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.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET1999SUBURBAN C2500, 6.5 FREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - TESTS W/CODES - DTC P1537-U1193DTC P1626DTC P1626: THEFT DETERRENT SYSTEM FUEL ENABLE CIRCUIT (3.4L "U" SERIES)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.
- Ensure battery is fully charged. Attempt to start engine. If engine cranks, go to next step. If engine does not crank, see appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT.
- Turn ignition off. Disconnect VTD module. Turn ignition on. Using DVOM, check voltage between ground circuit and fuel enable circuit at VTD module harness connector. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 6.
- Turn ignition off. Reconnect VTD module connector. Turn ignition on. Backprobing connector, check frequency between ground and fuel enable circuit terminal at VTD module connector. If frequency is 40-60 Hz, go to next step. If frequency is not 40-60 Hz, go to step 8.
- Using scan tool, select CLEAR INFO or CLEAR DTCs function to clear DTC P1626. Attempt to start engine. If engine starts and continues to run, see DIAGNOSTIC AIDS . If engine does not start or starts but does not continue to run, go to step 7.
- Check for an open, short to ground or short to voltage in fuel enable circuit. Repair as necessary. After repairs, go to step 11. If circuit is okay, go to next step.
- Check fuel enable circuit for poor terminal connection at PCM connector. Repair as necessary. After repairs, go to step 11. If connection is okay, go to step 9.
- Check for poor terminal connections at VTD module connector. Repair as necessary. After repairs, go to step 11. If terminals are okay, go to step 10.
- Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 11.
- Replace VTD module. After repair is completed, go to next step.
- Using scan tool, CLEAR INFO or CLEAR DTCs function to clear DTC P1554. Using scan tool, select ENG 2 data list. Observe VTD FUEL DISABLE display. If reading indicates inactive, repair is complete. If reading does not indicate inactive, repeat step 2.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.