FGX cruise control problems after gear ratio change

I've got an FGX XR6 6 speed manual ute (non Turbo) with a close ratio 5th and 6th gear fitted and the cruise control has stopped working in 5th and 6th gear and works fine in 3rd and 4th. It appears to be speed/RPM discrepancy perhaps simulating a slipping clutch with the lower ratio 5th and 6th causing the cruise control not to engage.

I'm wondering if anyone's come across this before maybe with diff ratio changes and found a remedy for it? I've tried a multitude of different settings in speedo parameters without success and I'm at a loss to know what else I can try altering in the tuning program to hopefully fix it.

do you have the gear indicator on the dash? if so what does it come up with for 5th and 6th?
ive got an ex taxi fg that was egas, when it was still egas I put a tr6060 in I had cruise in 1st-5th but 6th would come up on the cluster as D (I assume cause egas tunes never needed to know about 6 speeds) and cruise wouldn't work. it did my head in trying to figure it out and even put up a post on here but no one had any idea what I was on about.

I've now converted the whole car inc. modules etc to petrol but have been using a zf6 tune with manual settings, and again my indicated gear for most gears is all over the place and nothing I have tried works in changing it, so I again have no cruise.
I've done up a 6spd manual tune just a day or two ago to try it but haven't had a chance to swap it in to see if that actually fixes it, but that's not going to help you.
I assume its maybe something to do with the VID block? which we obviously cant edit...

No mate, the manual FGX doesn't have a gear indicator on the dash, but after trying everything I can think of with both HP Tuners and SCT software, I'm pretty sure there's a speed/RPM window factory set in the VID block we can't access. Apparently PCMtec software can access the VID block and may end up being the remedy. I tried a zf6 tune today with both HP Tuners and SCT with every setting change I could make but it didn't work unfortunately. I spoke with a guy last night who fitted a TR6060 to a BA turbo (5 speed) and cruise didn't work in 6th and to date he'd never discovered a fix for it. There doesn't seem to be much interpolation of the speed signal from the ABS sensors to the PCM as nothing alters the speedo reading on the dash, yet the over speed fuel cut works wherever you set it. Definitely a heady mate I'm hoping to somehow fix eventually.

I'm fkn devo I didn't buy pcmtec when it was on sale! it has heaps of features that would be handy as fuck for me cause I do conversion specific stuff.
ive even got ids and it doesn't have many features compared to what overseas people have access to

A mate of mine has IDS and we've looked through that with no access to change gearbox ratios or speed/rpm parameters. It's a matter of finding out which version of PCMtec accesses the program areas we need to adjust and will probably be the 3k workshop version. We predominantly tune Holden's and have never needed Ford parameters HP Tuners doesn't access to look at PCMtec when it was on sale. Just don't want to spend 3k on PCMtec to find out it doesn't fix the cruise control issue either. Problem is, a couple I've spoken with interstate who have PCMtec don't really know what I'm talking about with cruise control issue to really know if it will access what we're after. No one has it SA yet to hook it up and have a look.

msg brett hogno on fb, he should be able to sort you, or at least give you some more direction with pcmtec

Thanks mate, I give him a try