I removed a computer from a 1500 series truck and installed a 2500 series computer. Now it won't start. I turned the key on several times to allow for the security light to go out, but still no go. Any ideas?

Idea's??
questions more like it,. why change computers? Did the truck run before you changed computers?

then i might have some idea's,.

Nick

Was it starting before? any reason why you need to change it?

Need more information why?

Changing computer in this truck is not like changing your home computer.

What I have learned from this forum and the others is that ECM on this truck are specific for the truck type, like transmission type, 4WD vs. 2WD, type of IP, etc. I am not sure if 1500 vs. 2500 has a difference, my guess is it does. So it is not as interchangeable as you may think.

I changed the computer cause a code kept coming up telling me that the EGR system was not getting enough fresh air. My guess is this happened caused I changed the upper plenum eliminating the recirculating air.

The 2500 does not have the pollution devices on it.

And yes, the truck ran fine before the change.

Both trucks are 1998 and both are automatics and both are 4x4. They do have different gear ratios.

Maybe you should post the code.

Does anyone else think that a Top Dead Center Offset relearn may work? It couldn't hurt to try anyways.

K, I almost ran the battery down, cause each time it seemed to want to start initially,.... so I swapped back to the stock ECM, and it started right away. I ran it to charge the battery and all is well.

The ECM was from my truck in my signature, it ran great but I upgraded to the HP4. Therefore I know that the ECM works.

As for the codes in the stock ECM, even now it reads, 0409, (I think) then it says, EGR System valve leak. Before the swap swap, it also read insuffietient air flow, (I think) . Maybe my exhaust is plugged?

However that would not stop my replacement ECM to not fire up.

My 99 has the passlock system and has to be reset if any of the involved components are changed, including the pcm. I'm not sure if your 98 has the same setup or not. Maybe someone will know. I can give you the procedure if needed.

Search is a wonderful thing.

http://www.dieselplace.com/forum/showthread.php?p=341141

Does anyone else think that a Top Dead Center Offset relearn may work? It couldn't hurt to try anyways.

The different gear ratios will screw with things, each computer is specifically programed for the truck it is in. It may throw off your speedo, or your shift points.
The best way to solve your problems is to get the 1500 computer reflashed to a F computer

In that, I agree with thebratt.

My question would be, if i change the intake from and "S" to an "F" style on a blazer, then order the gl4 from heath, will this work together and be the computer swap i need to make the whole thing work. of course i would tell them the options and specs of the truck when ordering to make sure it communicates with the truck properly.

The different gear ratios will screw with things, each computer is specifically programed for the truck it is in. It may throw off your speedo, or your shift points.
The best way to solve your problems is to get the 1500 computer reflashed to a F computer
gear ratios don't matter as that pulse is handled by the drac unit(since 1992), now if both vehicles had different ratios and the drac from the other truck was swapped in without a gear change then shift points and the speedo would be off.

prior to 92 the speed reading pulse was handled with a chip in the cluster

In that, I agree with thebratt.

My question would be, if i change the intake from and "S" to an "F" style on a blazer, then order the gl4 from heath, will this work together and be the computer swap i need to make the whole thing work. of course i would tell them the options and specs of the truck when ordering to make sure it communicates with the truck properly.

When you order the GL4 from Heath ask for him to add the EGR Delete on there as well. And yes, he will ask if its an auto, rear end ration, i think 4x4, and some other stuff maybe I can't remember... And on a '94 you won't replace entire computer, but just the eeprom inside of it.

Thats what i did, and I have the little solenoid "pack" off the truck (one on intake) and I have all vacuum lines off the truck and the baro sensor (on firewall) unplugged as well.