Cdeez

It's been a while since I messed with this so I'm a bit rusty, forgive me.

I previously converted a vehicle from the 747 ecm to the 7427 pcm, had little trouble initially but got it up and going.

Now, I'm trying to convert a 6299 ecm to 7427 pcm. From what I've researched, the pinout for the 6299 is the same as the 747.

After repinning the wires based on the 747 to 7427 swap, I cannot get tunerpro to connect for a datalog, and upon key on, the chip is getting so hot you can't touch it. Double, Triple checked the wires, everything appears to be in order.

I'm at a loss here can someone help me?


EDIT:

I just burned a new chip and tried that, it isn't getting nearly as hot as fast, but the fuel pump prime stays on indefinitely upon key on.........

Cdeez

Total knuckleheaded mistake. I was putting the chip in backwards in the PCM.....

Interesting as to why this caused the chip itself to get hot and the fuel pump prime to be on indefinitely.

RBob

iTrader: (1)

Putting the chip in backwards reverses the voltage to the chip. Pin 28 is +5 volts, pin 14 is ground. Reverse the chip and those pins get swapped.

RBob.

Fast355

iTrader: (2)

The Serial Data wire needs to be repinned in the ALDL to get data on most scanners. 160 baud and 8192 baud transmit data on a different pin.

Cdeez

I wonder if you left the chip in backwards long enough if it would burst into flames

Serial data moves to pin "M" on the ALDL connector, I remembered that much correctly. Like I said, I haven't messed with this stuff in a while so I had become pretty rusty and had to brush up

Everything is up and going now on my 2nd 7427 PCM swap. I took some notes for the next time I might do this and have again forgotten things

Like my previous 7427 swap, I also added in the Efan code to this swap as well so it can also control fans.

I know most people think the 747 when properly tuned is just as capable as the 7427, but I think the 7427 is superior. The higher resolution fuel and spark tables, faster baud, easier datalogging, E trans and E fan capabilities..... I think that the 7427 is better, the cold start routines seem to be better, everything just seems better, to me anyways.

Fast355

iTrader: (2)

By no means is the 7747 even close to as capable as the 7427. I have done numerous 7427 swaps and even posted a thread on it years back in the TBi section. I believe it is still stickied there. The 7747 to 7427 swap is similar to what I did with my Express van. I went from the Vortec Black Box to the 0411 and then onto a 1-meg PCM with the 2004 Mexico 5.7 GMT800 tune. I then swapped to the 24x coil per cylinder in it. Each progression had better manners and it ran better each time.

RBob

iTrader: (1)

It may, this chip wasn't even in backwards and had a major fail (see pic).

Not sure about that, just a week or so ago I recommended going to the '7427 PCM on the TBI board here (over a '7747).

RBob.

Cdeez

Fast, tell me more about your CPP swap, I guess i missed that one. My friend Justin that runs the GMtruckcentral forum did that on his L31 vortec, he referred to it as the LS31 I think lol.

All I'm saying is that in a fair bit of searching the internet over time, I seemed to come across quite a few individuals that were of the opinion that a properly tuned 747 is no better than a 7427, which I personally disagree with. And what caused that major fail to melt that chip?

RBob

iTrader: (1)

Hard to say, it could have been a manufacturing defect in the chip or a voltage spike. I will admit that most chips don't spontaneously go into combustion unless outside interference takes place.

RBob.