aw4 compatability

An AW4 is a AW4 accept for the spline count and adaptor.

Watch out for the flexplate, you must use the 90, the 91 will not work with the Renix system.

While were on the AW$ subject I'm swapping in a 1998 AW4 inot my 1996. I noticed the NSS is different for those two years is this a wiring thing or what is different about the two?

ARBOGASTER said:

While were on the AW$ subject I'm swapping in a 1998 AW4 inot my 1996. I noticed the NSS is different for those two years is this a wiring thing or what is different about the two?

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The NSSs are identical but have different connectors.

"An AW4 is a AW4", except when you cross 1996/1997. With the change to ODBII in late 1996, the AW4 added a front input shaft speed sensor near the front, mid-way up on the drivers side. The rear output shaft speed sensor also changed from a reed switch one-pulse per rev, to an inductive pickup that puts out 4-pulses per rev.

Since your NSS connector and probably the sensor/solenoid connector are different, I think your 1996 is the earlier setup. You should check the rear sensor output with a ohm/volt-meter before you do the swap. Looking at the FSM, you can pull the back of the AW4 case off and swap the rotor and sensor between the two setups. If you go that route, just leave the front sensor unhooked as the 1996 TCU won't have wiring for it anyway. Swapping TCUs to match will cause problems as one will be ODBI and the other ODBII.

I learned this the hard way when swapping a 99 AW4 into an 89 MJ.

On the 90->91 swap, I think the spline count changed from 21 to 23 so you're right on track keeping the xfer case with it. Otherwise it should bolt right up and plug right in. You should not need to swap the TCU. I think the 4th gear ratio changed from .705 to .75 with the switch to the HO engine which might change your 4->3rd downshift point a 100 rpm or so.

Wow . . .lots of great information. I'm going to print your message and keep it with me while I do the swap. I appreciate you taking the time to go through all that.

lawsoncl said:

.I learned this the hard way when swapping a 99 AW4 into an 89 MJ.

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Quick question - What actually happened?

I've had a garage swap the AW4 gearbox in my '88 Laredo with another AW4 (of unknown origin). Now the truck will not run properly (very rich blackness in tailpipe) I calcualted it averages around 8mpg, cannot get over 25mph, another garage looked at it and could not find the problem - could it be the gearbox from your experience?

Garages over in the UK seem to get confused with the earlier Renix system, as the official import didn't start until '93, whereas mine was an earlier private import, so I have no idea whether it is a sensor prob' or a gearbox causing my problems

1988 Cherokee 4.0 Laredo 4WD Auto