PONTIAC FIERO 1988 Service Repair Manual

700-R4-12 HY DRAULlC DIAGNOSIS
- Nicks or burrs on servo pin or pin bore
- 4th Servo piston in backwards.
0 2-4 Band Assembly - 2-4 Band worn or damaged.
- Band anchor pin not engaged.
seals missing, cut or damaged.
- lnput housing to forward clutch housing
"0" ring seal missing, cut or damaged.
- Damaged forward clutch housing. - Forward clutch housing retainer and ball
assembly not sealing or damaged.
0 Forward Clutch - Piston seal missing, cut or damaged.
Accumulator
- Piston out of its bore.
- Stuck abuse valve.
- Auxiliary accumulator valve tube leaks,
not seated in pump cover or missing.
Input Housing
& Shaft - Turbine shaft seals missing, cut or dam-
- Accumulator valve stuck. - Face not flat, damaged lands or inter-
connected passages.
- Spacer plate or gaskets incorrect, mis-
positioned or damaged.
T.V. Cable - Binding or broken.
Low Roller Clutch
- Damage to lugs or inner ramps.
- Rollers not free moving.
- Inadequate spring tension
- Damage to inner splines.
- Lube passage plugged.
Figure
10 Diagnosis Chart D

HYDRAULIC DIAGNOSIS 700434-13
CONDITION I INSPECT COMPONENT I FOR CAUSE
SLIPS IN 1 ST GEAR 1-2 Accumulator Piston
(Continued) Assembly
I
0 Oil
Pressure
- Porosity in piston or 1-2 accumulator
cover and pin assembly.
- Damaged ring grooves on piston.
- Piston seal missing, cut or damaged.
- 1-2 Accumulator cover gasket missing or
damaged.
- Leak between piston and pin.
- Broken 1-2 accumulator spring.
- (See Causes of High or Low Oil Pressure.)
- 4th Servo piston in backwards.
1-2 SHIFT SPEED
- HIGH
OR LOW T.V.
Cable
I Governor Assembly
Throttle Lever
& Bracket
Assembly
Valve Body
I
0 Oil Pump Assembly or Case
- Binding or broken.
- Not correctly adjusted.
- (See 1 st Gear Range Only - No Upshift.)
- Misassembled, binding or damaged. - T.V. link missing, binding or damaged.
- T.V. exhaust check ball stuck.
- T.V. plunger sticking.
- Face not flat.
- Face not flat.
SLIPPING OR ROUGH 1-2
SHIFT Throttle
Lever
& Bracket
Assembly
Valve Body Assembly
* 2-4 Servo Assembly
2nd Accumulator
- Incorrectly installed or damaged. - T.V. cable broken or binding.
Throttle valve sticking.
T.V. bushing turned in its bore.
1-2 Shift valve train stuck.
Gaskets or spacer plate incorrect,
mis-
positioned or damaged.
Line bias valve stuck.
Accumulator valve stuck.
T.V. limit valve stuck.
Face not flat.
, - Apply pin too long or too short.
1 - Servo apply piston seal missing, cut
or damaged.
I - Restricted or missing oil passages.
1 - Servo bore in case damaged.
/ - Porosity in 1-2 accumulator housing or
piston.
- Piston seal or groove damaged.
- Nicks or burrs in 1-2 accumulator housing.
- Missing or restricted oil passage.
I I JH0011-700R4
Figure 11 Diagnosis Chart E

700-R4-14 HYDRAULIC DIAGNOSIS
SHIFT SLIPPING, ROUGH
OR HUNTING Governor Assembly - Valve stuck.
- Drive gear retaining pin missing or loose.
- Governor weights binding.
- Governor drive gear damaged. - Governor support pin in case too long or
- Stator shaft sleeve scored or off location.
- 2-3 Valve train stuck.
- Accumulator valve stuck. - Spacer plate or gaskets incorrect, mis-
positioned or damaged.
- Throttle valve stuck.
- T.V. limit valve stuck.
Input Housing Assembly
- Clutch plates worn (3-4 or forward).
- Excessive clutch plate travel.
- Cut or damaged piston seals (3-4 or
- Restricted apply passages. - Forward clutch piston retainer and ball
assembly not seating.
- Sealing balls loose or missing.
- 3rd Accumulator retainer and ball assem-
bly not seating.
2-4 Servo Assembly
OR ROUGH 3-4 SHIFT
- Governor valve stuck. - Governor drive gear retaining pin missing
- Governor drive gear damaged. - Governor support pin in case too long
or too short.
Figure
12 Diagnosis Chart F

HYDRAULIC DIAGNOSIS 700434-15
OR ROUGH 3-4 SHIFT
omitted or damaged.
Valve Body Assembly
- Valves stuck.
2-3 Shift valve train.
Accumulator valve.
Throttle valve.
@ T.V. limit valve.
1-2 Shift valve train.
3-2 Control valve.
- Manual valve link bent or damaged.
- Spacer plates or gaskets incorrect, mis-
positioned or damaged.
2-4 Servo Assembly
- Incorrect band apply pin. - Missing or damaged servo seals.
- Porosity in pistons, cover or case.
- Damaged piston seal grooves. - Plugged or missing orifice cup plug.
- 3rd Accumulator retainer and ball assem-
- Porosity in 3-4 accumulator piston or bore.
- 3-4 Accumulator piston seal or seal
grooves damaged.
- Plugged or missing orifice cup plug.
- Restricted oil passage.
2-4 Band Assembly
- Worn or misassembled.
- Forward clutch not releasing. - Turbine shaft seals missing, cut or dam-
@ Manual Linkage - Not adjusted.
Oil Pump Assembly
- Retainer and ball assembly missing or
- Stator shaft seal rings or ring grooves
- Stator shaft sleeve scored or damaged.
- Reverse boost valve stuck, damaged or
misassem bled.
- Cup plug missing.
- Restricted oil passage.
- Faces not flat. - Converter clutch apply valve stuck.
Figure 13 Diagnosis Chart G

700-R4-16 HYDRAULIC DIAGNOSIS
I CONDITION I INSPECT COMPONENT I FOR CAUSE
NO REVERSE OR SLIPS IN
REVERSE (Continued) Valve
Body Assembly
Reverse Input Clutch
Auxiliary Valve Body
1 Lo And Reverse Clutch
- 2-3 Shift valve stuck.
- Manual linkage not adjusted.
- Spacer plate and gaskets incorrect, mis-
positioned or damaged.
Clutch plate worn.
Reverse input housing and drum assembly
cracked at weld.
Clutch plate retaining ring out of groove.
Return spring assembly retaining ring out
of groove.
Seals cut or damaged.
Restricted apply passage.
Porosity in piston.
Belleville plate installed incorrectly.
Excessive clutch plate travel.
- Lo overrun valve stuck. - Orificed cup plug restricted, missing or
damaged.
- Clutch plates worn. - Clutch plate retaining ring mispositioned.
- Porosity in piston.
- Seals damaged. - Return spring assembly retaining ring mis-
positioned.
- Restricted apply passage.
NO PART THROTTLE OR
DELAYED DOWNSHIFTS T.V.
Cable
T.V. Bracket Assembly
2-4 Servo Assembly
Governor Assembly
Valve Body Assembly
I
- Loose or incorrectly installed.
- Bent.
- Servo cover retaining ring omitted or mis-
assembled.
- 4th Apply piston damaged or misas-
sembled. - Servo inner housing damaged or mis-
assembled.
- Governor weights binding.
- Governor valve stuck.
- Valves stuck.
Throttle valve
3-2 Control valve
T.V. modulated downshift
- 4-3 Sequence valve body channel
blocked.
I I JH0014-700R4
Figure 14 Diagnosis Chart H

HYDRAULIC DIAGNOSIS 700-R4-17
0 Valve Body Assembly - Valves stuck.
4-3 Sequence valve
Throttle valve
- Check ball #3 mispositioned. - Spacer plate and gaskets incorrect, dam-
aged or mispositioned.
Input Clutch Assembly
- Turbine shaft oil passages plugged or not
- Turbine shaft seal rings damaged.
- Turbine shaft sealing balls loose or
- Porosity in forward or overrun clutch
- Electrical short (pinched solenoid wire).
- Solenoid not grounded. - Incorrect or damaged pressure switches.
- Internal damage.
Oil Pump Assembly
- Converter clutch apply valve stuck or
assembled backwards.
- Converter clutch apply valve retaining
ring mispositioned.
- Pump to case gasket mispositioned.
- Orifice cup plug restricted or damaged.
- Solenoid "0" ring seal cut or damaged.
- High or uneven bolt torque (pump body
Valve Body Assembly
- Valves stuck.
* Converter clutch shift valve.
* Throttle valve.
(* Non ECM controlled vehicles)
Input Housing and Shaft
- Turbine shaft "0" ring seal cut or dam-
restricted or damaged.
Figure
15 Diagnosis Chart I

-*Converter clutch shift valve stuck.
(* Non ECM controlled vehicles)
0 Oil Pump Assembly - Converter clutch apply valve stuck.
- Restricted oil passage.
- Crack in filter body.
- Flash restricting filter neck. - "0" ring seal cut or damaged.
0 Miscellaneous - Low oil pressure.
- Engine not tuned properly.
0 Input Housing and Shaft - Turbine shaft "0" ring cut or damaged. - Turbine shaft retainer and ball assembly
restricted or damaged.
- lnternal damage.
Oil Pump Assembly
- Converter clutch apply valve stuck.
0 Manual Linkage - Incorrectly adjusted.
- Disconnected.
- Face not flat.
- lnternal leakage.
pport pin too long or missing.
0 Forward Sprag Clutch Sprag assembly installed backwards.
- Parking bracket damaged or not torqued
Figure
16 Diagnosis Chart J

NO PARK (Continued]
RATCHETING NOISE
OIL OUT THE VENT
VIBRATION IN REVERSE
AND WHINING NOISE IN
PARK
HYDRAULIC DIAGNOSIS 700.R4-1
INSPECT COMPOMEMT FOR CAUSE
Parking Unkage (Cont.) - Inside detent lever not torqued properly.
- Detent roller mispositioned or not torqued
properly. - Parking pawl binding or damaged.
Parking Pawl - Parking pawl return spring weak, dam-
aged or m isassern bled.
Oil Pump
Valve Body
Miscellaneous
I
- Chamfar in pump body rotor pocket too
large.
I - T.V. limit valve stuck.
- Fluid level - overfilled.
Oil Pump

7MI44.20 HYDRAULIC DIAGNOSIS
PARK
JHOW-TOM4 I
Figure 17 Park - Engine Running

HYDRAULIC DIAGNOSIS 700.R4-21
PARK- ENGlNE RUNNING
CONVERTER CLUTCH - RELEASED 34 CLUTCH - RELEASED 2.4 MUD - RELEASE0
REVERSE INPUT CLUTCH - RELEASED LO AND REVERIE CLUTCH - RELEASED OVERRUN CLUTCH - RELEASE0
FORWARD WUTCH - RELEASED LO ROUM CLUfCH - NOT HOLOlWO FORWARD SPRAQ CLUTCH - NaT HOLDIIYG
With the selector lever in the Park (PI position, oil from the pump is directed to the following:
1. Pressure Regulator Valve
2. Releasg Side of the Converter and the Lubrication System
3, Decrease Side of the Pump Slide
4. Manual Valve
5. T.V. System (Limit Valve, Throttle Valve, Line Bias Valve, M.T.V. Up Valve and M.T.V. Down Valve)
6. Pressure Relief Valve
7. Line Pressure Tap
Oil
flows from the pump to the pressure regulator vatve which regulates the pump pressure. When
the pump output exceeds the demand of line pressure, oil from the pressure regulator valve is directed
to the converter clutch apply valve. The converter clutch apply valve directs oil to the release side
of the converter clutch. Converter return oil is directed to the transmission cooler by the converter
clutch
apply valve, Oil from the cooler is directed to the transmission lubrication system.
Oil is also directed from the pressure regulator valve to the pump slide to decrease pump output in
relation to the combined pressure of M.T.V. oil and regulator valve spring force. Line pressure acts
on the pressure relief valve which will exhaust any oil above 2,240 to 2,520 kPa (320 to 360 psi).
Line pressure at the manual valve is available for use in other drive ranges.
Line pressure at the T.V. limit valv~ is limited to 620 kPa (90 psi). This limited pressure is directed
to the throttle valve where it is regulated to a variable pressure called throttle valve (T.V,) pressurn
T.V. pressure increases with carburetor opening and is directed to the line bias, MXV. up and M.T.V.
down valves.
At the line bias valve, T.V. pressure is modulated to M.T.V. pressure. M.T.V. pressure helps to control
line pressure
at the pressure regulator valve and accumulator pressure at the sceumulator valve.
T.V, pressure at the M.T.V. up valve and M.T,V. down valve js available for use when accelerating in
other ranges.
SUMMARY
The convener is filled from the release side; all clutches and the band are released. The manual linkage
has the parking pawl engaged in the reaction internal gehr lugs. At idle, them is not sufficient T,V.
pressure to open the MXV, up or M.T.V. down vakes.
JHO176.7OOR4 1
Figure 18 Park - Engine Running