Dfi Sys/component Tests Cadillac Eldorado IX

TESTING INFORMATION

For testing with Codes information, refer to DFI ECM TESTS/CODES article or DFI BCM TESTS/CODES article in this section. For trouble shooting by symptoms, see DFI TESTS W/O CODES article in this section. For removal and installation of DFI components, see the DFI COMOPONENT R & I article in this section.

CCDIC SEGMENT CHECK

The segment check illuminates the Instrument Panel Cluster (IPC) and CCDIC to ensure that all segments of the vacuum flourescent displays are working. The turn signal indicators do not light during this check. If all segments are not illuminated, diagnosis should NOT be attempted, as a misdiagnosis may occur (Code E034 appears as E031, etc.). For testing with Codes procedures, refer to the DFI ECM TESTS/CODES or DFI BCM TESTS/CODES article in this section. If any portions or segments of the CCDIC display are inoperative, it must be replaced before continuing with diagnosis.

SYSTEM PERFORMANCE TEST CHART IDENTIFICATION

DFI SYSTEM PERFORMANCE CHARTS

SYSTEM TEST CHART IDENTIFICATION

ECM COMPUTER SYSTEM CHARTS

FIXED SPARK MODE (SETTING IGNITION TIMING)

1. Initial base timing is set by jumpering pins "A" and "B" together at ALDL connector, while NOT in diagnostic mode. The ALDL connector is located near brake pedal, just below dash. (Scheme 295)
2. Set timing to specification shown on EMISSION CONTROL LABEL. Jumpering pins "A" and "B" together will cause a "SET TIMING" message to appear on CCDIC. This indicates that ECM is in set ignition timing mode.

Scheme 295

DFI SYSTEM CHECK

Note. As a carryover from the previous year, manufacturer refers to the "SERVICE SOON" light as the "ENGINE CONTROL SYSTEM" light in flow charts. This light was renamed "SERVICE SOON" in late 1988.

The DFI SYSTEM CHECK is an organized approach for identifying a problem caused by DFI system. Driver comments normally fall into one of the following areas: steady "SERVICE SOON" light, driveability problems, engine will not start, or engine stalls after start.

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

1. If "SERVICE SOON" light comes on while cranking, then the ECM is getting battery power and ground.
2. If "SERVICE SOON" light is on with engine running, check for ECM codes. Diagnose codes before proceeding with DFI system check.
3. After codes are corrected, ability of DFI system to control fuel delivery to engine must be checked.
4. Checks for proper closed/open loop operation.
5. If closed loop is achieved, fuel system has to be checked for rich, lean or proper fuel control. The DFI system has an integrator which monitors oxygen sensor rich/lean status and drives fuel system richer if oxygen sensor signal is lean, or drives the fuel system leaner if sensor signal is rich. The integrator has a range of 0-250 counts. The integrator value will be 128 when ECM does not have to modify fuel rate to engine. The integrator will reset to 128, if fuel system is in acceleration, power enrichment, some deceleration or open loop modes. The integrator resets to 128 when oxygen sensor is not in control of fuel. If integrator sees an oxygen sensor that is lean most of the time, the integrator value will go higher to try and add more fuel to engine. If integrator sees an oxygen sensor that is rich most of the time, the integrator value will go lower to try and drive fuel system leaner. In this test, operate engine at closed loop (1000-2000 RPM with steady throttle) to stabilize integrator reading of 88-160. In most cases, this will indicate that fuel delivery system is okay.

Performance Check Flow Chart. Scheme 296

Chart A1, Inoperative "Service Soon" Light Wiring Diagram. Scheme 297

Note. As a carryover from the previous year, manufacturer refers to the "SERVICE SOON" light as the "ENGINE CONTROL SYSTEM" light in flow charts. This light was renamed "SERVICE SOON" in late 1988.

The "SERVICE SOON" light is powered through the 10-amp "IGN-1" fuse No. 18 in fuse block, and grounded by ECM terminal C1 to illuminate. As a bulb check, "SERVICE SOON" light illuminates with key on and engine off. Light is illuminated steadily during cranking and is illuminated whenever a trouble code with service message is set.

If a service trouble code is set, the ECM will send a service status to BCM via the data link. At the same time, ECM grounds terminal C1 to turn on light.

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

1. If Code EO18 is present, diagnose Code EO18 before proceeding. The "SERVICE SOON" light illuminates with engine cranking only if crank input is present to ECM.
2. If Code B334 is current ("NO ECM DATA" is displayed), go to CHART A1 (2 OF 2) to check for loss of power or ground to ECM.
3. If "STOP ENGINE/OIL" light is displayed with key on/engine off, power to cluster lights is okay. Diagnose location of open ground circuit to "SERVICE SOON" light or check for a blown "SERVICE SOON" light bulb.
4. Starting at ECM, this branch of chart follows circuit No. 325, grounding circuit No. 325 as ECM would do to turn bulb on. If a ground at given point on circuit No. 325 brings "SERVICE SOON" light on, circuit from grounded point to light is okay.

Flow Chart A1 & Schematic (1 of 2). Scheme 298

Flow Chart A1 & Schematic (1 of 2). Scheme 299

Chart A1, (2 of 2) - Inoperative "Service Soon" Schematic. Scheme 300

Note. As a carryover from the previous year, manufacturer refers to the "SERVICE SOON" light as the "ENGINE CONTROL SYSTEM" light in flow charts. This light was renamed "SERVICE SOON" in late 1988.

If "SERVICE SOON" light is inoperative and Code B334 is current, the ECM may not be powering up with key on, may not be receiving full time power from battery, or may be damaged due to electrical overload or water intrusion.

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

1. Check for switched ignition power to ECM.
2. Check for ground to ECM. Terminal A12 and terminal D1 are redundant grounds. If either ground is okay, ECM should be able to perate normally. If both grounds are open, ECM will not power up.
3. Check for full time memory voltage supply to ECM. Terminals C16 and B1 are redundant power supplies to ECM. If either power supply is okay, ECM should be able to operate normally.
4. If power, grounds and connections are okay, be sure to perform CHART C1 - ECM REPLACEMENT CHECK before replacing ECM. The ECM may have been damaged by electrical overload due to a low resistance component.

Flow Chart A1 (2 of 2) - Inoperative "Service Soon" Light. Scheme 301

Flow Chart A1 (2 of 2) - Inoperative "Service Soon" Light. Scheme 302

Chart A2, "Service Soon" Light On - No Codes Set Schematic. Scheme 303

Note. As a carryover from the previous year, manufacturer refers to the "SERVICE SOON" light as the "ENGINE CONTROL SYSTEM" light in flow charts. This light was renamed "SERVICE SOON" in late 1988.

The "SERVICE SOON" light is powered through the 10-amp "IGN-1" fuse in fuse block, and grounded by ECM terminal C1 to illuminate. The "SERVICE SOON" light checks the bulb with key on. Light is illuminated steadily during cranking, and is illuminated whenever a trouble code with service message is set. If a service trouble code is set, ECM sends a service status to BCM via the data link. At the same time, the ECM grounds terminal C1 to turn on "SERVICE SOON" light.

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

1. Intermittent loose grounds or power connections can cause ECM to repeatedly power-up, power-down or to reset.
2. Check for bulb grounded by ECM through terminal C1 or through a circuit fault.
3. Remove and replace both ECM connectors and ensure that they are latched. Check MEM-CAL unit for proper orientation, bent terminals, and full seating in socket. Subsitute a known good MEM-CAL unit to see if unit is causing the light to flicker. If test MEM-CAL unit does not correct condition, replace ECM. Be sure to perform CHART C1 - ECM REPLACEMENT CHECK.

Flow Chart A2, "Service Soon" Light On - No Codes Set. Scheme 304

Flow Chart A2, "Service Soon" Light On - No Codes Set. Scheme 305

Chart A3, No Start Or Stalls After Start Schematic. Scheme 306

All internal combuston engines require spark, fuel, air, and proper timing to operate. The DFI system is no different. If battery is at proper charge level, first step should be to determine which of these elements is missing.

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

1. Check for codes stored and for proper "SERVICE SOON" light operation. Repair stored codes and improper "SERVICE SOON" light operation before proceeding with CHART A3.
2. Injectors should spray only when engine is cranking or running. Look for spray, drips or leaks with key on/engine off.
3. Check for both injectors to spray fuel while cranking engine.
4. If fuel is okay, then check for spark. Use Spark Tester (ST-125) to test for spark. A spark plug with a wide gap or allowing a plug wire to arc to ground, may not test HEI for sufficient output and may damage coil, cap, or rotor.
5. This step by-passes EST system. If vehicle will start and run with EST system disabled (by-pass open), the no start condition may be due to an EST system fault. If ECM has poor ground to engine, or if distributor has a poor ground connection to ECM, distributor may not be able to recognize EST pulses and the engine will stall as ECM tries to enable EST. The system uses EST to control spark timing.
6. If vehicle will not start, the fuel system must be checked next. Connect Fuel Pressure Gauge (J-25400-300) and observe fuel pressure while cranking. The gauge should be installed in fuel inlet line at service fitting. A fuel pressure reading of 9-12 psi during cranking indicates that fuel system is operating properly. Improper fuel pressure indicates a fuel problem. See CHART A4A - FUEL SYSTEM DIAGNOSIS. Having spark and fuel spray from both injectors at correct fuel pressure, all DFI functions for starting are operating normally. Thus the cause of no start condition is a mechanical problem (i.e. spark plugs, valves, valve timing, etc.).

Flow Chart Code A3, No Start Or Stalls After Start. Scheme 307

Flow Chart Code A3, No Start Or Stalls After Start (1 Of 2). Scheme 308

Flow Chart Code A3, No Start Or Stalls After Start (2 Of 2). Scheme 309

Chart A4A, Fuel System Diagnosis Schematic. Scheme 310

The DFI system requires that fuel pressure be maintained at 9-12 psi and steady under all driving conditions. Fuel Pressure Gauge (J-29658/BT8205) should be attached to fuel line service fitting with Schrader valve fitting from Gauge Set (J-34730-1). This set up will give technician a more precise and more responsive reading.

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

1. Fuel pressure should be 9-12 psi and steady. If fuel pressure is not in this range, go to CHART A4B - FUEL PRESSURE OUT OF RANGE.
2. If fuel pressure drops (leaks down) with key off, either the fuel pressure regulator cannot hold pressure or the fuel pump check ball is not seating. This branch of trouble tree will determine which is causing the fuel pressure leak-down.

Flow Chart A4A, Fuel System Diagnosis. Scheme 311

Flow Chart A4A, Fuel System Diagnosis. Scheme 312

Chart A4B, Fuel Pressure Out of Range, Schematic. Scheme 313

This procedure tests for fuel supply system problems that can cause incorrect fuel pressure or incorrect fuel pump operation.

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

1. Fuel system diagnosis should begin by determining if fuel pump is operating properly. Fuel Pressure Gauge (J-25400-300) should be installed at fuel line service fitting. Measure fuel pressure while cranking engine. If fuel pressure is 9-12 psi, go to CHART A4A - FUEL SYSTEM DIAGNOSIS. If necessary, Fuel Pressure Gauge (J-29658/BT8205) may be attached to service line fitting with Schrader valve fitting from Gauge Set (J-34730-1). This set up will give technician a more precise and more responsive reading.
2. If fuel pump relay or ECM were cause of low fuel pressure, there would be an ECM Code EO20 set. This step is to check for voltage supply to fuel tank 5-way connector.
3. If voltage signal to fuel tank connector is okay, an open may exist between 5-way fuel tank connector and fuel pump. If fuel pump runs with an alternate power source connected, the fuel tank unit is okay. Check throttle body fuel metering assembly for cause of low fuel pressure.
4. Check for fuel supply system (tank, filter, pump, sender, lines) ability to deliver at least 9 psi pressure or for throttle body fuel pressure regulator fault.
5. If fuel pressure is low with fuel return line plugged, throttle body fuel metering assembly is not at fault. A restriction or blockage may exist in fuel supply system. The fuel supply line should be checked visually for kinks and damage. The fuel filter element can also restrict flow. Check for proper fuel line routing, sender tubes for restrictions, check rubber between fuel pump and sending unit for leaks or restrictions, or collapsed fuel strainer in tank. If all of the above are okay, replace fuel pump.
6. Fuel pressure greater than 12 psi is caused either by a malfunction of pressure regulator or by a restriction in fuel return line. It should be noted that a secondary condition of spark plug fouling, Code EO45 or oxygen sensor contamination resulting in Code EO13 accompanied by Code EO45, may result from too rich fuel flow. To isolate cause of high fuel pressure, disconnect return line at throttle body and connect a fitting to throttle body which will accept a length of flexible rubber fuel hose. Insert other end of hose into a container and observe fuel pressure as ignition is tuned on. If fuel pressure remains greater than 12 psi, replace fuel metering assembly. If fuel pressure drops into 9-12 psi range, with fuel return line by-passed, the fuel return line is restricted. A restricted fuel return line can be diagnosed by visually inspecting line for kinks or damage. A kink in the Teflon fuel line (braided stainless steel clad) may not be visually obvious.
7. If fuel pump will not run with externally applied power, fault is an open circuit in fuel sending unit wiring to pump, or an open circuit at RFI suppression connector inside tank, or faulty fuel pump. The fuel sending unit must be removed from vehicle to check.

Flow Chart A4B, Fuel Pressure Out of Range. Scheme 314

Flow Chart A4B, Fuel Pressure Out of Range. Scheme 315

Chart A5, Injector System Diagnosis Schematic. Scheme 316

Fuel injectors are powered through the 3-amp injector fuses. ECM turns on injectors by appling a ground to ECM connector terminals D15 and D16 (injector drive circuits). ECM grounds injector drive circuits to turn on fuel injector to supply fuel to engine. ECM data parameter ED06 (injector pulse width), reflects time in milliseconds that ECM turns on ground to injectors for each injector pulse.

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

1. If this procedure is being followed for a no start condition, crank engine for 5 seconds to check distributor reference signal. If Code EO12 does not set, turn ignition off for 10 seconds and observe injectors as ignition is turned back on. If there is no spray, then injectors are not stuck open. Observe injectors while cranking engine.
2. To determine if injector is being activated electrically, repeat procedure listed in step 1) with electrical connector removed. If injector continues to spray, injector is defective and must be replaced. If injector no longer sprays, the drive circuit of the affected injector must be shorted to ground or the ECM is grounding internally.
3. If both injectors spray or if neither injector sprays, it must be determined if the fuel system is operating properly. Fuel Pressure Gauge (J-25400-300) should be installed at fuel line service fitting. Measure fuel pressure while cranking engine. If fuel pressure is not 9-12 psi, go to CHART A4A - FUEL SYSTEM DIAGNOSIS.
4. If fuel pressure is between 9-12 psi and there was no spray from either injector while cranking, the injector circuit must be checked for proper voltage. If there is voltage at injector fuses, then the ECM must be faulty because it is not grounding both injector circuits. If there is no voltage at fuse, check for voltage at 10-amp ECM fuse which feeds the injector fuses. If there is voltage here, then an open circuit must exist between fuses and circuit No. 439. If there is no voltage at ECM fuse, then circuit No. 3 must be repaired for an open or short to ground.
5. If fuel pressure is betweeen 9-12 psi and there was fuel spray from both injectors while cranking engine, check fuel system to determine if injectors leak. To check for injector leakage, start and run engine for 10 seconds. Turn engine off for at least 10 seconds. Turn ignition on to pressurize injectors. Visually check fo dripping fuel from bottom of injectors. If fuel is dripping, check for damaged "O" rings. If "O" rings are okay, replace injector(s). If fuel does not drip, fuel system is okay.
6. If there is spray from only one injector, then there is a malfunction in the injector assembly or in the signal to the injector assembly. Malfunction can be isolated by switching injector connectors. If problem remains with the original injector after switching connector, the injector is defective and must be replaced.

Flow Chart A5, Injector System Diagnosis. Scheme 317

Flow Chart A5, Injector System Diagnosis (1 Of 2). Scheme 318

Flow Chart A5, Injector System Diagnosis (2 Of 2). Scheme 319

Chart A5, Injector System Diagnosis Schematic. Scheme 320

Note. The injector circuit test should only be performed when driveability condition is present or when one injector is visually verified to be inoperative. For the injector circuit test to result in a positive diagnosis of an injector circuit fault, the voltage measurements requested by CHART A5 must be taken with injector fault present.

The fuel injectors are powered through the 3-amp injector fuses. The ECM turns on injectors by applying a ground to ECM connector terminals D15 and D16 (injector drive circuits). The ECM grounds injector drive circuits to turn on fuel injectors to supply fuel to engine. ECM data parameter ED06 (injector pulse width), reflects the time in milliseconds that ECM turns on ground to injectors for each injector pulse.

When measuring voltages between ECM connector terminals D15 and D16, the voltmeter should read "00.0" volts if ECM is able to control both fuel injectors to provide equal amounts of fuel. If one injector loses power from fuse or loses ground from ECM, the voltage measured between terminals D15 and D16 will not be zero. This reflects unequal voltage drops across injector coils. The voltage reading obtained when an injector fault is present can be used to diagnose injector open to voltage, injector open to ECM, injector coil open, or ECM unable to ground injector drive circuits.

To obtain an accurate and useable voltage reading, Digital Volt/Ohmmeter (DVOM J34029-A) must be used. The DVOM must be connected as directed by CHART A5 (Cont.) and must be set on 200-volt (DC) scale.

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

1. If DVOM reads "00.0" volts, both injectors are being powered through fuses and grounded by ECM an equal amount. No fault exists at this time.
2. If DVOM reads "00.2" or "02.0" volts and voltage polarity is negative, injector "B" is inoperative. Terminal D15 of Red ECM connector is not grounding injector drive circuit No. 468. The cause is an ECM connector fault or an ECM fault. If voltage polarity is positive, injector "A" is inoperative. Terminal D16 of Red ECM connector is not grounding injector drive circuit No. 467. The cause is an ECM connector fault or an ECM fault.
3. If DVOM reads greater than "2.0" volts, the fault is an open circuit from one of the 3A injector fuses to ECM. A negative voltage polarity means that an open exists between injector "A" voltage supply and ECM. Check circuit No. 481, injector coil of injector connected to Blue and Red wires and circuit No. 467, for open or short circuits to ground. A positive voltage polarity means that an open exists between injector "B" voltage supply and ECM. Check circuit No. 482, injector coil of injector connected to Green and White wires, circuit No. 468 for open or short circuits to ground.

Flow Chart A5, Injector System Diagnosis. Scheme 321

Flow Chart A5, Injector System Diagnosis. Scheme 322

Chart A6, Oxygen (O2) Sensor Not Ready Schematic. Scheme 323

The ECM provides a .45-volt reference to O2 sensor on circuit No. 412. When warm, a properly operating O2 sensor will drive the .45-volt reference lower (less than .45 volt) to indicate lean mixtures and higher (greater than .45 volt) to indicate a rich mixture.

When O2 sensor is cold (less than 200°C), the output voltage will be around 0.5 volt and the ECM will keep the system in open loop operation. When the ECM sees that the O2 sensor is varying from cold voltage of .45 volt and engine coolant value is greater than 85°C, it will send the system into closed loop operation. In closed loop operation, the ECM will adjust fuel delivery rate based upon oxygen sensor readings. CHART A6 should only be used when vehicle will NOT go into closed loop operation.

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

1. With key on and oxygen sensor disconnected, BCM data parameter ED07 should read .45 volt (nominal). Lower or higher voltage indicates circuit problems.
2. The ECM compares voltage on circuit No. 412 to ground voltage on circuit No. 413B. It is essential that oxygen sensor ground and ECM ground show good continuity (no voltage difference with engine running).

Flow Chart A6, Oxigen Sensor Not Ready. Scheme 324

Flow Chart A6, Oxigen Sensor Not Ready (1 Of 2). Scheme 325

Flow Chart A6, Oxigen Sensor Not Ready (2 Of 2). Scheme 326

Chart A7, Lean Exhaust Signal Schematic. Scheme 327

The ECM provides a .45-volt reference signal to oxygen sensor on circuit No. 412. When oxygen sensor is cold (less than 200°C), the output voltage will be around .45 volt. The ECM will keep system in open loop operation. When warm, a properly operating oxygen sensor will drive the .45-volt reference lower (less than .45 volt) to indicate a lean mixture and higher (greater than .45 volt) to indicate a rich mixture.

The oxygen sensor signal voltage will swing from rich to lean rapidly (one swing every 2 seconds), if ECM is in control of air/fuel mixture. The low oxygen sensor voltage readings are normally evidence that the air/fuel mixture is lean and closed loop system is unable to compensate sufficiently due to a failure in some part of engine emission or fuel systems.

Less likely is the possibility that the oxygen sensor has failed and is giving an incorrectly low reading. However, if this is the case, closed loop fuel system will be overcompensating and causing rich operation while oxygen sensor is indicating lean readings.

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

1. If Code EO13 is stored, DO NOT use this chart. See CHART A6 - OXYGEN SENSOR NOT READY.
2. With sensor disconnected, oxygen sensor reference voltage (.38-.63 volt) should appear. If parameter ED07 reading is less than .38 volt, check for grounded signal circuit No. 412 or open ground circuit No. 413.
3. Check for ECM and oxygen sensor circuitry ability to record rich readings. The DVOM set on "VOLTS" scale will provide a few billionths of an amp to drive circuit No. 412 to greater than .64 volt (rich). Similar results may be obtained by placing one finger on battery positive terminal and another finger on oxygen sensor circuit No 412 harness terminal. The ECM compares oxygen sensor signal voltage received on circuit No. 412 to ground voltage on circuit No. 413B. If the ECM does not have a good ground to engine on circuit No. 413B, oxygen sensor can appear falsely high or low. With engine running, use a voltmeter to measure voltage from oxygen sensor to terminal A1 at ECM. If voltage is -.05 volt to +.05 volt, ground circuit is okay. If voltage is less than -.05 volt or more than +.05 volt, repair poor ground connection between ECM terminal A1 and oxygen sensor ground eyelet on engine, at rear bank of cylinders, with a ground eyelet on power steering line retainer clip.
4. If oxygen sensor circuit is okay, lean exhaust is caused by fuel or emission systems not controlling the following: A fuel delivery system which is not functioning properly may cause a lean fuel mixture. This malfunction can be caused by fuel pressure less than 9 psi at injectors or by defective injectors. See CHART A4A - FUEL SYSTEM DIAGNOSIS. A loss of EGR will cause a lean fuel mixture. See CHART C6 - EGR DIAGNOSIS. If AIR management system were to send air to exhaust ports at all times, this would give a lean indication at oxygen sensor. See CHART C6 - AIR MANAGEMENT DIAGNOSIS. If CHART A9 - OXYGEN SENSOR DIAGNOSIS indicates that sensor is okay, check all connectors and terminals for an intermittent condition. Check for vacuum leaks at hoses, intake manifold and throttle body gaskets. Check for intermittent injector operation. See CHART A5 - INJECTOR SYSTEM DIAGNOSIS.

Flow Chart A7, Lean Exhaust Signal. Scheme 328

Flow Chart A7, Lean Exhaust Signal. Scheme 329

Chart A8, Rich Exhaust Signal Schematic. Scheme 330

The ECM provides a .45-volt reference signal to oxygen sensor on circuit No. 412. When oxygen sensor is cold (less than 200°C), output voltage will be about 0.5 volt, the ECM will keep system in open loop operation. When warm, a properly operating oxygen sensor will drive the .45-volt reference lower (less than .45 volt) to indicate a lean mixture and higher (greater than .45 volt) to indicate a rich mixture.

The oxygen sensor signal voltage will swing from rich to lean rapidly (one swing every 2 seconds), if ECM is in control of air/fuel mixture. Fixed high oxygen sensor voltage readings are normally evidence that air/fuel mixture is rich and closed loop system is unable to compensate sufficiently due to a failure in some part of engine emission or fuel systems.

Less likely is the possibility that the oxygen sensor has failed and is giving an incorrectly high reading. If the oxygen sensor is giving false rich readings, the closed loop fuel system will be overcompensating and causing lean operation while oxygen sensor is indicating rich.

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

1. If Code EO13 is stored, DO NOT use this chart. See CHART A6 - OXYGEN SENSOR NOT READY.
2. With sensor disconnected, oxygen sensor reference voltage (.38-.63 volt) should appear. If parameter ED07 reading is greater than .64 volt, check for circuit No. 412 shorted to voltage or poor ground on circuit No. 413B.
3. Check for oxygen sensor and ECM's ability to record lean readings. The ECM compares oxygen sensor signal voltage received on circuit No. 412 to ground voltage on circuit No. 413B. If ECM does not have a good ground to engine on circuit No. 413B, oxygen sensor can appear falsely high or low. With engine running, use a voltmeter to measure voltage from oxygen sensor at exhaust manifold to terminal A1 at ECM. If voltage is -.05 volt to +.05 volt, the ground circuit is okay. If voltage is less than -.05 volt or more than +.05 volt, repair poor ground circuit connection between ECM terminal A1 and oxygen sensor ground eyelet on engine, at rear bank of cylinders, with a ground eyelet on power steering line retainer clip.
4. If oxygen sensor circuit is okay, rich exhaust is caused by fuel or emission systems not controlling the following: A restricted air cleaner could cause a rich fuel mixture. Inspect air cleaner and replace if necessary. A fuel delivery system which is not functioning properly may cause a rich fuel mixture. This malfunction can be caused by fuel pressure which is greater than 12 psi at injectors or by defective injectors. See CHART A4A - FUEL SYSTEM DIAGNOSIS. Excessive EGR flow displaces oxygen and causes a rich exhaust indication. See CHART A5 - INJECTION SYSTEM DIAGNOSIS. Injector dripping or injector leaks can cause rich exhaust. See CHART A5 - INJECTION SYSTEM DIAGNOSIS to check injectors. Fuel evaporation (carbon) canister loaded with fuel can cause rich operation. See CHART C3 - CANISTER PURGE DIAGNOSIS. Vacuum leak to MAP hose can cause a false high MAP reading. High MAP readings cause ECM to deliver too much fuel for current driving conditions. See Code EO34 chart to diagnose. If CHART A9 - OXYGEN SENSOR DIAGNOSIS indicates that sensor is okay, check all connectors and terminals for an intermittent code.

Flow Chart A8, Rich Exhaust Signal. Scheme 331

Flow Chart A8, Rich Exhaust Signal. Scheme 332

Chart A9, Oxygen (O2) Sensor Diagnosis Schematic. Scheme 333

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

1. With engine running, coolant temperature 185°F (85°C) or greater, and at fast idle, observe engine data parameter ED07.
2. While running engine at fast idle, observe open/closed loop status light, and "AUTO" indicator light in CCDIC. If ECM switches system to closed loop operation, the oxygen sensor is okay. If ECM remains in open loop operation, coolant temperature parameter ED04 is greater than 185°F (85°C), and ECM and harness are operating properly as verified by CHART A6, replace oxygen sensor.
3. If voltage remains between .30-.60 volt for a minimum of one minute, check for the possibility of leaded or contaminated fuel before checking for a faulty oxygen sensor connection or a faulty oxygen sensor, as leaded fuel can damage catalytic converter and oxygen sensor.
4. If there is no voltage variation and if ECM and harness are operating properly as verified by CHART A6, check for faulty oxygen sensor.

Flow Chart A9, Oxygen (O2) Sensor Diagnosis. Scheme 334

Flow Chart A9, Oxygen (O2) Sensor Diagnosis. Scheme 335

DFI CHART B1 - RESTRICTED EXHAUST CHECK

Note. The following procedure will require a known good vehicle of same make, model and year to be used for comparison.

1. Check for exhaust restrictions. Use Pressure Gauge Tap J-35314) with a 0-15 psi (0-1.1 kg/cm 2 ) range pressure gauge. Block drive wheels. Apply parking and service brakes.
2. Place vehicle in Drive and load the engine at a steady 1600 RPM. If there is a 1.0 psi (0.1 kg/cm 2 ) or greater backpressure difference between tested vehicle and a known good vehicle, exhaust system is restricted.

Chart C1 - ECM Replacement Check Schematic. Scheme 336

Prior to replacing ECM, check for poor connector terminal to ECM contact. Check for a short circuit to battery voltage on an ECM ground circuit. Also check for shorted solenoids or relays. If a short is found, the circuit must be repaired BEFORE replacing ECM. This will prevent repeated ECM failures.

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

1. Check for poor terminal contact due to damaged or dirty ECM terminals. Remove suspected terminals to inspect, replace if damaged or dirty. If coolant is present at ECM connector, replace coolant temperature sensor, sensor connector, and sensor signal and ground wires. Also, replace ECM connector terminals and blow coolant out of harness. Clean ECM connector with alcohol and replace ECM.
2. This step check for a short circuit to ignition or for a shorted solenoid or relay. All terminals MUST be tested since several are connected together internally by ECM. A short in one circuit may cause another circuit in ECM to be inoperative. Any circuit testing less than 20 ohms is shorted and should be diagnosed for cause of short.
3. Check ISC motor extend/retract circuits for short circuit to ground or shorted together. Normal resistance for an ISC motor circuit is 4-100 ohms.

Flow Chart C1 - ECM Replacement Check. Scheme 337

Note. Always check MEM-CAL for correct application and installation before replacing an ECM.

Flow Chart C1 - ECM Replacement Check (1 Of 2). Scheme 338

Flow Chart C1 - ECM Replacement Check (2 Of 2). Scheme 339

Chart C3, Canister Purge Diagnosis Schematic. Scheme 340

The fuel vapor canister purge solenoid receives 12 volts from 10-amp fuse No. 5 in underhood relay panel through circuit No. 639. The ECM energizes the canister purge solenoid by grounding terminal A2 (circuit No. 428). When the solenoid is energized it allows the canister to purge.

The canister is commanded to purge when closed loop has been reached, throttle switch is open, or when Codes EO13, EO44, or EO45 are present. The ECM will de-energize the solenoid when Code EO16 is set or the ECM is running in back-up mode (no normal program control).

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

1. This step checks to see if canister purge solenoid is able to hold vacuum. If solenoid cannot hold vacuum, it must be replaced.
2. Vacuum should release when solenoid is cycled on when in output cycling mode.
3. This step checks for proper vacuum signals from throttle body.
4. This step checks for proper electrical signals to canister purge solenoid.

FUNCTIONAL TEST OF FUEL VAPOR CANISTER

Attach hose to lower tube of Tank Pressure Control Valve (TPCV) on top of fuel vapor canister and attempt to blow through it. Little or no air should pass into canister. Using a hand-held vacuum pump, apply 15 in. Hg of vacuum through TPCV upper tube. If canister does not hold vacuum for at least 20 seconds, diaphragm is leaking, replace fuel vapor canister. If diaphragm holds vacuum, try to blow through hose connected to lower tube while vacuum is still applied. An increased flow of air should be observed. If not, replace fuel vapor canister. Unplug canister purge solenoid connector, attach a hose to purge solenoid and attempt to blow through it. Air should not pass into canister. If air passes, replace canister purge solenoid. Measure resistance of canister purge solenoid. Resistance should be 20-200 ohms. If not, replace solenoid.

Flow Chart C3, Canister Purge Diagnosis. Scheme 341

Flow Chart C3, Canister Purge Diagnosis (1 Of 2). Scheme 342

Flow Chart C3, Canister Purge Diagnosis (2 Of 2). Scheme 343

Chart C4, EST System Check Wirng Diagram. Scheme 344

The HEI distributor produces one 5-volt distributor reference pulse each time a cylinder reaches 10 degrees BTDC (base ignition timing). These pulses are sent from distributor to ECM on circuit No. 430. ECM adds spark timing information to reference pulses received from HEI and sends out a 5-volt EST pulse over circuit No. 423.

The ECM can choose to control spark timing. The HEI by-pass circuit (circuit No. 424) is turned on by the ECM when the ECM wishes to control timing. The HEI by-pass circuit is turned off and the HEI module grounds EST circuit No. 423. Circuit No. 453F is a common ground between ECM and HEI. The ECM and HEI compare by-pass, EST, and reference pulses to ground over this circuit. A circuit No. 453 open to the HEI or ECM can cause a failure of the ECM to recognize a reference pulse, or the HEI module to recognize an EST pulse. The ECM compares status of EST circuit to the status of the by-pass circuit in order to detect a fault Code E023. Possible causes for this code are: circuit No. 423 open or grounded, circuit No. 424 open or grounded, circuit No. 453F open to ground at HEI or ECM, poor connections in circuit No. 450, and ECM or HEI module faults.

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

1. Four 12" jumper are needed for this diagnostic procedure. Jumper wires MUST have male and female Weatherpack Connectors (12014836 and 12014837) on either end. With distributor connector unplugged, use jumper wires to reconnect terminals. Use instructions provided in ECM CODE EO23 - EST CIRCUIT PROBLEM chart.
2. With only distributor reference and distributor reference ground umpered, engine will run on back-up spark control. This step checks for proper ground connection between ECM and engine, and between ECM and HEI.
3. This step ensures that ECM is providing an EST output signal over circuit No. 423.
4. This step checks the ability of the HEI module to ground EST signal with an open by-pass circuit. NOTE: Test numbers refer to test numbers on diagnostic chart.
5. This step checks the ability if the HEI module to recognize a voltage on by-pass circuit and to stop grounding EST (ECM controlled timing).
6. This step checks by-pass signal to HEI module. If by-pass signal is being sent by the ECM to the HEI, and if module is interpreting by-pass voltage correctly, then the module will switch off ground to EST.
7. If chart leads to "EST CIRCUIT IS OKAY", then a fault may exist in the 4-wire Weatherpack connector. Check connector and connector terminals. If connector is okay, clear codes and retest.

Flow Chart C4, EST System Check. Scheme 345

Flow Chart C4, EST System Check. Scheme 346

Chart C6, Air Managment Diagnosis Schematic. Scheme 347

Air diverter and air switching solenoids are supplied with 12 volts on circuit No. 639 from 10-amp fuse No. 5 in underhood relay panel. The ECM controls AIR management system by grounding the air switching solenoid circuit No. 436 and air diverter solenoid through circuit No. 429.

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

1. With engine cold, the AIR management system should switch air to exhaust ports to help oxidize the rich mixture that exists during cold starts and warm-up.
2. With engine warm, the air should be switched to catalytic converter to oxidize exhaust gases flowing into second stage of converter.
3. This step checks AIR management system's ability to divert air away from catalytic converter during acceleration and deceleration.
4. This step checks for vacuum supply to AIR management solenoids.
5. This step checks air pump operation.
6. This step checks ECM's ability to control air switching and air diverter solenoids.
7. This step checks for an open voltage circuit to solenoid.
8. This step checks for a low resistance solenoid. If resistance is less than 20 ohms, replace solenoid.

Flow Chart C6, Air Managment Diagnosis. Scheme 348

Flow Chart C6, Air Managment Diagnosis (1 Of 2). Scheme 349

Flow Chart C6, Air Managment Diagnosis (2 Of 2). Scheme 350

Chart C7, EGR Diagnosis Schematic. Scheme 351

Before entering diagnostic chart check 10-amp "SERVICE SOON" fuse No. 5 of fuse block. Measure EGR resistance. Resistance should be 20-100 ohms. The DFI system use a positive backpressure type EGR valve which limits EGR flow with a low exhaust backpressure. Ensure that exhaust tubes which decrease backpressure (pull air through) are NOT hooked to vehicle when diagnosing EGR system.

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

1. Connect vacuum gauge to source side of EGR solenoid. Start engine and check for manifold vacuum. If manifold vacuum is not indicated, repair leaks or obstruction between EGR solenoid and throttle body.
2. Connect vacuum gauge to EGR valve vacuum supply. There should be no vacuum with engine running. If there is, follow diagnostic chart.
3. With vacuum gauge connected to EGR valve vacuum supply, unplug the EGR solenoid connector. There should be more than 8 in. Hg of vacuum available. If not, repair leak or obstruction in EGR valve vacuum hose.

Flow Chart C7, Air Managment Diagnosis. Scheme 352

Flow Chart C7, Air Managment Diagnosis. Scheme 353

Chart C7, EGR Diagnosis Schematic. Scheme 354

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

1. This step checks for voltage to EGR solenoid and ground signal from ECM. If either of these is missing, the EGR solenoid will command EGR to come on at all times.
2. This step checks ECM's ability to turn solenoid off. If light goes off, the electrical portion of the EGR system is okay.

Diagnostic Aids

Check vacuum supply hoses for damage or obstructions. Clean out or replace as necessary. Check intake manifold passages for any obstructions that would prevent exhaust gases from passing through.

Flow Chart C7, EGR Diagnosis. Scheme 355

Flow Chart C7, EGR Diagnosis. Scheme 356

Chart C8, VCC Diagnosis Schematic. Scheme 357

The Viscous Converter Clutch (VCC) solenoid is turned on when the ECM applies ground to circuit No. 422. The power for the VCC solenoid comes from the 5-amp cruise control fuse in fuse block. Current flows through VCC brake switch, into transmission VCC solenoid, and then into the transmission overtemp switch. The overtemp switch is normally closed and is opened when transmission sump temperature 315°F (157°C) is or greater.

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

1. This step checks continuity from brake switch through solenoid coil to circuit No. 422.
2. This step checks for ECM to ground through circuit No. 420.
3. This step checks for VCC to apply using the ECM override. If VCC does not apply, check transmission for hydraulic diagnosis of VCC.
4. The VCC electrical system is operating properly. Check transmission for hydraulic diagnosis of VCC.

Flow Chart C8, VCC Diagnosis. Scheme 358

Note. This chart cannot be used if a Code EO16 or EO24 is present.

Flow Chart C8, VCC Diagnosis. Scheme 359

Chart C8, VCC Diagnosis Schematic. Scheme 360

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

1. This step checks for voltage coming from ignition switch to fuse.
2. If resistance measurement is infinity (open circuit), either overtemp switch, VCC solenoid, or related wiring inside transmission needs to be repaired.

Flow Chart C8, VCC Diagnosis. Scheme 361

Flow Chart C8, VCC Diagnosis. Scheme 362

SELF-DIAGNOSTIC SYSTEM CHECK

The SELF-DIAGNOSTIC SYSTEM CHECK is an organized approach for identifying a problem caused by the on-car computer-controlled electronics. Understanding the chart and using it correctly reduces diagnostic time and prevents the unnecessary replacement of parts.

The SELF-DIAGNOSTIC SYSTEM CHECK should be used to BEGIN DIAGNOSIS if any customer complaint which DOES NOT directly relate to a specific subsystem.

If the "SERVICE SOON" light fails to illuminate during cranking, the problem could be in the power supply circuit of the BCM/ECM computer system. The SELF-DIAGNOSTIC SYSTEM CHECK will direct technician to an appropriate diagnostic chart. If the CCDIC display is not operating properly, BCM/ECM COMPUTER SYSTEM SELF-DIAGNOSTICS mode CANNOT be used. In this case, the SELF-DIAGNOSTIC SYSTEM CHECK will direct technician to an appropriate diagnostic chart. If a trouble code is identified the BCM/ECM computer system self-diagnostics mode, problem can be corrected following the appropriate numbered code chart(s). If no code has been identified, the SELF-DIAGNOSTIC SYSTEM CHECK will direct technician to an appropriate diagnostic chart.

Flow Chart Self Diagnostic System Check. Scheme 363

Flow Chart Self Diagnostic System Check. Scheme 364

Chart B1, Odometer Power/Ground Problem Schematic. Scheme 365

An incorrect odometer reading can be caused by problems relating to power and ground circuits not only in Instrument Panel Cluster (IPC), but those of other components within the computer network, the computer wake-up signals, the vacuum fluorescent power supply, the odometer mileage memory chip (EEPROM) contained in BCM, or by data link between computer components.

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

1. If no codes are set in diagnostic memory, observe state of odometer reading with headlight switch and twilight sentinel switch in the "OFF" position. This is important because these signals can wake-up the BCM and otherwise cause a misdiagnosis of a malfunctioning primary circuit.
2. When odometer reads all zeros, actuating the interior courtesy light switch helps to isolate exact cause of problem. This symptom is caused by a failure in computer system other than the IPC. Further isolation of this fault is diagnosed in CHARTS B2, B3 and B4.
3. When odometer is blank or reads all 8's, actuating headlight switch will help to isolate cause of problem. If odometer reads all zeros, cause of problem is due to a faulty "ISO IGN-3" feed circuit to BCM (open or shorted to ground) or BCM itself. If odometer is blank or reads all 8's, cause is due to one of several other problems within computer network.
4. Cycling the high beam or headlight dimmer switch will help to further isolate cause of problem. If high beams cycle, problem is related to IPC itself, IPC ground circuit, vacuum flourescent power supply circuit or components related to these circuits. Further fault diagnosis is contained in CHART B5.
5. If high beams did not cycle when dimmer switch was actuated, turning on courtesy lights switch will help to further isolate system problem. If courtesy lights turn on, problem is related to IPC itself, the CPS-to-IPC logic circuits ground, the 12-volt power circuits from CPS to IPC, or the CPS itself. Further problem isolation is contained in CHART B6.
6. If courtesy lights did not turn on when switch was actuated, several other causes for problem can be isolated by following CHART B7 and CHART B8, depending on whether the lights on chime sounds when test is run.

Flow Chart Odometer Power/Ground Problem. Scheme 366

Flow Chart Odometer Power/Ground Problem. Scheme 367

Chart B2, BCM-To-IPC Communication Problem Schematic. Scheme 368

You are at this chart because the odometer, with key on, read all zeroes and courtesy lights turned on when switch was actuated. These symptoms indicate a loss of BCM data communication to Instrument Panel Cluster (IPC), which is a result of one of several different possible problems.

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

1. If ALDL connector cover is off or loose, this could cause a break in data circuit, cutting off BCM communication to IPC under certain electrical conditions. If so, securely connect ALDL cover and return to beginning of the SELF-DIAGNOSTIC SYSTEM CHECK.
2. Isolates ALDL connector, the ECM and programmer from data circuit in order to determine location of fault. If odometer reads actual accumulated miles, the fault lies within network between ALDL connector, the ECM and programmer.
3. Checks to see if fault is due to ECM and its related data circuits, or the programmer and its related circuits.
4. Determines if fault is associated with IPC or BCM.
5. Determines if fault is due to programmer, progammer's logic, or ground circuit No. 801 from Central Power Supply (CPS).

Flow Chart B2, BCM-to-IPC Communication Problem. Scheme 369

Flow Chart B2, BCM-to-IPC Communication Problem. Scheme 370

Chart B3, CCDIC Problem Schematic. Scheme 371

You are at this chart because odometer problem has been isolated to CCDIC components or related data link circuitry.

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

1. This step restores circuit No. 800E into data link circuit. If odometer reads zero, the circuit is shorted to ground or voltage.
2. This step restores circuit No. 800C into data link circuit. If odometer continues to read correct mileage, the CCDIC must be replaced. If zeros return to the IPC, circuit No. 800C is at fault.

Flow Chart B3, CCDIC Problem. Scheme 372

Flow Chart B3, CCDIC Problem. Scheme 373

Chart B4, BCM-CPS Power/Ground Problem Schematic. Scheme 374

You are at this chart because odometer, with key on, read all zeroes and courtesy lights did not turn on when switch was actuated. These symptoms indicate that BCM has lost power or ground with Central Power Supply (CPS).

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

1. Checks for maximum blower speed with key on. Step will indicate whether BCM has lost logic ground circuit No. 801E with CPS.
2. This step determines if loss of logic ground is due to BCM, CPS or circuit No. 801E wire and terminals.
3. This step checks for 12 volts to BCM. If 12 volts is not present at BCM, fault is due to CPS or wiring.
4. This step checks for 7 volts to BCM, which has 2 individual inputs fed from CPS. Loss of both signals would result in system fault, otherwise fault is due to a bad CPS or BCM.

Flow Chart B4, BCM-CPS Power/Ground Problem. Scheme 375

Flow Chart B4, BCM-CPS Power/Ground Problem. Scheme 376

Chart B5, Vacuum Fluorescent Power Supply Problem Schematic. Scheme 377

You are at this chart because odometer, with key on, read all 8's or was blank, but the high beams cycled when dimmer switch was activated. These symptoms indicate a problem with vacuum fluorescent power supply, located in IPC, display components, or related wiring.

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

1. Determines if fault is due to a bad CCDIC component.
2. Determines if fault is due to a bad radio component.
3. Checks for ground integrity to Instrument Panel Cluster (IPC).
4. Determines if fault is due to a bad IPC or a short to ground in one of vacuum fluorescent power wires to CCDIC or radio.

Flow Chart B5, Vacuum Fluorescent Power Supply Problem. Scheme 378

Flow Chart B5, Vacuum Fluorescent Power Supply Problem. Scheme 379

Chart B6, IPC-CPS Power/Ground Problem Schematic. Scheme 380

You are at this chart because odometer, with key on, read all 8's or was blank, the high beams would not cycle, but courtesy light came on when switch was activated. These symptoms indicate Instrument Panel Cluster (IPC) has lost 12 volts power or ground with Central Power Supply (CPS).

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

1. Checking CCDIC display indicates whether IPC has ground.
2. Disconnecting IPC and checking resistance in circuit No. 801A determines if fault is due to IPC, wiring and terminals, or CPS.
3. This step checks if 12 volts is available from the CPS. If not, fault is due to wiring or CPS.
4. With 12 volts available from CPS, this step checks if fault is due to IPC or flex circuit between transition block and IPC.

Flow Chart B6, IPC-CPS Power/Ground Problem. Scheme 381

Flow Chart B6, IPC-CPS Power/Ground Problem. Scheme 382

Chart B7, BCM-CPS Wake-Up Signal Problem Schematic. Scheme 383

You are at this chart because odometer, with key on, read all 8's, was blank, high beams would not cycle, courtesy lights would not turn on, but lights on chime would sound when activated. These symptoms indicate a loss of 7 volts from Central Power Supply (CPS) to data network components, used to power the microprocessor chip. Or, the CPS has lost system wake-up signal from BCM, which is used to turn on 7 volt power supply.

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

1. This step checks circuit No. 555, CPS wake-up signal, for a short to ground, a fault in BCM or BCM connector, or a bad CPS.
2. This step checks for an open in circuit No. 555.
3. This step checks for an open circuit in CPS ground, which will disable 7-volt power supply.
4. This step checks for short to ground in each 7-volt circuit from CPS, for a faulty component in newtork, or a faulty CPS.

Flow Chart B7, BCM-to-CPS Wake-Up Signal Problem. Scheme 384

Flow Chart B7, BCM-CPS Wake-Up Signal Problem. Scheme 385

Chart B8, Power Loss From CPS to Other Components Schematic. Scheme 386

You are at this chart because odometer, with key on, read all 8's, was blank, high beams would not cycle, courtesy lights would not turn on, or light on chime would not sound when test was attempted. These symptoms indicate a loss of 12 volts from Central Power Supply (CPS) to other components in system.

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

1. This step checks whether battery voltage is feeding CPS.
2. This step checks for an open in circuit No. 640, CPS battery feed, poor terminal contact, or a faulty CPS.
3. Checks for an intermittent short to ground condition on any of 12-volt circuits from CPS or in circuit No. 640 feed.
4. This step checks for a short to ground in circuit No. 640.
5. This step checks each individual 12-volt circuit from CPS for a short to ground, a faulty component, or a faulty CPS.

Flow Chart B8, Power Loss From CPS to Other Components. Scheme 387

Flow Chart B8, Power Loss From CPS to Other Components. Scheme 388

Chart C1, CCDIC Symptom Diagnosis Schematic. Scheme 389

This chart should be used to identify symptoms relating to CCDIC problems. There are 2 major checks that must be made, a visual check of the display, and a keyboard functional check.

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

1. If the CCDIC display is totally blank, go to CHART C2. If Climate Control Panel (CCP) is blank, but Driver Information Center (DIC) reads "SYSTEM PROBLEM", go to CHART C3. Any other display problems are due to the CCDIC and it should be replaced.
2. If the "TEMP/TIME" button is the only inoperative button, go to CHART C4. Cause of problem may be an open in circuit No. 1018. If none of the buttons on the engine panel respond, the CCDIC panel or BCM should be replaced.
3. If the DIC buttons do not respond, check BCM input B130. This checks to see if the BCM and related wiring are at fault, or the CCDIC panel.
4. This step checks to see if there is a short to ground in circuit No. 1018, a faulty BCM, or a faulty CCDIC panel.

Flow Chart C1, CCDIC Symptom Diagnosis. Scheme 390

Chart C1, CCDIC Symptom Diagnosis Schematic. Scheme 391

Chart C2, CCDIC Completely Blank Schematic. Scheme 392

You are at this chart because the CCDIC display is completely blank. Cause for this problem could be a loss of Central Power Supply (CPS) power or ground, or loss of vacuum fluorescent power from the Instrument Panel Cluster (IPC).

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

1. Unplugging the CCDIC connector and performing individual circuit checks will determine if wiring connector, terminals, or component is faulty.

Flow Chart C2, CCDIC Completely Blank (1 of 2). Scheme 393

Flow Chart C2, CCDIC Completely Blank (1 of 2). Scheme 394

Flow Chart C2, CCDIC Completely Blank (2 of 2). Scheme 395

CHART C3 - CCDIC DISPLAY READS "SYSTEM PROBLEM"

You are at this chart because the CCDIC display reads "SYSTEM PROBLEM". This symptom is the result of a data link problem.

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

1. This step checks to see if data link is faulty or the CCDIC panel.
2. This step checks to see where problem exists in data link, including the CCDIC panel.

Flow Chart C3, CCDIC Display Reads "SYSTEM PROBLEM". Scheme 396

Flow Chart C3, CCDIC Display Reads "SYSTEM PROBLEM". Scheme 397

CHART C4 - CCDIC DISPLAY READS "SYSTEM PROBLEM"

You are at this chart because the "TIME/TEMP" button does not respond on CCDIC panel.

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

1. This step determines if fault is due to loss of 12 volts to CCDIC panel from CPS, including components, or an open in circuit No. 1018 from CCDIC panel to the BCM, including components.

Flow Chart C4, CCDIC Display Reads "SYSTEM PROBLEM". Scheme 398

Flow Chart C4, CCDIC Display Reads "SYSTEM PROBLEM". Scheme 399

Eldorado & Seville DFI ECM Wiring Diagram. Scheme 400