Isuzu 1999 RODEO Workshop Manual page 1800

7A–18 AUTOMATIC TRANSMISSION (4L30–E)
Chart 9c: Coastdown Harsh Shift Or Clunk At 3–2 Downshift
Step
1 Check line pressure. Refer to Line Pressure Test in this section.
Was line pressure normal?
2 Does DTC P1850 set?
Chart 10: Intermittent 4TH TO 2ND Gear Downshift At Steady Speed
Step
1 Check for consistent speed sensor reading with scan tool.
Was the reading correct?
2 1. Check for wiring harness damage or short to ground. If OK, go
to (2).
2. Check transmission speed sensor connections. If OK, go to
(3).
3. Replace transmission speed sensor.
Was the replacement complete?
Chart 11: Engine Flare At Shifting During Turning Only (Usually With Warm Engine)
Step
1 Check for oil leaks at transmission.
Was the problem found?
Chart 12: Engine Flare During 1–2 Or 2–3 Shift
Step
1 Check line pressure. Refer to Line Pressure Test in this section.
Was line pressure normal?
2 1. Check for a stuck 1–2 accumulator valve (320).
2. Check for servo piston (106) leaks.
3. Check for a stuck band apply solenoid (323).
Was line pressure normal?
Action
Action
Action
Action
Yes
Use Chart 15b:
Possible Causes
of High Line
Pressure in this
Go to Step 2
Replace band
Diagnose P1850 apply solenoid
(PWM) (323).
first.
Yes
Replace mode
switch for
intermittent
contact. Go to Step 2
Replace speed
—
Yes
Replace
transmission oil
filter and gasket.
Yes
Use Chart 15a:
Possible Causes
of Low Line
Pressure in this
Go to Step 2
Repair or replace
No
section.
No
sensor.
No
—
No
section.
—