I have my pcm wired up to the 4 power feeds and four ground feeds, and i checked for proper voltage or ground at each. I have connected an ALDL cable to the tan wire on PCM connector D pin 30 and to ground just like it instructs but i cannot not get any communicatin between the computer and the PCM. Is there any way to test the PCM to make sure it is good, or to test the ALDL cable? Or does the PCM need all the connections? All i am trying to do right now is read the PCM so i can strat the tunning and turn off the VATS. Please help!

 

OK i got FreeScan to read data from the PCM but ALDL test, Datamaster and Tunercat all wont work. Anybody?

 

If freescan works, the other ones should work but these things can get weird.

What year LT1? Is it a serial to ALDL cable, or USB to ALDL, or do you have a USB to serial converter in there somewhere?

Its a possiblility you don't have the other programs' connection settings right.

 

its a 94 LT1, a serial to ALDL, the laptop has not USB ports on it. And the only settings i can find in the other programs is the com port.

 

Somewhere in my notes, I wrote "Connected Wire at LT1 C220-F under dash to LT1 C105-E to DLC connector pin 9". Now, I checked out http://shbox.com/1/harness_connector_faces.htm and its not showing a C105 connector for 1994.

I had to connect those 3 wires(for serial data) to get anything to work on my 95. But you're getting something to work, and mine is a 95.

Usually people have issues with the usb thing but you don't have usb in your setup.

I don't know, i'm stuck right now on what it would be.

 

I have the serial data wire from the PCM going strait to the cable and the cable ground going to a ground.

 

Freescan shows actually shows what the sensors are doing? Not just saying its receiving data?

You might have to have connect a power wire to the ALDL cable.

 

yup i tried playing with the TPS and turned the battert charger up and down and the changes registered perfectly
Do you think i have to connect the "feild service mode"?

 

The "field service mode" wire from the LT1 wiring. No, I've never had to do anything with that. I used datamaster on a friend's 94 camaro before and never had to connect to that wire.

 

Damn, well i'm gunna go home and sleep on it. Thanks for all the help thus far.

 

Other than serial data wire and ground wire, do you have a +12V wire, or a cigarette lighter plug-in attached to the cable?

 

NO its a serial powered cable, so it gets power from the Laptop.

 

You still have to have 12v going into the port, my ALDL has 12v constant, two grounds, and the serial data connector. The serial ports on laptops don't have power coming from them to power the adapter.

 

The cable i bought only has for leads and a serial connection.
RED ==== 8192bps DATA - which i have connected to the Serial Comunications on the PCM
BLUE === 160bps DATA - which isn't used on a 94 LT1
BLACK == GND - which i have connected to a good ground
WHITE == ALDL 10kOhm Mode for TPI w/ MAF - also not used for 94 LT1

I took apart the serial connector and there is power going to the convereter.

 

it's possible the cable you have won't work with the LT1 computer, I got mine from akmcables and it works like a charm, and has to have 12v going to the cable from the aldl

Ok, looks like the '94 only needs 3 wires for the connect.

For the older rectangular 12-pin style, the under dash connector has the following pinout:

F E D C B A
G H J K L M

A = Ground
B = Mode Select
M = Serial Data
(on some older cars E = Serial Data, my cable has "E" and "M" tied together anyway)

On to the PCM now. The PCM has the serial data on Blue 30 (D30). This needs to go to "M", "E", or 09, depending on your connector above. It's a tan wire on my 1994 PCM.

Mode select needs to go to Blue 20 (D20). It's a White/Black wire on my 1994.

ALDL Ground needs to be tied in to Blue 1 (D1). This ground wire actually winds its way through the chassis to get to the PCM, but it wouldn't hurt to run a jumper wire directly to it. The better your ground, the better your ALDL communications reliability.

 

ok so i went to radio shack and got the parts to make a 2 transistor cable... put it together quick with a crappy old soldering iron.... and BAM works right away....