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I'm currently reading up on other Can Bus threads, but can anybody give me some short version answers on reading data from the can bus in my 2000 TA?
I use the ALDL sometimes and a scan tool to read codes and data.
I'm interested in if there's a way to read data from the can bus in the car other than plugging in to the ALDL. Are there any other can bus connectors there somewhere provided by GM when the car was made?
Specifically, I'm very interested in if there's any way to read data to supply to a Holley virtual dash when it's set for standalone use without also using one of Holley's EFI systems with their dash? Holley's short answer is "no," hard wire all the sensors / senders you need.
I'm also interested in this cheapo unit --
At Amazon -- search -- "VJOYCAR V70 New Hud Onboard Computer with OBD2 Scanner Digital Speed RPM Coolant Turbo Pressure Faulty Code Reader, Works on All Cars Since 1996"
Any guesses if this would work plugged in to the TA's ALDL? Some people seemed to report it did not yet work right with some GM cars, but it does work for a lot of USA cars fairly well.
Or, are other can bus connectors provided anywhere on the car? Or only the ALDL?
Thank you for understanding that I'm VERY new to can bus issues and usage!
Yes, it's J1850, also known as VPW. It's one of a handful of OBD2 protocols that were part of the OBD2 spec in 1996.
The industry standardized on CAN in 2009. Some cars had it a few years before that, but I don't think any GM vehicles had it before 2005.
I'm going to read the 1-2 star reviews on Amazon, and see which GM cars the toy above did not work on!
I remember one failure was on a Toyota.
The reviews were generally good so far actually, these models that work with cars from 96-2008 were just released.
It's getting 4 star reviews right now out of 5.
Don't understand why Holley's virtual dash can't read the data in our cars directly, at least it can't so far.
The Chinese figured out they could sell more of their units if they worked on more cars, for $25-60 dollars!
So far Holley (based in Kentucky) has not deduced their $1000 dollar units would sell more if they worked in standalone mode (without the Holley EFI, using the car's OEM PCM).
And Holley should also have standalone data sheets for the more popular older cars that explain how to wire and configure their unit for that specific car, like Crutchfield publishes for multiple brands of car radios.
I think that's really dumb! They've been selling these dashes since at least 2015.
These American companies! They always want the big hit sale, Holley EFI and add on digital dash that communicates with it, probably $2000+ with lots of not included accessories! My business partner taught me the smaller sales sold in volume add up quickly! Not just the big hits. WTF!
For $2000, I can be halfway though the needed rebuild on my 91 Trans Am...
Yes, it's J1850, also known as VPW. It's one of a handful of OBD2 protocols that were part of the OBD2 spec in 1996.
The industry standardized on CAN in 2009. Some cars had it a few years before that, but I don't think any GM vehicles had it before 2005.
Very Few GM Vehicles. I read there was a Cadillac that started using a version of CAN as early as 1997.
BMW Started using it even earlier, around 1990.
The problem with those dlc plug-in/Bluetooth gauge adapters and such is that they are limited to GM’s class 2 bus speed, which is pretty slow. If you’re looking for data other than what the dash provides, sure, it’s better than a $2,000 scan tool, but depending on what you’re trying to accomplish with these data, it’s still going to be lagging as it has to convert from class 2 to whatever global J1850 protocol it uses, then give it to you. Holley’s dash hooked to the individual gauges in analog form will give you faster data. If all you want it to make a HUD for you windshield, the Amazon thing should be fine. But don’t rely on it in court lol. Some guys try to duplicate an OEM “track recorder” and and say “see, I wasn’t speeding, I never exceeded xx mph...” not gonna do that with an Amazon HUD kit and cage mounted GoPro.
Thank you slowpoke, that's a great point about the data speed. Did not think of that.
I'm trying to understand electrically what it would take to tap the speedo, rpm, coolant temp, oil pressure, and fuel, without compromising the signals the PCM needs from those sending units?
I have some experience, but this is new to me, it's not an alarm or remote starter!
Well for something like rpm, you can use a coil trigger wire, same as a stand-alone tachometer would, oil pressure can come from the side of the oils pan right above the oil filter adapter, coolant temp can come from the other head where the gauge sender fitting is plugged, or you could tie into the one already there. I’ve also heard of people tapping the water pump and putting a sender in it. Then there are companies that make interfaces to tap into 5 volt sensors.
Funny I come across this post. I just bought one the other day off Amazon, and should be receiving it tonight. Will be using it as a digital dash for my 1988 Jeep YJ that I swapped a 2002 4.8 from a Silverado in to. Also runs off the Class 2/J1850 bus, and I have been researching these carefully as a lot of the cheapie China stuff leaves out the extra circuitry to talk to J1850 protocol-based vehicles like your TA, my Camaro and my Jeep swap. They of course work fine on CAN/GMLAN vehicles (like my gf's Saturn Sky Redline). Let you know later how it works.....
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Short Answer! Reading data from the Can Bus 
