AW4 Solenoid Kit 1990-1992, new and ready to install. Fits the AW4. Ships fast from the USA.
An early-90s Jeep Cherokee XJ or Comanche with the 4.0L and AW4 automatic that will not upshift, starts off in the wrong gear, shifts at random or never locks the converter on the highway very often has a tired solenoid on the valve body. This is a new aftermarket AW4 solenoid kit for 1990-1992 applications: the two shift solenoids and the lockup solenoid shown in the photos, enough to replace every electrical control valve inside the pan in one service. The AW4 shares its solenoid design with the Aisin A340 family, which is why the kit is also marked A340.
The AW4 was built by Aisin for AMC and Jeep, and it differs from older hydraulic automatics in one big way: a separate transmission control unit decides when to shift. It does that by switching two shift solenoids, usually called S1 and S2, on and off in combinations that move the shift valves for first through fourth. The third solenoid, S3, controls torque converter lockup. Owners who have taken these apart report that S1 and S2 are the same part and S3 is different. A solenoid with a weak coil, a worn seat or a plunger gummed with varnish leaves a shift valve in the wrong place even though the computer is commanding the right gear.
1990-1992 Jeeps predate OBD-II, so do not expect the P0750-series solenoid codes that later 1996-2001 XJs set. On these years the diagnosis is done with a meter and a road test, not a generic code reader.
Start with the simple things. Check the fluid level hot and look at the color; dark, burnt fluid means the clutches have been slipping. Then check the wiring. Corroded connectors, a chafed harness near the exhaust, and a worn neutral safety switch are common causes of AW4 shift complaints that look like a solenoid failure. Unplug the solenoid connector and measure each solenoid's resistance, then compare the three; a solenoid that reads open or shorted, or far off its neighbors, has failed. Our guide on testing a transmission solenoid with a multimeter covers the method. If the lockup complaint stays after new solenoids, the lockup relay valve in the valve body is a known wear point, and a replacement AW4 valve body is the next step.
This kit is listed for 1990-1992 Jeep applications with the 4.0L six and the AW4, including the Comanche pickup. The 1990-1992 Cherokee XJ uses the same transmission. The AW4 ran from 1987 to 2001 with running changes, mainly the 1991 output shaft change and the 1996 speed sensor redesign, but the solenoid layout stayed the same; still, compare the old solenoids side by side with the new ones before installing, matching the connector and mounting bracket. If you are not sure, send us your year and VIN. For later trucks see the AW4 solenoid kit for 1993-1998, and browse every AW4 part in our Aisin transmission parts collection.
On an XJ the solenoids are reached by dropping the pan with the transmission in the truck. Drain the fluid, remove the pan and filter, and disconnect the wiring from each solenoid. Mark which solenoid came out of which position, especially the lockup solenoid, because swapping S3 with a shift solenoid gives you shift faults that look like a new part failure. Lube the new O-rings with clean ATF, set each solenoid in by hand, and torque the bolts evenly so the body is not cocked in its bore. Route the wires away from the valve body's moving manual valve linkage.
Install a new filter and pan gasket and refill with the Dexron/Mercon type ATF the AW4 calls for, checking the level hot on the dipstick. If the cooler lines are crusty or the radiator tank cooler is suspect after years of service, a separate AW4 auxiliary transmission cooler helps these trucks run cooler when towing or off-road. Road test through all four gears and confirm lockup engages in fourth before calling the job done.
| Fits | AW4 1990-1992 |
| Part type | Solenoid Kit |
| Condition | New |
| Brand | OEM |
| Reference | A340 |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
The kit is listed for 1990-1992 4.0L AW4 applications, and the 1990-1992 Cherokee uses the same AW4 solenoid layout. Compare your old solenoids with the photos before installing, or send us your VIN.
Solenoid 3 (S3). S1 and S2 are the shift solenoids and are typically the same part. Keep track of S3's position when you remove the old set.
Yes. 1990-1992 Jeeps are pre-OBD-II, so a generic scan tool will not show solenoid codes. Measure each solenoid's resistance and check the wiring and neutral safety switch.
A Dexron/Mercon type automatic transmission fluid. Check the level with the engine running and the fluid at operating temperature.
No. It is a new aftermarket replacement solenoid kit for the AW4, also listed for the related Aisin A340.
The filter and pan gasket every time. If the lockup problem continues with new solenoids, look at the valve body's lockup relay valve.
