The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Problems running at operating temperature

**hatzie** · 09-19-2021, 01:51 PM

1988 GM truck will have an ALDL (assembly line diagnostic link) jack. People call this OBD I, it's not. OBD I is mid 1990's California emissions only. Everything else is whatever proprietary diagnostics the manufacturer used.

You don't need a scan tool to read the diagnostic info from an 88.
Name: ALDL Jack.gif
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Name: ALDL Jack.gif
Views: 260
Size: 4.4 KB

Turn the ignition on and DO NOT START THE ENGINE.
Short the ground to the diag terminal of the ALDL jack. Terminals A & B. This will start the diagnostic mode.

The MIL will flash code 12 three times. Code 12 is one flash, a short pause, then two flashes.
The MIL will then flash the two digit codes stored in the same manner as code 12.
All stored codes are displayed 3 times each then a code 12 will repeat.

You can build a serial to ALDL interface and use an old PC or laptop with an actual Rockwell RS232 serial port or buy a USB to ALDL cable to talk to an ALDL equipped vehicle with WinALDL, TTS Datamaster, or Tunerpro RT.

Moates GMECM will run on MS DOS 6.22 or Windows 95/98. It doesn't play well with NTVDM so 32bit versions of Windows 2000, ME, XP, Vista, and Windows 7 will not have a lot of success running this. NTVDM ended with 32 bit Win 7 so there's no chance with 8, 10, or 11.

There's not a lot of data coming from these early ECMs. If you had a Tech1 or Tech 1a or a Bosch Mastertech 3100 you could get some bi-directional control of a handful of things. The Tech1/1a is 30+ years old and likely any you'll find will be in need of a fair amount of repair if it's even possible to resurrect them. The Mastertech is over 20 years old. They won't give you enough to make it worth the scavenger hunt to find the cartridges, cables, and working handheld tool.
I sold my Tech1 with my 1990 Corvette. I recently repaired it for the buddy that bought it from me. Capacitors, a couple other discretes, and corrosion from being stored without a plastic bag. Luckily no proprietary chip damage. The PVC diag cable jackets are cracking and they're made of unobtainium now. I don't miss it.

You're better off with a decent quality digital multimeter, analog multimeter, the GM service manuals and, maybe a 4channel scope.

09-19-2021, 01:51 PM	#6
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,913	Re: Problems running at operating temperature 1988 GM truck will have an ALDL (assembly line diagnostic link) jack. People call this OBD I, it's not. OBD I is mid 1990's California emissions only. Everything else is whatever proprietary diagnostics the manufacturer used. You don't need a scan tool to read the diagnostic info from an 88. Turn the ignition on and DO NOT START THE ENGINE. Short the ground to the diag terminal of the ALDL jack. Terminals A & B. This will start the diagnostic mode. The MIL will flash code 12 three times. Code 12 is one flash, a short pause, then two flashes. The MIL will then flash the two digit codes stored in the same manner as code 12. All stored codes are displayed 3 times each then a code 12 will repeat. You can build a serial to ALDL interface and use an old PC or laptop with an actual Rockwell RS232 serial port or buy a USB to ALDL cable to talk to an ALDL equipped vehicle with WinALDL, TTS Datamaster, or Tunerpro RT. Moates GMECM will run on MS DOS 6.22 or Windows 95/98. It doesn't play well with NTVDM so 32bit versions of Windows 2000, ME, XP, Vista, and Windows 7 will not have a lot of success running this. NTVDM ended with 32 bit Win 7 so there's no chance with 8, 10, or 11. There's not a lot of data coming from these early ECMs. If you had a Tech1 or Tech 1a or a Bosch Mastertech 3100 you could get some bi-directional control of a handful of things. The Tech1/1a is 30+ years old and likely any you'll find will be in need of a fair amount of repair if it's even possible to resurrect them. The Mastertech is over 20 years old. They won't give you enough to make it worth the scavenger hunt to find the cartridges, cables, and working handheld tool. I sold my Tech1 with my 1990 Corvette. I recently repaired it for the buddy that bought it from me. Capacitors, a couple other discretes, and corrosion from being stored without a plastic bag. Luckily no proprietary chip damage. The PVC diag cable jackets are cracking and they're made of unobtainium now. I don't miss it. You're better off with a decent quality digital multimeter, analog multimeter, the GM service manuals and, maybe a 4channel scope. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful. Last edited by hatzie; 09-19-2021 at 01:56 PM.