WG Jeep Geek - Tinkering with Jeep Electronics

[Clarky]

Originally Posted by oldon

Hey Clarky, I read in jeepaction mag about a bloke with a commander who had his computer done by JeepKraft when he went 4.1 gears.

JeepKraft wanted $1100 to reprogram (in the states), I didn't think this was reasonable and even with my failed attempts I only spent around $700. If you want to run 3:73 ratios in a WH/XH CRD it will cost around $250au for a TCM from a USA wreck (that's landed here in Oz).

[Tyvokka]

Originally Posted by JeanLuke

..I should see about buying one of the new DRB-3 micro-pods. They are down to a couple of hundred now for the knock-offs. I have read that you can set the diff ratio via DRB-3. If so, it is much less "fun" but a far simpler solution..

Sorry to digress and hijack this thread

Which specific DRBIII tool would you recommend? I'm looking for a read/write JTEC DRBIII, so I can fix my trans ratio. Axles are 5.38.

ABS is stuffed as the front axle did not come with tone rings, I had them made and correctly installed but the ABS system is still wonky. I've ABS and handbrake lights illuminated. I do have the ABS module wiring diagram and plan to splice the rear working ABS signals. Shhhh.......don't tell anyone, especially the fun police.

[Adrian D]

Originally Posted by Clarky

I had a hell of a time trying to get my TCM reprogramed when I changed diff ratios from 3.55 to 3.73. I sent it to the states but they couldn't read it. Sent me one from a SRT8 that worked kind of but would go into limp when low range was selected.

I ended up buying a TCM from a USA based wrecker after discovering that all USA WK CRD's are 3:73 factory ratio.

To this day I have not been able to find anyone who can reprogram a TCM/U from a WH/WK CRD. If I had of found the OFFGEAR site I probably would have purchased that kit.

Using the standalone controller would make the standard TCU go into limp mode. I don't know (yet) if it will affect the ECU. On the other hand once you have a standalone controller it could be removed and you can just place CAN=bus terminators on the lines going in the TCM. Would that cause a limp mode in the ECU? I don't know yet.

Originally Posted by JeanLuke

Yeah, the WG uses the wheel sensors to drive the speedometer and to check for transmission slip. If you change diff ratios you'll cause transmission slip errors. I *thought* there was a diff ratio setting available via a drb-3 tool. No?

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So I've heard...basically the section of the TCU which has that information should be available as a calibration, it shouldn't be hardcoded. The newer JK's use the 722.6 also and the users can set new axle ratios using the Pro-cal module as far as I know, so that would back up my theory about calibration parameters.
jeepswj is working on a DRB3 clone on Android, maybe we will have access to the calibration parameters after all, who knows, I've seen the software, it's amazing but not ready yet.

Originally Posted by Hoobz

A question;
If it was 'just' the signal from the wheel sensor causing an out of expectation with the programming parameter/algorithm (and then a resulting malfunction), couldn't a micro controller be used to intercept the wheel sensor signal, process it by the 1.1(example of a ratio change), then outputting the original sensor signal by the 1.1(still only an example) changing the signal going to the ECU TCU? Fixing the issue?

Or am I missing something?

It's possible, you could feed all ABS sensor signals into an MCU, and reproduce them according to the new gear ratio.

Originally Posted by JeanLuke

I cannot see why that would not work, except it would throw out the OBD speed measurement. I'm not sure the wheel sensors are linked directly to the TCU. In fact, I'm not sure where they are physically wired to. The primary function of the wheel sensors is for the ABS, so I would expect them to be connected to this system. The TCU could be getting it's data via the bus system.

I should see about buying one of the new DRB-3 micro-pods. They are down to a couple of hundred now for the knock-offs. I have read that you can set the diff ratio via DRB-3. If so, it is much less "fun" but a far simpler solution.

BTW - Just because I know how to dismantle, solder and reassemble the TCU, don't assume I know how to hack one. I have not tried, but I am not confident I could. There are often several layers of protection programmed into these devices.

ABS sensors go into the ABS computer, then the speed values are passed to the entire system via CAN. If you look at the wiring diagrams there is a can line between the ABS unit, ECU and TCU. I've heard of two cases so far of sloppy engine changes and forgetting to connect the CAN line between the ECU and the TCU, both resulted in loss of drive.

As far as protection goes, these early control units are not very strongly protected.

Give us a link to the DRB3 clones. I want to reprogram my cooling fan

In my opinion, the simplest possible way to edit the data on the TCU for new ratios would be to read everything possible from a WK 3.55 TCU and a 3.73 TCU and compare the data. The ratio should be visible as 355 / 373 somewhere in the data.

[Hoobz]

Originally Posted by Tyvokka

Sorry to digress and hijack this thread

Which specific DRBIII tool would you reco...

Not a hijack.

Title is matching your query.

There are guys in the states who run the speedo drive signal off their WJ transfer case. You heard about that? I was reading it yesterday. Only some cases have the socket

But the above is not nerdy enough.

Let us work out how to do it with a MC, like I want you to.

[skipperau]

Would these help with the speedo issue?

https://hmbe.com.au/speedometer-calibratior

[skipperau]

http://shop.12oclocklabs.com/index.p...&product_id=59


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[Adrian D]

Originally Posted by Hoobz

That's exactly what I was talking about in this pirate4x4 thread I started
ecm-tcm-programming-discussion

It's been a good read for me.

I was going further though, than just the speed sensor data, thinking about tapping into every single wire coming and going from the ecu and tcu, and plotting exactly what is going on.
But, as my friend in there mentioned, you will have problems with echo, which puts me out for now. For sure. Plus, depending on the ECU TCU it could very well have tampering mechanisms in place.

To me, I'd be very surprised if the WJ/G's ecu tcu's would be that encrypted and have any tampering protection. Highly doubt it.

Like I also said in that thread, it's not like you can find out which pins on the ecu tcu should be wired into your usb, then look at the program in C language (ecu and tcu being commonly programmed in C language) in and IDE on your laptop, because it would only be stored in memory in machine code. Not source code as that would be ridiculously easy to look through. If, else if, while loops within loops would be fun to see.

It will have some CRC for sure, especially for calibration data, as you don't want a communication error to write gibberish and then the processor will try to read that gibberish.

My job has me looking through and intepreting disassembled code, so it's not completely unfamiliar territory.