Considering buying a tech 2 knockoff to tinker with my '90 5.7 4WD. I specifically want to activate the ABS and see if it even works/get a more robust pedal, but would also like to have a more in-depth diag tool around so I can learn more about the truck. The cheapo websites state that their knock-off Tech 2's work on '91 and up GM cars, so first question is, will this even work on my '90? Second question: I'm having trouble finding a good resource for what the Tech 2 can do such as a manual specific for GM vehicles that lets you know what data/operations would be available to me. I did find a Tech 2 manual, but it seems to be geared more toward how to connect, update and self test the unit. Any direction on where I can find diag resources using the tech 2 specific for early '90s OBD systems would be greatly appreciated. Many thanks.
First of all. There was no European, US, or Canadian standardization of OBD til 1996. OBD I is a 1991-1995 CALIFORNIA standard. The rest of GM production used ALDL... Assembly Line Diagnostic Link or Assembly Line Data Link depending on who you ask. It was not a standard even within one GM brand... More like the Tower of Babel. For Example: There are several flavors ALDL of data from Pontiac vehicles in the same model year and even in the same model depending on when they were manufactured and from what assembly plant. Does your head ache yet? How did they get away with that crap?
To get decent functionality you're going to end up spending some money.
Your best least expensive bet for 1980-92 GM is a red brick Snap-On MT2500 with the proper cartridges, cables, connectors, and personality keys. Getting the manuals would be darn handy too.
It won't have all of the bi-directional capabilities of the Tech 1 variety tools but it'll come close enough for most stuff.
It can become a small treasure hunt but it's not as bad as the Tech 1 variety tools and generally less expensive.
As with most vintage electronics I would get it re-capped by a competent electronics tech. Electrolytic and Tantalum capacitors don't age well and 30ish years is definitely past their replace-by date. Electrolytic capacitors turn into resistors and damage components as they age. Tantalum caps just fry everything around them. I doubt GM went to the expense of using Tantalums in anything but they liberally sprinkled electrolytics through everything. The electrolytic caps in Your wiper delay board and various other small electronic bits of your truck, including the ECM, have no doubt gotten to this stage in their lifecycle.
Since our workshops aren't well heated... Storing in a pelican case with a re-chargeable desiccant pak or even just jumbo Ziploc freezer bags inside the original box will keep moisture from aging it as fast as leaving it loose in the original box where temp and humidity extremes can cause condensation.
If you're looking for the kind of functionality that GM dealers had 30 years ago you'll need to assemble a Vetronix Tech 1, Tech1A, or a Bosch Mastertech 3100. All three use the same program cartridges. You'll likely end up spending in the $1,000-$1,500 range by the time you complete your treasure hunt. I found a complete GM equipped MTS3100 several years ago for $600 but prices are really out of hand now.
If you actually find a working Tech1 or 1A... Again... I would get it re-capped by a competent electronics tech.
Make sure the membrane keypad is in working order as they are made of unobtainium.
The Mastertech 3100 is more likely to be close enough to complete to be useful as purchased and it will do everything the Tech1/1A will do with a larger LCD screen.
The Tech 1 tools tend to become a serious treasure hunt as sellers seem to think they can make more money breaking up the tool sets into the constituent parts and selling them one piece at a time... maybe yes maybe no but really quite obnoxious for someone that's trying to find a mostly usable tool.
The IEEE or D-Sub to ALDL data cables are made of unobtainium. The truly frustrating thing is that, even tho there are known good cables out there and the IEEE, D-Sub, and ALDL plugs and connector bits are available, there doesn't seem to be a reference with the cable pinouts and there's a complete lack of interest in making them available.
For any one of the three you'll need the Body, ECM, and Brake (ABS) cartridges that cover your model year or an earlier revision of the Mass storage cartridge that hasn't had the 1990 functions neutered.
My $399 Chinese Tech 2 works just fine on 1992-2010 GM, SAAB, Isuzu, etc. There are a few things to be aware of.
They're all coming from Mainland China. Likely from the same outfits that Bosch used to build the originals.
The power supply on some of the really cheap clones is less than stellar. Easy enough for a competent tech with the right tools to replace if need be. I swapped in a Mornsun in about 20 minutes but I have the tools and the experience. None of the clones have the ultra low voltage input DC-DC converter that Vetronix/HP used on the real deal so the unit will re-boot when you start the vehicle. We can't buy one either... However the Datel and Mornsun bricks work just fine down to 7VDC or so. I never had a situation where I needed it to stay up during a re-start. I'll probably just use a battery pak on the external power jack if I do.
The VCI on the super duper cheap units doesn't work properly if at all. Again if you get the $300 ish and up units from known sources that's not an issue.
The surface mount MAX232 RS232-TTL level shift chip in the serial port has been noted to be an incorrect part on some older clones. If your board has a MAX202 and you want to use the serial port you get to do float that chip off and float a MAX232 on.
IMHO the Tech 2 is dangerous to use as a J2534 passthrough tool. It depends on truly stable RS232 communication and that requires a real RS232 serial port with a Rockwell compliant UART that most computers just do not have anymore. Since the Tech 2 doesn't support 2010 and later rigs I bought a WiFi MDI clone for programming from AC Delco TIS. Your 1990 ECM likely uses EPROMs, not flash memory, and I doubt TIS still supports these rigs anyway... so this is a non-issue for you.
The Tech 2 linear flash card images, that are available in the wild, start with the 91 model year coverage. I'm not sure how good the Tech 2 1991 Model year coverage is. I generally use my Mastertech 3100 on the earlier stuff. You might or might not get away with lying to the Tech 2 about the model year.
The SAAB guys put together a pretty decent Tech 2 WiKi with binary images of the linear flash cards for the Tech 2 and even a locator to find someone local that has one. There's a "request membership" Tech 2 facebook page where you can get technical help as well.
http://tech2wiki.com/doku.php