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Electronic: Diagnosis Lincoln LS I

Electronic Steering ~762 words

DIAGNOSIS & TESTING

Note. A New Generation Star (NGS) Tester (007-00500) or equivalent is required for testing VAPS system.

Before performing individual component or system tests, check following for possible cause of system malfunction

  1. Tire Pressure
  2. Mechanical Condition Of Steering
  3. Power Steering Fluid Level
  4. Pump Pressure
  5. Faulty Fuse No. 425 (40-amp) Or 422 (20-amp) In Battery Junction Box (BJB)
  6. Faulty Fuse No. 207 (5-amp) Or 230 (5-amp) In Central Junction Box (CJB)
  7. Loose Or Corroded Connectors
  8. Damaged Wiring

If problem remains after inspection, connect and operate New Generation Star (NGS) Tester (007-00500) following manufacturer's instructions. Perform data link diagnostics test. See appropriate MODULE COMMUNICATIONS NETWORK article in ACCESSORIES & EQUIPMENT. If scan tool displays CKT 914, CKT 915 or CKT70 - NO RESPONSE/NOT EQUIPPED for front electronic module, see TEST A: NO COMMUNICATION WITH FEM under SYMPTOM TESTS.

If front electronic module passes data link diagnostics test, retrieve and record continuous Diagnostic Trouble Codes (DTC) and perform on-demand self test front electronic module to retrieve current DTCs. See DIAGNOSTIC TESTS . If no DTCs are displayed, see SYMPTOM TESTS .

DTCDescriptionGo To
B1342FEM DefectiveDTC B1342
C1924VAPS Solenoid Actuator Output Circuit Short To GroundDTC C1924
C1925VAPS Solenoid Actuator Return Circuit FailureDTC C1925

DIAGNOSTIC TEST INDEX

SymptomGo To
No Communication With FEMTest A
Steering Is Very Difficult/Very EasyTest B

SYMPTOM TEST INDEX

HYDRAULIC SYSTEM PRESSURE TEST

  1. Reservoir must be kept full and at normal operating temperature during testing. Connect Power Steering System Analyzer (014-00207) between pressure line and pump, with gauge between pump and tester valve. Start and idle engine for 2 minutes.
  2. With engine idling and fluid hot, record pressure and flow rate with tester valve open. If flow rate is less than 1.6 gals. (6.1L) per minute, pump may require service; however, proceed with testing at this point.
  3. If idle pressure is greater than 150 psi (10.5 kg/cm 2 ), check hoses for restrictions. Partially close tester valve. Allow pressure to increase to 740 psi (52 kg/cm 2 ). Record flow rate. If flow rate is less than 1.7 gals./min. @ 740 psi (6.6L/min. @ 52 kg/cm 2 ), replace power steering pump.
  4. Close and partially open tester valve 3 times. Tester valve must not remain closed more than 5 seconds. Observe and record pressure each time valve is closed. If readings differ more than 50 psi (3.5 kg/cm 2 ), flow control valve may be sticking. If relief pressure (valve closed) is less than 1200 psi (84 kg/cm 2 ), replace power steering pump.
  5. Increase engine speed to about 1500 RPM. Observe and record flow rate. If flow exceeds 1 gal./min. (3.78L/min.), replace power steering pump.
  6. Return engine to idle speed. Turn wheel from stop to stop. Observe and record flow rate at both stops. Pressure should be 1200-1380 psi (84-97 kg/cm 2 ). Flow rate should drop to less than .5 gal./min (1.9L/min). If pressure fails to reach maximum or if flow rate does not drop to less than .5 gal./min (1.9L/min), internal leakage of steering gear exists. Replace steering gear. See «STEERING GEAR»(ref-96949-S06129085022001041900000) under REMOVAL & INSTALLATION.

TEST A: NO COMMUNICATION WITH FEM

  1. Cycle ignition switch from OFF to ON position to enable switched system power feature. Turn ignition switch to OFF position. Disconnect FEM connectors C201c and C201f. Turn ignition switch to ON position. Measure voltage between ground and FEM harness connector C201c terminal No. 6 (Orange/Green wire) and FEM harness connector C201f terminal No. 1 (Orange/Yellow wire). (Схема №3) If voltages are not greater than 10 volts, repair circuit(s) in question. Test system for normal operation. If voltages are greater than 10 volts, go to next step.
  2. Turn ignition switch to OFF position. Disconnect FEM connector C201a. Measure resistance between ground and FEM harness connector C201c terminal No. 12 (Black/Red wire). See «WIRING DIAGRAMS»(ref-96949-S20012811152001041900000). Measure resistance between ground and FEM harness connector C201a terminals No. 11, 13, 14 and 15 (Black/Red wires). If resistance is less than 5 ohms, see appropriate MODULE COMMUNICATIONS NETWORK article in ACCESSORIES & EQUIPMENT. If resistance is greater than 5 ohms, repair circuit(s) in question. Clear DTCs. Repeat self-test.

TEST B: STEERING IS VERY DIFFICULT/VERY EASY

Start engine. Check power steering pump for leaks by rotating steering wheel while observing pump. Check pump flow and pressure. See HYDRAULIC SYSTEM PRESSURE TEST under SYSTEM TESTS. If pump leaks or does not pass system test, replace power steering pump. Recheck system operation. If pump is okay, check hoses for damage and replace as needed. Check steering linkage. Check ball joints for worn surfaces. See appropriate FRONT article in SUSPENSION. Repair steering linkage component(s) as necessary. Recheck system operation.

DIAGNOSTIC TESTS

Note. To identify circuits and terminals referenced in testing, see WIRING DIAGRAMS . After repairs are complete, recheck system operation to verify problem has been corrected.

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