73-87 Chevy _ GMC Trucks > Fuel Systems and Drivability

Writeup PC ALDL (OBD 1) Diagnostic Software and Interfaces

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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.
ALDL is not always OBD 1 but OBD 1 was ALDL...  OBD 1 was the 1991 California stab at standardization of automotive diagnostics prior to Federal adoption of the much more comprehensive SAE OBD II standards.

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 can 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 I)
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
[M] 8192 Baud TTL serial data TX & RX [/FONT]
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[/FONT]

"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...[/list]
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. [/list]
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
[*]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.
The OS tends to determine minimums more than any diagnostic software.
[*]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).
[*]14" 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.
-  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. [/list]
Here are some YouTube video searches that should give you an idea of what they are capable of doing and how to use them.

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.
[*]TTS Datamaster

USB and RS232 ALDL Interface Cables
1982-1994 12 terminal or 1995 16 terminal molded plugs.
Commercial cables are fairly inexpensive... around $55.
[*]1320 Electronics USB or Bluetooth to ALDL 12 & 16 terminal moulded plugs.  These interfaces have status LEDs and their 12 terminal USB only cable has a very very nice feature that I have not seen on any other cable... data is dipswitch selectable for D, E, & M you do not have to buy a bare terminal cable to talk to the "terminal D" CLCC 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 molded plugs unless you can find a supplier.  The molded ends are usually expensive.

Hopefully this is useful to you folks.

Android ALDL OBDII & CAN (GMLAN) Diagnostics
I will be adding to and refining this writeup.
Android Devices
Android tablets and phones are not my first choice for ALDL datalogging and diagnostics. Android devices with displays, memory, and and file space even close to a cheap laptop are expensive and the Android ALDL software is expensive compared to the free offerings for the PC that have more functionality.  If you already own an Android tablet or phone with good screen resolution, enough memory, enough storage, and enough processor speed the software becomes somewhat easier to justify.
If you're doing OBD II and CAN the price gets a lot more reasonable because most decent PC based OBD II diagnostics packages are very expensive and the Android packages are not.
I don't recommend using USB interfaces with Android yet.  There are very fast high quality Bluetooth interfaces for both ALDL and OBD II for not much more money. The Android Bluetooth stacks and the Bluetooth chipsets in most Android devices are very robust and work quite well. 
It's not as straightforward to use USB Host (USB OTG) interfaces in Android.  Not all phones and tablets support the whole USB OTG stack because most consumers are just looking to plug in thumb drives not the serial output from a car or truck.  You might have USB OTG with Serial Host mode right out of the box or you might have to root your phone or tablet and hack Serial USB OTG into the kernel along with the Chipset drivers assuming it's even possible.  Android also has a limited number of supported USB to Serial chipsets when the USB Serial host is actually installed.  It's not just the OS.  The application software has to support the chipset too.
The cheap Chinese Android tablets and phones are not usually worth getting.  Typically the screen pixel density is very low in comparison to decent tablets... Good 10" tablets are 1920x1080 while cheap 10" tablets are 1024x600 same as a quality 7" tablet so text and images end up pixellated and fuzzy.  On top of that they are typically filled with poorly replicated chips or blems that didn't make the QC cut.  Functionality like Bluetooth and WiFi is adversely affected.

[*]ALDL Droid From Sébastien Giroux.  Can use USB OTG (FTDI only) or Bluetooth interfaces.
Note: You will need TunerPro ADX config files for your ECM.  You can also edit BIN files for tuning with Craig Moates chip tuning hardware.
[*]ALDL Scan From 1320 Electronics. Can use Bluetooth interfaces.
Note: You will need to download and install the correct ALDL config file for your ECM from his page.

[*]Torque Pro $5.00 US. Capable of using free and paid plugins and several other features not in the LITE version.
You should enable extended GM PIDs. From the main screen press Menu->Settings->Manage extra PIDs/Sensors.  Then. "Menu->Add predefined set->Pontiac/GM/Opel/Vauxall".  Viola! You just added all Pre-Defined GM PIDs to the available PID list.
Torque Pro Wiki
[*]TorqueScan Very Useful FREE Torque plugin.
After you install this goto Menu->settings->plugins and tick the "Allow plugins full access check box" TorqueScan will show all the known sensors that it can read from the installed list of PIDs along with the realtime data being read. That's useful enough, but if you want some real magic goto Menu->PID Scanner to scan for additional PIDs while you're on a longer drive. The PID scanner says it will take a long time... YUP it does.  Be sure your device is plugged into a charger.  It's worth the wait. The PID Scanner function of TorqueScan will compile a list of all available extended PIDs on your vehicle including those not in the pre-defined list.
Note: I use TorquePro with TorqueScan.  There are several other OBD II apps in the Play Store.  I don't use them so I have no idea of their functionality.

Interfaces Bluetooth & USB
1982-1994 ALDL 12 terminal moulded plugs
1994-1995 16 terminal J1962 moulded plugs.
1996-2005 OBDII and 2006 and later J2411 CAN with 16 terminal J1962 moulded plugs.
NOTE Commercial ALDL, OBD II, and even OBD II/J2411 CAN interfaces are again fairly inexpensive... around $55-$100.

ALDL 12 & 16 terminal Interface
[*]1320 ElectronicsBluetooth to ALDL 12 & 16 terminal moulded plugs. 
Note: 1320 electronics is the developer of ALDL Scan. Their interface has COM status lights and easy configuration dipswitches. Their USB-only cable has user selectable switches to select data from pins D, E, & M.  The Bluetooth adapters data pin settings are internal jumpers with a default of E & M that covers 90% of users and possible custom configuration of data from D by request.
[*]Red Devil RiverBluetooth to ALDL 12 & 16 terminal moulded plugs.

OBD II & CANBUS J1962 Interface
It's worth noting the Chinese ELM327 Bluetooth OBD II interfaces are very very cheap.  The price should be a red flag.
There are more than a few stories of damaged PCMs using the super Cheap Chinese OBD II devices. 
They usually have various issues some large some small.  They seem to be luck of the draw.  You might not get a lemon but you are very likely to.  If you buy one be SURE you can return it if it doesn't work. 
Don't ask for guidance here making the Chinese interfaces work.  Most are full of poorly copied stolen chip designs in either the ELM327 PCM ECM connection or the Bluetooth radio or both and there's no way to tell what you're getting. 
IMHO the cheap and super cheap Chinese interfaces are not worth your time.

[*]OBDLink™ MX Secure Bluetooth Wireless
Goes on sale for $79.95 fairly often.  Multi-protocol interface covers OBDII GM (J1857 VPW) & SAE J2411 Single-Wire CAN (GMLAN) and others.
Note: TorquePRO; This is the best adapter if you want the fastest PID read speed. Read speeds can be as fast as 100PIDs/sec over Bluetooth (Tested on a Galaxy S4, CANBUS protocol). This device also offers security to prevent unauthorized use.

Hopefully this provides a good jumpstart to your search...

LTZ C20:
Ok I find all of this extremely interesting. I am very familiar with using Tech I and Tech II units. Use them at work alot. It seems now the only times we use the Tech I is when the odd ball older car comes in which is pretty rare or I use it for my truck.

We have 6 Tech II's, all with the "CanDI" modules and we also have 4 or 5 MDI 1's and we just got 4 MDI 2's.

So trying to find a scan tool to buy for myself has been a giant pain the butt, I would be happy with a Tech I, however I have found just like you, that finding one of those is not easy. And my work as no interest in selling me theirs.

I have a Matco Code reader/clearer that also does I/M monitors and some other things but it only works with OBD II vehicles 1996-present. Since my truck runs on ALDL OBD I, I have to borrow works when I need to communicate with the ECM.

So now here are my questions as you seem to have a way better understanding of how this works than I do.

I have a laptop that uses Windows 7. What is the easiest way to have all of the functionality of a Tech I to use for my truck.

Even better, I have a Samsung Galaxy S6 Active smart phone, what is the easiest way for my to get all of the functionality of a Tech I on my phone. Honestly on my phone would be even better than my laptop because then I done have to have my nice laptop out where it could get damaged. My phone is about three quarters the size of a Tech II screen and way better than a Tech I screen ever was obviously.

So how do I turn my phone in to a working Tech I?

 I'm only concerned with the trucks OBD I system, if I have an issue with any of my OBD II vehicles, I'll just read codes with my Matco handheld unit and then use a scan tool at work for anything advanced I need.

With all the info you provided in your posts and watching the videos and following links, I've become a little lost and confused I will admit.

Information is more than a little fragmented.  I was attempting to put together a place to start.

I assume you have a 1982-1986 CLCC (Closed Loop Carburetor Control) ECM with data on terminal D of the ALDL jack? 
WinALDL states that it supports those ECMs.  I'm not sure about ALDL Droid or TunerPRO RT.  I quickly looked at the available ADX files and didn't see the 1982-86 CLCC computers listed.

If you have a CLCC truck I would start inexpensive.  Get one of the 1320Electronics USB & Bluetooth - ALDL cables and try listening to the ECM with WinALDL on your laptop.

LTZ C20:
I have an 89 TBI system, controls TCC lock up also, 1 4-wire O2 sensor. It's the same system as an 89-91 2500 TBI truck with a 350. Mine has a big block TBI tho because the small block TBI can't sufficiently support my engine mods.


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