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2007 Silverado 6.6L LBZ Duramax P0699 and P2526 Fault Diagnosis - High Voltage Circuit Issues

Model: 2007 Silverado 6.6L LBZ Duramax Fault Code: P0699 Posted: 2016-11-26 14:30

My 2007 Silverado with the 6.6L LBZ Duramax engine is currently displaying two diagnostic trouble codes: P0699 (High Voltage Circuit C) and P2526 (Turbo Vane Position Sensor High Voltage). Additionally, I have a P0106 code related to Manifold Absolute Pressure (MAP) sensor performance. The issue initially presented as P0699. After checking the MAP sensor, I observed 6.8 volts when the key is in the ON position and 10.5 volts during engine operation. I replaced the MAP sensor with a new one, but the problem persists—P0699 returns immediately after clearing the codes. The vehicle runs and drives, though it exhibits noticeable delayed throttle response and gear shifts that feel like the truck is in tow haul mode.

Related fault codes
P0699P2526
Comments (3)
Anonymous 2016-11-26 14:32

The vehicle runs and drives but shows delayed throttle response and gear shifts resembling tow haul mode—this may indicate a sensor or control issue affecting throttle modulation.

Anonymous 2016-11-26 15:54

Are there any additional fault codes present? (e.g., MAP, EGR, TVP, APP)? Have you tried using any aftermarket programmers or chip tuning devices? The MAP, EGR, and Turbo Vane Position (TVP) sensors share a common 5V reference signal. To troubleshoot: unplug each sensor one at a time while the key is in ON position and verify if the reference voltage returns to 5 volts. This helps isolate whether the issue lies with wiring or sensor failure. Note: Terminal C on the GY wire provides the reference voltage for these sensors.

Anonymous 2016-11-27 08:43

The truck has been EFI-tuned since 2011 and includes an Edge CTS2 for monitoring engine performance. This may influence how codes are interpreted or displayed, so stock vs. aftermarket modifications should be considered when diagnosing.