Am here now

[Padgett]

Have nearly always just used my name since before the Internet was the Internet. First computer game in 1957, bouncing messages off a satellite a decade later, and designing digital controls for large afterburning gas turbine engines and flight controls for aircraft in the '70s. Been into cars for as long (as a teen could not afford a TR3B, could afford a Jag XK. Then found out why. Still have whitworth tools. Took the cure but a fan of DOHC-6s just now with VVT and redline 7,000 (Jag would go 7,000. Once.).

Been a fan of instrumentation ever since well ever. Have a Prince On-Board Computer from the '70s (had a smaller version in my '78 Sunbird with SBC). First reprogramming was an '84 Fiero with "Computer Command Control" and 2Kx8 PROM. Mostly reprogram cars to run cooler, 180-190F. Find that everything under the hood lasts longer when I do.

Got very deep into reprogramming the '88 Reatta 3800. Bought in '01 & still have. As my wont, collected nearly all the 5B computer .bins and played with a few. Found that after about 20 years the 27C256 PROM would not reliably erase so now mostly Am here now.use a bag on the side from Moates.

Teens were kind of a blur had a '93 GTP with Twin Dual Overhead Cam V-6 and a Getrag that I played with the tuning a bit and would give Porches fits. Sounded great while doing it. Is nothing like a healthy 6.

Fast forward to 2020 and in central Florida the bottom drops out of the car market thanks to Florida being closed for the foo. Sold my last Reatta convertible a few years earlier & replaced with a SLK320 Merc. Was in a retractable phase but soon found that with the top down there is not even room for groceries. Is common for retracables. So nice to drive around & easy to park (157" long). Still had an open slot in the garage so began looking. First thought about an XLR but same trunk issues and peculiar way of retracting, the tonneau would hit the overhead door track in the garage.

Then discovered something I had looked at several times but rejected because was too expensive and I really did not like the steering wheel (didn't like on an '84 Thunderbird either, no place to hang thumbs). After careful study fixated on the 89 Allante.(first year of 4.5 engine (4100 is too sloooooow), last year before decontenting began (still had standard removable hardtop).

Fact is that when I look I usually find. After looking at several (Northstar in '93 is good but needed wind wings to prevent drafts (I sit reclined and about as far back as possible. Screwey position saved life when flew a split window) and telescopic steering was also gone. Found a very nice 64k '89 with everything working including A/C and clear Florida title ($300 value & no hassle) down in Port St Lucie for pocket change. FWD is nice for a tow dolly. And soon was occupying the garage.

Problem is they tend to attract others. About a month later a neighbor inherited a not-so-nice '89 with hardtop, cold air, & also 64k miles. Had a Texas title and did not really want despite everything working so lowballed but said would pay $300 more with a clear Florida title.

Skipping to end, he did, and I did and now have two running driving 89 Allantes wedged into garage for a total cost of about 1/4 an XLR & nice sized trunk even with convertible (both have two tops, cloth and hardtop) Pocket change.

So cats being unable to help and an empty nest turns out it takes two people to remove the hardtop. Or a hoist & tree-saver 3" strap. Next I replace the U-gly steering wheel with a three spoke Reatta wheel.

Then the real problem emerges: the electronics that seem to have been designed by a Japanese (lotsa little white wires - no color coding) High School class from magazine articles. I have never seen coolant fans controlled by pulse width modulation before. And that is just the start. Turns out the ecm, a 1227750, has no documentation. Anywhere. No TunerCat defintions. Nuttin (probably the PWM).

Have dumps of most of the 27C256 PROMs and disassembilies but not commented. OTOH in 90 the PWM was replaced by more conventional relays and the same engine (LQ6) is used through the '92 model year so tables probably the same. ECM is now 16132240 and definitions exist but now has a 512k Flash.

Which brings up the just discovered by me Gearhead. Have a lot of .bins, mostly 3800 and now Allante (HT4100 & 4.5 V8) but very little on the 1227750. Ludis has nothing. TC has nothing. Does anyone here have any locations particularly for switch parameters ?

Please help,

Padgett

[1project2many]

Howdy and welcome. I've long wanted an '89. I fell in love with the cartoon-like gauges years ago, drove one around while in ASEP, promised myself I'd return some day.

Piles of white wires? Nothing new there. Found the same thing once in a Toronado with CRT. Harness must have been made from scratch, no pictures or guides, in place in the car. Everything was so snug and tight but it was lotsa work to remove and re-install. Helped me get a raise though. Nothing like laying a pile of components and an all-white wire harness on the dealership floor before lunch then leaving with a promise of no return unless we talk pay.

I have never seen anything on the 7750. Those cars weren't exactly laying around and much of what Ludis cataloged came from junk yard finds or ebay sales. The ECM looks like a C3 so it might not be too difficult to locate some of the switches and easier to find tables during a disassembly. Have you checked the Mask ID to see if the code matches another 4100/4500 equipped car?

[Padgett]

No, the problem is the Allante was the only GM car I know of to use PWM for the engine cooling fans and the ECM program reflects that. Means there is a table for fan speeds and not just switches.

AFAIK the Computer Command Control (C3 or CCC) were only used in early (Fiero) computer cars. By the time the Allante came along the 1227750 was P4 with and 8192 baud ALDL and a 27C256 but with a pair of PWM pinouts instead of discrete outputs. Hence the dump is over 19,000 lines and just have not found a round tuit. Pretty sure it looks like most GM ECMs but have enough oddball programming that nothing I've found lines up even close.

Have been through A Lot of Reattas and most had touchscreens. No Big. Allante has analogs to just about everything and ALDLSTUFF has a group (A86) for the Allante (V) with 4.5 (LQ6). May be able to use the 1632240 ECM also for a later LQ6 and suspect the maps may be the same.just uses a flash 512k PROM instead of a 27c256. Such fun.

[1project2many]

My bad... ECM looks like P4. Trying to rush an answer before leaving the shop.

Maybe oddball code... Lotus programmed Quad 4 engines were like that. Not really oddball, but they didn't re-use old GM code and they optimized better than US programmed ecm's. The datastream is key to cracking the nut so at least that's available.

Do you have a mask ID?

[Padgett]

That is one problem. Byte 0008 of Allante PROMS contain $00 which does not seem to match anything. Been working mostly with an 89 ANSU /7126 but have several 87-89 Memcals which use the 27C256 Prom. Several later ones also.

[1project2many]

Is there any chance GM loaded the file into the upper 1/2 of the chip? It wouldn't be the first time..