Do I need a PCM to run a 12 valve?

R

rage_blue

dieselneck
Joined
Aug 26, 2009
Messages
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Okay i have a friend thats putting a p pumped 12 valve into a 80's chev suberban, hes got the engine, can't remeber but i think an auto trans. I'm pretty sure he can get away without useing a dodge PCM to run everything, but i'm not there to look and veryify so can some of you guys that have done swaps inform me?
 
depends on the trans setup i would assume. the engine shouldnt need anything the trans he might depending on which one it is.
 
What trans is he useing? if its the dodge trans then possibly yes not a 100 percent sure tho. if hes gonna use a non elctronic trans then he wont need it. That engine only needs 2 hot wires and a ground for the shut down solenoid.
 
Okay so he is useing a 5 speed manual, so other than reverse lights the trans will be stand alone. But he does have a question about the tach, is there an autometer adaptor to make it work with an autometer guage? or does he have to put a differnt pickup on?
 
get the cummins alt turned into a one wire and have a tach pickup installed on it and you might be able to get it to work. i would think that you could hook the tach wire from the dash to the one on the alt and i can bet that the rpms will be off. also there is no pcm for the reverse light it is run off a sensor on the the transmission up on the shifter cover. if you want an aftermarket one autometer has a diesel tach that you could use that uses a sensor on the balancer
 
to run that motor in that age of a truck you just need the power supply for your lights and to start the truck. its pretty simple to put one of these in with a manual transmission.
 
The PCM is necessary to regulate the alternator, control the heater intake grid( they turn on and off depending on the IAT sensor), to Run the AC pressure, and the fuel heater. If your friend uses the Dodge instrumentation, the speedo, tachometer, fuel in water sensor, and wait to start are nice to have, and make the swap easier. If he uses the 12ver and instrument cluster from the Dodge, he will need to use the wiring harness from the Cummins.

My experience is from converting an 88 Ford to a 12 valve Cummins, and putting a 24 valve into a HMMWV.
 
The alt can use a voltage reg from a 1st gen dodge, the grid use a starter relay and a push botton switch . The stock oil and coolant send get reused in the Cummins ( brass adapters will be needed ) .
 
use the chevy alternator. its already tapped for a tach thats how i did mine. you may ave to put a bigger or smaller pulley on it to make your tach work right but thats pretty easy. it also eliminates the whole externally regulated deal. you dont need your pcm if you dont want water in fuel wait to start lights and all that. but its really not that hard to wire in a pcm. with a good wiring diagram its not too bad
 
also if you have the cummins alt you can convert it and keep from making a custom bracket. i spent $35 and had one turned into a one wire and also had the tach pickup installed on it you could save some coin and do it yourself the part to turn it into one wire is simple and comes with instructions.
 
Biohmmwv said:
The PCM is necessary to regulate the alternator, control the heater intake grid( they turn on and off depending on the IAT sensor), to Run the AC pressure, and the fuel heater. If your friend uses the Dodge instrumentation, the speedo, tachometer, fuel in water sensor, and wait to start are nice to have, and make the swap easier. If he uses the 12ver and instrument cluster from the Dodge, he will need to use the wiring harness from the Cummins.

My experience is from converting an 88 Ford to a 12 valve Cummins, and putting a 24 valve into a HMMWV.
Click to expand...

a 1 wire alternator or using the existing GM regulation will work, no need for heater grid (but you can put them on a push button if you want, use the existing GM high/low connections for the AC, no need for the fuel heater, but you can just wire it up on a toggle for cold weather.

no need for a PCM to run a 12v :eek:
 
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