Vehicle: 2016 Chevy Tahoe, 2WD, V8-5.3L, Automatic Transmission/Transaxle

Mileage: 166,008

Problem: Originally, the vehicle came in with a misfire on cylinder No. 8 caused by a failed fuel injector. The extended warranty would only replace the injectors on the right bank and would not pay for spark plugs. The customer refused to pay any extra out of pocket. The vehicle left with no issues.

A few months later, the car came back needing a fuel pump and fuel pump control module. After that repair, the vehicle drove with no issues

The Tahoe came back again a few months later with the No. 3 cylinder misfiring and DTC P129D-Fuel Pump Driver Control Module Ignition On/Start Switch Circuit Low Voltage. The technician replaced the fuel pump control module again and retested. All was fixed, so the vehicle was returned to the customer. Two weeks later, the customer was back with multiple complaints and symptoms. Intermittently, the engine would have crank/no start issues, and the No. 3 cylinder would randomly misfire. There were also DTCs for both front headlamp assemblies, plus the following DTCs:

• P1682-Ignition 1, Switch Circuit 2
• P129D-Fuel Pump Driver Control Module Ignition On/Start Switch Circuit Low Voltage
• P0300-Random/Multiple Cylinder Misfire Detected

The technician tested the fuel pump control module but found no issues.

Case Details: After checking fuses, power, and grounds, the technician decided to disconnect the headlamp assemblies.

NOTE: Both headlamps had aftermarket LED H11 bulbs installed—the kind with the turbo fan on them. No real testing was done for this, but acting on a hunch, the technician removed both LEDs and put regular halogen bulbs back in.

With the halogen headlamp assemblies installed, all problems were cured, and the DTCs did not return. When the LED headlamps were reconnected, the malfunction indicator light (MIL) came back on within five minutes. The technician tried plugging one headlight in at a time. Regardless of which side was plugged in, the symptoms persisted, and the MIL came back on. There were no obvious signs of water intrusion or corrosion found in the headlamps, fuse block, or connectors.

Confirmed Repair: After multiple ignition cycles and road tests, no DTCs came back, and the vehicle ran perfectly. One month later, the owner reported that no problems had returned. Weird but welcome fix!