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Guide to converting your 2nd gen 24v to a 12v

Posted

Perhaps this should go in the 24v powertrain section, however I figure I will just piss people off over there  :rolleyes:

 

Introduction

I am in the process of swapping a 12v into a 1998.5 24v 5 speed.  This should be an extremely easy process but I have had trouble finding the details on how to go about this swap.  The info I post here should be at least 100% compatible with 98.5-2000 manual transmission trucks.

 

If I make a mistake, have tips, or you would like to add something, let me know.

 

2 philosophies

There are 2 trains of thought, the first is to fool your truck into thinking it still has the 24v in it.  This is done by transferring sensors over to the 12v, this seems to be the most common, especially among p-pumpers.  The benefit is cost, but the downside is you can't fool everything, you will still have your check engine light on, and I believe you will still have sensors that are known for failing like the throttle position sensor(apps).

 

The other method is to use early 98 PCM and wiring harnesses, which is what I am in the process of attempting.  Benefits being it will be a 100% factory install.  Everything will work just like an early 98 pickup.

 

 

Details

You must use early model year 98 pcm and harnesses, 97 is different and will not be the same, I do not believe the 97 will be able to communicate with the 98 and later instrument clusters.  Manual trans vs auto and federal vs California effect component compatibility. (2wd / 4wd) (2500/3500) (reg cab vs extended) shouldn't matter.

 
PCM Part number info
ALL MODELS; 5.9L DIESEL; MANUAL TRANS; FEDERAL; 12 VALVE
Part #R6040139AC (newest#)replaces: 56040139AB, 56040139AC
Going price for used pcm is$300-350
 
 
Engine Wiring harness info 
Manual trans Part# P56045095AA
used price $150-300
 
Headlight to dash harness (Official chrysler name)
Basically this harness includes the fuse box, which the engine harness plugs into.
I am least sure on this part# but manual trans should be 56020499AD
used price $250-375

Edited by beee

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Details

You must use early model year 98 pcm and harnesses, 97 is different and will not be the same, I do not believe the 97 will be able to communicate with the 98 and later instrument clusters.  Manual trans vs auto and federal vs California effect component compatibility. (2wd / 4wd) (2500/3500) (reg cab vs extended) shouldn't matter.

used price $250-375

I have a parts donor truck that is a '97 5 speed and 4 wd. It has the exact same dash as my 2000, with the digital odometer. (Along with numerous 94-96 parts trucks) I used to think the 'type' of dash was the determining factor with which body harness needed?

My plan is to take the 12v out of this 97, and put together a nice rust free 94... (just about ready to start bolting it all together).. I better hurry up and figure out how deep I gotta get on the electrical part!

I haven't decided which dash to run.. I kinda like the looks of the 97's cluster, but my 94-96's are in better overall shape...

In either case, I have the harnesses to swap over to make any combination work...

  • Author

by 97 you mean build date 97, but its 98 spec with the new dash with passenger airbag?  If it is 98 spec can you find some part numbers for the ecm, and the part number for the main harness in the engine compartment, the one with the fuse block, that would be really helpful.

by 97 you mean build date 97, but its 98 spec with the new dash with passenger airbag?  If it is 98 spec can you find some part numbers for the ecm, and the part number for the main harness in the engine compartment, the one with the fuse block, that would be really helpful.

Time to shift gears and do a little investigation, I got vehicles/ parts all over, in 2 different locations. I'll get back with some info, thanks!

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Welcome To Mopar1973Man.Com LLC

We are privately owned, with access to a professional Diesel Mechanic, who can provide additional support for Dodge Ram Cummins Diesel vehicles. Many detailed information is FREE and available to read. However, in order to interact directly with our Diesel Mechanic, Michael, by phone, via zoom, or as the web-based option, Subscription Plans are offered that will enable these and other features.  Go to the Subscription Page and Select a desired plan. At any time you wish to cancel the Subscription, click Subscription Page, select the 'Cancel' button, and it will be canceled. For your convenience, all subscriptions are on auto-renewal.