1227727 oddities?

[dyeager535]

While learning about the 1227727 ECM, I ran across the VSS/radio pin on the ECM. I see it described as being for turning the radio volume up/down as vehicle speed changes. I've seen this in action in other cars, I like it. Especially since I have bad hearing, and my truck is loud at speed. I checked some of the bins I found in these threads http://www.gearhead-efi.com/Fuel-Inj...ull=1#post8630 and this one http://www.gearhead-efi.com/Fuel-Inj...hlight=1227727

But I see nothing referencing radio and/or VSS that looks related. Nothing specific in the $8F hac either.

Does anyone understand how that setup worked, and which vehicles had it? At least if I knew what vehicles had it I could delve in via service manuals or online resources.

Second, the bins I checked that are available in the above thread, F or Y body, all have CRAZY VE tables, the AUFR bin also has VE screwy compared to what I think it should look like. XDF is "8F complete V1.05".

Checked one of the "W" car bins here http://www.gearhead-efi.com/Fuel-Inj...hlight=1227727 and it seems to have a "normal" VE table.

What am I seeing with the VE tables the way they are on the F/Y body bins?

[Six_Shooter]

8F is Turbo Grand Prix, so it will not work with F or Y body bins, at least not well. LOL

The speed sensitive volume is just a VSS output that the radio then uses to control volume. This would be a similar signal to what the cruise control and speedometer would use.

[EagleMark]

That should be a $8D for F and Y body, do we have a misplaced file? You seem to be good at finding them...

The only car I know of that ran this radio Volume control in $8D was the Corvette, Y body.

[dyeager535]

Oh, that explains that then. I knew something was up. :)

So the radio just got the VSS signal and adjusted volume internally. I was hoping it was something more easily swapped...if I can find what cars had that capability (hopefully the ones I see in the wrecking yards, not vettes) maybe I can disassemble one of the radios and find out what makes it tick. I've been wanting to tap into the radio I have to add an auxiliary port so I can ditch the tape adapter anyways...

Just now saw Marks response below, so Corvette. Not paying that kind of money for a radio to play with lol.

[Six_Shooter]

There are other cars that would use the same thing, many of the mid to late '90s Pontiacs has some sort of SCV (Speed Controlled Volume), as did many of the trucks.

I think you'll find though, that it's all code controlled, and not much in the way of hardware.

[dyeager535]

As old as my radio is (same basic style since the early 70's) I'm guessing that retrofitting some sort of SCV into it would be quite difficult. Possible I'm sure, but the knobs do still work!

[JeepsAndGuns]

Wonder if there are any new aftermarket radios that can use that feature? Mabey try stopping by a local car stero store and seeing what they have.

[EagleMark]

Intresting topic as I have some hearing loss too... 357 Magnum at 22 years old no hearing protection right ear and 318 Detroit diesel with some pump changes, straight pipe left ear.

On the way back from Boise I had noticed several times when I slowed from 70+ MPH into a town the radio was very loud. Normally I never have it on, like to listen to engine, but a 10 hour drive with a good tune was getting boring listening (by brail) for any changes.

Did I mention the 1990 Suburban 2wd 5.7L got 19.78 MPG on way down and 18.6 on way back?

[dyeager535]

I really don't want to swap radios, as I'm running the Delco radio with integrated CB, and I don't want to cut my dash up for the newer style radios. By the time I get the CB portion hooked back up I'll be the only one left running a CB, but that's another topic. I sort of expect that Cadillac did something like this during the 80's since VSS was already there, but I haven't found anything conclusive. I've seen Delco radio's of this vintage offered on ebay with an external box that was wired up between the speakers, which was powered. I'm guessing it was an early amp, but maybe they integrated VSS to it.

I often notice that driving home 50MPH if I am listening to the radio, when I slow down to 10MPH the radio is higher than it should be (I'm trying to save whats left of my hearing). If I don't turn it down before I get home, when I start the car the next morning, it's way too loud.

That's some nice mileage Mark. If I recall, that rivals what the new trucks are capable of doing. I think the hybrid Silverado manages something like 22MPG highway lol. I've often wondered if it is really better (for the environment) to process and use all the resources that go into emissions equipment (converter, AIR, EGR), plus the resulting fuel economy loss from not running lean, instead of getting as much MPG as possible, regardless of emissions out the tailpipe. Perhaps new cars (direct injection?) can use a lot less fuel without the emissions normally associated with doing so.

[RobertISaar]

as stated before: the speed controlled volume setup simply uses the 4K PPM(or maybe 2K, depending on application) signal as an input to the radio, which processes the signal for use as a speed signal and essentially as a gain control.

a lot 95-99 monte carlo radios used it, but as for other specific applications, i wouldn't know off-hand. i could look at the wiring diagrams for any other suspected models to look for a VSS signal.

[dyeager535]

Do you have access to any of the ~1980-88-ish Cadillac diagrams? I believe Cadillac started using the 2000PPM VSS in 1980, and the radios in *most* cars were similar up until the late 80's, so I figure Cadillac being Cadillac, I am hoping at some point they may have added the functionality to the existing radios, prior to the change to the later style radios. I don't know Cadillac well enough to know what the top end Cadillac's were in the 80's.

I've not found any reference to anything like that in the forums, but Cadillac had a console cell phone offered in the late 80's apparently, which was integrated with the radio setup, so I don't think it outlandish to think they may have offered a speed sensitive radio setup the same vintage. Can't find any radios on ebay with the external boxes like I've seen before.

[RobertISaar]

i can pull 82 and up stuff. top end caddies from the 80s? i would think eldorado and brougham.

[RobertISaar]

82 eldo: CB, no SCV.
84 eldo: delco bose system, individual amps for each speaker? no SCV, other radio option has CB, no SCV
86 eldo: same amp setup, some more integration, but no SCV
88 eldo: essentially same as 86
90 eldo: essentially same as 86
92 eldo: WAY different, split radio setup, probably not what you're looking for.

fleetwood looks similar.

even started looking at the allante stuff, they didn't even use it, and those were even higher level than the eldos.

[EagleMark]

Those cars were quiet and didn't need it...

[dyeager535]

Well, maybe the Cadillacs were so nice they didn't need it! Definitely appreciate the lookup.

Any ideas on other vehicles GM might have used it on? Corvette's? I figure if Cadillacs didn't have it, pretty unlikely anything else did, but Corvette was somewhat of it's own brand. I'd never heard of this before though, so I suspect that it may have simply been used only later on. I try to stay focused on just a couple of makes and models, otherwise I'd get even less stuff accomplished.