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 MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 503 (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P1668: GENERATOR L-TERMINAL CONTROL CIRCUITCONDITIONS FOR CLEARING THE MIL/DTC
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8
Conditions for Clearing the MIL/DTC
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Conditions for Clearing the MIL/DTC
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
- The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
- The DTC can be cleared by using the scan tool Clear DTC Information function.
DTC P1668
| Step | Action | Value | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Starting and Charging Schematics Connector End View Reference: Engine Control Module (ECM) Connector End Views in Engine Controls - 3.6L (LY7) |
||||
| 1 | Did you perform the Engine Electrical Diagnostic System Check? | - | Go to Step 2 | Go to Diagnostic System Check - Engine Electrical |
| 2 |
|
- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 |
|
15-87% | Go to Step 5 | Go to Step 4 |
| 4 | Test the generator turn on signal circuit for a short or open. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 10 | Go to Step 5 |
| 5 | Test the generator battery positive voltage output circuit for a high resistance or open. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 10 | Go to Step 6 |
| 6 | Inspect for poor connections at the harness connector of the generator. Refer to Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 10 | Go to Step 8 |
| 7 | Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 10 | Go to Step 9 |
| 8 | Replace the generator. Refer to Generator Replacement (LA1) or Generator Replacement (LY7) . Did you complete the replacement? |
- | Go to Step 10 | - |
| 9 |
IMPORTANT:
The replacement ECM must be programmed. Replace the ECM. Refer to Engine Control Module (ECM) Replacement
in Engine Controls - 3.6L (LY7).Did you complete the replacement? |
- | Go to Step 10 | - |
| 10 |
|
- | Go to Step 3 | System OK |
RENDER: 1.0x
NO RELATED
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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.