Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 181 (ENGINE CONTROLS - SELF-DIAGNOSTICS - 2.2L)DIAGNOSTIC TESTSDTC P0201-P0204: INJECTOR 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 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
- Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
- Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
- Turn ignition off. Remove the air cleaner outlet resonator. Disconnect the fuel injector. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit of the fuel injector with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 10.
- Connect Injector Test Light (J-34730-405) between the control circuit and the ignition 1 voltage circuit of the fuel injector. Start engine. Does the test light flash? If yes, go to step 8. If no, go to next step.
- Does the test light remain illuminated at all times? If yes, go to step 7. If no, go to next step.
- Test control circuit of the fuel injector for an open and for a short to voltage. Did you find and correct the condition? If yes, go to step 13. If no, go to step 9.
- Test control circuit of the fuel injector for a short to ground. Did you find and correct the condition? If yes, go to step 13. If no, go to step 12.
- Test for an intermittent and for a poor connection at the fuel injector. Did you find and correct the condition? If yes, go to step 13. If no, go to step 11.
- Test for an intermittent and for a poor connection at the ECM. Did you find and correct the condition? If yes, go to step 13. If no, go to step 12.
- Repair the open or short to ground in the ignition 1 voltage circuit of the fuel injector. Replace the fuse as necessary. After repairs, go to step 13.
- Replace the affected fuel injector. After replacing injector(s), go to step 13.
- Turn ignition off. Replace ECM. Perform ECM relearn procedure. See ELECTRONIC CONTROL MODULE REPROGRAMMING under PROGRAMMING. After replacing ECM, go to next step.
- Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Operate vehicle within the conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate vehicle within the conditions observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step 2. If no, go to next step.
- With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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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.