'95 PCM Problems!!!

I just finished settin' up my 383 Lt1...well, it's still not in the car, but I wanted to make sure everything was alright w/ the engine before I put it in...so, I moved the engine to the side of the car and plugged it all up...Delteq blinked once, everything looked good...

So, I put my aldl cable in, turned on the laptop, and checked connections...It's a 233Mhz PII Sony Vaio w/ onboard Serial. Serial settings are 9600-8-N-1/Hardware Flow Control. I've also tried 2400, and a few in-between w/ no luck. EVERY port on the PC is not even installed. BASE Win98 install w/ ONLY Serial Port enabled. Cable is from ALDL Cable. Hyperterminal shows the scrolling data when the key is turned on. I tried PCMComm from Lt1_Edit, and I see battery voltage, TPS, Throttle Blade %...it all works when I open the blades...I don't have O2's/Maf and a few others hooked up, but it shouldn't matter...

I tried PCMRead from LT1_Edit and it'll "Sync Up" and run for about 10 minutes...still saying, "Retrieving VIN"...and sometimes will go, "Receiving Security Code"...then, "Sending Security Code"...it'll do this a few times and I notice thru the scrolling code saying, "locked" "locked" "locked"....this happens awhile, then it'll go, "Security PASSED"...then the Fan relay clicks and I get, "Error Communicating w/ PCM...Connection Lost"...almost like, once it "gets in", the PCM kicks it out.

So, I tried Datamaster, and it's showing all data pertaining to what's plugged in. I tried WinFlash from TunerCAT and it'll retrieve the VIN fine, but trying a Read OR Write, it'll go, "Incorrect Message Sent" almost within 5 seconds from clicking it. I then tried both thru REAL DOS, and same crap...fan relays will click for a second, failure, it'll try to reset, then "Incorrect Message Sent"...

So, from the data logging and HyperTerminal tests, I can't blame the cable. All connections are hard wired, so it can't be the "connections to the pcm"...Triple checked PCM ground and juice, all is good. I've waited MORE than 15 seconds after turning the key to attempt a memory Read or Write, no luck w/ either.

SO, I leave you guys w/ this... Could it be a bad PCM? I have no way to know the PCM is even "Good"...I get the SES Light when key is turned, as well as Fuel Pump relay priming. But, as far as anything else w/ it, no idea. The engine was off Ebay and completly rebuilt. From the looks of how it "Was", didn't look like it'd even run (but the guy said it ran fine...riiiight)

I don't know what else to try. I can't see the Laptop being the culprit either. I'm able to do EVERYTHING w/ it, other than "Read" or "Write"...so, it's not making sense to me.

Please, if anyone has input, I'm open to suggestions. Oh yeah, and battery voltage is above 11.9...12.8+ actually.

Thanks for any insight!

-Adam

I tried WinFlash from TunerCAT and it'll retrieve the VIN fine, but trying a Read OR Write, it'll go, "Incorrect Message Sent" almost within 5 seconds from clicking it. I then tried both thru REAL DOS, and same crap...fan relays will click for a second, failure, it'll try to reset, then "Incorrect Message Sent"...

from tunercat manual:

INCORRECT MESSAGE SENT – This error message indicates that the message that was actually sent to the PCM is not the message the program is trying to send. This indicates that there is a problem with the RS-232 to ALDL Signal Converter or the connection to the PC or there is some local source of electrical noise interfering with the communications.

So, I tried Datamaster, and it's showing all data pertaining to what's plugged in.

Just because it's showing data doesn't mean it's valid data.


It's either: Laptop, cable, or PCM. Try changing whichever one you can get your hands on the easiest.

Since you bought the cable, I'd suspect the laptop first.

I don't get how one PC it will never work on, yet, another one will work fine...What's the diff? Both have the same ports/resources/etc...I read that some computers & laptops just plain don't work...which doesn't make a bit of sense...

Oh yeah, and the data that Datamaster is showing alters when I move the throttle and seems to be correct...so, it's communicating right in that respect...

The pcm will experience a communication problem if the grounds are not properly connected. In particular the ground bus on the passenger side forward strut tower and the ground attached to the block below the passenger side cylinder head. I've had problems where a scanner will pull codes but not display data or the scanner will work fine but a laptop will not communicate and have traced it to a simple loose ground at one of those locations. I would be sure the block is grounded to the frame as well. In this case you may need to use a jumper cable.

I'm going to try it one more time w/ that PCM...I just got the engine in the car and we'll see what happens...Did you guys ever experience a problem where it does everything on the laptop, except "read" and "write"...and that lead to a bad PCM?