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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 139 (ENGINE CONTROL SYSTEM - SELF-DIAGNOSTICS)DIAGNOSTIC TESTSDTC P1690: ROCKER ARM ACTUATOR SOLENOID CONTROL CIRCUITDIAGNOSTIC PROCEDURES
1999 GMC Forward Control 5.7 R, Automatic

Diagnostic Procedures

1999 GMC Forward Control 5.7 R, AutomaticSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Use scan tool to clear DTCs. Start engine. Operate engine for one minute. Review scan tool data and check for DTC P1690. Is DTC P1690 set? If yes, go to step  4. If no, go to next step.
  3. Start engine. Allow engine to reach normal operating temperature. With transmission in Neutral, increase engine speed to 1500-2500 RPM. Using scan tool, command rocker arm oil control solenoid ON. Does engine idle very rough or stall when the rocker arm oil control solenoid is commanded ON? If yes, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article. If no, go to next step.
  4. Start engine. Ensure engine has reached operating temperature. Turn engine OFF. Disconnect harness connector to rocker arm oil control solenoid valve. Start engine. With transmission in Neutral, increase engine speed to 1500-2500 RPM. Connect rocker arm oil control solenoid to battery voltage and ground with a pair of fused jumper wires. Does engine idle very rough or stall when rocker arm oil control solenoid is connected to battery voltage? If yes, go to next step. If no, go to step  7.
  5. Check control high circuit of rocker arm oil control solenoid for an open or a short. Repair as necessary. Was a repair necessary? If yes, go to step  10. If no, go to next step.
  6. Check control low circuit of rocker arm oil control solenoid for an open or a short. Repair as necessary. Was a repair necessary? If yes, go to step  10. If no, go to step  8.
  7. Replace rocker arm oil control solenoid. After repair, go to step  10.
  8. Check electrical circuits and connections of rocker arm oil control solenoid for high electrical resistance. Check for poor connections at harness connectors of PCM and rocker arm oil control solenoid. Repair as necessary. Was a repair necessary? If yes, go to step  10. If no, go to next step.
  9. Replace PCM. After repair, go to next step.
  10. Use scan tool to clear DTCs. Turn ignition switch to OFF position for 30 seconds. Start engine. Operate vehicle within CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  11. Using scan tool, observe stored information, CAPTURE INFO. Does scan tool display any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.