Scan tools (ALDL not OBD-II)

[Padgett]

I have been scanning/tuning my cars since the mid-eighties (first PROM analysis was done with a FORTRAN disassembler on a VAX). It allows me to combine my two passions, cars and computers (with a touch of my third, cryptography)

 

The GM computer up to the OBD-III era has always been based on a Motorolla 6809 8 bit processor and can see bits of the original '81 CCC in the '93 GTP. Scanning and the ALDL is easy compared to the Manchester bus in an aircraft.

 

In the past, an OTC-2000 scanner  and the C.A.T.S. software plus a Pocket Programmer from XTRONICS was all I needed but by 2010, the aging EPROMs in my Reattae stopped programming reliably. Besides the Reattae had a built in scan tool equivalent to a Tech 1, and the 88 had a touchscreen in the dash to display it.

 

Early 2012 brought the Jeep and OBD-II which is much easier and I can program from my cell phone. This state continued with the arrival of the Crossfire but in March the GTP appeared on my doorstep and I have been learning ALDL all over again. Fortunately there was A Log going on at the turn of the century of disassembling GM ECMs and reprogramming them. I still had all of that in backup.

 

Some is still around but not as cheap as OBD-II. $55 to $80 for a 12 pin connector and USB circuit and a $39 "donation" for Tuner Pro RT (real time). Then took me about 4 hours to get and build all of the configuration files to make it work. Did I mention that documentation ranges from poor to none and the target OS was Win98 ? Fortunately it can be made to work with Win 10.

 

In any event I can now scan multiple parameters on the GTP at once and does not look like I have an inlet manifold vacuum leak. Does still need some tweaking but "good enough for government work" now.

 

 

Question is "Does anyone here care ?" Does not really matter to me but would be happy to help others avoid the learning curve.

[Galaxie500XL]

I'd be very interested, as I'll begin the learning curve for my '88 IROC soon.  GM never offered the L98 350 TPI with a manual transmission, which means ideally, I'm going to have to learn how to tune the Camaro to get the best possible performance and fuel mileage.

 

As things sit now, it runs well enough, and surprisingly gets 20-23 MPG on my usual daily commute (the LQ1 Cutlass convertible I was DD got around 20-21)....but I think things can be improved, at least incrementally.

[Padgett]

Few years ago I helped a friend retune an 88 Reatta for an L67 & Getrag (Reatta never came with a manual either) Was mainly removing 4T60 related error routines and adapting maps from a '94 PA to run with the digital dash.

 

Didn't Corvette have a manual trans with that motor ? Or maybe a truck. It is always easier to start with a similar .bin.

[Imp558]

I start looking at the downloads on that Tunerpro software and Saar has done work on that project. He's everywhere

[Galaxie500XL]

Few years ago I helped a friend retune an 88 Reatta for an L67 & Getrag (Reatta never came with a manual either) Was mainly removing 4T60 related error routines and adapting maps from a '94 PA to run with the digital dash.

 

Didn't Corvette have a manual trans with that motor ? Or maybe a truck. It is always easier to start with a similar .bin.

Gets a little weird there. The Corvette L98 had aluminum heads. The F-bodies got cast iron. For transmissions the years the Corvette used the L-98, they got a weird Doug Nash "4+3" setup, a 4-speed transmission, coupled to a 3-speed overdrive unit, which gave the cars 7 possible gear ratios,

[Imp558]

From moates.net:

 

"This is for any pre-1995 (OBD1) GM vehicle. Everything except the 1995 LT1. You should be able to datalog all of them, and reflash the 94 LT1 as well"

 

That's very odd, both years use the 16188051 PCM, Tunercat processes both years exactly the same.

[RobertISaar]

From moates.net:

 

"This is for any pre-1995 (OBD1) GM vehicle. Everything except the 1995 LT1. You should be able to datalog all of them, and reflash the 94 LT1 as well"

 

That's very odd, both years use the 16188051 PCM, Tunercat processes both years exactly the same.

 

if i had to guess, I'd say the change to the OBD2 connector under the dash is the only real issue.

 

Gets a little weird there. The Corvette L98 had aluminum heads. The F-bodies got cast iron. For transmissions the years the Corvette used the L-98, they got a weird Doug Nash "4+3" setup, a 4-speed transmission, coupled to a 3-speed overdrive unit, which gave the cars 7 possible gear ratios,

 

I believe starting in 1989, a conventional 6-speed manual was used, the 89 model year calibration has parameters in it for the stupid 1-4 forced upshift solenoid(CARS/CAGS).

 

I start looking at the downloads on that Tunerpro software and Saar has done work on that project. He's everywhere

 

reminds me, I actually still have a lot of files to upload to Mark to fill out the list.

[Galaxie500XL]

I had forgotten about the 6-speed used in Corvettes beginning in '89...I've really not paid much attention to the 'Vette over the years, I always knew I couldn't afford one, and two seats don't work well for a guy with 3 kids.  But, the kids are grown now, so maybe one day, when the current Stingray depreciates enough, I might actually be able to afford one. 

[Padgett]

Depends on what you want. Fieros stopped being comfortable so I moved to Reattas. Think of it as a commuter car.

 

I have a lot of 5B stuff but with the ALDLStuff suite of .ds modules all you really need is the custom dash. I also use TunerCat (or a hex debugger) to modify .BINs.

 

The thing that changed in 94-95 was the error code flags. Through 93 they were the first words (GM called bytes, words which is incorrect but in the 80s who cared ?) in the data stream, but OBD-II added many more codes so they were moved to the end.

 

Have to understand that an ALDL transmission is just a serial datastream with the length in the header. Code reader just requests and then the fire hose opens up. GM uses many, many different data streams depending on the year, make, and drivetrain. Values may be bits (flags), bytes/words (8 bits), or double words (16 bits) and it is up to the requester to know which is who.

 

Scan tools have to store all of the streams for all of the years they cover. My latest OTC-2000 has everything from 84 to 94 for GM, Ford, and Chrysler. With the DIY-EFI tools like TunerPro RT, everything is manual. It needs both the full datastream sequencing (the .XDF file) and then what you want from it with screen location and output format and requires parameter adjustment in two different places. Still it is a lot better than having to do everything by hand.

 

And that is just for a display. Tuning requires a whole different set of parameters relating to where what is in the PROM. And the tuners just well, tune. They do not edit. So if you want to remove all of the 4T60E related parts and errors because you just switched in a Getrag and GM never made one of those, then you need a real programmer who understands the Motorolla 6809 (actually supplied to GM by Hitatchi). With adding maps for the L-67 with a larger capacity MAF, that took me about a month. Not trivial.

 

ps still tweaking the display for the LQ1/M27

 

 

Edited May 6, 2016 by Padgett

[Imp558]

if i had to guess, I'd say the change to the OBD2 connector under the dash is the only real issue.

.

But that was only the F body, the B&D kept the 12 pin until the 399 PCM came and brought OBD II to the LT1/L99. Maybe there's some confusion because of that p.o.s 333 PCM the vette had in 94-95.

[Padgett]

OK have been studying my files again (thanks Robert for all the data) and until I see a 94-95 this is what I think (have not dug my Fiero C3 stuff out so all is P4).

 

1) ALDL aka OBD-I (OBD is actually a military term grabbed by either the Fed or the SAE and was not used until later). 12 pin connector. GM format.

2) 94-95 OBD-1.5 LQ1 used 12 pin, LT1 used 16 pin that looks like OBD-II but isn't.  See here. GM type commands/messages. OBD-II error codes.

3) OBD-II. 16 pin connector. SAE standard command and messages. Requred for US cars after 1 January, 1996

Note: OBD-II standardized commands and message for defined functions. Each manufacturer has proprietary PIDs (commands) and responses. Tuners and professional scan tool manufacturers (Tech-1, Autoenginuity) usually have the undocumented features such as ABS and Automagic transmission data.

 

Note the commands are standardized, the transmission protocols (think: types of serial data. Be glad they did not use Manchester coding or BCD).

 

Two major differences between ALDL and OBD

ALDL displays two digit error codes. 12 is normal, rest start at 13 (O2).

OBD used a prefix letter (P-powertrain) followed by a four digit code (P03xx means misfire. The last two digits mean which cylinder. 10 cyl and larger must specify which bank.

The codes themselves must be interpreted, the data stream just has a single bit flag. Which code it is must be interpreted from the position in the stream.

 

Prior to '96 Ford, Chrysler, AMC, and some imports had their own coding systems.

 

There was some panic that since the odo is just software, rolling back would be easy. The response was to hide the reading and use redundancy. The reality was that the computer had to be able to display the ODO so the code to set/retrieve was all in the program. Programs can be dumped (actually there are ways to prevent dumping but fortunately they also had to be designed for less than brilliant service personnel.

 

I decoded the PROMs for an 84 Fiero I acquired on a VAX. Had to write the disassembler in Fortran. Still have it.

 

So getting back in and have about 25 years of notes. Was a lot more ALDL activity a decade ago. Need to visit the recycling center and get some 3.1 or 3.4 Calpacs. Since under the reservoir may still be some there.

Edited May 8, 2016 by Padgett

[Imp558]

Anybody know of a list of OTC Cartridges and their applications for the 4000e? I see Padgett on a page with a lot of info on an earlier model but I can't find a breakdown of available carts for the one I got from another member a while back.

[55trucker]

All the cartridges for the 4000E would be the Pathfinder series.

 

Pathfinder/Pathfinder II/Pathfinder III/Deuce '01/Deuce '02

[Padgett]

I have a couple of 2000s from the last time I got deep, 4000s were too expensive then. Any more I do everything with a netbook so can log and display multiple things at onece.

[Imp558]

I just bought a brick too, Snap On MT2500 with a ton of extras.