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 MANUALSCHEVROLET1999SUBURBAN C2500, 6.5 FREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - TESTS W/CODES - DTC P1537-U1193DTC P1571DTC P1571: TCS TORQUE REQUEST CIRCUIT (4.6L "E" & "K" BODIES)DIAGNOSTIC PROCEDURES
1999 Chevrolet Suburban C2500, 6.5 F
Diagnostic Procedures
1999 Chevrolet Suburban C2500, 6.5 FSECTION Diagnostic Procedures
- Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
- Using scan tool, record any failure records and DTC information. Clear DTCs. Start and operate engine at idle for several minutes. Check for stored DTCs again. If DTC P1571 failed this ignition cycle, go to next step. If DTC P1571 did not fail in this ignition cycle, fault is not present. See DIAGNOSTIC AIDS .
- Turn ignition off. Disconnect EBTCM harness connector. Turn ignition on, engine off. Using DVOM, check voltage between ground and desired torque circuit at EBTCM connector terminal. If voltage reading is 4.8-5.4 volts, go to next step. If voltage reading is not 4.8-5.4 volts, go to step 6.
- Ensure EBTCM connector is still disconnected. Start and operate engine at idle. Using scan tool, monitor the desired torque output. Momentarily short the desired torque circuit to ground at EBTCM connector terminal. If scan tool display reading drops to near zero torque when circuit is grounded, fault is in EBTCM system. Diagnose EBTCM system. See appropriate ANTI-LOCK article in BRAKES. If scan tool reading does not drop, go to next step.
- Turn ignition off. Disconnect both PCM harness connectors. Check for short between desired torque circuit and all other 5-volt reference PCM circuits (i.e. TP sensor, EGR position sensor, MAP sensor). Repair as necessary. If circuits are okay, go to step 9.
- If voltage reading is greater than 5.4 volts, go to step 8. If voltage reading is not greater than 5.4 volts, go to next step.
- Turn ignition off. Disconnect both PCM harness connectors. Check for short to ground, open or short to another circuit on desired torque circuit. Repair as necessary. If circuit is okay, go to step 9.
- Check for short to voltage on desired torque output circuit. Repair as necessary. If circuit is okay, go to next step.
- Check PCM terminals. Repair as necessary. If terminals are okay, go to next step.
- Replace PCM. Program replacement PCM using required equipment.
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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.