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.
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HOMESERVICE MANUALSCHEVROLET1990LUMINA APV V6-191 3.1LREPAIR AND DIAGNOSISTRANSMISSION AND DRIVETRAINAUTOMATIC TRANSMISSION/TRANSAXLEDESCRIPTION AND OPERATIONFLUID POWER FLOW DESCRIPTIONREVERSE RANGE
1990 Chevrolet Lumina APV V6-191 3.1L
Reverse Range
1990 Chevrolet Lumina APV V6-191 3.1LSECTION Reverse Range
In this range, the direct clutch and the low-reverse clutches are applied. The transaxle is in Reverse range.
With selector lever in Reverse position, the manual valve is positioned to allow line pressure to enter the three following passages:
1. Reverse.
2. RNDI (Reverse, Neutral, Drive and Intermediate).
3. RND (Reverse, Neutral and Drive).
Reverse oil from the manual valve seats direct clutch and reverse check ball in the direct clutch passage and flows to both the inner and outer areas of the clutch piston, applying the direct clutch. Reverse oil also seats the low-reverse check ball in the low 1st passage and applies the low- reverse clutch. Reverse oil flows to the reverse boost valve and boosts reverse line pressure to about 120 psi. RNDI oil from the manual valve flows to the throttle valve and is regulated to TV pressure. TV oil flows through the shift TV valve and is limited by it to about 90 psi. Oil from the shift TV valve is directed to the TV boost valve. Shift TV oil acting on the TV boost valve will boost reverse line pressure to about 210 psi. RND oil from the manual valve is directed to the 2-3 shift, but has no function in Reverse.
With selector lever in Reverse position, the manual valve is positioned to allow line pressure to enter the three following passages:
1. Reverse.
2. RNDI (Reverse, Neutral, Drive and Intermediate).
3. RND (Reverse, Neutral and Drive).
Reverse oil from the manual valve seats direct clutch and reverse check ball in the direct clutch passage and flows to both the inner and outer areas of the clutch piston, applying the direct clutch. Reverse oil also seats the low-reverse check ball in the low 1st passage and applies the low- reverse clutch. Reverse oil flows to the reverse boost valve and boosts reverse line pressure to about 120 psi. RNDI oil from the manual valve flows to the throttle valve and is regulated to TV pressure. TV oil flows through the shift TV valve and is limited by it to about 90 psi. Oil from the shift TV valve is directed to the TV boost valve. Shift TV oil acting on the TV boost valve will boost reverse line pressure to about 210 psi. RND oil from the manual valve is directed to the 2-3 shift, but has no function in Reverse.
RENDER: 1.0x
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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.