I have a 95 that the previous owner lost the key fob. The PKE is a cool feature in my book, but I cant find them cheaper than around $120. Am I able to get a cheaper, normal clicker that can unlock the doors and hatch without the PKE function?

 

You can always install an aftermarket system. Where can you find a key fob for $120? I can't find one anywhere for any price!

 

The pke function requires the OEM remote. IDK if a universal will program to operate locks or hatch.

 

Yeah, I get it about the "passive" part of the fob and PKE.
I would be ok without that in an aftermarket.

I worked for Honeywell Security for over 35 years.
I may have to dissect the PKE and find out if I can create a hack for it.
Seems like it could be profitable to sell a new dongle for this thing. LOL

 

Oh jesus christ PLEASE DO. I would've done it already but I don't have RF analysis equipment in my lab, so my hands are tied. If you need some information to help you get started, the company that remade the keyfob for GM, Zylor Inc, has a ton of information in their FCC filing: https://fccid.io/PNZ0202T

 

Wow. Thanks for the link. That is a WEALTH of information.
Interesting that they used 120kHz, not the standard 433 that everyone else uses.
I'll look into it and let you know what I think.

 

Hey there! Bringing this back a little bit.

I found this patent, and couldn't help but notice that it shares a lot in common with our PKE system. For one, the proposed system uses a 32 kHz clock and runs the antenna on the 3rd harmonic at 98 kHz, while ours uses a 40 kHz clock and runs the antenna on the 3rd harmonic at 120 kHz. For another, the proposed transmitter in the patent is precisely the same as our keyfob (including even the illustrated drawing!). For another, the proposed mechanism seems to jive with what we know about our own system (like the just-under-30-second cutoff after the tilt switch stops moving). I then confirmed that Lectron Products Inc, the one who filed the patent, did in fact create the original keyfob for GM in 1993 (FCC ID ABO0202T). There's info on how the data encoding scheme works in the patent filing, including stuff about the code word and the encoded output. Here's the patent: https://patentimages.storage.googlea.../US4942393.pdf

If you have the second-generation keyfob handy (this is the one with the green PCB that says XILOR INC on it), that's the one that's referenced in the FCC filing I linked earlier. And on the backside are test pads, and among the test pads are output for the code word and the encoded data from the IC. So it may not even be necessary to rely on the antenna output.

Further, watching the dealership VHS tape that described the technical advancements for the C5 Corvette, GM noted that the C5 was the first to feature rolling codes in their passive keyless entry. I would link this but the forum has a nasty habit of changing any youtube link to an embedded video. If you search for "C5 Corvette Building The Fifth Generation Corvette VHS Movie" on YouTube and skip to 31:40, you'll see the part about rolling codes. This, of course, means that our system in the C4 does not use rolling codes, and so our transmitters are 'dumb' and just broadcast the same signal over and over and over. There is no bidirectional communication between the keyfob and the car. That should simplify things significantly.

Hope that helps spur things on!