AW4 Transmission Swap

['89_Wagon]

Here are some pics of the mocked up TPS sensor bracket. This is on a TBI unit. I think this type of setup would work with most types of systems.

The black thing looks like a collar arc weld stud. I have no idea how it ended up in my miscellaneous hardware, but it fits perfectly in the TPS sensor. It's slightly less than 10mm in diameter on the side that has a slot cut into

The throttle rod is temporary. Looking for something that's a bit more stiff.

I'll try to disassemble it and write something it. Not difficult make... could even get away with not welding.

Stud


Stud in the TPS sensor








5/18/21 update: The GM TBI TPS can be tapped for a signal. Works fine. No need to buy a separate TPS sensor for those that have TBI. Be aware, different years of AW4s has different TPS setups... ie resistance decreases or increases with increased throttle input.

[JeepsAndGuns]

Ok, I am really confused.
You appear to be running a GM throttle body fuel injection system. Do you know the jeep and GM systems both use the same 0-5v signal from the TPS sensors right? Why are you not simply splicing into the signal wire from the TPS on the throttle body?

['89_Wagon]

At first, I was hoping to use the GM TPS reference wire and I might still do that. But, I did some initial comparisons between the GM and Jeep sensors at 0%, 50%, and 100% throttle and the differences were large enough that I though it best to run the Cherokee sensor first and test the GM sensor later... one less potential issue to have at the start. Although, I tested the Cherokee sensor on the bench with its full sweep. When installed, the sweep is much shorter. I'll run the test now with it installed just to see what the values come in at.

I do have a question about the brake "sense"... I'm getting conflicting info. I think applying the brake opens the circuit to the TCU (Ov). Is that correct? This is for a 96 system. Mikrestrawbridge.com says it's the opposite for later years but the manuals and information I see on other sites seem to say that all years behave the same.... 12v when off the brake and 0V on the brake.

[67GMC]

Hello-I had an AW4 in my 87 Cherokee XJ. The Cherokee Forum https://www.cherokeeforum.com/f2/ is a good site for information on the AW4. It might be helpful for your project.

I used this PDF manual for the transmission. There's a link here:

https://issuu.com/memonunez/docs/aw4_manual

Not sure if you will need a speed sensor for your set up. My AW4 had one. It tells how fast you're going for the up and downshifting and sends that to the TCU. The TCUs are different for different years. I think they all use the same connector but have different numbers of wires connected but have some different programming. May want to research that.

Good luck. It looks like it will be a great project.

['89_Wagon]

Thanks for the heads up. I think the speed sensor(s) are attached to the transmission. The 87s used a Renix based system which is different than the Asini based system I’m working with. I think the big changes in electronics happened in 1990.5 and 97. I found some pretty good info on the electronics on this page. From what I can tell… 1990.5+ are the ones to get for our FSJs. They have the right spline count on the output shaft of 23.

https://www.naxja.org/forum/showthread.php?t=1053970

The transmission harness has been carved of the body harness, and for the most part it’s self contained. It just needs ground, battery, switched 12+, and some outputs hooked up. Most of the confusion I have is about those outputs.

This probably only applies to 1990.5-1996 models for the most part. There were some changes made to 97+ years and I’ll try to note them here. Please chime in if anything is wrong or vague. I haven’t done the install yet so take this with a grain of salt. My next post has all the related wiring diagrams

1. Switches for backup lights and neutral. All the “switches” for backup lights and nuetral are really just the NSS switch on the right side of the transmission. I’ll be taking it apart to clean it. Apparently it’s common for these to get gummed up and stop working.

a. Park/Nuetral switch: Brown/Yellow* wire from black plug. Luckily, this grounds out the starter relay in the Cherokee so this can be connected directly to the GW starter relay and everything should work.

b. Backup light switch: Brown/Green* from black connector. This switch feeds the backup lights directly on the Cherokee using what I think is a similar bulb, 1156 on the Cherokee vs a 1157 on the GW. No relay needed here. The AW4 NSS should be able to handle the current.

2. Switched Power: Everything seems to indicate that the TCU is powered in the “run” and “start” positions. Obviously, it needs to be at least powered in the run position.

3. Brake “sense” wiring: White/pink* wire from TCU. I had some confusion about whether this was switched to 12+ or ground. In 96, the circuit switched to ground. In 97, the circuit seems to switch to 12+. From there, they both operate the same, open circuit means brake on, closed circuit means brake off. This “sense” circuit locks/unlocks the toque converter.
The plan is to use the GW cruise control brake signal (pink wire) and wire it to a relay that switches to ground. Here’s the pinout using a 5 terminal mini relay.

Coil
1. 12V from GW brake switch (PNK wire from cruise control)
2. Ground

Switch
3. White/pink* from TCU
4. Ground
5. Empty

The overall plan is to use the power distribution box that came from the Cherokee. The TCU is already hooked up to it and I’ll have options to put other circuits in there. It’s going to live where the vacuum reservoir and cruise control components used to be in the engine bay. I’m also going to wire the fuel pump and TBI ECU there too because right now, the relays are buried above the AC panel, behind the dash, and duct taped to something. Should just make things a big cleaner and easier to replace. This will also give me an opportunity to plug everything in before installing the transmission just to test out that things are working properly and as expected.

I’ll follow up with wiring diagram pictures….

['89_Wagon]

Here are some wiring diagrams. Keep note that the manual transmission wiring and automatic wiring is shown side by side.

Brake Sense


Starter Relay


Back up Lights. Can also see that the P/N swtich grounds out here.


Downstream backup lights diagram. No reference to fuses or relays.

['89_Wagon]

Did some more work on the wiring harness.

Here's the fuse block I'm using from a 95/96 cherokee. I've already prepped this one and removed/moved some circuits for my needs. I'll do a write-up on this in another post.

Back side with cover removed.


Here's the bracket with some extraneous stuff cut off (left)


Here's everything mounted in the engine bay using the spot where some of the cruise control used to be.


This is before I prepped the fuse/relay block so there are a ton of extra wires hanging out the back. I checked the clearance with some play-do and there seems to be about 1/2" of clearance between the hood and fuse block.


Now some more helpful wiring diagrams. These confirm that the TPS signal is shared between the TCU and ECM, the sensor ground from the TCU can go straight to ground, the TPS ground can go straight to ground, and the 4WD sense circuit does not communicate to the AW4 TCU. I removed those wires from the plug.

[pickledtoast]

Thanks for posting the wiring diagrams.

So for the TCU, it's power, ground (chassis and sensor), TPS, brake light signal, and the 4 wires to the AW4 (3 to the solenoids, one to the VSS). That's what it seems like to me. The VSS/solenoids need power from somewhere. Those 3 solenoid wires are what you intercept if you want to shift it manually.

I ordered my AW4 flexplate today, mostly so I can bench run my trans before getting too involved with the swap.

['89_Wagon]

Thanks for posting the wiring diagrams.

So for the TCU, it's power, ground (chassis and sensor), TPS, brake light signal, and the 4 wires to the AW4 (3 to the solenoids, one to the VSS). That's what it seems like to me. The VSS/solenoids need power from somewhere. Those 3 solenoid wires are what you intercept if you want to shift it manually.

I ordered my AW4 flexplate today, mostly so I can bench run my trans before getting too involved with the swap.

In a nut shell, that sounds right. Looks like the tcu powers the solenoids directly.

Here are the wires from the ECU harness that need to be connected. Everything else is kept within the harness. Haven't tested this wiring.. but have done quite a bit of research.

Yellow: Ignition 12+ in start and run
White/Orange - brake sense: See relay wiring in previous post.
Red: Battery 12+
Brown/Green: Backup lights. Connect to Brown/White wire on GW backup
light plug.

Brown/Yellow: Park/Neutral sense. Connect to starter relay. Black/White wire
on GW NSS plug.

Blue/White: NSS power. 12+ in start and run.

Why do you need the flexplate to bench run it? Are you going to turn the transmission with it? I would like to bench run mine and confirm the wiring before I drop everything too.

[pickledtoast]

Why do you need the flexplate to bench run it? Are you going to turn the transmission with it? I would like to bench run mine and confirm the wiring before I drop everything too.

Yeah, I plan to spin the torque converter on a bench and the flywheel will help with that. Also I will be able to measure the difference between the 360 and the 4.0 flexplate in terms of where the torque converter mounts. That way I can design a spacer/adapter to reuse the 360 balanced flexplate and starter with the 4.0 torque converter, hopefully.

Assuming the 360 and 4.0 crank flanges are in the same spot, big assumption there.

['89_Wagon]

Yeah, I plan to spin the torque converter on a bench and the flywheel will help with that. Also I will be able to measure the difference between the 360 and the 4.0 flexplate in terms of where the torque converter mounts. That way I can design a spacer/adapter to reuse the 360 balanced flexplate and starter with the 4.0 torque converter, hopefully.

Assuming the 360 and 4.0 crank flanges are in the same spot, big assumption there.

I'm debating going this route, although I'm not sure if a spacer I made would work all that well. Would Love to see what you come up with.

How much does it cost to balance a flexplate? The aw4 starter and flexplate is $100-$150 total + flexplate balancing.

[SC/397]

The flex plate and starter for the 4L and AW4 is a direct bolt up to any of the AMC V8 engine and bell housing. The solenoid is on the the 4L starter so, you will have to wire it up as such.
Don't forget to have the AW4 flex plate match balanced to the 727 Flex Plate. It costs between $30.00 and $50.00 depending how well you know your machinist.
Any machinist should be able to do that for you. If you have a problem, send them both to me and I will get it done for you.

http://theamcforum.com/forum/aw4-conversion-by-rick-sc397_topic15549.html

[pickledtoast]

I guess you would need the crank/damper to balance the flexplate, as the 360 flexplate is not zero balance. Or you can probably eyeball the 360 flexplate weight and holes and copy them on the AW4 flexplate.

I have overlaid 360 flexplate images and the rectangular weight is not always in the same exact spot. In other words, I think eyeball/close enough is probably ok if you were to use the 4.0/AW4 flexplate. Not something I would want to do though.

I just replaced my 360 starter and I'm stubborn so I'm going to keep the 360 stuff.

[SC/397]

No, you don't need a crank adapter of any kind. They just mount the 360 flex plate on the balancing machine and find out how many grams heavy it is at the weight. Then, they mount the 4L flex plate in and find out where it is light. They mark it and weld on a weight in the exact same spot as the 360 which is all relative to the mounting holes. They will weld or take metal away until they are with a gram or less of each other. No eyeballing and pretty simple to do.

[pickledtoast]

Yeah, makes sense. Should be a simple job for those equipped and a smart solution overall.