OBD1 1995 Silverado

**geekazoid** · 05-18-2005, 12:28 PM

I purchased an ALDL cable form ALDLcable.com for use on my chevy OBD (pre OBDII). I have a 1995 Silverado 1500 6.5L turbo diesel.

Anybody know what software will work for OBD1 systems?
I have tried several, with no luck. I was kind of rushed when I tried it out last night, but could not get any software to read the data. I will continue trying, but would appreciate anybodys input.

**lostreception** · 05-19-2005, 03:11 AM

what type of engine is it tbi efi? 5.7 ltr try searching for that in google itll generate some hits ALDL + "your make model" "type of engine"(if you know) etc

have u tried winaldl that might have it

also try getting the number off of your ecu and googling that thats how i found mine

**geekazoid** · 05-19-2005, 09:22 PM

It is a 6.5L turbo Diesel engine.

I have retried a bunch of the applications with no luck. Datamaster, FreeScan, TunerRT, EFILive, WinAdl, ECM852.

I did however find an application that probes the comport with an F4,56,01,checksum, the Truck echoes the command back, then sends a 25 byte reply of f4,6b,01,00,00,00,00,00,00,00,01,00,00,00,00,00,00 ,00,00,00,00,00,00,00,9f. The 6b in this reply is the number of bytes which is 52-6b, or 25 bytes in decimal, so it is some sort of valid reply. That is the end of the transmission of data.

Should this data continue to stream?
How do I know if the cable supplied by ALDLCABLE.COM will work with a 1995 Silverado (pre OBDII) ????

Anybody know anything about the Pre OBDII cables, what is valid, what isnt???

TIA.

**geekazoid** · 05-21-2005, 10:08 AM

Ok, I found the codes on the ECM.

They are:

BPAK

16216935

Serv No. 16212488

When I check the broadcast code BPAK on
http://www.efitune.com/broadcast_codes/

The only matching ECM ID is: 16212450

Is this an incomplete list?
What next?

**lostreception** · 05-21-2005, 10:20 AM

try searching for that ecm num in goggle and the key word obd etc yu might find what ur loking for that way

**geekazoid** · 05-22-2005, 05:52 PM

Well, I have been doing some more research and playing around. Since I am a professional software engineer, I started playing with some source code to probe.exe. I have found that my cable/truck combo has no problem communicating. When I send a request of "F4 57 01 00" I always get a correct response...likewise with other commands.

I am able read plenty of data from the ECM.

However one issue that I have is that there is never a steady stream of data from the ECM. It only returns data as the result of a request. It seems all of these aldl programs expect a steady data stream from the ECM.

I have used PORTMON to monitor com port activity while running most of the applications, and it appears that every single application is just monitoring the port to get data, but my vehicle/cable combo do not provide constant data.

Is there two protocols here? Why wouldn't any of the aldl programs send requests and get responses?

The aldlcable.com circuit does not use the more complictated max232 design, is the max232 design required to get constant data flow?

Anybody know about constant data flow?

...

**ManicMechanic** · 03-11-2008, 08:34 PM

Depending on what your trying to do you might try GMTD Scan. I have found it very helpfull in diagnosing Injection, Fuel and Boost issues on two 1995 6.5L TD's. Turbo Scan Basic is free, pro is for cost if your interested.

http://www.enghmotors.com/basic/default.aspx

Best of Luck
Tim

**perk03z06** · 03-12-2008, 05:41 PM

Originally Posted by geekazoid

Well, I have been doing some more research and playing around. Since I am a professional software engineer, I started playing with some source code to probe.exe. I have found that my cable/truck combo has no problem communicating. When I send a request of "F4 57 01 00" I always get a correct response...likewise with other commands.

I am able read plenty of data from the ECM.

However one issue that I have is that there is never a steady stream of data from the ECM. It only returns data as the result of a request. It seems all of these aldl programs expect a steady data stream from the ECM.

I have used PORTMON to monitor com port activity while running most of the applications, and it appears that every single application is just monitoring the port to get data, but my vehicle/cable combo do not provide constant data.

Is there two protocols here? Why wouldn't any of the aldl programs send requests and get responses?

The aldlcable.com circuit does not use the more complictated max232 design, is the max232 design required to get constant data flow?

Anybody know about constant data flow?

...

GM's first generation diagnostic platform (OBD1) as well as their second generation (OBD2) both rely on request/response data transmissions. The only way to get constant data flow is to repeatedly be pinging the ECM with requests, and of course, waiting the appropriate amount of time in between for responses (I think GM's max response time is 200 msec) ... but ... where I was headed with this ...

Why not just buy a product from a company that has already done all the legwork, and has the OE specs to know how to interpret the returned data? It'll be a PITA for you to know the response ranges that the ECM could give you and what they mean ... trust me.