Shift cable
Shift cable refers to the cable or cables that connect the interior shifter to the manual or automatic transmission in a Pontiac Fiero.
Shift cables transfer driver input from the shifter to the transmission. Cable condition, adjustment, routing, and correct application are important for proper gear selection.
Overview
The Pontiac Fiero uses cables to operate the transmission shifter mechanism because the transmission is mounted behind the passenger compartment.
Manual-transmission Fieros use cables between the manual shifter and the transaxle. Automatic-transmission Fieros use a shift cable between the automatic shifter and the TH125 automatic.
A worn, damaged, misadjusted, or incorrect shift cable can cause shifting problems that may be mistaken for clutch or transmission failure.
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Location
Image wanted: Photo showing Fiero shift cables at the transmission end, preferably showing cable brackets, cable ends, and the shift/select linkage. A second photo of the shifter-end connection would also be useful.
Shift cables run from the shifter inside the passenger compartment to the transmission in the rear engine compartment.
At the transmission end, the cables attach to brackets and linkage arms on the transmission.
At the shifter end, the cables connect to the shifter assembly inside the center console area.
Manual transmission shift cables
Manual-transmission Fieros use cables to operate the transmission shift mechanism.
Depending on the transmission, the car may use a shift cable and a select cable. One cable generally controls fore-and-aft shifter movement, while the other controls side-to-side gate selection.
Factory manual transmissions include:
Cable design, routing, brackets, and adjustment can differ between transmission types. Parts should be matched to the actual installed transmission.
Automatic transmission shift cable
Automatic-equipped Fieros use a shift cable between the automatic shifter and the TH125 automatic.
The cable selects transmission ranges such as Park, Reverse, Neutral, Drive, Second, and Low.
A misadjusted or damaged automatic shift cable can cause the shifter position to disagree with the actual transmission range.
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Shift cable versus select cable
In manual-transmission discussions, owners may refer to the shift cable, select cable, or both together as “shift cables.”
The exact naming can vary, but the important point is that manual Fieros use cable-operated linkage between the shifter and the transmission.
A problem with either cable can affect gear selection.
Common problems
Common shift cable problems include:
- Worn cable ends
- Broken cable end clips
- Stretched cable
- Binding cable
- Melted or heat-damaged cable
- Damaged outer sheath
- Loose or damaged cable bracket
- Misadjustment
- Incorrect cable for the installed transmission
- Incorrect cable routing
- Previous-owner modification or repair
- Worn shifter-end connection
- Worn transmission-end linkage
Because the cables pass through the car and into the rear engine compartment, heat, age, corrosion, and previous repairs can all affect cable operation.
Symptoms
Possible symptoms of shift cable problems include:
- Difficulty selecting one or more gears
- Shifter feels loose or vague
- Shifter moves but transmission does not select the expected gear
- Cannot select reverse
- Cannot select first or second gear
- Cannot select fifth gear
- Gear indicator or shifter position does not match actual gear
- Transmission pops out of gear because it is not fully selected
- Shifting feels stiff or notchy
- Shifting problem changes with engine movement
- Shifting problem appears after transmission, clutch, or engine work
Some symptoms can overlap with clutch hydraulic problems or internal transmission problems.
Manual shifting complaints
A shift cable problem can feel like a clutch or transmission problem.
If the clutch releases properly but the driver still has difficulty selecting gears, the shifter, cables, cable brackets, and transmission linkage should be inspected.
Useful clues include:
- Shifts normally with cables disconnected at the transmission
- Shifter feels loose or sloppy
- Some gears are unavailable
- Cable end moves but linkage does not move fully
- Cable sheath moves in its bracket
- Problem appeared after engine cradle, transmission, or clutch work
- Cable routing is incorrect or binding
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Automatic range-selection complaints
On automatic Fieros, a shift cable problem can affect range selection.
Possible symptoms include:
- Difficulty selecting Park
- Difficulty selecting Reverse
- Difficulty selecting Drive
- Car starts only in certain shifter positions
- Range indicator does not match transmission range
- Transmission does not engage the expected range
- Shifter feels loose or stiff
These symptoms should be diagnosed carefully because they may involve the cable, shifter, transmission range mechanism, neutral safety circuit, or adjustment.
Cable adjustment
Shift cable adjustment affects how shifter movement corresponds to transmission linkage movement.
Incorrect adjustment can prevent full gear engagement or make some gears difficult to select.
Adjustment procedures can differ by transmission type. The installed transmission should be identified before following an adjustment procedure.
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Cable brackets
Shift cable brackets hold the cable sheath in the correct position.
If a bracket is loose, bent, cracked, missing, or incorrect, the cable may move instead of moving the transmission linkage fully.
Bracket problems can cause symptoms similar to cable stretch or internal transmission problems.
Cable brackets should be inspected whenever shift travel seems incomplete.
Heat damage
The Fiero rear engine compartment can expose shift cables to heat.
Heat-damaged cables may bind, melt, crack, or lose smooth operation. Routing and shielding are important, especially near exhaust components.
Symptoms of heat-related cable problems can include:
- Stiff shifting
- Binding after the car is hot
- Damaged cable sheath
- Cable movement that does not feel smooth
- Failure after exhaust work or engine swap work
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Relationship to clutch problems
Shift cable problems can overlap with clutch problems.
A clutch hydraulic problem may cause grinding or resistance because the clutch does not fully disengage.
A shift cable problem may prevent the transmission from being fully or correctly selected even when the clutch releases properly.
Useful diagnostic distinction:
- If the car shifts easily with the engine off but not with the engine running, check clutch release first.
- If certain gears cannot be selected even with the engine off, check the shifter, cables, cable brackets, and linkage.
- If the shifter feels loose or the cable sheath moves, inspect the cables and brackets.
- If grinding occurs only while trying to engage a gear, diagnose both clutch release and cable adjustment.
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Relationship to transmission swaps
Transmission swaps often require attention to shift cables and brackets.
The Muncie 4-speed, Isuzu 5-speed, and Getrag 5-speed do not all use the same shift cable arrangement.
When changing transmissions, verify:
- Correct shifter
- Correct shift cable
- Correct select cable
- Correct cable brackets
- Correct transmission linkage
- Correct routing
- Full gear engagement
- Reverse-light switch wiring, where applicable
A transmission swap can physically bolt in but still have shifting problems if the cable system is mismatched.
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Diagnosis
Basic diagnostic checks include:
- Identify the installed transmission.
- Determine whether the car is manual or automatic.
- Check whether the problem affects one gear, several gears, or all gears.
- Check whether the problem occurs with the engine off.
- Inspect the shifter assembly.
- Inspect cable ends at the shifter.
- Inspect cable routing.
- Inspect cable ends at the transmission.
- Check cable brackets.
- Check for cable sheath movement.
- Check for binding or heat damage.
- Check cable adjustment.
- Verify that the transmission linkage moves fully.
- Check clutch release if the problem occurs mainly with the engine running.
A shift cable diagnosis should include both ends of the cable and the brackets that hold the cable sheath.
Service notes
When working on Fiero shift cables:
- Identify the actual installed transmission before ordering cables.
- Do not assume cables interchange between Muncie, Isuzu, and Getrag transmissions.
- Inspect cable brackets as well as the cable itself.
- Check for heat damage near exhaust components.
- Verify full gear engagement after adjustment.
- Check shifter-end and transmission-end connections.
- Be careful with used cables because original cables are decades old.
- Recheck cable routing after engine, clutch, transmission, or cradle work.
Notes
Shift cable problems are often confused with clutch or transmission problems.
A careful diagnosis should consider the shifter, cables, brackets, clutch release, transmission linkage, mounts, and actual transmission type together.