Circuit/System Testing

WARNING: This page is about a different car, the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, 2018 Chevrolet Suburban 3500 HD, and 2018 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.

Verify the transmission line pressures are within the specified ranges. Refer to Line Pressure Check .
- If pressures are not within range
  Refer to Fluid Pressure High or Low .
- Go to next step: If pressures are within range
Ignition OFF. Remove the Q8 Control Solenoid Valve Assembly.
Verify a pressure change occurs for each solenoid when performing the solenoid test. Refer to Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test .
- If a pressure change does not occur for each solenoid
  Replace the Q8 Control Solenoid Valve Assembly.
- Go to next step: If a pressure change does occur for each solenoid
Verify the conditions listed below do not exist. Carefully inspect each component for that condition. Repair or replace as necessary.

P0796 or P0797 - Control Valve Upper Body Assembly (304)

4-5-6 Regulator Valve (327) stuck/sticking - debris, binding, damaged valve, or scored bore.

P0796 - 4-5-6 Clutch Housing Assembly (441)

Turbine Shaft Seals (442) damaged or leaking.

P0796 or P0797 - Q8 Control Solenoid Valve Assembly (314)

O-ring seals leaking.
Valve body filter plate assembly cracked, blocked or damaged gasket seal.

P0796 or P0797 - Control Valve Lower Body Assembly (307)

Clutch select valve (352) stuck/ sticking - debris, binding, damaged valve, or scored bore.

P0796 - 4-5-6 Clutch Housing Assembly (441)

4-5-6 Clutch Piston Assembly (439) damaged/ leaking.

P0796 - Transmission Cooling/Lubrication

Restriction/leak in OAC, oil to air, cooler/radiator.
Restricted/leaking/kinked/damaged transmission oil cooler lines.
Restriction/leak in transmission fluid pump assembly.

P0796 - Torque Converter (w/Fluid Pump) Housing Assembly (2)

Fluid pump housing vanes/rotor/slide damaged/scored.
Fluid pump or torque converter overstressed due to high temperature.

P0796 - 4-5-6 Hub/Shaft Assembly (58)

4-5-6 Hub/Shaft - broken hub weld.

P0796 - Automatic Transmission Fluid Filter Assembly (26)

Oil filter (26) or filter seal (25) loose or damaged.

P0796 - 1-2-3-4 and 3-5-R Clutch Housing Assembly (51)

1-2-3-4 Clutch Backing Plate Retaining Ring (429) not seated/oriented, causing clutch pack/piston over travel.

P0796 - Control (with body and valve) Valve Assembly (21)

Valve Body to Pump Transfer Seal Assembly (18) damaged/leaking.