Pcm no bus

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Cadillacman

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Changing my 318 pcm for a 360 pcm. First one i had would start then stall and give no bus message. Got a second one and it runs fine but every light is on the dash amd no bus message. Ive rewrote the vin into the 360 pcm and still no bus. Runs perfect with the 318 pcm with no lights so I know it's something with the pcm. Could I just have a dud pcm twice over or am I missing something?
 

Yeret

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First of all, the 318 and 360 computers are not interchangeable. Fuel mapping and ignition timing are different between the two.

Generally, engine stalling and "No bus" is a problem with the computer, however in this case it could simply be your attempting to use a non-compatible ECU. There also might be some programming differences between the years but there are others who know more about that than me.
 

jlbayes

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What year are the pcms coming out of?
 
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Cadillacman

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If i were to buy a remanufactured pcm for my exact truck but with a 5.9, is there anything else that has to be programmed aside from the vin?
 

dapepper9

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There were several differences between 98 and 01. Run a 00 or 01 pcm.

If using 360pcm because you swapped the 5.2 for a 5.9, no issues. If you're still running a 5.2, just run the correct program
 

SYKRAMMAN

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Correct dap, Cadillac it has to be from the same size engine otherwise you'll have major problems like yeret said, they have different idle air fule mappings. It will never work dude, sorry for putting a damper on your day bud, good luck.
 

dapepper9

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Actually it will work but not correctly. Many people swap to the 5.9, assume nectar they're pretty similar that the tuning is the same or that its "self- adjusting" and run 360s with 318 PCMs. However, due to different cam shafts, strokes and bores they do require a different program for proper operation. They do adjust within a very specific spread of variables but it's not much. If it was crazy as some success there'd be no such thing as custom tuning because you'd be able to do whatever mods you wanted and it would "adjust". You will see more accurate air/fuel ratios in all conditions and more power using the correct program
 

SYKRAMMAN

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Actually it will work but not correctly. Many people swap to the 5.9, assume nectar they're pretty similar that the tuning is the same or that its "self- adjusting" and run 360s with 318 PCMs. However, due to different cam shafts, strokes and bores they do require a different program for proper operation. They do adjust within a very specific spread of variables but it's not much. If it was crazy as some success there'd be no such thing as custom tuning because you'd be able to do whatever mods you wanted and it would "adjust". You will see more accurate air/fuel ratios in all conditions and more power using the correct program

See and I'm thinking that the ci's have to be the same but I learned somthing new today.
 

dapepper9

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See and I'm thinking that the ci's have to be the same but I learned somthing new today.

They do but they don't. Correct program goes a long way but they'll both run each other long as they're within the right year range. Or you can swap, keep your pcm and run a 360 pcm tune with sct and it'll basically be like you swapped it
 
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Cadillacman

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Ya cuz right now the 360 pcm will run it good, but no 4th gear and all the dash lights are on. The 318 pcm is definitely running it lean. Gives a bad stumble when cold and a little bit when warm. But there is a huuuge difference running the 5.9 pcm
 

SYKRAMMAN

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If the 5.9 runs good then just have it programmed so it will communicate with the tcm.
 
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Cadillacman

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So then if I get a used pcm for the exact truck except 5.9 then all I should have to do is put the vin into it and all should be good then correct?
 
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Cadillacman

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Unfortunately a 3 hr drive for me so it's cheaper to get a plug n play pcm I think
 

SYKRAMMAN

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No, It will still need to be flashed for the two modules to communicate. sorry.
 

jlbayes

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98 pcm into 01

You would need an 99 or newer pcm. The 98 is different than the newer controller. Or someone with the ability to tune the pcm to correct for the communication differences.
 
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Cadillacman

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Ya kind of figuring that out lol. I got a matching year pcm coming tomorrow from a wrecker. Hopefully that'll fix it up
 
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Cadillacman

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Swapped out the pcm with another one and everything wprks perfect. Got a pcm to match my year and that was the ticket. Thanks for all the help folks. Much appreciated.
 

Rammythe2ndgen

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so any suggestions for my 5.9 swap im having a no bus with no gauge reading my fuel pump constantly runs. but the truck run fine
 
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