Tunercat PCM Read Error : /

I've got a 94Z.
I've got TC 2.0
Made my own cable.
Using it on a (VERY) old laptop.. (133MHz.. other specs avail. if needed)
Other programs get raw running data.. (speed, rpm, temps, spark, blah)
But when I try to get the PCM's contents, TC gives me a "PCM Read Error"...
It did this on mine, so I checked it on my bros. 95 TL1 B-body.. Same error..
Is there something I should do to / check on the laptop (com port setting??) or should I just try it again using my PC (which is MUCH more powerful than the laptop)?
Could it be the cable?
I've used a "newer" (466+ MHz CPU) laptop with something a long time ago to get the contents, and it worked with the same cable..

All input is appreciated..
Thanks in advance!

(BTW.. what are TC's minimum sys requirements?)

So not a single person here has had this problem??

I had the problem with it not reading. I had to turn off the anti-virus.

Make sure you have all the background services off on the pc. Antivirus, screensaver, hibernation, etc...

Tails

Thanks guys..
Every feature is off..
It's a bare minimum install of 98SE on the laptop now..
Still gives the error..
I wrote it down wrong last time..
The error is actually:
"Invalid responce from the PCM. Press OK"
Then:
"Resetting PCM"
Then:
"PCM read error. Press OK"

I've used another program a long time ago that made a bin of the PCM(or so I think), does anyone know of any PCM dumpers? Is TunerCat's "PCM dumping only" program free?

If one works, but not TC 2.0, It's got to be the laptop.. I havent had the time to check with my (this) PC.. : /

FreeScan get's all the data live when the engine is running.. I can understand the differences of transmitted data, and getting raw "PCM data" only.. But why would only one work?

Thanks again guys :)

I know this is a couple of years old but this the same problem that I'm having.
Can any one help??

I have an OBD1 tester application that might help us determine what the problem is. Pls send email if you are interested.

It actually turned out that I had a bad ground connection.. :p I was using 12V and ground from the lighter socket, but I found that if I use the ground in the ALDL connector, it worked great! I could read on both my car and my brother's b-body. (And I wrote back to my PCM after editing it) I hope that helps.

Another forum member was running into similar problems and his PCM was reporting a low-voltage condition. The PCM will refuse to be read or perform a write if the system voltage is low.

That is another good direction to look.. Charge your battery over night, and be sure to have a good ground..

I'm using the lighter connection aswell but wont even try if I unplug it.

Yeah.. did you make your own cable? if so dont be afraid to hack it up. Pin A is ground (for 12 pin) If anything make a converter to plug your Cig lighter into, an branch the ground to pin A, and 12V+ to the cig lighter socket.. :confused:

No I got one from aldl I see next to the serial plug there is a red connector that looks like you could connect two wires if you had a plug to plug in it. I'm looking for something to connect them with now!!!

Well that didnt work ether :(

As soon as I put a paper clip in it the fans came on!

hold on :) When I make my connections, I connect my Data line to pin M, ground to pin A and 12V+ to my lighter socket.

I have the cable with the plug. Not the two pins.

Here's something you can try. :D (Safest solution I can think of) At your local electronics store, purchase a male cig lighter (I think I bought the cheapest phone car charger so I had a LED power light) and female cig lighter socket. On the female socket, you have 2 connections, 12V+ and Ground. Take the 12V+ from the female and wire it to the 12V+ connection in your new male plug (with like 6" of wire. You will not use the ground connection in your new male plug). Then take the ground wire from your female, and make a short cord with some wire like #18 or maybe #20, and have it long enough to plug into your ALDL socket. Strip the end about 3/8" long, and leave it unsoldered. Just carefully thread that into pin A (for 12 pin(top right)), and then carefully plug in your ALDL connector. Hopefully your ALDL connector has a ground pin, and will hold your ground jumper wire securly in place.

Now for the disclaimer :rolleyes: : Of course I can't guarantee this will work for you, so dont spend a lot of money on parts, but it will prevent you from having to hack up your nice ALDL cable.. If you need help making your connections, or dont understand what I'm saying, ask. :D Let me know if this works out for you, and what your final solution is.

Why are you needing to feed 12V into your ALDL cable. It gets that from the serial port.

http://camaroholic.com/yabb_holic/YaBB.pl?num=1170226374

It wont even try to download the file if its not pluged in.
I dont know. I have tryed everthing I know.

I've charged the battery over nite. Even left the charger hook up while Trying to download,

Turned off anti virus and firewall.

Cut the Cig. Adaptor off and wired it to a know good hot and ground.

The cable will work with datamaster .
So what gives???

So, you are saying you can read the runtime data with datamaster, but you cannot read the PCM's contents?

Yes!!!
It will get 1/2 way sometimes 3/4 but then come up with the same error as above.

My OBD1 cable tester program might be able to help. If you want to try it, send me an email (look in my profile for my email address).

Did you ever fix this cause i am having the EXACT same problem.

I'll reply when I get home after work (and have time to explain).

Ok.. It's late so I'll try to keep it short. I'm not sure what part of my problem you are having, but I've fully read/edited/and wrote back to 3 seperate PCM's.. The main thing is getting your 3 connections SOLID. Data must be solidly connected obviously, but the 12v+ and ground are equally needing a solid connection.. In my 94 Z28, and my 95 Trans Am, at my ALDL connector, I've got 12V Data and ground among a couple other pins.. In my brothers 95 Caprice 9C1, there's only a Data, ground, and some diagnostic pin that I dont use. In his car, I connect the positive lead from my cable to a 12V+ source..

If you bought a cable, make sure your ALDL connector in the car has the pins in the right locations. My 95 Trans Am has them in the right place (16 pin port), but my brothers 16 pin aldl port has 3 wires (missing the +12V as said above)

What do you have for a cable? What year make and model vehicle are you trying to connect it to? Does it fail completly??

Get back with your details, and I'll try to help. I got it figured out, so anyone can do it.

OK i got the cable from aldl cable about a year ago, i can use free scan, datamaster all that with out a problem but it just wont read the pcm. I checked all the powers and grounds to the pcm, and i even back probed the ground terminal on the aldl and jumpered it to ground. Then i got a female 12v socket and connect that directly to the battery (which i charged for good measure). The resistance in both the serial data and field service enable wires is less that .5 ohms in the harness. Maybe its the cable but i am in no hurry to plunk down another 70 bucks on one.

The car is a 1994 Chevrolet Camaro Z28

So let me get this straight...

You hook up the cable, load free scan, hit start, turn on the ignition, and you get a data stream, start the car, and continue to get a data stream, which is being displayed in free scan?

If you are getting data in free scan, your laptop / cable / port settings are all setup correctly, and it's down to your tuning software port settings. I have to ask, is the port set to the same port number that free scan is using? Sorry. Had to ask.

(BTW. Are you using Tuner Cat or LT1 Edit?)

I've seen the same sort of thing. Connects properly to Freescan, Datamaster etc.. and programs properly with LT1-edit. I tried reading the PCM w/ Tunercats program and came up with a similar failure. Didn't spend a lot of time trying to troubleshoot it, just copied the tune to LT1-edit and reprogrammed with that.

Vomit God you are correct that is exactly what is happening .The comm settings are the same, and if i change them i get a cable error instead of this PCM response error. So i know i am on the right one. As far as using LT1 edit i that costs $200 and i just paid $90 for tuner cat so if it wont work i want my money back. I just rechecked my power and ground to the PCM and they all have only a tenth of a volt drop, except the ign. feeds which are a half volt drop.

Any one else have any ideas?

stupid question, is this an early 94?

pm me if so, i can help. just dont want to step on any toes.i tune for cheap

Get a good cable from Andrew at AKMcables. Doesn't need any BS 12v plug in. His cables get their 12v power from the serial port and they work.