WG Jeep Geek - Tinkering with Jeep Electronics

[skipperau]

Originally Posted by Hoobz

---snipped for brevity---The best way is for people to ask, suggest, comment and be peer reviewed. But, it takes a massive amount of humility to do it and risk being corrected, feel a bit silly, when that's exactly how we improve.



---snipped---it.

Many years ago, a very wise man (my Dad) said to me "Never be afraid to ask questions, or be involved, it's the best way to learn".
That attitude fits in well with what you said. [emoji846]

Anyway, I've been thinking about what's involved in changing ratios in the diffs, and correcting for that in the TCM. In the older manual systems, it was a relatively simple case of changing the drive gear in the box to provide the corrected information to the speedo. But with the electronic transmissions the information comes from the ABS tone rings right? Is it one feed only? Or are there 2 mutually exclusive feeds? One to the ECU and one to the TCM? If they are both fed from the same feed then it would be possible to make a single module that takes that feed, interprets it in 2 separate sub-units to feed to each modules to correct both, right?



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[Hoobz]

Originally Posted by Tyvokka

I have speedodrd and it works fine with correction for the bigger tires by comparing speedo vs gps.

Anyway, I haven't actually read up on all the recent posts anf have no heads or tails on what's going on tbh.

Speedo fixing isn't too hard. If the ecu tcu isn't fussing over the tone ring speed relevence.

The WJ/G 4.7s are more forgiving than the next model diesels and others. They're a lot more picky.

(*ahem* my front abs is discon too *ahem*)

[skipperau]

Originally Posted by Tyvokka

I have speedodrd and it works fine with correction for the bigger tires by comparing speedo vs gps.



Anyway, I haven't actually read up on all the recent posts anf have no heads or tails on what's going on tbh.

Thanks, I wanted to hear from someone local to see how good they are.


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[Hoobz]

Originally Posted by skipperau

Many years ago, a very wise man (my Dad) said to me "Never be afraid to ask questions, or be involved, it's the best way to learn".
That attitude fits in well with what you said. [emoji846]

Anyway, I've been thinking about what's involved in changing ratios in the diffs, and correcting for that in the TCM. In the older manual systems, it was a relatively simple case of changing the drive gear in the box to provide the corrected information to the speedo. But with the electronic transmissions the information comes from the ABS tone rings right? Is it one feed only? Or are there 2 mutually exclusive feeds? One to the ECU and one to the TCM? If they are both fed from the same feed then it would be possible to make a single module that takes that feed, interprets it in 2 separate sub-units to feed to each modules to correct both, right?



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My head has gone a bit foggy, so last post for tonight

It depends on the model, I've lost track a bit there. The diesels are much more picky with making sure wheel speed, tranny out put speed and tranfser case selection always are within a certain algorithm formula. If one of them is out >>> Fault code and/or bad transmission performance and engine behaviour.

Oh, there's engine rpm, transmission input speed sensor, transmission output speed sensor, transfer case selection sensor and abs tone ring sensors. Just having one of those out can cause problems for some cars and sometimes they're not so fussy. There's a bunch of variables...which means head aches

As far as the last few sentances you asked, yes, one unit (Micro Controller) could take the one speed sensor reading, compute two different formulas and output two separate different corrected frequency signals on two separate wires. One to the ECU, one to the TCM, and even a third to the speedo if it was required. I think that's what you mean.

PS. Other posters in here could answer much more clearly on model specific electronic architecture to your question.

[Tyvokka]

Hey Hoobzy, My head hurts!

I've been reading up links to pirate, Adrian's links and I'm getting a bit lost tbh. Can't see the forest for the trees lol! , so help me see the big pic please.

The WJ speed signal comes off the two rear ABS sensors to the ABS module. SpeedoDRD splices into these wires and one does the speed correction accordingly, so no worries there.

The problem is when one changes axle diff ratio and the ecu tcu is not happy, is that right? Can this be solved by as JeanLuke wrote : DRBIII Pod JTEC read/write? If there's a cheapy one that works, would that help?

I'm having problems with my gearbox, in the sense that the gear changes is a bit wonky with 5.38 and 37s. I have gone back to 33s for on road driving and saving the gnarly tyres for the bush. I do have tranny codes, not so happy front ABS sensors, ABS and handbrake lights.

[JeanLuke]

Originally Posted by Tyvokka

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.

I'm not seeing any hijacking here!

The tool I was considering is one of these: http://www.ebay.com.au/itm/2017-New-...4/263124909160

Has anybody played with one of these puppies?

[Tyvokka]

Cool thanks for the link.