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 MANUALSCHEVROLET2001VENTURE BASE, VAN CARGO EXTENDEDREPAIR AND DIAGNOSISBRAKESTRACTION CONTROLANTI-LOCK BRAKE SYSTEM WITH TRACTION CONTROL SYSTEM - DELPHI DB 7DIAGNOSTIC TESTSDTC C1277 OR DTC P1571: REQUESTED TORQUE SIGNAL MALFUNCTION
2001 Chevrolet Venture Base, Van Cargo Extended
DTC C1277 Or DTC P1571: Requested Torque Signal Malfunction
2001 Chevrolet Venture Base, Van Cargo ExtendedSECTION DTC C1277 Or DTC P1571: Requested Torque Signal Malfunction
- Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK under DIAGNOSIS & TESTING. After performing diagnostic system check, go to next step.
- Check EBCM and PCM ground. Ensure each ground is clean and tightened properly. Repair as necessary. After repairs, go to step 13 . If grounds are okay, go to next step.
- Install scan tool. Start engine. Using scan tool, observe Torque Request Signal parameter in the PCM data list. If scan tool displays less than 100%, problem is intermittent. See INTERMITTENTS & POOR CONNECTIONS under DIAGNOSIS & TESTING. If scan tool does not display 100%, go to next step.
- Turn ignition off. Disconnect EBCM harness connector. Install Universal Pinout Box (J-39700) using Cable Adapter (J-39700) to EBCM harness connector and EBCM. Start engine. Check DC duty cycle between the requested torque signal circuit and good ground. If duty cycle is within 5-95%, go to next step. If duty cycle is not within 5-95%, go to step 6 .
- Measure DC Hz between requested torque signal circuit and a good ground. If frequency measures within 121-134 Hz, go to step 8 . If frequency does not measure within 121-134 Hz, go to next step.
- Turn ignition off. Disconnect cable adapter from EBCM connector. Turn ignition on, with engine off. Check voltage from requested torque signal circuit to a good ground. If voltage reading is 4-6 volts, go to step 10 . If voltage reading is not 4-6 volts, go to next step.
- Turn ignition off. Disconnect PCM harness connector. Check requested torque signal circuit for short to voltage or short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 10 .
- Turn ignition off. Disconnect PCM harness connector. Check requested torque signal circuit for open or high resistance. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to next step.
- Check for poor connections at PCM harness connector. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
- Check for poor connections at EBCM harness connector. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
- Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 13 .
- Replace EBCM. After replacing EBCM, go to next step.
- Using scan tool, clear DTCs. Recheck DTCs. If DTC resets, go to step 2 . If DTC does not reset, 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.