Info on Renix Keyless Entry/Gen 4 Camaro keyless

[XJyoungster]

On 8/31/2020 at 8:55 PM, eaglescout526 said:

Little info I found on the Renix keyless system from an XJ FSM.

 

To use another transmitter fob, the coded chip needs to match the code on the receiver. So if one was hoarding these fobs and receivers, sets could be made with some soldering and swapping of the fob chips to match. AMC did supply replacement fobs but the PDC had to be notified of the code number on the receiver to code the fob. Kinda neat but still a primitive system today but was neat and advanced back then. 

Do you know how todo this? I have a remote and module I need paired. I just don't know how todo it myself.

[eaglescout526]

 

10 minutes ago, XJyoungster said:

Do you know how todo this? I have a remote and module I need paired. I just don't know how todo it myself.

 

The chips in the remotes and the chips in the module need to have matching numbers. Otherwise no there really isnt a way to pair them. If I had to take an absolute educated guess, the chips were probably coded with numbers via an EPROM machine or something like that. A lot of this info from the AMC|Jeep era is lost to time and not a lot of info was shared nor documented unless someone worked for the vendor or for Jeep. Renault was the company that first started the keyless entry fad and there might be more info from them but I did a quick search a while back and got nothing back.

[XJyoungster]

10 minutes ago, eaglescout526 said:

 

 

The chips in the remotes and the chips in the module need to have matching numbers. Otherwise no there really isnt a way to pair them. If I had to take an absolute educated guess, the chips were probably coded with numbers via an EPROM machine or something like that. A lot of this info from the AMC|Jeep era is lost to time and not a lot of info was shared nor documented unless someone worked for the vendor or for Jeep. Renault was the company that first started the keyless entry fad and there might be more info from them but I did a quick search a while back and got nothing back.

Okay thank you! 

[Minuit]

If I had to guess based on my experience with test equipment of this age, the "code" is probably stored on an EEPROM or similar non-volatile memory chip. The remote likely has a similar chip, and it works by blinking a LED in a pre-programmed pattern, which the receiver compares to what's stored in its memory. That chip was probably programmed on a very expensive and rare machine. [1]

 

Even if you had the equipment and knowledge to read and alter the programming, desoldering the chips can cause loss of memory or permanent damage. You'd have to be very careful.

 

This is a very specialty electronics thing. To find people who know anything of the way it works, you'd probably have to luck out and find a retired engineer on a site like the EEVBlog forums who worked with similar systems back in the day.

 

Frankly, I don't consider the system worth the effort of reverse engineering it. If someone has one of these modules kicking around (I did at one point, but hell knows where it is now), I guess I could take a look at it and try to figure out how it works, but that would have to be an absolute bottom priority task for me, because there wouldn't be any money in it and I wouldn't be able to find a personal use for it.

 

[1]: All of this is conjecture, but I think it's as plausible an explanation as any considering I have little hands-on experience with the factory keyless entry's inner workings, but I do have a fair amount of experience working with equipment of this era.

[eaglescout526]

Couldnt we make something today using the modern tech we have to fit in those little housings? I mean I find it odd that the modules got bigger as time went on until full integration into the ECU but I have an HO module and the board it long and skinny and I have been searching for something that would just fit into the XJ housing.

[Minuit]

4 minutes ago, eaglescout526 said:

Couldnt we make something today using the modern tech we have to fit in those little housings? I mean I find it odd that the modules got bigger as time went on until full integration into the ECU but I have an HO module and the board it long and skinny and I have been searching for something that would just fit into the XJ housing.

You definitely could. But you'd run into all sorts of FCC mumbo jumbo if you ever wanted to legally sell it (any halfway decent keyless entry being an RF transmitter-receiver) and you'd have way more man-hours into designing a circuit and PCB to fit there than you'd ever get back considering how much easier the alternatives are.

 

and a perfectly good junkyard Camaro module can be made to fit anyway, and it's very easy to make an adapter harness to plug it straight into the factory wiring.

 

and I had to cut out that part of the overhead console to get it short enough to fit the MJ's headliner anyway

[eaglescout526]

25 minutes ago, Minuit said:

But you'd run into all sorts of FCC mumbo jumbo

 

Oh yeah. FCC stuff.

 

I am interested in the Camaro one very much, I just need to find one. 

[eaglescout526]

So I made a sacrifice for the sake of info but I took my later style board with the ceiling dome and removed the board and uncovered the chip that had a printed tape with numbers on it to look at the chip

 

It is a Phillips chip:

TEA       5500

228       98

HSS      9144  6

[Minuit]

4 minutes ago, eaglescout526 said:

So I made a sacrifice for the sake of info but I took my later style board with the ceiling dome and removed the board and uncovered the chip that had a printed tape with numbers on it to look at the chip

 

It is a Phillips chip:

TEA       5500

228       98

HSS      9144  6

Does it have a window in roughly the center of the chip? If so, dollars to donuts that's an old-school EPROM that is erased by shining UV light directly onto the silicon of the chip.

 

Any pics? Miiiight be able to pull up a datasheet for it.

[eaglescout526]

3 minutes ago, Minuit said:

Does it have a window in roughly the center of the chip

 

Indeed it does. I am uploading pics of it right now.

[eaglescout526]

[Minuit]

https://pdf1.alldatasheet.com/datasheet-pdf/view/19716/PHILIPS/TEA5500.html

[eaglescout526]

Reading that is what makes me wish I wasnt so damn illiterate to older tech. Ive learned quite a few things from the popular youtube channels that restore old computers but not enough to know if it is possible or not to recode those chips.