1995 3.4L Camaro No ECU Response

Hey guys, I wasn't really sure where to post this but here goes.

I'm struggling to get my ALDL cable to receive any information from the car. I've tried connecting with Scan9495 (v6 edition), ALDLDroid (USB), TunerPro. I've also tried Steveo's flash-hack tool as well as ALDL Fast Test and no matter what I do I can't get it to connect. The wiring seems to be good. I have 0 resistance on the grounds, power port has 12v and I have continuity from the wire at the pcm to the pin on the OBD port. I'm seriously at a loss here. Been battling this since early August and figured it was my Red Devil River cable. Ordered a new one that took a month to arrive and still nothing. I was able to read it once with the old cable before it stopped working. The car will start and Idle fine, but driving it is a no-go since it needs to be tuned.

Anyone have any ideas or suggestions I can try? I've read somewhere that the drivers can cause issues when using laptop programming, but the creator of ALDLDroid told me using it with the app shouldn't have those same issues and the fact that I'm having the same type of connection error across all programs makes me think it's not driver related. Also of note, while using Scan9495 it tells me in the communication tab that I'm missing an engine signal and and actuator signal, but can't seem to figure out why that's happening.

Any help is appreciated guys

Thanks,
Johnny

just a few sanity checks i forgot before, it's a 95 so it's a 16 pin aldl connector, right?

what pin are you testing for continuity to the ECM data pin? bottom left?

what part number is the ECM?

do you only have one COM port on your laptop with the cable connected?

if you run flashhack, in the 'select interface' screen, what's displayed in the info pane (vendor serial# etc)

Yeah its a 16 pin. I'm testing continuity at pin 9 (bottom left),

Im not sure which is the part number on the pcm, but service no. Is listed as 16196742 BPCN
*86BPCNK350540207* is on the bottom of the tag

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Originally Posted by steveo

just a few sanity checks i forgot before, it's a 95 so it's a 16 pin aldl connector, right?

what pin are you testing for continuity to the ECM data pin? bottom left?

what part number is the ECM?

do you only have one COM port on your laptop with the cable connected?

if you run flashhack, in the 'select interface' screen, what's displayed in the info pane (vendor serial# etc)

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Just ran the flash hack with it plugged in. Says
SER : #AK08HBBZA
VENDOR: 403
PRODUCT: 6001

can't see why it wouldn't work, cable is a normal ftdi thing, ecm seems to be the right part#. i wonder if something is wrong with the ECM?

run something to monitor the bus, is there any data on the bus at all, key on engine off? you can use a terminal program. my eehack tool, in the 'raw command' section does have an idle traffic monitor that's designed for that too

Not having much luck figuring that out. Just keeps saying "bus is silent"

well something should be talking on that aldl bus......i can only really jump to the conclusion that if the cable is working you don't actually have data/ground to the aldl port where it's supposed to be

Decided to pull the pins on the obd port to check them. Serial Data pin had ALOT of corrosion. Decided to use the other UART pin from the ls1 in it's place. Still having the same issue, so I pulled the power pin as well. Seems to be dark with a minor green crust on the pin intself. Wondering if I can just forget the OBD port for now and hook up some female wiring ends and hook those up to the appropriate pins on the ALDL cable.

Swing and Miss. Rewired it all without using the obd port and connected female ends onto the ALDL cable. Have 12v, good grounds and continuity from the ALDL pin to the pcm and no dice. Can't get the ECU to connect at all

If I wanted to try another ECU, would I just find one with the matching part number, plug it in and check it? If it works I can copy the base p66 table from mine onto it and I'd be good right?

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Have 12v, good grounds and continuity from the ALDL pin to the pcm and no dice.

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you generally only need data and ground for a usb ftdi based aldl cable, you can stop worrying about that power wire

where are you grounding the aldl cable to in this test? most cables ive seen use pin 5, but it's possible some use pin 4 (or both)

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If it works I can copy the base p66 table from mine onto it and I'd be good right?

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not sure what a base table is but you should be able to load whatever compatible bin you want onto another P66 ecm

I'm grounding both wires to the same chassis ground. I've tried it on a ground in the drivers side footwell area as well as a chassis ground in the engine bay. I'm still new to this so the terminology might be a bit off but I just meant the basic info from the P66 Bin files onto the new pcm. I'm really lost here, I don't see how it can be the PCM when the car will start and idle

Going to give this a bump as it's still an ongoing issue. I ordered a replacement PCM to test in case mine was shot and I'm still having no dice reading it. I purchased a new RedDevilRiver cable and I'm just stuck. I've updated the drivers and gone through that process at least a dozen times and factory reset the laptop twice in between to ensure that I'm doing the correctly. I'm just stuck guys. What the hell could be going on? I've even tried using the cable with ALDLDroid on my phone and still can't get any info. But, the car will start and run, just not well due to the bad tune on it for the current injectors.

I can suggest you build a bench setup to test pcm. Than you can open the case and look for water corrosion.

Just test on bench first, to remove all incar variables.

I've opened it up, no visible corrosion or burns or anything in either pcm

I know you don't want to spend any money probably...but how about a known-good cable? The cable I use is this one: http://aldlcable.com/products/aldlobd2u.asp

It has worked on two different computers, one Windows XP, one Windows 7, with zero issue on either machine.

If you have a totally different PCM now and get the same exact result...that suggests the problem isn't the PCM at all, but is either between the PCM and ALDL connector, or between the ALDL connector and the software.

I need to get this sorted out, with a baby on the way it's just time.
For those seeing this for the first time and don't want to look at page 1, I've got a 1995 3.4L camaro engine that I'm trying to tune and I'm struggling to get the PCM to communicate with my ALDL cable and Laptop. I'm using Scan 9495 v6 for all my scanning.

I'm going to go back to basics in the wiring and see if I can't get it to read anything off either PCM.. At it's basics, the ONLY wires that need to be connected to the OBD port are power, ground and the serial data line correct?
So orange to the battery,
Tan to the Serial Data Line off the PCM,
Both blacks to a ground. From what I've been told, they can share a ground and it won't affect it either way. (If anyone can confirm that would be great)

I'm using a Red Devil River ALDL cable. I've followed several guides on the drivers, and there's so much back and forth info given on which ones work and don't that I'm not even sure which threads to trust.
For those seeing this for the first time and don't want to look at page 1, I've got a 1995 3.4L camaro engine that I'm trying to tune and I'm struggling to get the PCM to communicate with my ALDL cable and Laptop. I'm using Scan 9495 v6 for all my scanning.

First[for testing purposes] Get flashhack program from steveo website. It is the best comm tool for obd1. It will help you narrow down problems faster than anything else.

For the pcm you need to wire
B16-ground
B14 - B+
C3 - Ign
B19-serial data

B=black
C=blue

I am suspecting a defective cable. or wiring issues. This pcm needs good solid ground for flashing. Also I don`t suggest flashing in car. It is very sensitive. Setup a bench with fully charged battery.

I have his flashhack program downloaded, currently just telling me I have aa "Silent Bus" when I try and read the pcm with it.

I'm leaning towards wiring issues as the cable worked once, and I made a couple routing changes to the wiring and it hasn't worked since. It's attempting to track down the wiring issue that's giving me such a headache which is why I've resorted to trying to just splice in the needed wires in the engine bay and working from there.

I dont think I'm currently trying to flash, just trying to read the data already on there so it's just a read if I'm not mistaken?

Gonna give this a bump as it's still an on going issue. Starting to wonder if it's a pc issue vs cable/pcm. Anything I can check on that side of things to potentially get this resolved?

Trying to dive back in on this after a few weeks away from it.

Using ALDL-Test V230 I've confirmed that the ALDL cable is working on the laptop side of things. It passes all the tests, and I've also used Realterm to verify that it's working on the pc end correctly as well.

Using ALDL-Test I've confirmed that the grounding is good, I have continuity from the PCM serial data line to the serial data line on the obd port as well.

When trying to use Steveo's flashhack tool to ensure the cable is connecting, things go a little south. This is what it says:

Reconnecting to ALDL bus, please wait....
DEBUG:Listening for ALDL heartbeat to determine current bus master...
The bus is silent.
DEBUG:Trying to reconnect to bus...
DEBUG:Trying to reconnect to bus...
DEBUG:Trying to reconnect to bus...
DEBUG:Trying to reconnect to bus...
ERROR: Error reading mode2 segment 0[40]
ERROR: Could not complete read procedure

Despite failing this, I attempted to use the program Scan9495-V6 from Gary Doug. It also failed, giving me this error:
Response: cs=80 Bad checksum!

Could really use some experienced vets assistance on this. Can have door dash or whatever your local food delivery service is drop off a case of beer for your troubles

something is wrong with your tests, as if the vehicle wiring was truly okay and the aldl cable was truly okay, it would be working with some the many software packages you've tried

are you 100% sure of your tests on the vehicle wiring? or just 99% sure

if so, the only reasonable conclusion i can draw then is that the aldl-test program that i have never heard of before is not a truly good test of your serial interface and the cable is faulty.

it's totally possible that the aldl-test program is just a dumb thing that ensures a serial port can be set to 8192 baud and that the data loops reliably between rx and tx, which would prove your driver works and it's actually an aldl cable, but doesn't prove that there isn't something broken between the serial chip and the external data pin on that cable.

Yeah, at this point I'm truly just at a loss. I've tried full on cutting the OBD port out of the car and wiring it independently. Grounds are good, it's directly to the serial data line at the pcm and still nothing.

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Originally Posted by Robindehood

I'm leaning towards wiring issues as the cable worked once, and I made a couple routing changes to the wiring and it hasn't worked since. It's attempting to track down the wiring issue that's giving me such a headache which is why I've resorted to trying to just splice in the needed wires in the engine bay and working from there.

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This stood out to me. I know you tested for continuity, but sometimes broken wiring can pose strange side effects

Since you now have 2 ECMs, are you open to building a harness to do this on a bench? Looks like you’ve tried everything else

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Originally Posted by Bent72

This stood out to me. I know you tested for continuity, but sometimes broken wiring can pose strange side effects

Since you now have 2 ECMs, are you open to building a harness to do this on a bench? Looks like you’ve tried everything else

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What all do I need?

I’ll be honest, I’ve only done test benches for other applications, but looks like post 17 above has at least some of that information

Yeah I'd be open to giving that a shot. I'm also inclined atm to just use this stock tuned ecm that I picked up along with a set of the stock 3400 injectors and see how it runs with those. If it at least runs, I can stop getting so damn demoralized about not being able to plug it in right now