I'm about 90% sure that as long as the numbers match it's okay to use it. I was once told, but could never confirm, the two letters at the end indicate software updates/recall work done to the PCM. With AA being the factory letters and AB, AC, AD, AE, AF, etc. indicating software updates done and the label changed.

 

Well, we're gonna find out! Ya'll will be the first to know (after me!). Thanx for your help and support! Spence.

 

Well, I went to the van with replacement computer in hand. After splicing the ASD ground wire and making sure everything was back to normal, I installed the computer (with the battery disconnected). I reconnected the battery and turned the key to the "on" position and saw that the clock reset to "12:00" (a good sign). I turned the motor over and........... no start! Pulled the #5 plug and....no spark! Do you think that the problem could be something as simple as a bad ignition switch? Intermittent problems like these are usually something as simple as this, in my experience. Does anyone know, off hand, what color the wire is on the ignition switch that powers up the ignition side of things? I know that the 12V switched side of the ASD relay is hot when the key is on and the ground connection for it is made by the computer. Is there a wire from the ignition switch that tells the computer that the key is on? Thanx, Spence.

 

Did you ever check all of the vehicle grounds to make sure they're okay? Like the small one that comes off the battery negative and goes to the body? The ones at the rear passenger side of the engine? Is the PCM securely attached to the body?

 

Hi, Alloro,
Yeah, I've pretty much checked all of the grounds (even that little one). I even went so far as to sand the "feet" and mounting contact areas of the computer before I put it in. So far, I haven't found any bad cables or connections, either. I've been looking at the "Fuel Ignition" and "Automatic Shutdown" schematics that Autozone puts up on their website this afternoon, and it looks to me like there are all kinds of sensors that could wreak havoc with the ASD system. The no power to the coil thing has really got me stymied. I disassembled the ignition switch enough to test the output, but I already knew it was there because I've got power to the ASD relay. Just no ground at the relay (coming from the ECM). Question: Is it posible that the battery temperature sensor is bad and shutting things down? I know that about 10 years ago, I had gotten a shipment of bad ones from an inverter manufacturer that wound up shutting down a half dozen inverters we'd installed. That problem was difficult to troubleshoot because by the time I got there, they had cooled down and everything was working fine. The difference here is that I'm not getting power to the coil even when the vehicle's "cold", like today. It also appears, if I understand the drawing correctly, that the O2 sensor can interfere with the ASD system. Your thoughts? Thanx, Spence.

 

Have you done a check for trouble codes since putting in the new PCM?

 

Alloro,
The van is out at Stovall's place, about 15 miles from civilization. For now, computer is no-can-do. I may be able to get it on a car hauler and run it by Advance Discount A/P on the way home sometime next week, but that would be the soonest. I don't know anyone with a code reader, So I'm S.O.L. there. In the mean time, I'll keep slogging through the system, trying to get a good handle on how it's supposed to work and what the interactions between the various components are, and hopefully come to a solution. Thanx, Spence.

P.S. Not to sound too old school, but if this thing had a real distributor and a carb, it would have been back on the road a week ago, cheap!

 

You don't need a code reader to get the trouble codes in a 2000. Turn the key on, off, on, off, on and wait a few seconds. The codes will start displaying on the digital odometer. Write them down and post them here, if there are any.

 

Why not ground out that ASD relay coil wire, start it, and drive it home?

 

Hey, Alloro,
Thanx for the input! I didn't know that you could get the codes like that. I'll get them and post them when I get home. On the ground wire thing - I had cut the ground wire to (from?) the ASD relay and ran it to the negative post of the battery. The van wouldn't start so I assumed it was because the computer needed to be grounded via the other end of that wire to make other things happen that were necessary for the starting sequence. So I grounded that end to the negative side of the battery, too, and it started and ran. So I made for the home 20 but, about 2 miles down the road the van started coughing and gagging and died. This time it wouldn't start for love nor money. The clock was locked at 10:45 (the time it started gagging), and stayed frozen there. We came back later in the day to tow it back to Stovall's place, and with the key "on", the clock still was at 10:45. It didn't change during the half hour tow to Stovall's. I assumed that the computer had finally gone to the great beyond. The van would still turn over and the fuel pump ran, but there was no spark. You stated that I need to put a switch in line. Does that negative connection have to be broken for the computer to reset or something? Or do you have to turn the switch on, start the van and then turn the switch off in order to keep it running? Please advise. Thanx, Spence.