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 U1192DTC U1192: LOSS OF EVO/PASSLOCK® COMMUNICATION (6.5L "G" SERIES)DIAGNOSTIC PROCEDURES
1999 Chevrolet Suburban C2500, 6.5 F
Diagnostic Procedures
1999 Chevrolet Suburban C2500, 6.5 FSECTION Diagnostic Procedures
- Before clearing DTCs, record Freeze Frame and Failure Records information for reference. 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.
- Turn ignition on, with engine off. Using scan tool, select DIAGNOSTIC CIRCUIT CHECK and CLASS II MESSAGE MONITOR. If scan tool displays EVO/Passlock® active, go to next step. If scan tool displays that controller is not active, go to step 4.
- DTC is intermittent. If no additional DTCs are set, see DIAGNOSTIC AIDS . If additional DTCs are set, diagnose affected DTCs.
- Check Class II serial data circuit from EVO/Passlock® controller to splice for open circuit or proper connection to controller. Repair as necessary. After repairs, go to next step. If circuit or connection is okay, diagnose EVO/Passlock® system. See appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT.
- Clear DTCs using scan tool. Warm engine to normal operating temperature. Using scan tool, select DTC, SPECIFIC then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this diagnostic passed, go to next step. If scan tool does not indicate that this diagnostic passed, repeat step 2.
- Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, system is okay.
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.