JEEP MECHANIC

Engine diagnostic, repair and maintenance

ALTERNATOR TEST / BATTERY CHECK

    AUTOMATIC TRANSMISSION NAG1 WA580 – W5A580

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The NAG1 automatic transmission is an electronically controlled 5-speed transmission with a lock-up clutch in the torque converter. The ratios for the gear stages are obtained by 3 planetary gear sets. Fifth gear is designed as an overdrive with a high-speed ratio.

NAG1 identifies a family of transmissions and means “N”ew “A”utomatic “G”gearbox, generation 1. Various marketing names are associated with the NAG1 family of transmissions, depending on the transmission variation being used in a specific vehicle. Some examples of the marketing names are W5A300, W5A380, and W5A580. The marketing name can be interpreted as follows:

• W = A transmission using a hydraulic torque converter.
• 5 = 5 forward gears.
• A = Automatic Transmission.
• 580 = Maximum input torque capacity in Newton meters.

    The gears are actuated electronically/hydraulically. The gears are shifted by means of an appropriate combination of three multi-disc holding clutches, three multi-disc driving clutches, and two freewheeling clutches.
   Electronic transmission control enables precise adaptation of pressures to the respective operating conditions and to the engine output during the shift phase which results in a significant improvement in shift quality.
Furthermore, it offers the advantage of a flexible adaptation to various vehicle and engines.
Basically, the automatic transmission with electronic control offers the following advantages:

• Reduces fuel consumption.
• Improved shift comfort.
• More favorable step-up through the five gears.
• Increased service life and reliability.
• Lower maintenance costs.

TRANSMISSION IDENTIFICATION
    The transmission can be generically identified visually by the presence of around 13-way connector located near the front corner of the transmission oil pan, on the right side. Specific transmission information can be found stamped into a pad on the left side of the transmission, above the oil pan rail. 

TRANSMISSION GEAR RATIOS
    The gear ratios for the NAG1 automatic transmission are as follows:
1st Gear . . . . . . . . . . . . . . . . . .. 3.59:1
2nd Gear . . . . . . . . . . . . . . . . . . 2.19:1
3rd Gear . . . . . . . . . . . . . . . . . . 1.41:1
4th Gear . . . . . . . . . . . . . . . . . . 1.00:1
5th Gear . . . . . . . . . . . . . . . . . . 0.83:1
Reverse . . . . . . . . . .  . . . . . . . . 3.16:1

TRANSMISSION HOUSING
      The converter housing and transmission are made from a light alloy. These are bolted together and centered via the outer multi-disc carrier of multi-disc holding clutch, B1. A coated intermediate plate provides the sealing. The oil pump and the outer multi-disc carrier of the multi-disc holding clutch, B1, are bolted to the converter housing. The stator shaft is pressed into it and prevented from rotating by splines. The electrohydraulic unit is bolted to the transmission housing from underneath. A sheet metal steel oil pan forms the closure.

MECHANICAL SECTION
      The mechanical section consists of an input shaft, output shaft, a sun gear shaft, and three planetary gear sets which are coupled to each other. The planetary gear sets each have four planetary pinion gears. The oil pressure for the torque converter lock-up clutch and clutch K2 is supplied through bores in the input shaft. The oil pressure to clutch K3 is transmitted through the output shaft. The lubricating oil is distributed through additional bores in both shafts.
All the bearing points of the gear sets, as well as the freewheeling clutches and actuators, are supplied with lubricating oil. The parking lock gear is connected to the output shaft via splines.
Freewheeling clutches F1 and F2 are used to optimize the shifts. The front freewheel, F1, is supported on the extension of the stator shaft on the transmission side and, in the locking direction, connects the sun gear of the front
planetary gear set to the transmission housing. In the locking direction, the rear freewheeling clutch, F2, connects the sun gear of the center planetary gear set to the sun gear of the rear planetary gear set.

2001 XJ Jeep Cherokee AW4 AUTOMATIC TRANSMISSION

The procedures contained in this manual include specifications, instructions, and graphics needed to diagnose the AW4 AUTOMATIC TRANSMISSION. The diagnostics in this manual are based on the failure condition or symptom being present at the time of diagnosis. Please follow the recommendations below when choosing your diagnostic path.
1. First make sure the DRBIIIt is communicating with the appropriate modules; ie., if the DRBIIIt displays a “No Response” condition, you must diagnose this first before proceeding.
2. Read DTC’s (diagnostic trouble codes) with the DRBIIIt.
3. If no DTC’s are present, identify the customer complaint.
4. Once the DTC or customer complaint is identified, locate the matching test in the Table of Contents and begin to diagnose the symptom. All component location views are in Section 8.0. All connector pinouts are in Section 9.0. All system schematics are in section 10.0. An * placed before the symptom description indicates a customer complaint. When repairs are required, refer to the appropriate service manual for the proper removal and repair procedure. Diagnostic procedures change every year. New diagnostic systems may be added; carryover systems may be enhanced. READ THIS MANUAL BEFORE TRYING TO DIAGNOSE A VEHICLE CODE. It is recommended that you review the entire manual to become familiar with all new and changed diagnostic procedures. After using this book, if you have any comments or recommendations, please fill out the form at the back of the book and mail it back to us.

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