AW4

From JeepForum.com Community Jeep Wiki

From Novak Conversions, Knowledge Base

• The Aisin Warner AW4 transmission is a four-speed overdrive automatic transmission used in the 1987-2001 Jeep XJ Cherokee and MJ Comanche models with the AMC 4.0L (242 cid) in-line six cylinder engine.
• Its only year in the ZJ Grand Cherokee was 1993, and only with the AMC 4.0L engine.

• A similar transmission is used in some Toyota 4WD applications, known as the A340F or A340H depending on the transfer case.
• It is also used in some Toyota 2WD / RWD applications, known as the A340E.
• Another user is Isuzu, which uses this tranmission with their V6 engine.

The AW4 is a light to medium-duty transmission. Ours, our callers' and customers' experiences with the AW4 are less than stellar. They have a tendency to generate excessive amounts of heat, and are known for unnecessarily consuming more engine power than some other automatics. The shift points in the AW4 feel odd, and the spotty engagment of the lockup torque converter is idiosyncratic.

Gear Ratios for the AW4 are 2.80, 1.53, 1.00 & .75.

Identification

• The AW4 has a removable bellhousing.
• The case is smaller in diameter than most automatics, and features cast-in ribbing down the rear half of the case.
• The bell housing for the AMC 4.0L I6 engine has a port for the crank position sensor.
• The earlier Jeep AW4 has a 21 spline output shaft for connecting to the transfer case input shaft.
• With the release of the HO 4.0L in the 1991 the AW4 was upgraded to a 23 spline output shaft.
• The AW4 may be identified as model #40-30LE for 4wd versions. and as model #30-43LE for 2wd versions.

Transfer Case Compatibility The Jeep AW4 was factory-married to the Jeep New Process (aka New Venture) Model 231 transfer case, in addition to the NP242 Full-Time transfer case.

Engine Compatibility

• AMC / Mopar Jeep - As the AW4 was married to the Jeep 4.0L in-line six cylinder engine, it is OEM compatible with them.
• By using the Isuzu bell housing, the AW4 can be bolted to the GM 60degV6 (2.8L/3.1L/3.4L) engines and others using that bell housing bolt pattern, such as the FWD Buick 3800 V6, and the early 1990s Cadillac 4.9L (pushrod) V8 engine, among others.
• There are no known bell housings to bolt this transmission to the small block Chevy V8 / 4.3L Chevy V6, nor the Ford 5.0L V8.

• The AW4 is an electronically controlled transmission, and receives commands from a remote mounted electronic module.
• On Jeeps 1996 and earlier equiped with this transmission the Transmission Control Module (TCM) was an independent unit.
• On later Jeeps the transmission controls are integrated into the engine / power train control module.
• It appears that third party vendors can supply stand alone controllers for the Jeep AW4 / Toyota A340 transmissions.