'94 LT1 F-Body/ $EE tuning change for '95 transmission (PWM)

[Gojira94]

This is what I put together a little while ago. I made it as simple as I could, using what I had and what I understood of the connections. I found the PCM connectors I had. One was red, the other blue. So I scraped off the key on the red one and am using it as my black connector. I used Gerry Massie's 2 connector OBDI/OBD2 benchtop diagram to guide me http://www.gmassie.net/13secss/pcm_harness.html and just left off the OBD2 data wire. I guess I could always add it later if I wanted to. I need a switch for the ignition wire to make it pretty (double pole, single throw?) and my 12V & ground source. I have a 12V wall adapter somewhere, need to check the mA rating on it. Not sure how many mA (or full Amps) I need. Here's what I have so far. I used spade connectors to connect to ground and serial data on my ALDL cable.

[Gojira94]

So I had to try it out. It connects in TunerPro, but not in $EEHack or Winflash. Winflash gives squat for logging, but I turned on verbose debug in $EEHack and got the following:

Loading Definition DEVICE=0xF4 MSG=0x0 Loading Definition DEVICE=0xF4 MSG=0x1
Loading Definition DEVICE=0xF4 MSG=0x2
Loading Definition DEVICE=0xF4 MSG=0x3
Loading Definition DEVICE=0xF4 MSG=0x4
Loading Definition DEVICE=0xF4 MSG=0x5
Loading Definition DEVICE=0xF4 MSG=0x6
Loading Definition DEVICE=0xE4 MSG=0x0
Loaded 1014 elements into 8 definitions.
VERSION re-checking, network went online!
VERSION offline status, skipping versioning
Using monotonic reference clock.
EEHack Version 4.60
Current OS : Windows XP
Built with THROTTLE_MS=2
Opened serial port COM1 Description Communications Port MFR (Standard port types)
START SILENCE ROUTINE
SERIAL: ECHO CORRUPT! (bad serial interface?)
SERIAL: ECHO CORRUPT! (bad serial interface?)
START SILENCE ROUTINE
SERIAL: ECHO CORRUPT! (bad serial interface?)
SERIAL: ECHO CORRUPT! (bad serial interface?)
START SILENCE ROUTINE
SERIAL: ECHO CORRUPT! (bad serial interface?)
[SERIAL WRITE]*F45608AE
[SERIAL DISCARD ECHO]
[SERIAL READ]*FA030000
SERIAL: ECHO CORRUPT! (bad serial interface?)
START SILENCE ROUTINE
Listening 2000ms for broadcast heartbeat...
Timeout waiting for heartbeat after: 2000ms
SHUTUP DEVICE f4
[SERIAL WRITE]*F45608AE
SHUTUP DEVICE f9
[SERIAL WRITE]*F95608A9
DATASTREAM: Send MODE8 keepalive*F95608A9
[SERIAL WRITE]*F45608AE
[SERIAL DISCARD ECHO]
[SERIAL READ]*B7030000
SERIAL: ECHO CORRUPT! (bad serial interface?)
[SERIAL WRITE]*F45608AE
[SERIAL DISCARD ECHO]
[SERIAL READ]*70040202
SERIAL: ECHO CORRUPT! (bad serial interface?)
START SILENCE ROUTINE
Listening 2000ms for broadcast heartbeat...
Timeout waiting for heartbeat after: 2000ms
SHUTUP DEVICE f4
[SERIAL WRITE]*F45608AE
SHUTUP DEVICE f9
[SERIAL WRITE]*F95608A9
DATASTREAM: Send MODE8 keepalive*F95608A9
[SERIAL WRITE]*F45608AE
[SERIAL DISCARD ECHO]

[steveo]

'echo corrupt' means the rx and tx lines aren't synchronized well or the buffer is gimpy. anything you transmit when rx and tx are tied together on a serial line should echo back an identical copy.

[Gojira94]

I'm not an EE, so this part might be more than I understand yet. My gut says maybe something with the ground on the ALDL side. What I did was use a good battery with charger on it (2A trickle setting). I used alligator clips to make connections in the following order: the PCM batt connection to the battery + / PCM ground to the battery - / PCM IGN to the battery +

To power the RS-232 I used a jump box with a lighter jack, plugged up to its own charger as insurance.

[steveo]

it could be, but keep this in mind; even with the cable unhooked from the aldl port, you still shouldn't get 'echo corrupt' messages while trying to connect. all that is required for a serial echo is loopback

[Gojira94]

Is there a loopback test I can do on the serial cable to see if it's the cable? Like short A & M together?

[Gojira94]

I ran across Dave W's posts about making a bench for LT1 vehicles and am trying his pinout ( http://www.gearhead-efi.com/Fuel-Inj...ch-harness-LT1 ). I removed an extra BATT connection on black and moved the Data to blue 29. Will try it as soon as I get a moment to set up the bench again.

[Gojira94]

Tried it again with the updated pinout and got exactly the same result. Connetcs in TunerPro, fails in Winflash and $EEHack. Maybe it's time for a new, USB ALDL cable? I still have a hard time believing the serial cable would be bad. It came from AKM cables and works in every other way in/ on the car. Just having issues with it on the bench that I didn't have before.

[Gojira94]

It looks like I've been wrong about the A & M pins on the DLC end. Over at Shbox, I see this:

Attachment 10853

Most of the diagrams I've been seeing everywhere else I've been reading upside down the orientation of A&M. Will try again...

[Gojira94]

Well, that wasn't it. I'm about out of ideas at this point. Same result, except with serial data to Blue 30, even TunerPro won't connect anymore. I don't want to throw money at it but I'd like to try a USB ALDL to see if that works.

[Gojira94]

So- one more to try. I saw this on another site. Looks to be meant for a 9C1 Caprice application, but I'll try it. Moving D30 back to D29 since I at least saw serial data in TunerPro before moving to 30.

Attachment 10858

[Gojira94]

Still not working, same results. Is there something fundamentally wrong with trying to simply plug the ALDL interface to A&M into the harness? If the serial version of the ALDL cable didn't require a 12V power source I'd try pulling apart an old 9-pin serial cable or null modem cable and eliminating the ALDL cable entirely. So why does a serial ALDL cable need a power source to work?

[lionelhutz]

I have no idea why your serial port cable requires 12V. I have a serial adapter and it's powered from the serial port of the PC. The Express Card serial port adapter I was using wouldn't work with EEhack so I switched to a USB adapter.

I used an adapter from the Ebay link in post 4 of this thread.

http://www.gearhead-efi.com/Fuel-Inj...4-95-Camaro%29

I combined it with a 1N914 diode and a 1k resistor I already had. I also bought a cheap 10' USB extension cable so I could hard wire the adapter and use the USB cable to plug into my laptop. I simply plugged the adapter into my Windows 10 PC and it worked with the driver Windows found. The Red Devil River driver could also be tried if you have issues.

Some people say you can just connect the TX and RX together without the resistor and diode but I never tried it that way so I can't say if it would work that way or not.

[Gojira94]

It's a cable from either AKM or ALDLcable.com, bought it several years ago, exactly like this one:

http://www.aldlcable.com/products/aldlobd1.asp

I don't think it requires 12V, just needs a 12V connection, undoubtedly stepped down inside the serial connector end. To what, I don't know. I guess it's a rite of passage to build your own cable, but I'm getting further away from what I'm trying to do (yes, I'm whining). I'd feel comfortable working with one of these to do a USB cable (Thanks Mr. Isaar for the idea):

http://www.ebay.com/itm/FT232RL-USB-...sAAOSw9uFW-f7h

But getting one of these from China or Hong Kong bothers me. I'd buy one in the US if I could find one (just started searching, may be out there somewhere). What I want (whining again) is a USB OBDI ALDL that works for logging and flashing, period or an answer on why the serial is giving me issues. I may bite the bullet and buy one from ALDL.com

[Gojira94]

Got a real USB cable from Red Devil River. Still had problems with it in the car in EEHack and WinFlash. Went back to the original design on my bench harness and it worked flawlessly. I flashed the PCM and a spare from a '94 Z28. Pulled the .bin after flashing and compared to what I assumed I was uploading and it was a match. I had modified the .bin slightly with TunerPro per my comments in post 9.


I still have code 84 setting after about 4-5 seconds. Watched it in Scan9495, reset, comes back in 4-5 seconds.


I tried looking at it in hex using the editor in TunerPro but don't know enough other than to look for addresses 00004dbe & 00004dc2. I don't see those addresses in any 95 auto bin I looked at from fbodytech. So it must be right. My sanity would be more stable if I'd seen those addresses with some sort of data next to them.

.bin file attached, if anyone can give me some assurance that 95 PWM code is present I would greatly appreciate it. I'm using the factory 16188051 PCM.

The ohm reading on all solenoids are within spec as read from the PCM harness connectors and PCM ign/ckt439. Maybe it's a fault in the trans wiring harness?

Thanks