step 15 . If test light does not illuminate, go to next step.
6. Check continuity of fuel pump relay driver circuit between PCM and fuel pump relay. See appropriate wiring diagram in WIRING DIAGRAMS article. If circuit is open, repair as necessary. If circuit is okay, go to next step.
7. Check fuel pump relay driver circuit for poor terminal connection at PCM. If connection is faulty, repair as necessary. If connection is okay, go to step 20 .
8. Check for poor fuel pump relay terminal connection. If connection is faulty, repair as necessary. If connection is okay, go to step 18 .
9. Using a test light connected to ground, probe ignition feed circuit at fuel pump relay connection. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 17 . If test light does not illuminate, go to step 16 .
10. Remove fuel filler cap and listen for fuel pump operation. If fuel pump is running, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) . If fuel pump is not running, go to next step.
11. Using a fused jumper wire connected to battery positive, jumper fuel pump feed circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Raise and support vehicle. Disconnect fuel sending unit harness connector at fuel tank. Connect a test light between fuel pump feed circuit and fuel pump ground circuit at fuel sending unit harness connector. If test light illuminates, go to step 19 . If test light does not illuminate, go to next step.
12. Using a test light connected to ground, probe fuel pump feed circuit at fuel sending unit harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light does not illuminate, go to next step. If test light illuminates, go to step 14 .
13. Locate and repair open in fuel pump feed circuit.
14. Locate and repair open in fuel pump ground circuit.
15. Locate and repair short to ground in fuel pump relay driver circuit.
16. Locate and repair open in ignition feed circuit to fuel pump relay.
17. Locate and repair open in ground circuit to fuel pump relay.
18. Replace fuel pump relay.
19. Replace fuel pump.
20. Replace PCM. Perform PCM relearn procedures.

Fuel System Electrical Circuit (Grand Prix)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition off. Install fuel pressure gauge. Remove fuel pump relay. Using a fused jumper wire, jumper fuel pump feed circuit at fuel pump relay connector to battery positive. See appropriate wiring diagram in WIRING DIAGRAMS article. Fuel pressure should be 41-47 psi (2.9-3.3 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 5 .
3. Turn ignition off. Connect test light between fuel pump relay driver circuit and ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on. Test light should illuminate for about 2 seconds. If test light illuminates, go to step 19 . If test light does not illuminate, go to next step.
4. Turn ignition off. Using a test light connected to battery positive, probe fuel pump relay ground circuit at fuel pump relay connector. If test light illuminates, go to step 17 . If test light does not illuminate, go to step 18 .
5. Check FUEL PUMP fuse (15-amp), located in underhood junction block. If fuse is faulty, go to next step. If fuse is okay, go to step 8 .
6. Remove FUEL PUMP fuse. Using a test light connected to battery positive, probe battery feed circuit at fuel pump relay connector. If test light illuminates, go to step 11 . If test light does not illuminate, go to next step.
7. Raise and support vehicle. Disconnect fuel pump harness connector. Lower vehicle. Using a test light connected to battery positive, probe fuel pump feed circuit at fuel pump relay connector. If test light illuminates, go to step 16 . If test light does not illuminate, go to step 20 .
8. Leave fuel pump relay disconnected. Using a test light connected to ground, probe battery feed circuit at fuel pump relay connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
9. Leave fuel pump relay disconnected. Connect a fused jumper wire between battery feed circuit and fuel pump feed circuit at fuel pump relay connector. Raise and support vehicle. Disconnect fuel pump harness connector. Connect a test light across fuel pump harness connector terminals. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
10. Check for poor terminal connections between fuel pump harness connector and fuel pump assembly. Repair as necessary. After repairs, go to step 22 . If connections are okay, go to step 21 .
11. Locate and repair short to ground in battery feed circuit to fuel pump relay. After repairs, go to step 22 .
12. Locate and repair open in battery feed circuit to fuel pump relay. After repairs, go to step 22 .
13. Using a test light connected to ground, probe battery feed circuit at fuel pump harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 15 .
14. Locate and repair open in fuel pump ground circuit. After repairs, go to step 22 .
15. Locate and repair open in battery feed circuit to fuel pump. After repairs, go to step 22 .
16. Locate and repair short to ground in battery feed circuit to fuel pump. After repairs, go to step 22 .
17. Check fuel pump relay driver circuit for an open or short to ground. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 22 . If circuit and connections are okay, go to step 21 .
18. Locate and repair open in ground circuit to fuel pump relay. After repairs, go to step 22 .
19. Replace fuel pump relay. After repairs, go to step 22 .
20. Replace fuel pump. After repairs, go to step 22 .
21. Replace PCM. Perform PCM relearn procedures. After repairs, go to step 22 .
22. Turn ignition on. Using scan tool, select FUEL PUMP RELAY OUTPUT CONTROL. Command fuel pump on and observe fuel pressure gauge. If fuel pressure is 41-47 psi (2.9-3.3 kg/cm 2 ), system is okay. If fuel pressure is not as specified, go to step 2 .

NO START - ENGINE CRANKS OKAY (3.5L)

Note. No-start/ignition system diagnosis information is not available. Manufacturer provides no-start/fuel system electrical circuit diagnosis only.

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Using scan tool, command fuel pump on. If fuel pump operates, no problem is present at this time. Check for intermittent problem. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If fuel pump does not operate, go to next step.
3. Using scan tool, check for DTCs. If DTC P0230 is set, go to DTC P0230 in appropriate SELF-DIAGNOSTICS article. If DTC P0230 is not set, go to next step.
4. Inspect F/PMP fuse (15-amp), located in underhood fuse block. If fuse is okay, go to step 9 . If fuse is faulty, go to next step.
5. Turn ignition off. Disconnect fuel pump relay. Using DVOM, measure resistance between ground and battery positive feed circuit at fuel pump relay connector. If resistance is greater than 2 ohms, go to next step. If resistance is not as specified, go to step 13 .
6. Disconnect fuel pump harness connector. Using DVOM, measure resistance between ground and fuel pump feed circuit at fuel pump relay connector. If resistance is greater than 2 ohms, go to next step. If resistance is not as specified, go to step 14 .
7. Replace faulty fuse. Reconnect fuel pump relay. Using scan tool, command fuel pump relay on and off. Recheck fuse. If fuse is okay, go to next step. If fuse is faulty, go to step 19 .
8. Reconnect fuel pump harness connector. Using scan tool, command fuel pump relay on and off. Recheck fuse. If fuse is okay, problem is intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If fuse is faulty, go to step 21 .
9. Disconnect fuel pump relay. Using a test light connected to ground, probe battery feed circuit at fuel pump relay connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 15 .
10. Using a fused jumper wire, connect fuel pump relay battery feed circuit to fuel pump feed circuit in fuel pump relay connector. If fuel pump operates, go to step 18 . If fuel pump does not operate, go to next step.
11. Leave jumper wire connected. Raise and support vehicle. Disconnect fuel pump harness connector. Connect a test light between fuel pump feed circuit and fuel pump ground circuit at fuel pump harness connector (harness side). If test light illuminates, go to step 20 . If test light does not illuminate, go to next step.
12. Using a test light connected to ground, probe fuel pump feed circuit at fuel pump harness connector (harness side). If test light illuminates, go to step 17 . If test light does not illuminate, go to step 16 .
13. Repair short to ground in battery feed circuit to fuel pump relay connector. After repairs, go to step 22 .
14. Repair short to ground in fuel pump feed circuit. After repairs, go to step 22 .
15. Repair open or high resistance in battery feed circuit to fuel pump relay. After repairs, go to step 22 .
16. Repair open or high resistance in fuel pump feed circuit. After repairs, go to step 22 .
17. Repair open or high resistance in fuel pump ground circuit. After repairs, go to step 22 .
18. Check for poor terminal connections at fuel pump relay connector. Repair as necessary. After repairs, go to step 22 . If connections are okay, go to next step.
19. Replace fuel pump relay. After repairs, go to step 22 .
20. Check for poor terminal connections at fuel pump harness connector. Repair as necessary. After repairs, go to step 22 . If connections are okay, go to next step.
21. Replace fuel pump. After repairs, go to step 22 .
22. Using scan tool, command fuel pump on. If fuel pump operates, system is okay. If fuel pump does not operate, go to step 2 .

NO START - ENGINE CRANKS OKAY (3.8L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank. After fault is isolated and repairs are completed, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Check Ignition Control Module (ICM) ignition feed circuit fuse and fuel injector ignition feed circuit fuse. If either fuse is blown, locate and repair short to ground in suspect ignition feed circuit. If fuses are okay, go to next step.
3. Turn ignition off. Install fuel pressure gauge to fitting on fuel rail. Turn ignition on and observe fuel pressure. Fuel pressure should be 48-55 psi (3.4-3.8 kg/cm 2 ) and hold steady. If fuel pressure is as specified, go to step 5 . If fuel pressure is not as specified, go to next step.
4. If fuel pressure is indicated, but not as specified, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) . If fuel pressure is not present, go to «FUEL SYSTEM ELECTRICAL CIRCUIT (VIN K)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-electrical-circuit-vin-k) or «FUEL SYSTEM ELECTRICAL CIRCUIT (VIN 1)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-electrical-circuit-vin-1) .
5. Turn ignition off. Remove fuel pressure gauge. Install scan tool. Turn ignition on. Using scan tool, select ENGINE DATA 1. Observe engine RPM while cranking engine. If scan tool indicates engine RPM, go to step 17 . If scan tool does not indicate engine RPM, go to next step.
6. Turn ignition off. Disconnect Ignition Control Module (ICM) harness connector. Turn ignition on. Connect a test light between ignition positive feed circuit and ground circuit at ICM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
7. Leave ICM harness connector disconnected. Using a test light connected to ground, probe ignition positive feed circuit at ICM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 39 . If test light does not illuminate, go to step 40 .
8. Turn ignition off. Reconnect ICM harness connector. Disconnect 18X Crankshaft Position (CKP) sensor harness connector. Turn ignition on. Using DVOM, measure voltage between 18X CKP sensor feed circuit and CKP sensor ground circuit at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is near battery voltage, go to next step. If voltage is not as specified, go to step 11 .
9. Measure voltage between 18X CKP sensor signal circuit and CKP sensor ground circuit at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is 6-8 volts, go to next step. If voltage is not as specified, leave DVOM connected and go to step 14 .
10. Check for poor connections at CKP sensor. Repair as necessary. If connections are okay, go to step 41 .
11. Measure voltage between engine ground and 18X CKP sensor feed circuit at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is near battery voltage, go to next step. If voltage is not as specified, go to step 13 .
12. Turn ignition off. Leave CKP sensor harness connector disconnected. Disconnect Ignition Control Module (ICM) harness connector. Check for open in CKP sensor ground circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If ground circuit is okay, go to step 38 .
13. Turn ignition off. Leave 18X CKP sensor harness connector disconnected. Disconnect Ignition Control Module (ICM) harness connector. Check 18X CKP sensor feed circuit for an open or short to ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If sensor feed circuit is okay, go to step 38 .
14. Turn ignition on. If DVOM displays battery voltage, go to next step. If voltage is not as specified, go to step 16 .
15. Locate and repair short to power. See appropriate wiring diagram in WIRING DIAGRAMS article.
16. Turn ignition off. Check 18X CKP sensor signal circuit for an open, short to chassis ground or short to sensor ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If signal circuit is okay, go to step 38 .
17. Turn ignition off. Disconnect all fuel injector harness connectors. Turn ignition on. Connect fuel injector test light to each fuel injector harness connector (one at a time). If test light illuminates for any of the injectors, go to next step. If test light does not illuminate for any injector, go to step 19 .
18. Leave fuel injector harness connectors disconnected. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Connect fuel injector test light to each fuel injector harness connector (one at a time). If test light illuminates for any of the injectors, go to step 43 . If test light does not illuminate for any injector, go to step 46 .
19. Leave fuel injector harness connectors disconnected. Connect fuel injector test light to a fuel injector harness connector and crank engine. Repeat for each fuel injector. If test light flashes for each fuel injector, go to step 24 . If test light does not flash for each fuel injector, go to next step.
20. If test light flashed for any fuel injector, go to next step. If test light did not flash for any fuel injector, go to step 22 .
21. Turn ignition off. Leave fuel injector harness connectors disconnected. Disconnect PCM harness connector. Check for an open fuel injector control circuits associated with fuel injector circuit that did not flash test light. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If fuel injector circuits are okay, go to step 44 .
22. Leave fuel injector harness connectors disconnected. Turn ignition on. Using a test light connected to ground, probe ignition positive feed circuit to each fuel injector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 44 . If test light does not illuminate, go to next step.
23. Locate and repair open in ignition positive feed circuit to fuel injector. See appropriate wiring diagram in WIRING DIAGRAMS article.
24. Turn ignition off. Install Spark Tester (J-26792) to cylinder No. 1, 2 and 3 (one at a time). Connect the spark plug wire of companion cylinder to ground (i.e., 1/4, 2/5, 3/6). Crank engine and observe spark tester. If spark is present at all cylinders, go to step 34 . If spark is not present at all cylinders, go to next step.
25. If spark is present at any cylinder, go to step 30 . If spark is not present at any cylinder, go to next step.
26. Turn ignition off. Disconnect 18X CKP sensor harness connector. Turn ignition on. Measure voltage between ground and CKP sync signal at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is 6-8 volts, go to next step. If voltage is not as specified, go to step 28 .
27. Check for poor connections at CKP sensor harness connector. Repair as necessary. If connections are okay, go to step 41 .
28. Turn ignition off. Disconnect Ignition Control Module (ICM) harness connector. Turn ignition on. Check CKP sensor sync signal circuit for a short to power or short to 18X CKP sensor feed circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If sync signal circuit is okay, go to next step.
29. Turn ignition off. Check CKP sensor sync signal circuit for a short to chassis ground or sensor ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If sync signal circuit is okay, go to step 38 .
30. Inspect ignition coils and spark plug wires associated with cylinders that did not indicate spark. Repair as necessary. If ignition coils and spark plug wires are okay, go to next step.
31. Measure ignition coil secondary resistance. If resistance is 5000-8000 ohms, go to next step. If resistance is not as specified, replace ignition coil.
32. Measure resistance of spark plug wires associated with cylinders that did not indicate spark. If resistance is 1000-1500 ohms per foot, go to next step. If resistance is greater than specified, replace spark plug wires.
33. Remove ignition coils associated with cylinders that did not indicate spark. Connect a test light across ignition coil primary circuit associated with cylinders that did not indicate spark. See appropriate wiring diagram in WIRING DIAGRAMS article. Crank engine and observe test light. If test light flashes continuously, go to step 45 . If test light does not flash continuously, go to step 42 .
34. Remove spark plugs from all cylinders. Inspect spark plugs for excessive fouling. If spark plugs are fouled, check engine mechanical condition. Repair as necessary. If spark plugs are okay, go to next step.
35. Check for the following: Short between 18X CKP and CKP sync signal inputs to ICM. Short between 18X and 3X reference signal inputs to PCM. Stuck TP sensor. Faulty ECT sensor. Unresponsive MAP sensor. Repair as necessary. If no problem is found, go to next step.
36. Test fuel for contamination. Clean fuel system if necessary. If fuel is okay, go to next step.
37. Check for bent push rods, faulty or incorrect camshaft, leaking or sticky valves or rings, excessive valve deposits, loose or worn rocker arms, weak valve springs, incorrect valve timing or a leaking head gasket. Repair as necessary.
38. Check for poor connections at ICM harness connector. Repair as necessary. If no problem is found, go to step 42 .
39. Locate and repair open in ICM ground circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
40. Locate and repair open in ignition positive feed circuit to ICM. See appropriate wiring diagram in WIRING DIAGRAMS article.
41. Replace 18X CKP sensor.
42. Replace ICM.
43. Locate and repair short to ground in fuel injector control circuits associated with test light that remained illuminated. See appropriate wiring diagram in WIRING DIAGRAMS article.
44. Check for poor connections at PCM. Repair as necessary. If connections are okay, go to step 46 .
45. Replace ignition coils associated with cylinders that did not indicate spark.
46. Replace PCM. Perform PCM relearn procedures.

Fuel System Electrical Circuit (VIN K)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition off. Install fuel pressure gauge. Remove fuel pump relay. Using a fused jumper wire, jumper fuel pump feed circuit at fuel pump relay connector to battery positive. See appropriate wiring diagram in WIRING DIAGRAMS article. Observe fuel pressure. Fuel pressure should be 48-55 psi (3.4-3.8 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 10 .
3. Disconnect jumper wire from fuel pump relay connector. Connect test light between ignition feed circuit and ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on and observe test light. If test light illuminates, go to next step. If test light does not illuminate, go to step 9 .
4. Turn ignition off. Connect test light between fuel pump relay control circuit and ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Observe test light while turning ignition on. Test light should illuminate for about 2 seconds. If test light illuminates for about 2 seconds, go to step 8 . If test light does not illuminate for about 2 seconds, go to next step.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) harness connectors. Using a test light connected to battery positive, probe PCM harness connector fuel pump relay control circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 15 . If test light does not illuminate, go to next step.
6. Check for continuity in fuel pump relay control circuit between fuel pump relay and PCM. See appropriate wiring diagram in WIRING DIAGRAMS article. If circuit is faulty, repair as necessary. After repairs, go to step 21 . If circuit is okay, go to next step.
7. Check fuel pump relay control circuit for poor terminal connection at PCM. See appropriate wiring diagram in WIRING DIAGRAMS article. If connection is faulty, repair as necessary. After repairs, go to step 21 . If circuit is okay, go to step 20 .
8. Check for poor terminal connection at fuel pump relay. If connection is faulty, repair as necessary. After repairs, go to step 21 . If connections are okay, go to step 18 .
9. Using a test light connected to ground, probe fuel pump relay connector ignition feed circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 17 . If test light does not illuminate, go to step 16 .
10. Remove fuel filler cap and listen for fuel pump running. If fuel pump is running, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) . If fuel pump is not running, go to next step.
11. Using a fused jumper wire, jumper fuel pump feed circuit at fuel pump relay connector to battery positive. See appropriate wiring diagram in WIRING DIAGRAMS article. Raise and support vehicle. Disconnect fuel sending unit harness connector at fuel tank. Connect test light between fuel pump feed circuit and fuel pump ground circuit at fuel sending unit harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 19 . If test light does not illuminate, go to next step.
12. Using a test light connected to chassis ground, probe fuel pump feed circuit at fuel sending unit harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 14 . If test light does not illuminate, go to next step.
13. Locate and repair open in fuel pump feed circuit. After repairs, go to step 21 .
14. Locate and repair open in fuel pump ground circuit. After repairs, go to step 21 .
15. Locate and repair short to ground in fuel pump relay control circuit. After repairs, go to step 21 .
16. Locate and repair open or short to ground in ignition feed circuit to fuel pump relay. After repairs, go to step 21 .
17. Locate and repair open in ground circuit to fuel pump relay. After repairs, go to step 21 .
18. Replace fuel pump relay. After replacing fuel pump relay, go to step 21 .
19. Replace fuel pump. After replacing fuel pump, go to step 21 .
20. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to next step.
21. Turn ignition on. Using scan tool, select FP RELAY OUTPUT CONTROL function. Observe fuel pressure gauge while commanding fuel pump on with scan tool. Fuel pressure should be 48-55 psi (3.4-3.8 kg/cm 2 ). If fuel pressure is not as specified, go to step 2 . If fuel pressure is as specified, system is okay.

Fuel System Electrical Circuit (VIN 1)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. If any Diagnostic Trouble Codes (DTCs) are present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
3. Turn ignition off. Install fuel pressure gauge. Using scan tool, select FP RELAY OUTPUT CONTROL function. Observe fuel pressure gauge while commanding fuel pump on with scan tool. Fuel pressure should be 48-55 psi (3.4-3.8 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 5 .
4. Start engine. Using scan tool, select FP SPEED OUTPUT CONTROL function. Observe fuel pressure gauge while commanding fuel pump speed between normal and high with scan tool. Fuel pressure should slightly increase when high fuel pump speed is selected. If fuel pressure increases, system is okay. If fuel pressure does not increase, go to step 31 .
5. Turn ignition off. Disconnect fuel pump control module harness connector. Using a fused jumper wire, jumper fuel pump feed circuit at fuel pump control module harness connector to battery positive. See appropriate wiring diagram in WIRING DIAGRAMS article. Connect a second jumper wire between fuel pump ground circuit at fuel pump control module harness connector and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Observe fuel pressure gauge. Fuel pressure should be 48-55 psi (3.4-3.8 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 26 .
6. Disconnect jumpers from fuel pump control module harness connector. Connect test light between fuel pump control module feed circuit at fuel pump control module harness connector and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on. Using scan tool, command fuel pump relay on. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
7. Using a test light connected to battery positive, probe ground circuit at fuel pump control module harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 25 .
8. Turn ignition off. Disconnect Powertrain Control Module (PCM) harness connectors. Using a test light connected to battery positive, probe fuel pump PWM control circuit at PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
9. Locate and repair short to ground in fuel pump PWM control circuit. After repairs, go to step 39 .
10. Turn ignition off. Reconnect PCM harness connectors. Turn ignition on. Connect DVOM between fuel pump PWM control circuit and ground circuit at fuel pump control module harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Using scan tool, command fuel pump relay on and off. DVOM should display greater than 8 volts while fuel pump relay is commanded on. If voltage is as specified, go to next step. If voltage is not as specified, go to step 38 .
11. Turn ignition off. Reconnect fuel pump control module harness connector. Turn ignition on. Using test light, backprobe between fuel pump feed circuit and fuel pump ground circuit at fuel pump control module harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Using scan tool, command fuel pump relay on and off while observing test light. Test light should illuminate when fuel pump relay is commanded on. If test light illuminates, go to next step. If test light does not illuminate, go to step 34 .
12. Check for poor terminal connection at fuel pump control module. Repair as necessary. After repairs, go to step 39 . If connections are okay, check PCM and connectors for improper mating, check for rubbed through wire insulation or wires broken inside insulation.
13. Turn ignition off. Remove fuel pump relay. Turn ignition on. Using a test light connected to ground, probe fuel pump relay ignition feed circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 19 .
14. Connect test light between fuel pump relay feed circuit and ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 20 .
15. Connect test light between fuel pump relay control circuit and fuel pump relay ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Using scan tool, command fuel pump relay on while observing test light. If test light illuminates when fuel pump relay is commanded on, go to next step. If test light does not illuminate, go to step 21 .
16. Connect jumper wire between fuel pump relay feed circuit and fuel pump control module feed circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Using a test light connected to ground, probe fuel pump fuel pump control module feed circuit at fuel pump control module harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light does not illuminate, go to step 24 . If test light illuminates, go to next step.
17. Check for poor terminal connection at fuel pump relay. Repair as necessary. After repairs, go to step 39 . If terminal connections are okay, go to next step.
18. Replace fuel pump relay. After replacing fuel pump relay, go to step 39 .
19. Locate and repair open in fuel pump relay feed circuit. After repairs, go to step 39 .
20. Locate and repair open in fuel pump relay ground circuit. After repairs, go to step 39 .
21. Turn ignition off. Disconnect PCM harness connectors. Using a test light connected to battery positive, probe fuel pump relay control circuit at PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 23 .
22. Locate and repair short to ground in fuel pump relay control circuit. After repairs, go to step 39 .
23. Check fuel pump relay control circuit for poor connection or open circuit between fuel pump relay and PCM. Repair as necessary. After repairs, go to step 39 . If connections and circuit are okay, go to step 38 .
24. Locate and repair open in fuel pump control module feed circuit. After repairs, go to step 39 .
25. Locate and repair open in fuel pump control module ground circuit. After repairs, go to step 39 .
26. Remove fuel filler cap and listen for fuel pump operation. If fuel pump is running, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) . If fuel pump is not running, go to next step.
27. Using fused jumper wires, connect battery positive to fuel pump feed circuit, and ground to fuel pump ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Raise and support vehicle. Disconnect fuel sending unit harness connector at fuel tank. Connect test light between fuel pump feed circuit and fuel pump ground circuit at fuel sending unit harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 36 . If test light does not illuminate, go to next step.
28. Using a test light connected to ground, probe fuel pump feed circuit at fuel sending unit harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light does not illuminate, go to next step. If test light illuminates, go to step 30 .
29. Locate and repair open in fuel pump feed circuit. After repairs, go to step 39 .
30. Locate and repair open in fuel pump ground circuit. After repairs, go to step 39 .
31. Using test light, backprobe between fuel pump control module fuel pump PWM control circuit and fuel pump control module feed circuit at fuel pump control module. See appropriate wiring diagram in WIRING DIAGRAMS article. Start engine and let idle. Using scan tool, select FP SPEED OUTPUT CONTROL function. Observe test light while switching scan tool between normal and high. Test light should illuminate when normal is selected, and then turn off when high is selected. If test light illuminates as indicated, go to next step. If test light does not illuminate as indicated, go to step 33 .
32. Using DVOM, backprobe between fuel pump ground circuit and fuel pump feed circuit at fuel pump control module. See appropriate wiring diagram in WIRING DIAGRAMS article. Start engine and let idle. Using scan tool, select FP SPEED OUTPUT CONTROL function. Observe DVOM voltage reading while switching scan tool between normal and high speed. On normal speed, DVOM should display about 8 volts. On high speed, DVOM should display battery voltage. If voltage readings are as specified, go to step 36 . If voltage readings are not as specified, go to step 34 .
33. Check fuel pump PWM control circuit for poor terminal connection, or an open or short to voltage between fuel pump control module and PCM. Repair connections or circuit as necessary. After repairs, go to step 39 . If connections and circuit is okay, go to step 38 .
34. Check for poor terminal connections at fuel pump control module. Repair as necessary. After repairs, go to step 39 . If connections are okay, go to next step.
35. Replace fuel pump control module. After replacing fuel pump control module, go to step 39 .
36. Check for poor terminal connections at fuel pump. Repair as necessary. After repairs, go to step 39 . If connections are okay, go to next step.
37. Replace fuel pump. After replacing fuel pump, go to step 39 .
38. Replace PCM. Ensure PCM relearn procedure is performed. After replacing PCM, go to next step.
39. Turn ignition on. Using scan tool, select FP RELAY OUTPUT CONTROL function. Observe fuel pressure gauge while commanding fuel pump on with scan tool. Fuel pressure should be 48-55 psi (3.4-3.8 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 5 .
40. Start engine and let idle. Using scan tool, select FP SPEED CONTROL OUTPUT function. Observe fuel pressure gauge while commanding fuel pump speed between normal and high with scan tool. Fuel pressure should slightly increase when high speed is selected. If fuel pressure does not slightly increase, go to step 31 . If fuel pressure increases as specified, system is okay.

NO START - ENGINE CRANKS OKAY (4.0L & 4.6L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. If Diagnostic Trouble Code (DTC) P0231, P0232, P0322, P0601, P0602, P1376, P1626, P1631, P1632 or P1634 is present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
3. Install Spark Tester (J-26792) to each spark plug wire (one at a time). Connect the spark plug wire of companion cylinder to ground. Crank engine and observe spark tester. If spark is present, go to next step. If spark is not present, diagnose ignition system. See «BASIC IGNITION SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) .
4. Reconnect all spark plug wires. Using scan tool, command fuel pump on. Remove fuel filler cap and listen for fuel pump operation. If fuel pump is running, go to next step. If fuel pump is not running, go to DTC P0231. See appropriate SELF-DIAGNOSTICS article.
5. Check all PCM power and ground connections and circuits. Repair as necessary. After repairs, go to step 11 . If connections and circuits are okay, go to next step.
6. Disconnect fuel injectors No. 1 and 3. Install injector test light on both injector harness connectors. Crank engine. If test light flashes, go to step 10 . If test light does not flash, go to next step.
7. Disconnect 2-pin fuel injector harness connector, located between fuel injectors and engine compartment fuse/relay center. See appropriate wiring diagram in WIRING DIAGRAMS article. Using DVOM, measure voltage at terminals of fuel injector harness connector (harness side). If voltage is 10 volts or greater on both terminals, go to step 9 . If voltage is less than 10 volts, go to next step.
8. Repair injector ignition feed circuits between 2-pin fuel injector harness connector and engine compartment fuse/relay center. See appropriate wiring diagram in WIRING DIAGRAMS article. After repairs, go to step 11 .
9. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to step 11 .
10. Check fuel system. Go to «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) . Also see FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. After repairs, go to next step. If fuel system is okay, go to step 12 .
11. Start engine. If engine starts and runs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. If engine still does not start, go to next step.
12. Check for engine mechanical condition causing a no-start condition. Check timing chain and valve timing. Repair as necessary. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.

See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.

NO START - ENGINE CRANKS OKAY (5.7L)

Note. Before performing the following tests, check battery condition, engine cranking speed and for adequate fuel in tank.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

Ignition System (Camaro & Firebird)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition on with engine off. Using a test light connected to ground, probe terminals of the following fuses located in underhood electrical center No. 2. A/C CRUISE ENG CTRL ENG SEN INJR1 INJR2 If test light illuminates on both sides of all fuses, go to next step. If test light does not illuminate, diagnose ignition relay circuit. See «IGNITION RELAY CIRCUIT (5.7L)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__ignition-relay-circuit-57l) under BASIC IGNITION SYSTEM CHECKS.
3. Using scan tool, check for Diagnostic Trouble Codes (DTCs). If DTC P0230, P0335, P0336, P0601, P0602 or P0604 is present, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
4. Using scan tool, monitor VTD fuel enabled status. If scan tool displays ACTIVE, go to DTC P1626. See appropriate SELF-DIAGNOSTICS article. If scan tool does not display ACTIVE, go to next step.
5. Using scan tool, monitor engine speed while cranking engine. If engine RPM is indicated on scan tool, go to step 9 . If engine RPM is not indicated on scan tool, go to next step.
6. Disconnect Crankshaft Position (CKP) sensor harness connector. Using DVOM, measure voltage at ignition feed circuit at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is about battery voltage, go to step 13 . If voltage is not about battery voltage, go to next step.
7. Disconnect Camshaft Position (CMP) sensor harness connector. Using DVOM, measure voltage at ignition feed circuit at CMP sensor connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is about battery voltage, go to step 14 . If voltage is not about battery voltage, go to next step.
8. Check for short to ground in CKP sensor ignition feed circuit and CMP sensor ignition feed circuit. Repair as necessary. After repairs, go to step 16 . If circuits are okay, go to step 15 .
9. Using scan tool, monitor engine coolant temperature. If scan tool value is close to actual value (ambient temperature), go to next step. If scan tool value is not close to actual value, go to DTC P0118. See appropriate SELF-DIAGNOSTICS article.
10. Using scan tool, command fuel pump on. If fuel pump operates, go to next step. If fuel pump does not operate, diagnose fuel pump relay circuit. See «FUEL SYSTEM ELECTRICAL CIRCUIT (CAMARO & FIREBIRD)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-electrical-circuit-camaro) .
11. Turn ignition off. Install fuel pressure gauge. Turn ignition on with engine off and observe fuel pressure. Fuel pressure should be 55-61 psi (3.8-4.2 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) .
12. Check for air leaks in ducts between Mass Airflow (MAF) sensor and throttle body. Ensure throttle angle is zero percent at closed throttle. A faulty MAF sensor may cause no-start or stalling after start condition. Disconnecting MAF sensor will cause PCM to default to speed density (MAP, IAT, RPM) to calculate load and intake airflow. If fault condition is corrected by disconnecting MAF sensor, or connections are okay, replace MAF sensor. Check if spark plugs are gas fouled by a rich condition. Check for engine mechanical failure causing no-start condition (i.e. timing chain, low compression, etc.). Compare MAP/BARO parameters to a similar vehicle and ensure values are similar. If a problem is found and repaired, go to step 16 . If no problem is found, see appropriate TROUBLE SHOOTING - NO CODES article.
13. Replace CKP sensor. After replacing CKP sensor, go to step 16 .
14. Replace CMP sensor. After replacing CMP sensor, go to step 16 .
15. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to next step.
16. Using scan tool, select DTC, and then CLEAR INFO function. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
17. Allow engine to idle until normal operating temperature is reached. Using scan tool, select DTC, and then FAIL THIS IGN function. If any DTC is present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
18. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.

Ignition System (Corvette)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition on with engine off. Using test light connected to ground, probe terminals of the following fuses, located in underhood electrical center No. 2. A/C ENG IGN1 INJR1 INJR2 THROT CONT If test light illuminates on both sides of all fuses, go to next step. If test light does not illuminate, diagnose ignition relay circuit. See «IGNITION RELAY CIRCUIT (5.7L)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__ignition-relay-circuit-57l) under BASIC IGNITION SYSTEM CHECKS.
3. Using scan tool, check for Diagnostic Trouble Codes (DTCs). If any DTCs related to Throttle Actuator Control (TAC) system are present, diagnose DTC. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
4. Using scan tool, check for DTCs. If any DTCs related to vehicle theft deterrent system are present, this indicates a problem with column lock or VTD fuel enable circuit. See appropriate BODY CONTROL MODULE article in ACCESSORIES & EQUIPMENT. If DTCs P0230, P0335, P0336, P0601, P0602, P0604 or P0606 are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
5. Using scan tool, monitor engine speed while cranking engine. If engine RPM is indicated on scan tool, go to step 9 . If engine RPM is not indicated on scan tool, go to next step.
6. Disconnect Crankshaft Position (CKP) sensor harness connector. Using DVOM, measure voltage at ignition feed circuit at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is about battery voltage, go to step 13 . If voltage is not about battery voltage, go to next step.
7. Disconnect Camshaft Position (CMP) sensor harness connector. Using DVOM, measure voltage at ignition feed circuit at CMP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is about battery voltage, go to step 14 . If voltage is not about battery voltage, go to next step.
8. Check for short to ground in CKP sensor ignition feed circuit and CMP sensor ignition feed circuit. Repair as necessary. After repairs, go to step 16 . If circuits are okay, go to step 15 .
9. Using scan tool, monitor engine coolant temperature. If scan tool value is close to actual value (ambient temperature), go to next step. If scan tool value is not close to actual value, go to DTC P0118. See appropriate SELF-DIAGNOSTICS article.
10. Using scan tool, command fuel pump on. If fuel pump operates, go to next step. If fuel pump does not operate, diagnose fuel pump relay circuit. See «FUEL SYSTEM ELECTRICAL CIRCUIT (CORVETTE)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-electrical-circuit-corvette) .
11. Turn ignition off. Install fuel pressure gauge. Turn ignition on with engine off and observe fuel pressure. Fuel pressure should be 55-61 psi (3.8-4.2 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__basic-fuel-system-checks) .
12. Check for air leaks in ducts between Mass Airflow (MAF) sensor and throttle body. A faulty MAF sensor may cause a no-start or stalling after start condition. Disconnecting MAF sensor will cause PCM to default to speed density (MAP, IAT, RPM) to calculate load and intake airflow. If fault condition is corrected by disconnecting MAF sensor, or connections are okay, replace MAF sensor. Check if spark plugs are gas fouled by a rich condition. Check for engine mechanical failure causing a no-start condition (i.e. timing chain, low compression, etc.). Compare MAP/BARO parameters to a similar vehicle and ensure values are similar. If a problem is found and repaired, go to step 16 . If no problem is found, see appropriate TROUBLE SHOOTING - NO CODES article.
13. Replace CKP sensor. After replacing CKP sensor, go to step 16 .
14. Replace CMP sensor. After replacing CMP sensor, go to step 16 .
15. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to next step.
16. Using scan tool, select DTC, and then CLEAR INFO function. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 2 .
17. Allow engine to idle until normal operating temperature is reached. Using scan tool, select DTC, and then FAIL THIS IGN function. If any DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
18. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.

Fuel System Electrical Circuit (Camaro & Firebird)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Check FUEL PUMP fuse (20-amp), located in underhood fuse block. If fuse is okay, go to next step. If fuse is faulty, go to step 9 .
3. Install scan tool. Remove fuel pump relay from underhood electrical center. Turn ignition on with engine off. Using a test light connected to ground, probe ignition feed circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
4. Using a test light connected to battery positive, probe fuel pump relay ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
5. Using a test light connected to ground, probe fuel pump control circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Using scan tool, command fuel pump on. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 .
6. Ensure ignition is on. Using a fused jumper wire, jumper fuel pump relay ignition feed circuit to fuel pump feed circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Fuel pump should operate. If fuel pump operates, go to step 18 . If fuel pump does not operate, go to next step.
7. Leave jumper wire connected. Disconnect fuel pump harness connector at fuel pump. Using a test light connected to ground, probe fuel pump power feed circuit at fuel pump harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
8. Leave jumper wire connected. Connect test light between fuel pump battery feed circuit and ground circuit at fuel pump harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 25 . If test light does not illuminate, go to step 15 .
9. Turn ignition off. Remove FUEL PUMP fuse (20-amp), located in underhood fuse block. Disconnect fuel pump harness connector at fuel pump. Using a test light connected to battery positive, probe fuel pump power feed circuit at fuel pump harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 16 . If test light does not illuminate, go to next step.
10. Using a test light connected to battery positive, probe fuel pump relay battery feed circuit at fuel pump relay connector. If test light illuminates, go to step 20 . If test light does not illuminate, go to step 21 .
11. Turn ignition off. Disconnect Powertrain Control Module (PCM) harness connector located on opposite side as manufacturer's logo. Using DVOM, measure resistance of fuel pump relay control circuit between fuel pump relay connector and PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If resistance is 5 ohms or less, go to step 22 . If resistance is not as specified, go to step 17 .
12. Repair open or short to ground in fuel pump relay battery feed circuit. After repairs, go to step 26 .
13. Repair open in fuel pump relay ground circuit. After repairs, go to step 26 .
14. Repair open in circuit between fuel pump relay and fuel pump. After repairs, go to step 24 .
15. Repair open in fuel pump ground circuit. After repairs, go to step 26 .
16. Repair short to ground in fuel pump feed circuit between fuel pump relay and fuel pump. After repairs, go to step 26 .
17. Repair fuel pump relay control circuit. After repairs, go to step 26 .
18. Check for poor connections at fuel pump relay connector. If connections are okay, go to next step. If connections are faulty, repair as necessary and go to step 26 .
19. Replace fuel pump relay. After replacing fuel pump relay, go to step 26 .
20. Repair short to ground in fuel pump relay battery feed circuit between fuel pump relay and FUEL PUMP fuse (20-amp). After repairs, go to step 26 .
21. Turn ignition off. Reinstall fuel pump relay. Instal NEW fuel pump fuse. Reconnect fuel pump harness connector. Turn ignition on. Using scan tool, command fuel pump on. If fuel pump fuse blows, go to step 24 . If fuel pump fuse does not blow, check for an intermittent problem. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
22. Check for poor connection at PCM. If connection is okay, go to next step. If connection is faulty, repair as necessary and go to step 26 .
23. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to step 26 .
24. Check fuel pump harness near fuel pump for a short to ground. After repairs, go to step 26 . If fuel pump harness is okay, go to next step.
25. Replace fuel pump. After replacing fuel pump, go to next step.
26. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and then stalls, go to step 2 .
27. Allow engine to idle until normal operating temperature is reached. Using scan tool, check for DTCs. If DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
28. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.

Fuel System Electrical Circuit (Corvette)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Check F/PMP fuse (20-amp), located in underhood fuse block. If fuse is okay, go to next step. If fuse is faulty, go to step 9 .
3. Install scan tool. Remove fuel pump relay from underhood electrical center. Turn ignition on with engine off. Using a test light connected to ground, probe ignition feed circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
4. Using a test light connected to battery positive, probe fuel pump relay ground circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
5. Using a test light connected to ground, probe fuel pump control circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Using scan tool, command fuel pump on. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 .
6. Ensure ignition is on. Using a fused jumper wire, jumper fuel pump relay ignition feed circuit to fuel pump feed circuit at fuel pump relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Fuel pump should operate. If fuel pump operates, go to step 18 . If fuel pump does not operate, go to next step.
7. Leave jumper wire connected. Disconnect fuel pump harness connector at fuel pump. Using a test light connected to ground, probe fuel pump power feed circuit at fuel pump harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
8. Leave jumper wire connected. Connect test light between fuel pump ignition feed circuit and ground circuit at fuel pump harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 20 . If test light does not illuminate, go to step 15 .
9. Turn ignition off. Remove F/PMP fuse (20-amp), located in underhood fuse block. Disconnect fuel pump harness connector at fuel pump. Using a test light connected to battery positive, probe fuel pump power feed circuit at fuel pump harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 16 . If test light does not illuminate, go to next step.
10. Reconnect fuel pump harness connector. Install NEW fuel pump fuse. Turn ignition on with engine off. Recheck fuel pump fuse. If fuse is blown, go to step 20 . If fuse is okay, check for an intermittent problem. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
11. Turn ignition off. Disconnect Powertrain Control Module (PCM) harness connector located on same side as manufacture's logo. Using DVOM, measure resistance of fuel pump relay control circuit between fuel pump relay connector and PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If resistance is 5 ohms or less, go to step 22 . If resistance is not as specified, go to step 17 .
12. Repair open or short to ground in fuel pump relay ignition feed circuit. After repairs, go to step 24 .
13. Repair open in fuel pump relay ground circuit. After repairs, go to step 24 .
14. Repair open in fuel pump feed circuit between fuel pump relay and fuel pump. After repairs, go to step 24 .
15. Repair open in fuel pump ground circuit. After repairs, go to step 24 .
16. Repair short to ground in fuel pump feed circuit between fuel pump relay and fuel pump. After repairs, go to step 24 .
17. Repair fuel pump relay control circuit. After repairs, go to step 24 .
18. Check for poor connections at fuel pump relay connector. If connections are okay, go to next step. If connections are faulty, repair as necessary and go to step 24 .
19. Replace fuel pump relay. After replacing fuel pump relay, go to step 24 .
20. Check fuel pump harness for damage. If harness is okay, go to next step. If harness is faulty, repair as necessary and go to step 24 .
21. Replace fuel pump. After replacing fuel pump, go to step 24 .
22. Check for poor connection at PCM. If connection is okay, go to next step. If connection is faulty, repair as necessary and go to step 24 .
23. Replace PCM. Perform PCM relearn procedures. After replacing PCM, go to next step.
24. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and then stalls, go to step 2 .
25. Allow engine to reach normal operating temperature. Using scan tool, check for DTCs. If DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, go to next step.
26. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any DTCs are present, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If DTCs are not present, system is okay.

BASIC FUEL SYSTEM CHECKS

Note. For fuel pump circuit testing, see appropriate FUEL SYSTEM ELECTRICAL CIRCUIT under NO START DIAGNOSIS .

FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)

Fuel system is under pressure. Pressure must be relieved prior to servicing fuel system. Fuel pressure may be relieved by using one of the following methods.

1. On 2.2L and 2.4L, loosen fuel filler cap to relieve fuel tank pressure (do not tighten at this time). Disconnect fuel pump harness connector. Start engine and allow it to run until it stalls. Crank starter for 3 seconds to remove remaining fuel from fuel lines. Turn ignition off. Reconnect fuel pump harness connector. Disconnect negative battery cable to avoid possible fuel discharge in accidental attempt to start engine.
2. On all engines except 2.2L and 2.4L, disconnect negative battery cable. Loosen fuel filler cap. Install Fuel Pressure Gauge (J-34730-1A) on fuel pressure connector of fuel rail. Wrap shop towel around pressure connection when installing fuel pressure gauge to absorb fuel leakage. Install gauge bleed hose in container. Open bleed valve to bleed fuel pressure.

FUEL SYSTEM PRESSURE RELIEF (SATURN)

Fuel pressure may be relieved by using one of following methods.

1. Disconnect fuel pump harness connector. Start engine and allow it to run until it stalls. Crank starter for 3 seconds to remove remaining fuel from fuel lines. Reconnect fuel pump harness connector.
2. Install Fuel Pressure Gauge (SA9127E) and 90-Degree Adapter (SA9403E) to fuel pressure test port. When installing fuel pressure gauge, wrap shop towel around pressure connection to absorb fuel leakage. Install gauge bleed hose in container. Open bleed valve to bleed fuel pressure.

FUEL SYSTEM PRESSURE TEST (EXCEPT SATURN)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition off. Turn A/C system off. On all models except 2.2L and 2.4L, connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. On 2.2L and 2.4L, install Fuel Pressure Gauge (J-29658-D). This kit modifies fuel pressure gauge so it may be installed in fuel delivery line with quick-connect fittings. On all models, place fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE (EXCEPT SATURN)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 12 .
3. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to step 10 . If fuel pressure does not decrease more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to next step.
4. Relieve fuel pressure until pressure is 10 psi (0.7 kg/cm 2 ). If fuel pressure decreases more than 2 psi (0.1 kg/cm 2 ) in 10 minutes, go to step 19 . If fuel pressure does not decrease more than 2 psi (0.1 kg/cm 2 ) in 10 minutes, go to next step.
5. If fuel pressure is suspected of decreasing during acceleration, cruise or hard cornering, go to next step. If fuel pressure is not suspected of decreasing during acceleration, cruise or hard corning, go to step 8 .
6. Inspect in-line fuel filter and fuel feed pipe for restriction. If restriction is found, go to step 24 . If restriction is not found, go to next step.
7. Remove fuel sending unit assembly. Inspect fuel pump strainer for restriction and correct installation. Check fuel pump flex pipe for leaks, and ensure fuel pump is correct for application. If a problem is found, go to step 24 . If a problem is not found, go to step 19 .
8. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Note fuel pressure. Start engine. Allow engine to idle until normal operating temperature is reached. If fuel pressure is less than previously noted pressure by 3-10 psi (0.2-0.7 kg/cm 2 ), see appropriate TROUBLE SHOOTING - NO CODES article. If fuel pressure is greater than previously noted pressure by 3-10 psi (0.2-0.7 kg/cm 2 ), go to next step.
9. Disconnect vacuum hose from fuel pressure regulator. With engine idling, apply 12-14" of vacuum to fuel pressure regulator. If fuel pressure decreases by 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 20 . If fuel pressure does not decrease by 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 21 .
10. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-pressure-relief-except-saturn) . Place bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Using scan tool, pressurize fuel system. DO NOT allow fuel pressure to exceed 65 psi (4.5 kg/cm 2 ). Excess pressure may damage fuel pressure regulator. Wait for fuel pressure to build. Using scan tool, obtain highest fuel pressure possible. Gradually pinch off fuel feed hose. If fuel pressure remains constant, go to step 19 . If fuel pressure does not remain constant, go to next step.
11. Gradually unpinch fuel feed hose. Using scan tool, pressurize fuel system. Wait for fuel pressure to build. Gradually pinch off fuel return hose. If fuel pressure remains constant, go to step 21 . If fuel pressure does not remain constant, go to step 22 .
12. If fuel pressure is greater than specification, go to next step. See «FUEL PRESSURE (EXCEPT SATURN)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) table. If fuel pressure is less than specification, go to step 15 .
13. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-pressure-relief-except-saturn) . Disconnect fuel return pipe from fuel rail. Attach a flexible fuel hose to fuel rail return outlet passage. Place other end of flexible hose into container. Turn ignition off for about 10 seconds. Turn ignition on. Observe fuel pressure gauge with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE (EXCEPT SATURN)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) table. If fuel pressure is within specification, go to step 23 . If fuel pressure is not within specification, go to next step.
14. Inspect fuel rail outlet passage for restriction. If restriction is found, go to step 24 . If restriction is not found, go to step 21 .
15. If fuel pressure is greater than zero psi, go to next step. If fuel pressure is zero psi, go to step 17 .
16. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-pressure-relief-except-saturn) . Place bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Using scan tool, pressurize fuel system. DO NOT allow fuel pressure to exceed 65 psi (4.5 kg/cm 2 ). Excess pressure may damage fuel pressure regulator. Wait for fuel pressure to build. Using scan tool, obtain highest fuel pressure possible. Gradually pinch off fuel return hose. If fuel pressure increases to greater than specification, go to step 21 . See «FUEL PRESSURE (EXCEPT SATURN)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) table. If fuel pressure does not increase to greater than specification, go to step 7 .
17. Check fuel pump electrical circuit. See appropriate FUEL SYSTEM ELECTRICAL CIRCUIT under «NO START DIAGNOSIS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__no-start-diagnosis) . If a problem is found in electrical circuit, go to step 24 . If electrical circuit is okay, go to next step.
18. Remove fuel sending unit assembly. Inspect in-line fuel filter, fuel feed pipe and fuel pump strainer for restrictions. Check fuel pump flex pipe for leaks. If a problem is found, go to step 24 . If a problem is not found, go to next step.
19. Replace fuel sending unit assembly. After replacing fuel sending unit assembly, go to step 25 .
20. Locate and repair loss of vacuum to fuel pressure regulator. After repairs, go to step 25 .
21. Replace fuel pressure regulator. After replacing fuel pressure regulator, go to step 25 .
22. Locate and replace leaking fuel injector(s). After replacing fuel injector(s), go to step 25 .
23. Locate and repair restriction in fuel return pipe. After repairing restriction, go to step 25 .
24. Repair problem as necessary. After repairs, go to step 25 .
25. Turn ignition off. Turn A/C system off. On all models except 2.2L and 2.4L, connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. On 2.2L and 2.4L, install Fuel Pressure Gauge (J-29658-D). This kit modifies fuel pressure gauge so it may be installed in fuel delivery line with quick-connect fittings. On all models, place fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE (EXCEPT SATURN)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 11 .
26. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to step 10 . If fuel pressure does not decrease more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, system is okay.

FUEL PRESSURE (EXCEPT SATURN)

FUEL SYSTEM PRESSURE TEST (SATURN)

Note. Ensure battery is fully charged when performing test.

1. Remove air induction tube. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (SATURN)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing__fuel-system-pressure-relief-saturn) . Install fuel pressure gauge and bleed off any fuel in system into a container. Close fuel pressure gauge shutoff valve.
2. Turn ignition on. Using scan tool, command fuel pump on. Fuel pump should run for about one minute. Allow pressure to stabilize. Record maximum fuel pressure. Fuel pressure reading should be 40-55 psi (2.8-3.9 kg/cm 2 ).
3. Bleed fuel pressure and repeat test at least 2 more times. If during test, fuel pressure drops more than 8 psi (.56 kg/cm 2 ) during a 5 minute period, isolate fuel supply side of fuel system by closing off return side with fuel pressure gauge shutoff valve.
4. Using scan tool, command fuel pump on. Allow fuel pressure to stabilize. Record maximum fuel pressure. If fuel pressure remains stable, replace fuel pressure regulator. If fuel pressure bleeds off more than 8 psi (.56 kg/cm 2 ), check fuel inlet line and injectors for leaks, and check for faulty fuel pump. Repair as necessary.

Spark

1. If factory tachometer is connected to coil tachometer terminal, disconnect tachometer before performing tests. When removing spark plug wire from spark plug, twist and pull on boot. DO NOT pull on wire.
2. Using Spark Tester (J-26792), check for spark at each spark plug wire. Leave other wires connected while checking for spark. Check spark plug wire resistance on suspect wires. See IGNITION SYSTEM in appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.

Ignition Coil Power Source

Turn ignition on. Check ignition positive voltage circuit at ignition control module for battery voltage. See appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage is not present, check ignition or PCM fuse. If fuse is okay, check for open in circuit between fuse and ignition control module.

Ignition Coil Resistance (Except 1.9L)

If ignition coil is suspected of causing a misfire or no-spark condition, switch coil locations on ignition control module. If problem follows questionable coil, check ignition coil resistance or replace original coil. For ignition coil resistance, see IGNITION COIL RESISTANCE table.

IGNITION COIL RESISTANCE

Ignition Coil Resistance (1.9L)

1. Disconnect ignition coil leads. Measure secondary coil resistance (secondary tower-to-secondary tower). Resistance should be 8000-15,000 ohms. If resistance is not within specification, replace ignition coil.
2. Ignition coil primary resistance value is not available from manufacturer. If ignition coil is suspected of causing a misfire or a no-spark condition, switch coil locations on EI module. If problem follows questionable coil, replace original coil.

Ignition Relay Circuit (5.7L)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition off. Remove IGN relay from underhood electrical center. Using a test light connected to ground, probe battery positive feed circuit at IGN relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
3. Turn ignition on with engine off. Using a test light connected to ground, probe ignition feed circuit at IGN relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 9 .
4. Turn ignition off. Using DVOM, measure resistance between chassis ground and ground circuit at IGN relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If resistance is less than 5 ohms, go to next step. If resistance is not as specified, go to step 10 .
5. Turn ignition off. Connect a fused jumper wire between IGN relay battery positive feed circuit and IGN relay load circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Using a test light connected to ground, probe terminals of the following fuses located in underhood electrical center No. 2. A/C (Corvette) A/C CRUISE (Camaro & Firebird) AIR PUMP (Corvette) ENG CTRL (Camaro & Firebird) ENG IGN (Corvette) ENG SEN (Camaro & Firebird) INJR1 INJR2 THROT CONT (Corvette) If test light illuminates on all fuses, go to next step. If test light does not illuminate, go to step 11 .
6. Check for poor terminal connection at IGN relay connector. Repair as necessary. If terminal connection is okay, go to next step.
7. Replace IGN relay.
8. Repair open in IGN relay battery positive feed circuit.
9. Repair IGN relay ignition feed circuit.
10. Repair open in IGN relay ground circuit.
11. Repair IGN relay load circuit.

Crankshaft Position (CKP) Sensor Short & Resistance Checks

1. Set DVOM on 2000-ohm scale. Connect DVOM leads to CKP sensor connector located on side of engine block. Turn ignition off. Disconnect ignition control module harness connectors. Measure resistance between CKP sensor terminals at ignition control module harness connector.
2. CKP sensor resistance should be within specification. See «CRANKSHAFT POSITION (CKP) SENSOR RESISTANCE»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-basic-engine-testing) table. If resistance is not within specification, replace CKP sensor. If sensor is within specification, go to next step.
3. With CKP sensor installed in engine block, connect one DVOM lead to either sensor terminal at ignition control module. Touch other lead of DVOM to engine block. Continuity should not exist. If continuity exists, CKP sensor or circuit is shorted to ground and must be repaired or replaced.

CRANKSHAFT POSITION (CKP) SENSOR RESISTANCE (1)

Crankshaft Position (CKP) Sensor Output Signal

Set DVOM on 2-volt AC scale. Connect DVOM leads to CKP sensor located on side of engine block. Crank engine and observe voltmeter reading. CKP sensor should generate a voltage signal of about 2 volts.

Tach Pulse (RPM) Signal

Connect scan tool to DLC. RPM should be indicated on scan tool when engine is cranked or running. Tach pulse (RPM reference) will be indicated as a voltage signal when a DVOM (with a minimum 10-megohm input impedance connected to ground) is used to backprobe RPM high reference circuit. If tach pulse signal is not present, engine will not run. For circuit and terminal identification, see appropriate wiring diagram in WIRING DIAGRAMS article.

1. Disconnect tachometer wire from IDI module (if equipped). A shorted tachometer will not allow engine to start. Temporarily remove IDI assembly and install Spark Plug Jumper Wires (J-36012).
2. Using Spark Tester (J-26792), check for spark at each spark plug wire. Leave other wires connected while checking for spark.

Turn ignition on. Check ignition battery voltage circuit at ignition control module for battery voltage. See appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage is not present, check ignition fuse. If fuse is not blown, check for open in circuit between fuse and ignition control module.

Ignition Coil Resistance

1. Disconnect ignition coil leads. Measure secondary coil resistance (secondary tower-to-secondary tower). Resistance should be 4000-8000 ohms. If resistance is not within specification, replace ignition coil.
2. Ignition coil primary resistance value is not available from manufacturer. If ignition coil is suspected of causing a misfire or a no-spark condition, switch coil locations on ignition control module. If problem follows questionable coil, replace original coil.

1. Set DVOM on 2000-ohm scale. Connect DVOM leads to CKP sensor connector located on side of engine block. Turn ignition off. Disconnect ignition control module harness connectors. Measure resistance between CKP sensor terminals at ignition control module connector.
2. CKP sensor resistance should be 500-900 ohms. If resistance is not as specified, replace CKP sensor. If sensor resistance is within specification, go to next step.
3. With CKP sensor installed in block, connect one DVOM lead to either sensor terminal at ignition control module. Touch other lead of DVOM to engine block. Continuity should not exist. If continuity exists, CKP sensor or circuit is shorted to ground and must be repaired or replaced.

Set DVOM on 2-volt AC scale. Connect DVOM leads to CKP sensor located on side of engine block. Crank engine and observe voltmeter reading. CKP sensor should generate a voltage signal of about 1100-1300 millivolts as crankshaft turns. Ignition control module can be triggered with a voltage signal as low as 200 millivolts.

Connect scan tool to DLC. RPM should be indicated on scan tool when engine is cranked or running. Tach pulse (RPM reference) will be indicated as a voltage signal when a DVOM (with a minimum 10-megohm input impedance connected to ground) is used to backprobe RPM high reference circuit. If tach pulse signal is not present, engine will not run. For circuit and terminal identification, see appropriate wiring diagram in WIRING DIAGRAMS article.

Disconnect tachometer wire (if equipped). A shorted tachometer will prevent engine from starting. Disconnect Camshaft Position (CMP) sensor. Attempt to start engine. If engine starts, see appropriate CMP sensor DTC test in appropriate SELF-DIAGNOSTICS article. Using Spark Tester (J-26792), check for adequate spark. Check for spark on plug wires No. 1, 3 and 5 (one at a time). Leave companion cylinder plug wire connected while checking for spark. When removing spark plug wire from spark plug, twist and pull on boot. DO NOT pull on wire.

Turn ignition on. Check for battery voltage on ignition positive voltage circuit at ignition control module. If battery voltage is not present, check for blown ignition fuse. If fuse is okay, check for open in circuit between fuse and ignition control module.

Disconnect ignition coil leads. Using DVOM, measure ignition coil resistance. Secondary resistance should be 5000-8000 ohms. If resistance is not as specified, replace ignition coil.

Connect scan tool to DLC. RPM should be indicated on scan tool when engine is cranked or running. Tach pulse (RPM reference) will be indicated as a voltage signal when a DVOM (with a minimum 10-megohm input impedance connected to ground) is used to backprobe RPM high reference circuit. If tach pulse signal is not present, engine will not run. For circuit and terminal identification, see appropriate wiring diagram in WIRING DIAGRAMS article.

POWER RELAY CIRCUIT (CATERA)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Inspect fuse V5 (80-amp), located in power distribution fuse block. If fuse is open, go to step 7 . If fuse is okay, go to next step.
3. Turn ignition off. Remove engine controls power relay from ECM housing. Using a fused jumper wire, jumper battery feed circuit and switched B+ circuit together at engine controls power relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Attempt to start engine. If engine starts, go to step 8 . If engine does not start, go to next step.
4. Using a test light connected to ground, probe both battery feed circuits at engine controls power relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates at both circuits, go to next step. If test light does not illuminate at both circuits, go to step 7 .
5. Turn ignition off. Using a test light connected to battery positive, probe engine controls power relay control circuit and switched B+ circuit at engine controls power relay connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on. If test light illuminates at both circuits, go to step 7 . If test light does not illuminate at both circuits, go to next step.
6. Turn ignition off. Disconnect ECM harness connectors. Using DVOM, check for continuity in engine controls power relay control circuit between engine controls power relay connector and ECM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If continuity is present, go to step 12 . If continuity is not present, go to step 9 .
7. Repair battery feed circuit.
8. Replace engine controls power relay.
9. Repair open or high resistance in engine controls power relay control circuit.
10. Check for poor ECM harness connections. After repairs, go to step 12 . If connections are okay, go to next step.
11. Replace ECM. Perform ECM relearn procedures. After repairs, go to next step.
12. Using scan tool, clear Diagnostic Trouble Codes (DTCs). Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and then stalls, go to step 2 .
13. Allow engine to idle until normal operating temperature is reached. Using scan tool, check for DTCs. If any DTCs are present, perform appropriate DTC test. See appropriate SELF-DIAGNOSTICS article. If no DTCs are present, go to next step.
14. If any additional DTCs were noted during On-Board Diagnostic (OBD) system check that have not been diagnosed, perform appropriate DTC test. See appropriate SELF-DIAGNOSTICS article. If no additional DTCs were noted, system is okay.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For specifications, see appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article. For adjustment procedures, see appropriate ON-VEHICLE ADJUSTMENTS article.

SUMMARY

If no faults were found while performing basic diagnostic procedures, or no trouble codes (or only intermittent ones) were found while performing On-Board Diagnostic (OBD) system check, and driveability problems still exist, proceed to appropriate TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.

See also:
• FUEL SYSTEM ELECTRICAL CIRCUIT
• BASIC FUEL SYSTEM CHECKS
• FUEL SYSTEM ELECTRICAL CIRCUIT
• POWER RELAY CIRCUIT (CATERA)
• FUEL SYSTEM ELECTRICAL CIRCUIT (EXCEPT GRAND PRIX)
• FUEL SYSTEM ELECTRICAL CIRCUIT (GRAND PRIX)
• FUEL SYSTEM ELECTRICAL CIRCUIT (VIN K)
• FUEL SYSTEM ELECTRICAL CIRCUIT (VIN 1)
• IGNITION RELAY CIRCUIT (5.7L)
• FUEL SYSTEM ELECTRICAL CIRCUIT (CAMARO & FIREBIRD)
• FUEL SYSTEM ELECTRICAL CIRCUIT (CORVETTE)
• NO START DIAGNOSIS
• FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)
• FUEL SYSTEM PRESSURE RELIEF (SATURN)