Workshop Manual

7A–14
AUTOMATIC TRANSMISSION (4L30–E)
Chart 2: No Forward Gears In Any Range/No Reverse
Step
Action
Yes No
1 Check line pressure. Refer to Line Pressure Test in this section.
Was line pressure normal?
Go to Step 2
Use Chart 15a:
Possible Causes
of Low Line
Pressure in this
section
2 1. Check internal linkage:
– Manual linkage (58) not moving manual valve (326).
2. Check for internal mechanical damage:
– Turbine shaft (506) broken loose.
– Overrun roller clutch (516) broken loose.
Was the problem found?
Repair or replace —
Chart 3: No Engine Brake In Any Range
Step
Action
Yes No
1 Check line pressure. Refer to Line Pressure Test in this section.
Was line pressure normal?
Go to Step 2
Use Chart 15a:
Possible Causes
of Low Line
Pressure in this
section
2 1. Check for overrun clutch leaks caused by:
– Damaged piston lip (513)
– Check ball defective (504)
2. Check for overrun lockout valve (705) stuck by foreign
material.
3. Check for leaks at turbine shaft (506) caused by:
– Teflon seal rings damaged (508)
– Excessive wear of turbine shaft bearing surfaces.
Was the problem found?
Repair or replace —