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AW4 trany overide

Try www.montanafab.com and it shows up on the first page with a link for more info.

Interesting but I would like to know someone who has it before I would buy one.
 
Haven't tried it, but neat! I'm betting 5-90 or some of the other more experienced electrical gurus can tell more about how this works, but it looks to me like what it does is switch the shift solenoids manually, add some indicator LEDs, and use those two big power resistors as dummy loads for the TCU when in manual-select mode to keep the TCU from thinking there is a burnt/missing solenoid and throwing a code+CEL. If it does what it says it does, well worth the price.

EDIT: their OBD I O2 sensor simulator cracks me up, it looks like it's a couple of SMT chip resistors used as a voltage divider, sealed up in some epoxy and sold for approx 2400% markup including the epoxy and case. I need to get into this market! :D The OBD II compatible O2 sensor simulator looks like it's got more to it though.

EDIT2: working link - http://www.montanafab.com/aw4_trany_overide.php
 
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Don't know about you newer XJ's, but doing a TCU mod on my '89 worked great! I did a mod about a year ago that allows me to lock in 2nd gear in the 1-2 position, and keep it in 2nd in the 3 position as well. Just an electrical switch, a diode, and some wiring. I don't have the link just now...but can vouch for how well it works. Nice to have 2nd for down hill gearing...and for high-range starting on icy roads.
 
There also use to me awshifting, but it seems their site is down and this one http://radesignsproducts.com/default.aspx. The montana fab isn't new as I know its at least a year old, but I haven't heard of anyone using it yet.
 
Yeah, the whole point of this particular mod is that it doesn't throw codes on OBD II XJs - it's a lot simpler when you don't need to worry about that, as I understand it.
 
Yeah, the whole point of this particular mod is that it doesn't throw codes on OBD II XJs - it's a lot simpler when you don't need to worry about that, as I understand it.

I'd be curious if it works. I though the TCU was throwing the error code because the input_shaft_speed/output_shaft_speed indicated it was in a different gear than commanded. I didn't think it was looking at the current going to the solenoids. I could be wrong though.

Their O2 simulator is more than a couple of resistors though. It provides a varying output that looks like an O2 sensor.
 
Yeah, the OBD II version of the O2 simulator is fairly complex - I was talking about the OBD I compatible one they show: http://www.montanafab.com/o2_sim.php (take a look at the "actual size of parts" picture at the bottom of the page, looks like an 0402-size chip resistor)
 
I'd be curious if it works. I though the TCU was throwing the error code because the input-shaft-speed/output-shaft-speed indicated it was in a different gear than commanded. I didn't think it was looking at the current going to the solenoids. I could be wrong though.

That is the same conclusion I came to.
I have the tried the shifting mods on my 2001 XJ and all it does is throw a code. Once the CEL lights, the transmission will not shift right, when switching back to the automatic mode. It will shift directly from 1st to 3rd, missing 2nd gear.
It requires the code to be cleared before normal operation resumes.

The earlier, non-OBDII, AW4s do not have the input and output shaft speed sensors.
 
ok now I really want pictures of that board... hmmmmm I think tbburg was gonna guinea pig it (from other thread) so hopefully his findings will clear some things up.
 
ok now I really want pictures of that board... hmmmmm I think tbburg was gonna guinea pig it (from other thread) so hopefully his findings will clear some things up.

Lets hope he tries it and lets us know if it works.
Not having control of 1st and 2nd gear can be very frustrating while off-roading, especially on steep downhills.
 
Yeah, the OBD II version of the O2 simulator is fairly complex - I was talking about the OBD I compatible one they show: http://www.montanafab.com/o2_sim.php (take a look at the "actual size of parts" picture at the bottom of the page, looks like an 0402-size chip resistor)

OBDI still wants to see a cycling input from the O2 sensor, so its probably at least a pair of transistors, a cap and resistor to setup an astable multivibrator. As I understand it, OBDII got a little smarter and checks that the signal isn't oscillating during warmup. Some apparently look at the heater current draw to check for a bad heater circuit.
 
Well, it came in today(yesterday actually, I didn't realize it until today). Probably not going to have a chance to play with it until the weekend, but for what it's worth:

When I talked to them on the phone, they said they keep them in stock,(that's a good sign!)and ship out same day. Purchased on Thursday, sitting in the office on Monday('had 'em ship it to where I work) It came in a priority mail box(USPS) with a $4.95 stamp on it. They charged me 5 bucks for S+H, so that seems pretty fair.

First impressions out of the box: Very good documentation, 4 pages of instructions including early and late model hookup, as well as for the '93 ZJ Grand Cherokee, which also had the AW-4. Another page containing diagrams and charts for pin-out on the early and late computer connector plugs. Also paper templates for drilling/installation.

The harness/controller is high quality construction, and looks a little more complex then the average 1-2 switch. As I understand it, a wired switch is usually 6 wires(3in, 3 out) on a DP/DT switch. This rotary switch appears to be a Quad pole/Triple Throw. It also has 10 wires coming out of the base of the board. It's also lighted and dim-able with the dash lights(might explain a few of those wires)

That's all for now, I'm going to cross-post this over in the mod tech. forum, and when I get it installed, I'll post a writeup in mod tech. I'll also have a full critique here in about a month(After I run the Rubicon with it :D. 'Gonna get me a "trail-rated" badge for Bone!)
 
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