The Jeep Cherokee XJ is a favorite among off-road fans and daily drivers. One key part of this SUV is its 40 automatic transmission. Owners and buyers often want to know about its specs, reliability, repair, and compatibility. This guide covers 40 essential points to help you understand and maintain the Jeep XJ 40 automatic transmission.
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Everything you need to know about the Jeep XJ 40 automatic transmission—features, maintenance, repair tips, and compatibility for owners and buyers.
Jeep Xj 40 Automatic Transmission: 40 Key Details
1. What Is The 40 Automatic Transmission?
The “40” refers to the AW4 transmission, a 4-speed automatic made by Aisin Warner. It’s used in Jeep XJs from 1987-2001.
2. Model Years
The AW4 was standard in most Cherokee XJ models sold in the U.S. between 1987 and 2001.
3. Engine Compatibility
The AW4 pairs mainly with the 4.0L inline-six engine. Some early models used it with the 2.5L engine.
4. Trim Levels
You’ll find the 40 automatic in trims like Sport, Country, Classic, and Limited.
5. Gear Ratios
Key gear ratios for the AW4 are:
- 1st: 2.804
- 2nd: 1.531
- 3rd: 1.000
- 4th (OD): 0.705
6. How It Compares To Other Jeep Transmissions
Compared to the JK’s 42RLE or JL’s 850RE, the AW4 is simpler and more durable for most XJ uses.
7. Shift Quality
The AW4 is known for smooth shifting and good low-speed control, which helps off-roading.
8. Towing Capacity
With the AW4 and 4.0L engine, max towing is 5,000 lbs (properly equipped).
9. Transmission Fluid Type
Use Dexron II/III ATF. Using the wrong fluid can cause hard shifts and wear.
10. Fluid Capacity
A full fluid change takes about 8.5 quarts (with torque converter).
11. Fluid Change Interval
Change fluid and filter every 30,000 miles or 2 years for best life.
12. Transmission Filter
Replace the internal filter with every fluid service. Cheap filters can cause flow issues.
13. Transmission Pan Gasket
Use a rubber gasket for best sealing. Avoid cork, which can leak.
14. Cooling Lines
Check for rust or leaks in metal lines—these can cause sudden failure.
15. Common Failure Symptoms
Watch for:
- Delayed shifting
- Slipping gears
- Fluid leaks
- Overheating
16. Trouble Codes
The AW4 is not OBD-II controlled. Transmission issues often need a mechanic’s scan tool.
17. Solenoid Issues
Shift solenoids can fail. Signs include staying in one gear or missing gears.
18. Internal Bands
The AW4 uses friction clutches, not bands. Regular fluid changes protect these parts.
19. Overdrive Function
4th gear is overdrive—helpful for fuel economy on highways.
20. Transmission Computer (tcu)
The AW4 has a separate TCU under the dash. If shifting is erratic, check TCU fuses and wiring.
21. Neutral Safety Switch
If your XJ won’t start in Park/Neutral, the neutral safety switch may need cleaning or replacement.
22. Throttle Position Sensor (tps)
A failing TPS can cause harsh or late shifts. Test with a multimeter.
23. 4wd Compatibility
AW4 works with both 2WD and 4WD XJs. Check tail housing style for swaps.
24. Transfer Case Compatibility
Fits NP231 and NP242 transfer cases. Match input shaft length for swaps.
25. Driveshaft Length
AW4 is longer than some manual transmissions. Driveshaft must match transmission length.
26. Swap Potential
You can swap an AW4 into other Jeeps (like MJ Comanche), but wiring and TCU must be included.
27. Rebuild Cost
A full rebuild usually costs $1,200–$2,000 at a shop, depending on part prices and labor.
28. Diy Repairs
Common home repairs:
- Fluid/filter change
- Solenoid replacement
- Pan gasket
29. When To See A Mechanic
Get help if you have no movement, burned fluid smell, or metal shavings in the pan.
30. Used Vs. Remanufactured
Used AW4s cost $400–$700. Remanufactured options offer a warranty for $1,500+.
31. Upgrades
Popular upgrades:
- External trans cooler
- Deep pan for extra fluid
- Shift kits (for firmer shifts)
32. Transmission Mount
Check the mount for cracks. Worn mounts cause vibration and stress on the trans case.
33. Bellhousing Pattern
The AW4 shares the AMC 4.0L pattern. Not compatible with JK, JL, TJ, or WK engines.
34. Speed Sensor
Speed signal comes from the transfer case, not the trans itself.
35. Bellhousing Bolts
XJ AW4 uses six bolts to attach to the engine. Tighten to spec to avoid leaks.
36. Transmission Crossmember
Make sure the crossmember is matched to the AW4 for proper support.
37. Shifter Linkage
If shifting feels loose, inspect the shifter bushings and linkage adjustment.
38. Transmission Cooler
The AW4 relies on the radiator’s built-in cooler. Add an external cooler for towing.
39. Common Buyer Mistakes
- Not checking for leaks or burnt fluid
- Mixing up AW4 with similar-looking A340 Toyota units
- Ignoring wiring harness differences in swaps
40. Longevity
With care, the AW4 can last 200,000+ miles. Overheating and poor maintenance are the main killers.
Jeep Xj 40 Automatic Transmission Specs
Here’s a quick look at the main specifications for the AW4 used in the Jeep XJ:
| Specification | Detail |
|---|---|
| Number of Gears | 4 (with Overdrive) |
| Fluid Type | Dexron II/III |
| Max Torque | 300 lb-ft |
| Towing Capacity | Up to 5,000 lbs |
| Weight (dry) | Approx. 160 lbs |
Aw4 Vs. Other Jeep Transmissions
Comparing the AW4 to other Jeep automatics:
| Transmission | Platform | Gears | Years | Main Strength |
|---|---|---|---|---|
| AW4 | XJ | 4 | 1987–2001 | Durability |
| 42RLE | TJ/JK | 4 | 2003–2011 | Compact Size |
| 850RE | JL | 8 | 2018–Now | Smoothness |
Buying And Maintenance Tips
- Always check fluid color (should be red, not brown or black).
- Ask for maintenance records if buying used.
- Test drive: Ensure smooth shifts in all gears.
- Use OEM or quality aftermarket parts for repairs.
Practical Owner Insights
- The AW4’s external cooler is a smart upgrade for off-roading or towing.
- Early diagnosis of leaks and electrical faults can prevent major breakdowns.
- Many XJ owners prefer the AW4 over newer Jeep automatics for its simplicity.
For more technical details, the Wikipedia page on the AW4 offers detailed specs and history.
Frequently Asked Questions
How Do I Identify If My Xj Has The Aw4?
Check the shift pattern: AW4 has a “1–2–3–D” gear selector. Or check the tag on the transmission.
What Are The Signs Of Aw4 Failure?
Look for slipping gears, delayed engagement, leaks, or burning fluid smell.
Can I Use Synthetic Atf In The Aw4?
Yes, but it must be Dexron III compatible. Always check the label.
Is The Aw4 Better Than The 42rle?
For XJs, the AW4 is usually more reliable and handles power better.
How Long Should The Aw4 Last?
With good maintenance, over 200,000 miles is common.
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Relevant internal-link anchor texts:
- Jeep XJ engine upgrades
- Common Jeep transmission problems
- Jeep XJ towing tips
