CS digital gauges: tach signal expected?

[old_olds]

OK, guys, don't hurt me. I don't have a W-body. What I do have, is a '70 Olds Cutlass S Sports Coupe, and an 88-91 UB3 digital gauge cluster. I've read and understand the base digital to UB3 digital cluster swap on the site, and I can make everything work, except the tach and speedo. So before I start hacking the cluster's housing to make it fit in the '70's dash, could ya help a fella out?

I know that the digital cluster gets the tach signal off of the ALDL line at C13 - what kind of signal is it expecting? My father in law is an EE, so I'm betting that we can condition the tach signal off of my HEI, if we know what the thing needs.

Second, I know that the speedo triggers off of the VSS. This is easier, as pulse generators that can be cable driven are available, but how many pulses per mile does the stock W-body VSS put out?

 

Thanks for any help - if I canget this up and running, I'll gladly post photos when the deed is done!

 

Kevin Wright krwright@wankel.net

Dallas/Ft. Worth, TX http://www.wankel.net/~krwright/cars/olds/70Olds.html

 

Snoopy: 1970 Oldsmobile Cutlass S Sports Coupe - It wants to be a W-31! And have EFI, 4-wheel discs, a 6-speed, a turbo or two...

[stockgp]

i don't have a cutlass, therefore no info to help you. but sounds like a commendable project. good luck with making it work and keep us posted. i'm sure someone on here can help you.

[old_olds]

the cluster gets a series of pulses from the ECM that it decodes and establishes a speed rating and engine speed.......

 

so i got from my 1989 Factory Manual.......

 

I dunno if you can recreate that my friend........

 

F-ing lovely. Why in the hell didn't they just use the bloody tach wire like on the analog cluster? Weeeeeel, I guess I *could* put an ECM in there with just power ground, tach signal and ALDL... It'll freak out since there'll be nothing else connected, but it should handle the tach. Hate to do that, since I intend to put a MegaSquirt EFI controller in the thing anyay...

 

Surely somebody knows what kind of data stream the cluster is expecting. I'd expect a PIC or something could be convinced to spew the proper chunks (eeeew!) I aready have to massage the signal to get the V6 tach to read V8 revs.

 

Kevin

[old_olds]

1992 Cutlass Supreme 3.1 Turbo 5-Speed

 

BTW - that sounds like a fun and interesting ride...

 

Kevin

[GnatGoSplat]

Speedo is 4000-pulses per mile (grounding pulses).

The tach is a serial data stream on the ALDL. I don't know why they did it this way, it might be because GM had these clusters built/designed by Denso, so they wanted them to be engine-independent. The ALDL is an 8192 baud bidirectional serial data. I believe the tach is 2 bytes. All you have to do is know what the offset of the 2-bytes is and simulate the datastream with a PIC or similar microcontroller. The redline is also transmit in the data stream, so that's how the cluster knows if redline is 5500rpm, 6000rpm, or 6500rpm and will turn on and off the various red bars to reflect the redline.

 

You might try sending a PM to "okidedrac" as he has built a microcontroller to do just you want to do.

[musthavemuzk]

sounds like a nice project ya got going.

 

good luck and keep us posted

 

Monty

[cutlsp]

i wanna see this 70 cutlass s but my damn 88 cutlass pwr steering is dead

[old_olds]

i wanna see this 70 cutlass s but my damn 88 cutlass pwr steering is dead

Well, just take a look at the link in my sig!

[old_olds]

I should also point out that the car isn't all that spectacular at the moment. Looks kinda sad, really, but mechanically sound. Definitely "in progress"

No turbos or EFI yet, working on the tall spindle/big brake setup.

[cutlsp]

if you need it painted i know the best place in the dfw area to take it

sure it costs a lot but they do a lifetime warrenty on the paint jobs there

[musthavemuzk]

if i might ask.....

 

where did this idea come from?

 

Monty

[old_olds]

if you need it painted i know the best place in the dfw area to take it

sure it costs a lot but they do a lifetime warrenty on the paint jobs there

Who's that?

Not that I can afford it now, but someday...?

[old_olds]

if i might ask.....

 

where did this idea come from?

 

Monty

Well, the origianl tick-tock-tach gauges cost a fortune, and I ran across the UB3 cluster while searching eBay once. I googled around, found w-body.com's article on it, and decided that it could be used as a standalone cluster (missed the lack of tach wire). I thought that the UB3 Cutlass cluster was one of the best-looking digital dashes I'd ever seen, and it looked fairly easy to refit, since it was more or less a regular box. No curves or fancy surfaces. Looks like the actual gauge cluster will fit, but I'm going to have to do some re-arranging of the idiot lights and turn indicators.

I was considering Dakota Digital or Cyberdyne gauges, or even a custom LCD solution partially driven off of the datastream from the MegaSquirt EFI controller that I will be installing (hopefully) soon. The UB3 seems like a cleaner, better-looking solution, and it's OEM Olds, even!

[cutlsp]

yeah about that place i'll have to get you a business card but anyways i need help with my pwr steering lines

[Jcrow]

The vss puts out 40,000 pulses a mile and the ecm converts it to 4000 pulses per mile for the speedometer and cruise control. The grand prix dash with the mechanical tach would probably hook up to an hei no problem, but the cutlass tach gets its info from the serial data line from the computer (the same wire a scan tool can read everything from the computer). Also the gauge cluster C1 goes to power - not the dimmer like it says in the directions. I forget which one the dimmer goes to, but it says "not used in the directions". I just upgraded my dash and the check engine and charge light would only come on with the headlights on

[old_olds]

The vss puts out 40,000 pulses a mile and the ecm converts it to 4000 pulses per mile for the speedometer and cruise control. The grand prix dash with the mechanical tach would probably hook up to an hei no problem, but the cutlass tach gets its info from the serial data line from the computer (the same wire a scan tool can read everything from the computer). Also the gauge cluster C1 goes to power - not the dimmer like it says in the directions. I forget which one the dimmer goes to, but it says "not used in the directions". I just upgraded my dash and the check engine and charge light would only come on with the headlights on

 

Actually, the instructions at http://w-body.com/upgrades/88-91cutlass-cluster/index.html say that C1 is IGN power (PNK/BLK)

I've rewired the plug I cut out of a base digital car (eBay-purchased cluster didn't come with a plug), and everything works on it fine.

Now to find a 4000 PPM pulse generator, and figure out the tach...

[musthavemuzk]

cool.

 

i was not necessarily reffering to just the UB3 but to the whole look and feel for your cutlass?

slammed, digital, 17's, big brakes and so on.

 

one of the car shows on spike tv have featured some similar cars in the past. basically old sheetmetal on top of new corner rolling stock and stoppers dropped sometimes.

i recall a 69 or so charger they featured as well as a chevelle i believe.

 

Monty

[old_olds]

Oh, OK.

I've been a fan of what has become Pro-Touring since the beginning. I think it was Car Craft, or maybe Popular Hot Rodding that used to have the Real Streat Eliminator - I think that's where it started.

I dig the old iron that can carve corners concept. I like all the modern stuff like EFI and such. I like my 30-year old A-body, but I want a lot of the goodies that they're putting in new cars. My '70 is emissions-exempt, I like the style, I like the rear-wheel-drive, I like the size (I'm 6'2" - but I also have a '79 RX-7 for when I want a go-kart). I liek the idea of an old car that can bnot only walk away on a straight, but around corners as well, all while I've got the stereo cranked and the AC on.

It really boils down to "I want a car that's MY car. No one else has this car. There are a few that are similar, but this one is truly unique."

I saw a lot of examples of what I want out at the Hot Rod Power Tour when it started in Arlington (only a few miles from where I live) this year.

I still can dig drag and street racers, but Pro Touring is where it's at for me. I autocross the RX-7, and I love it for it's handling, but it's only 100 HP, and small. I want the Cutlass to at least approach the '7 in that capability. Tough, I know, when you're throwing around nearly 4000 pounds, but I'm gonna try!

[old_olds]

Part of what drives me toward the technology aspect of the project is that I'm a computer geek and general techg weenie in addition to a car geek

[old_olds]

http://www.pro-touring.com/ is one website that features "my" kind of cars. they're also called "G-Machines" by Popular Hot Rodding, who tends to feature them more than other mags.

Here's another site: http://www.lateral-g.net/

Especially take a look at http://www.lateral-g.net/hrss454/ They've modified one of the new GTOs (Holden Monaro) into a "new" Chevelle SS!

[GnatGoSplat]

Especially take a look at http://www.lateral-g.net/hrss454/ They've modified one of the new GTOs (Holden Monaro) into a "new" Chevelle SS!

 

Yeah, I saw that, but I don't like it.

They took the round, sleek body of the GTO and chopped it up to make it look more boxy.

I would have preferred a real Chevelle that's been modernized rather than the opposite way around.

[musthavemuzk]

i think i was still in school or mayb just out of school ( i graduated high school in 88) that there was an article in one of the mags with old school sheetmetal on new corners aimed at competing scca against the new stuff.

i loved that. i think there was a camaro and a chevelle in that article.

 

as for the old style and the new creature comforts......i am all for that.

 

tis part of the reason i stay with a fairly new car. i love the creature comforts and such in the new cars too much.

and with the improvements in power they are at least decent to drive.

 

thanx for the info. tis much appreciated

 

Monty

[slick]

Sounds like one hell of a project you have going. Even though you don't have a w-body, stick around. There may be a few more things here other than the cluster that you may like(HUD, DIC).

[old_olds]

I've been looking at the HUD...

[old_olds]

Speedo is 4000-pulses per mile (grounding pulses).

The tach is a serial data stream on the ALDL. I don't know why they did it this way, it might be because GM had these clusters built/designed by Denso, so they wanted them to be engine-independent. The ALDL is an 8192 baud bidirectional serial data. I believe the tach is 2 bytes. All you have to do is know what the offset of the 2-bytes is and simulate the datastream with a PIC or similar microcontroller. The redline is also transmit in the data stream, so that's how the cluster knows if redline is 5500rpm, 6000rpm, or 6500rpm and will turn on and off the various red bars to reflect the redline.

 

You might try sending a PM to "okidedrac" as he has built a microcontroller to do just you want to do.

 

Shawn - I sent a okidedrak a PM, but I haven't got a response. Looks like he's still active, since he posted just today. Think I should just post a thread calling him out? I don't want to be rude, but I want this think to work! I'm willing to pay for work done and stuff built, of course.