Wiring Schematic for bench harness LT1

[EDZIP]

Mark supplied me a file with the schematic to make a bench harness for the OBD1 LT1, I can't locate the file right now but have a hard copy. Made a harness and checked it several times....

I pinned the harness by "pin numbers" used in the schematic but when using WinFlash...keep getting an Error that it can't communicate with the PCM..

Rechecked the pins again, have the correct Com Port, Selected V8 LT1 still can't read.

Looking at the schematic are we looking at the harness connectors or PCM side, also what is the view of the OBD connector in the drawing?

Thanks

[steveo]

a is red. b is black. c is grey. d is blue.

ground a2, c32, a18, d1

power b15, b31, b30, d3

d30 is your serial line.

the numbers are stamped right on the connector pins. you can't screw it up.

[EDZIP]

a is red. b is black. c is grey. d is blue.

ground a2, c32, a18, d1

power b15, b31, b30, d3

d30 is your serial line.



the numbers are stamped right on the connector pins. you can't screw it up.

The PCM connectors are numbered (and good to go). The OBD plug (car side) isn't numbered, my 95 LT1 manuals don't show the 16 pin connector...only the 12 pin.

So looking at the car side (female)...what are the pins numbers or assignments for the 16 pin OBD1 connector?

Thanks

[dave w]

Attached is the Schematic I'm using.

I'm using the OBD I Style ALDL connector.


dave w

[dave w]

The PCM connectors are numbered (and good to go). The OBD plug (car side) isn't numbered, my 95 LT1 manuals don't show the 16 pin connector...only the 12 pin.

So looking at the car side (female)...what are the pins numbers or assignments for the 16 pin OBD1 connector?

Thanks

OBD II Connector
Pin 4 Ground
Pin 5 Ground
Pin 9 Data
Pin 16 Battery +

dave w

[EDZIP]

OK...making progress, the schematic Mark gave me is from C.A.T.S. Titled - Off Board Programming Cable- LT1

The CATS Diagram has the ALDL connector pin 2 (data) connected to blue connector 7 (data)

Your drawing has ALDL pin 9 (data) connected to blue connector 29 (data)

One of the drawings is wrong and I bet your's works?

Ed

[EDZIP]

Looking at my manual.....it appears that the CATS schematic is for OBD2 LT1


So OBD1 would be as your schematic shows????

[roughneck427]

http://shbox.com/1/1995_pcm1.jpg

[EDZIP]

First Off "Thanks" to Dave W...repinned to your diagram Dave and WinFlash read and copied my PCM bin. The schematic that I got from Mark is pinned for the OBD2 LT1 data ports. I'll be sure to save your version.

Roughneck427...that schematic you posted is the same one I have...it shows the 12 pin ALDL and my 95 LT1 has the 16 pin (J1962) connector...in any event I'm good to go..Thanks for the help.

Ed

[roughneck427]

Hmm that's strange when I open the link on shoebox site it shows a 16 pin aldl for a 95 either way glad you got it working!

[dave w]

I broke down spent the MEGA $'s for a used wiring book for $6.82!:thumbsup: See attached picture.

That's less money than a pack of wire zip ties!:laugh:
dave

[EDZIP]

I broke down spent the MEGA $'s for a used wiring book for $6.82!:thumbsup: See attached picture.

That's less money than a pack of wire zip ties!:laugh:
dave


Just bought one (used also) on Amazon...cost me $10.81 shipped.....price of zip ties went up:-)

Some were selling for over $75 and approaching $100

Thanks

[EagleMark]

Sorry about that Ed. I renamed my file for OBDII so it does not happen again, it is in my OBDI folder...

Those 1995 LT1 are confusing as not all, but some do have the OBDII connector.

That looks like a good book for the money. Now we just need the binder pulled off and run it through a automated scanner, saved in .pdf and we are set... :innocent2:

EDIT: Prices sure have gone up since you guys started buying... :rolleye:

[dave w]

Sorry about that Ed. I renamed my file for OBDII so it does not happen again, it is in my OBDI folder...

Those 1995 LT1 are confusing as not all, but some do have the OBDII connector.

That looks like a good book for the money. Now we just need the binder pulled off and run it through a automated scanner, saved in .pdf and we are set... :innocent2:

EDIT: Prices sure have gone up since you guys started buying... :rolleye:

Maybe the 1994 ~ 2003 Domestic Light Truck is more to your wiring needs, LSx pickup wiring? Prices starting at $15.86

http://www.amazon.com/Engine-Control-Diagrams-Identification-1994-2003/dp/1582511756/ref=sr_1_3?ie=UTF8&qid=1391218363&sr=8-3&keywords=engine+control+module+wiring+diagrams+%26 +pin+identification+1994+-+2003

dave w

[EagleMark]

Ha! Got me a book! :thumbsup:

[lionelhutz]

You do know you can torrent a GM repair manual virtual image which says it covers 98 to 04 but it does have some earlier and 05 info too depending on the vehicle?

[xx_ed_xx]

Thanks for this info. I am getting ready to do one and of course i was going by the other 4 pin pcm guide which is different then the lt1
There is also a handy one that has most of the different pcms google lly bench harness efi live be in pdf format. i use the crap out of that one