PC Based ALDL (OBD 1) Diagnostic Software and Interfaces

[hatzie]

1982-1995 GM ALDL
PC hardware and software for diagnostic code reading and real-time data logging on the cheap... or at least a whack at it.

ALDL is an acronym that means Assembly Line Diagnostic Link It's a proprietary GM PWM TTL level Serial communications protocol. It was not standardized even loosely within GM divisions. It varied greatly by model, nameplate, year, and even engine choice.

Mr Goodwrench used the Tech I and later the Tech II to communicate with these vehicles. If you can find a working Tech I or a real Tech II they have more functionality than any aftermarket solution depending on your needs.
The Tech I is all but extinct (I haven't seen one for sale in over 2 years). Most of us can't afford a real Tech II and those are getting scarce. If I could afford a real Vertronix or HP Tech II I don't feel confident that I could weed out the Chinese counterfeits... there seem to be more poorly constructed Chinese knockoffs than the real thing now and they are priced the same or more.

12 terminal ALDL jack (OBD)
Repair parts Delphi 12020043 ALDL Jack with 15484100 FEM METRIPAK 280 18AWG Au PLTD terminals.

[A] ECM Ground
[B) Diagnostic Enable
[C] ECM to Air Switch Solenoid
[D] CLCC (If used) 160 Baud Serial Data TX only (1982-1986 Carburettor Trucks)
[E] 160 Baud TTL Serial Data TX only
[F] ECM Driver or Vac Switch for TCC
[G] Fuel Pump Prime
[H] RWAL VSS
[M] 8192 Baud TTL serial data TX & RX
Not all positions are populated on all vehicles and usually only one serial data line is present.

1995 16 terminal ALDL Jack (OBD 1.5)
This looks like 1996 and later J1962 OBD II jacks because it is physically the same jack. Electrically it is not the same. I would be sorely tempted to install the old ALDL jack if I owned a 1995 GM.
Repair Parts Molex 511151601 with Molex 50420-8000 terminals and Terminal Retainer 0511181605

[5] Ground
[9] 8192 Baud bi-directional TTL serial data RX & TX
[16]ECM + Power


"Paper clip" method

The diagnostic lamp is called several different things. SES (Service Engine Soon) MIL (Malfunction Indicator Lamp) CEL (Check Engine Lamp) these acronyms all refer to the same lamp... if it reliably lights during the bulb check, when the ignition is switched on, this method can probably be used.
NOTE: This will not work with 1994 & 1995 OBD 1.5 jacks

• With the ignition switched off... jumper ALDL jack terminals A & B with a piece of stiff wire or an ALDL Test Key.
  Lisle 22700 ALDL Test Key
• Further instructions and flash/blink code definitions by year/make/model here...
  GM Trouble Codes Through CEL

PC Method

• GM used 12 position Delphi Packard 12020043 ALDL diagnostic sockets on most US market vehicles from 1982-1994.
• 160 baud data on terminal E (sometimes on terminal D) is uni-directional TX only.
• 8192 on terminal M is bi-directional TX & RX on some models.
• In late 1994 & 1995 GM used the, soon to be OBD II, J1962 diagnostic socket with 8192 baud bi-directional ALDL data on terminal 9.
• You can read codes and some sensor data, like the CTS, MAP, TPS, and O2 sensor directly from the 1982-1995 ECM using the ALDL port.
  The older ECMs will have less available data. I'm not really sure what you'll get from the early 1982-1986 Electronic Carburettor engines... I've never tried.

You'll need

• An old PC or laptop for the garage
• Software
• 1982 - 1994 use a 12 terminal ALDL cable.

  It's worth noting... 1995 is the ONLY YEAR that GM vehicles with ALDL have the 16 terminal J1962 "OBD II" interface socket that some folks call OBD 1.5... It's 8192 baud TTL level serial TX & RX.
  If you don't have a late 1994 or 1995 don't worry about the orphan 16 terminal ALDL cable.

The PC

This used to be the most expensive part. Thankfully the requirements are pretty low even if you intend to use it for OBD II / GMLAN (CAN) diagnostics.
A lot of companies and schools are getting rid of their old Windows XP laptops now that support for XP really has ended. Since a diagnostic laptop doesn't need to access the internet that's not a problem. There are some pretty good deals on lightly used brand name laptops right now. Get em while they're cheap and plentiful.

Minimum specs needed OBD I, OBD 1.5 &, and OBD II/CAN Diagnostics with Windows XP.

• Windows XP or Windows 7 Skip Windows Vista.
• Lithium Ion Battery not Ni-MH
• Dual Core 1.5ghz Processor Windows XP and Windows 7 will run and multi-task better with more processor.
• USB Port(s).
• 15.4" HD screen... WXGA 1280 x 800 is very common... HD is 1280x720. More pixel density is nicer. My 13 year old HP NX7400 is 15.4" WUXGA 1920x1200 pixels.
• 1-4gb RAM. 32 bit Windows XP will not address more than 3.25gb RAM but will run better with more than 512mb. Windows 7 should have minimum of 4 gb.
• 80-100 GB+ HDD. More is usually better but usually costs more. Above 250-300gb SATA may run into BIOS and operating system (driver needed) compatibility problems on some older Windows XP laptops. For Windows XP make sure there's at least 30-40gb free. 300-500gb is minimum for decent Windows 7 performance.

- Whatever you buy be sure it's listed as completely WORKING, has the AC Power supply, has a charged battery even if it's tired (it proves the charge circuit is working), has the Hard drive, has USB ports, and has a legible Microsoft COA sticker just in case you have to reload Windows.
- If the seller has not wiped the HDD you may want to wipe it from a boot disc and re-install a fresh copy of Windows to get rid of the Prior owners personal information, viruses, Pirate software, corrupted registry settings, and other things you just don't want to know about or be associated with.
- It's very nice if you can get the OEM Windows install media included because it'll have the drivers you need slipstreamed into the installation media. However. You can usually find someone to get you bootleg copies of bare bones XP SP1 or SP2 OEM discs to legally use with your OEM COA... Dell, HP, Lenovo, etc have drivers for pretty old machines available for download.

- The Dell D500, D600 &, D800 series (D520, D530, D620, D630, D820, D830, ...) laptops were VERY popular so they are extremely plentiful, they have cheap Lithium Ion batteries, they can run Windows XP Pro or even Windows 7 Pro, many of these older laptops have a real 9Pin RS232 serial port and, most will have at least one or two USB Host jacks. Everything a garage laptop needs. http://www.ebay.com/bhp/dell-d620
- Some of the HP Enterprise class laptops that run Windows 7 like the HP Elitebook 8560P and the older NX series like the NX7400 are getting pretty reasonable but not as reasonable as the used Dell D-series I referenced above. You do get what you pay for because the HP Elitebook has a much tougher Aluminum case than the Dell units and both the Elitebook and NX series have an extended use secondary battery but the batteries are more expensive and less available because the HP was not as popular.
- Look on laptop forums for what commonly breaks on some of these machines... For instance. The HP NX series screen hinges tended to break if they were not lubricated.

Free ALDL PC Software

• GMTDScan Basic is a freeware diagnostic trouble codes reader for GM's 1994-1995 6.5TD trucks.
• WinALDL freeware. WinALDL will read sensor data.
• TunerPRO freeware. TunerPRO will read and log sensor data and clear codes.
• TunerPRO RT is donationware TunerPRO RT has a list of additional features not present in TunerPRO.
  There's a nag reminding you to register. I usually support donationware like this that actually works but you are not required to pay for continued use.

  Here are some YouTube video searches that should give you an idea of what they are capable of doing and how to use them.

• http://www.youtube.com/results?search_query=winaldl
• http://www.youtube.com/results?search_query=TunerPro

Commercial ALDL PC Software
I don't own any of these packages. All of them do much more than scan for trouble codes.

• GMTDScan Tech diagnostic scan tool for GM's 1994-1995 6.5TD trucks. It's supposed to be on-par with the GM Tech 1, 1A, & II for these trucks.
• TunerCat

USB and RS232 ALDL Interface Cables

1982-1994 12 terminal or 1995 16 terminal moulded plugs.
Commercial cables are fairly inexpensive... around $55.

• 1320 Electronics USB or Bluetooth or Both to ALDL 12 & 16 terminal moulded plugs. The 1320electronics interfaces have status LEDs. The Bluetooth can be set by the manufacturer to the CLCC data pin D but it's not user selectable. The Bluetooth interfaces can also be requested to draw power from pin G.
• 12 terminal USB only cable has a very very nice feature that I have not seen on any other cable... data is user dipswitch selectable for D, E, & M you do not have to buy a bare terminal cable to talk to the CLCC "terminal D" ECMs.
• Red Devil River USB or Bluetooth to ALDL 12 & 16 terminal moulded plugs.
• CK5 forum RS232 to ALDL DIY Howto DIY RS232 to ALDL.
  Note: Be sure the PC/Laptop has a DB9/DB25 RS232 Serial port on COM1-COM4 with a standard Rockwell compliant buffered UART using standard base addresses and standard IRQ channels. Introduction to IRQs, DMAs and Base Addresses
• Gearhead EFI Forum Uber-easy DIY USB to ALDL Cable DIY USB to ALDL
  Note: DIY cables will not have OEM type moulded plugs unless you can find a supplier. Moulded ends are not inexpensive.

Hopefully this is useful to you folks.