In 1990, development of a successor to the YJ began in Chrysler's "Jeep-Truck Engineering Pre-Program" department under Bob Sheaves and TJ program director, Craig Winn. Mules based on the YJ were built from 1990 to 1993, when formal approval was given for the TJ development program at a 0 million budget. From 1991 to 1992 designers worked at the new Chrysler Technical Center, building on various design proposals. In late 1992, Michael Santoro's TJ proposal was chosen by Tom Gale, Lee Iacocca, and executive management. In May 1993, now with engineering and supplier input, Santoro's final Wrangler production design was frozen at 32 months ahead of initial assembly. Verification prototypes using production bodies were built from early 1994 and tested through late 1995. As YJ production ceased in December 1995, the last pre-production TJ examples were assembled, with start of series of production in January 1996. Unveiled on January 2, 1996, at the 1996 Detroit Auto Show as an early 1997 model year introduction (1996 model year skipped), the TJ was an evolutionary update. It later arrived in Jeep showrooms in April 1996, after 6 years of overall investment and 36 month production development phase.Instead of leaf springs, this updated Wrangler featured a modern coil-spring suspension, front and rear, based on that of the Jeep Grand Cherokee, for better ride and handling, and a return to the classic CJ's round headlamps. The engine is the same 4.0 L AMC 242 Straight-6 used in the Cherokee and Grand Cherokee. A 2.5 L AMC 150 Inline-4 engine was available on entry-level models until 2002. The 2.4 L DOHC 4-cylinder engine previously used on the Chrysler PT Cruiser replaced it for 2003.A right hand drive version of the TJ was available for export markets, and was also offered for sale to U.S. rural route postal carriers. The version offered to U.S. postal carriers was only available with an automatic transmission.

In 1998 (MY1999), the fuel tank became standard at 19 U.S. gallons (72 L; 16 imp gal) capacity. There were some changes between the 2002 and 2003 years. From 1996 to 2002, the side door mirrors were black metal framed mirrors; and from 2003 to 2006 they were plastic molded mirrors. The fit of hard and soft tops is slightly different, and the fabric and colors available changed from 2001 to 2003. In 2002 (MY2003), the 3-speed automatic transmission was replaced with a 4-speed automatic with overdrive. The overdrive can be turned off with a dash switch. The radio bezels went from a rectangle in 2002 to a rounded-edged rectangle for 2003. The sound bar inside was changed to sound pods. The interior seats also changed design, going from a rounder model to one with a distinct separation between back and headrest areas. The standard skid plate was also revised for 2003 to make room for the Rubicon's bigger NV241OR transfer case. The change from the 30/32RH to the 42RLE also gained an additional skid plate. This version of the Wrangler is also notable for being the last production vehicle to use AMC-related parts. The AMC Straight-4 engine was retired after the 2002 model year, and both the AMC Straight-6 engine and the door handles (the latter of which first appeared on AMC vehicles in the 1968 model year) were retired along with this generation in 2006. Like the YJ Wrangler, the TJ Wrangler used both the AMC passenger car door handles as well as the larger door handles off the AMC-built Jeep CJ for higher-end models.

 

### Gearbox Oil Change on a Jeep Wrangler TJ

#### Tools Required:
- **Socket Set**:
- **Description**: A set of sockets (usually metric) to remove drain and fill plugs.
- **Usage**: Attach the correct size socket to a ratchet to loosen/remove the bolts.

- **Ratchet**:
- **Description**: A tool that allows you to turn sockets without removing them from the bolt.
- **Usage**: Attach the socket and use the handle to turn clockwise to tighten or counterclockwise to loosen.

- **Torque Wrench**:
- **Description**: A wrench that measures the torque applied to a fastener.
- **Usage**: Ensures that the drain and fill plugs are tightened to the manufacturer’s specifications, preventing leaks.

- **Oil Drain Pan**:
- **Description**: A container to catch the old oil as it drains out.
- **Usage**: Place it under the gearbox to collect the old oil.

- **Funnel**:
- **Description**: A tool to help pour new oil into the fill hole without spilling.
- **Usage**: Insert it into the fill hole of the gearbox to direct the new oil.

- **Shop Rags/Paper Towels**:
- **Description**: For cleaning up spills and wiping tools.
- **Usage**: Keep the work area clean and handle any excess oil.

- **Pliers**:
- **Description**: A tool for gripping and pulling, useful if plugs are stuck.
- **Usage**: Use to grip and twist stuck drain/fill plugs if needed.

#### Steps to Change Gearbox Oil:

- **Preparation**:
- Park the Jeep on a flat surface and engage the parking brake.
- Gather all tools and materials.

- **Drain the Old Oil**:
- Locate the drain plug on the gearbox (usually at the bottom).
- Position the oil drain pan under the drain plug.
- Use the socket and ratchet to remove the drain plug. Let the old oil fully drain into the pan.

- **Inspect the Drain Plug**:
- Check the drain plug for metal shavings or debris. If excessive wear is visible, consider replacing the plug or inspecting for internal damage.

- **Replace the Drain Plug**:
- Clean the drain plug and the area around it.
- Reinstall the drain plug using the torque wrench to tighten it according to manufacturer specifications (check Jeep manual for specific torque settings).

- **Fill with New Oil**:
- Locate the fill plug on the gearbox (usually on the side).
- Remove the fill plug with the socket and ratchet.
- Use the funnel to pour new gearbox oil into the fill hole. Check your Jeep manual for the type and amount of oil required.
- Fill until the oil reaches the fill hole (it should slightly overflow).

- **Replace the Fill Plug**:
- Clean the fill plug and the surrounding area.
- Reinstall the fill plug using the torque wrench to tighten it to specifications.

- **Clean Up**:
- Dispose of the old oil properly at a recycling center.
- Wipe any spills and clean your tools.

#### Replacement Parts:
- **Gear Oil**: Ensure you have the correct type of gear oil (check the owner's manual for specifications).
- **Drain and Fill Plugs**: If damaged or corroded, consider replacing them to ensure a good seal.

### Additional Notes:
- Always consult the Jeep owner’s manual for specific details on oil type, quantity, and torque specifications.
- Regularly changing the gearbox oil maintains performance and prolongs the lifespan of your gearbox.
rteeqp73

Concise ordered theory + repair sequence for the Jeep Wrangler TJ gear shift linkage (manual-transmission TJ 1997–2006). Each step says what to do and why it fixes the fault.

Overview — parts and how they work
1. Shifter (cab) — the lever you move; connects to the linkage rod(s).
2. Linkage rods and ball joints/clevises — translate lever motion to the transmission’s shift shaft(s).
3. Transmission shift shaft / pivot / tower — the transmission input for gear selection; has a pivot/cup and bushings that index the internal shift rails.
4. Bushings, cups, retaining clips, jam nuts — control clearance and alignment; when worn they create slop, false neutrals, hard engagement.
Theory of common faults
- Worn bushings/cup or pivot ball: cause excessive lateral/back-and-forth play, sloppy shifts, missed gates, false neutral. Theory: the bushing is the interface that locates the shift shaft; wear lets the shaft move off-index.
- Bent/loose shift rod or damaged ball joint: changes geometry so motion at the lever doesn’t produce correct angular displacement at the shift shaft; causes incomplete gear engagement or hard engagement.
- Incorrect rod length/adjustment: center point misaligned so neutral at lever ≠ neutral at transmission; causes false neutral or first/second engagement problems.
- Worn internal shift rail forks or synchros (transmission internal): feel like linkage issues but persistence after correct external linkage repair indicates internal fault.

Ordered diagnostic and repair procedure (theory included with each action)
1. Safety and preparation
- Park, chock wheels, engage parking brake, disconnect battery if you’ll be under the car. Raise and support the Jeep securely on jack stands if needed to access underside.
- Why: prevents injury and allows safe access to linkage connections and transmission top.

2. Symptom check and isolate
- With engine off, sitting in the driver seat, move the shifter and note play, sticking directions, noise, and which gears are hard to select. Have an assistant watch underside/top of trans while you move lever to observe movement of rods/ball joints.
- Why: correlates operator input to component motion to locate the worn or disconnected element (shifter side vs. rod vs. trans side).

3. Visual inspection
- Remove center console/shift boot to expose shifter base. Inspect linkage rods and ball joints for torn boots, slop at joints, missing clips, rusted/bent rods. Inspect top of transmission: look at pivot cup, bushing, and retaining hardware.
- Why: worn boots indicate contamination; missing clips/jam nuts cause slop; damaged pivot/cup indicates the likely source of play.

4. Check for slop vs. misalignment
- With lever in neutral, feel for lateral (side-to-side) and fore-aft play. Use a pry tool to see movement at the transmission shaft and at each rod joint. Identify which joint shows most movement.
- Why: if most movement is at the transmission pivot cup → replace bushings; if at the rod ends → replace rod/ball joints or adjust; if all joints tight but still bad → internal transmission issue.

5. Remove and disassemble linkage components
- Remove shifter knob and boot; remove retaining clip/pin at the top of the shifter if doing pivot rebuild. Under vehicle, remove retaining clips at rod ends and disconnect rods from trans/transfer case. Mark positions or take photos for reassembly.
- Why: to gain access to individual parts for replacement/measurement and to avoid uncertain reassembly.

6. Replace worn bushings / pivot cup (most common TJ fix)
- Remove the transmission shift lever or pivot housing per service access (usually includes removing retaining pin/clip and lifting the lever assembly). Remove old bushing/cup and pivot ball if worn.
- Install a new bushing kit (OEM or higher-durometer polymer/urethane) and pivot ball/cup. Lightly grease the contact surfaces with a transmission-safe grease.
- Reassemble and secure retaining pin/clip.
- Why this fixes it: the bushing/cup locates and controls the pivot motion. Worn bushing lets the shaft wander; the new bushing restores precise location and reduces slop so the internal shift rails travel to correct detents every time.

7. Replace or repair bent/loose rods and joints
- If rods are bent, replace with new rods (do not reuse badly bent rods). Replace worn ball joints, clevis pins, and split clips. Replace torn boots and any corroded components.
- Re-torque or tighten jam nuts, ensuring rod ends are secure.
- Why: straight rods and solid joints give predictable geometry and transmit the exact angular movement needed to engage gears; replacing restores precise movement and prevents binding.

8. Adjust rod lengths / center the shifter
- With transmission in actual neutral (rotate shift tower as required or verify on the transmission), set the shifter in neutral. Adjust rod lengths and jam nuts so lever’s neutral equals trans neutral. Typically loosen jam nut, turn rod until centered, then lock jam nut.
- If two rods (e.g., shift and range), set both so that neutral positions align.
- Why: proper rod length makes neutral at the shifter correspond to neutral in the transmission. Misadjustment causes false neutrals and hard engagement in specific gears.

9. Reassemble interior and test mechanical travel
- Reconnect rods and secure clips. Reinstall boot, console, and knob. Before driving, with vehicle supported or in neutral, cycle the shifter through gears and feel for direct, crisp engagement. Have assistant watch rod motion and listen for interference.
- Why: tests reassembled linkage in a safe static condition to confirm mechanical correction.

10. Road/test and final checks
- Road test in a safe area: shift through all gears under load and light throttle. Confirm smooth engagement, no false neutrals, no chattering. If a problem persists only under load or at certain RPMs, suspect internal transmission wear (forks/syncros) rather than linkage.
- Why: dynamic testing verifies the repair under real conditions and confirms the root cause is resolved.

11. If symptoms persist after correct external linkage repair
- Theory: persistent issues that remain after bushings, rods, and adjustments are correct imply internal transmission problems (worn synchronizers, bent forks, or detent issues). Those require transmission removal and internal inspection/repair.

How each repair action fixes the fault — summary
- Replace bushings/pivot cup: removes play where the shift shaft is located; restores repeatable indexing of shift rails.
- Replace bent rods/ball joints: restores correct linkage geometry so lever motion produces correct shaft rotation/translation.
- Tighten/lock jam nuts: prevents rods from changing length in service and losing adjustment.
- Proper adjustment/centering: aligns neutral positions between lever and transmission; eliminates offset-related false neutral.
- Grease and replace seals/boots: prevents contamination-driven accelerated wear of mating surfaces and joints.

Quick troubleshooting clues (no fluff)
- Big lateral play at trans pivot → replace pivot cup/bushing.
- Play at rod ends and torn boots → replace ball joints/rod ends.
- Gear engagement fine when moving shifter with hand at trans but not from lever → problem in the cab linkage or rods.
- Problem only under load or in certain gears after linkage repair → internal transmission fault.

End.
rteeqp73

### Air Intake Tube on a Jeep Wrangler TJ: Detailed Explanation

#### Components of the Air Intake System

1. **Air Filter**:
- **Function**: Cleans the air entering the engine by trapping dirt and debris.
- **Location**: Usually housed in a box near the engine.
- **Analogy**: Think of it as a coffee filter, preventing grounds from entering your drink.

2. **Air Intake Tube**:
- **Function**: Connects the air filter to the throttle body, directing clean air to the engine.
- **Material**: Typically made from plastic or rubber for flexibility.
- **Analogy**: Like a straw that carries your drink from the cup to your mouth.

3. **Throttle Body**:
- **Function**: Controls the amount of air entering the engine based on the position of the accelerator pedal.
- **Location**: Mounted on the intake manifold.
- **Analogy**: Similar to a valve that opens wider when you want more air (or gas) in your drink.

4. **Mass Air Flow (MAF) Sensor**:
- **Function**: Measures the amount of air entering the intake system to help the engine control module (ECM) adjust fuel delivery.
- **Location**: Usually located in the air intake tube.
- **Analogy**: Think of it as a measuring cup that ensures the right amount of ingredients for your recipe.

#### Theory Behind the Repair

The air intake system is crucial because it provides the engine with the correct amount of clean air for combustion. If the air intake tube or any of its components are damaged or clogged, it can lead to:

- **Poor Engine Performance**: Insufficient or dirty air can affect fuel efficiency and power.
- **Increased Emissions**: An improper air-fuel mixture can lead to higher exhaust emissions.
- **Engine Damage**: Contaminants could enter the engine, causing wear or damage over time.

#### How the System Works

1. **Air Flow**: Air enters the air filter through the front grille of the Jeep.
2. **Filtration**: The air filter cleans the air, removing dust and debris.
3. **Transportation**: Clean air travels through the air intake tube to the throttle body.
4. **Control**: The throttle body regulates the flow of air based on driver input (accelerator pedal).
5. **Measurement**: The MAF sensor sends data to the ECM, which adjusts fuel injection accordingly for optimal combustion.

#### Common Issues

1. **Cracks or Leaks**: If the air intake tube has cracks, it can allow unfiltered air into the engine. This is like a leak in your straw, causing you to sip air instead of just juice.

2. **Clogs**: Dust and debris can accumulate, restricting airflow. This is similar to a clogged coffee filter, making it hard to brew a proper cup.

3. **Faulty MAF Sensor**: If the MAF sensor fails, the ECM may not get accurate readings, leading to poor engine performance. Think of it as a faulty measuring cup that gives incorrect measurements for your recipe.

4. **Dirty Air Filter**: A clogged air filter can prevent sufficient airflow, leading to reduced power. It’s like trying to drink through a filter that’s too dirty.

#### Repair Steps

1. **Safety First**: Disconnect the battery to avoid electrical issues.
2. **Remove Air Filter**: Take off the air filter cover and remove the filter to access the intake tube.
3. **Disconnect the Air Intake Tube**: Loosen the clamps securing the tube to the air filter box and throttle body. Gently pull the tube out.
4. **Inspect for Damage**: Check the tube for cracks, holes, or significant wear. Inspect the MAF sensor for dirt or damage.
5. **Replace or Clean Components**: If any component is damaged (like the intake tube or filter), replace it. Clean the MAF sensor with a special cleaner if necessary.
6. **Reinstall**: Place the new or cleaned components back, ensuring all connections are secure and tight.
7. **Reconnect Battery**: Once everything is back in place, reconnect the battery and start the engine.

### Conclusion

Understanding and maintaining the air intake system is vital for your Jeep Wrangler TJ’s performance. Regular checks can prevent problems and ensure your engine runs smoothly.
rteeqp73