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 MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 70 (AUTOMATIC TRANSMISSION SERVICING)REMOVAL & INSTALLATIONLOWER CONTROL VALVE BODY ASSEMBLY (4T80-E)REMOVAL

1999 GMC Forward Control 5.7 R, Automatic

Lower Control Valve Body Assembly (4T80-E): Removal

1999 GMC Forward Control 5.7 R, AutomaticSECTION Removal

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

Remove the nine 10-mm bolts (534) from the oil transfer plate (956) and wire harness assembly (943). See Fig 1 . Remove the oil transfer plate (956). Disconnect the wire harness extension (943) from the wire harness assembly (12). See Fig 2 .

NOTE: Do not reuse retainer (915), it must be replaced. See Fig 3 .

Use a small screwdriver in order to disconnect the manual valve link retainer (915) from the manual valve link (913).

NOTE: DO NOT pry against the internal mode switch assembly.

Lift the manual valve and link assembly link (913) out of the inside detent lever (17). Remove the two, 10-mm nuts (955) and the fourteen, 10-mm bolts (958) from the lower control valve body assembly (903). See Fig 4 .
Lift the lower channel plate, control valve body and accumulator assembly (903) and the lower control valve body wire harness extension (943) from the case as a single unit.

Fig 1: Identifying Oil Transfer Plate

Courtesy of GENERAL MOTORS CORP.

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.

Shop Manual-Ready Tools Free Quote Check Quote Shield Pro

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.