converting 99 24 valve to 12 valve problem

slrrls

slrrls

Water fuel 1st diesel 2nd
Hope I'm posting in the right section. Maybe 24 valve section would be best?

I'm swapping my 99 24 valve with the 53 block for a 98 12 valve.
It may be a 96 12 valve in a 98 I dunno, doubt that makes a difference it is just what the sticker on the motor says is 96.

My problem lies here, wire harness. I read to get the pcm and the wire harness.
I retrieved the pcm and the firewall harness but did not get the rest of the harness. It is different than the 24 valve in that it has three connectors that connect into a wirepack that feeds into the engine compartment fuse block.

Is there a reasonably easy way to wire this 12 valve firewall harness to the 24 valve fuseblock that is in the engine bay? Or am I going to need to get the rest of the harness that is the fuse block and harness that goes thru the firewall into the cab?
 
I believe you have to have a harness out of a 98 12 valve. The under hood one at least. I could be wrong but I've looked into doing it and that's what I found out
 
That is the harness that I have; the engine harness which also is the way I read everyones post that said you just need the pcm and the harness.
It has a couple of couplers where it coupled into the rest of the harness on the 98.
But my 98.5 sold in 99 does not have those couplers. It is a little bit different harness which feeds into the engine compartment fuse block.
It is looking like I need that engine compartment fuse block as well as the rest of the harness that feeds into the cab.
Unless someone has dealt with this before and can help me with the details of splicing this 98 engine harness into my 98.5 harness.

Another question that has popped up is if I get the fuse block from the engine compartment and the rest of the harness that feeds into the cab then will it just snap into the the harness inside the cab? or will there still be some type of splicing there?
The details are few and far between looking on the groups and the net.

I'm stuck and don't want to install the engine till I have this worked out.
Otherwise I'm going to have to look at getting another block for my 24 valve then installing the P-Pump on that motor.

Gonna be easier to install this 12 valve which is the motor of choice for me from all the reading and from what I understand about these motors, because it is mechanical with no electrics.

If anyone has experience with this your help will be much appreciated.
 
I'm doing this with a 12V going into a 01', I couldn't find a 12V harness so I used the existing harness and converted the pipe thread 12V over to metric to use the 24V sensors, other have said it will work so that is what I did.....keep in ind it was a P-Pump 24V prior.

Jim
 
Can you post a photo of the fuse box that is under your hood? I want to see if the wiring looks like my 24 valve box.

If it looks like I can get this wiring mess sorted out then I can go ahead and stick the motor in the truck and then get it hooked up after.
 
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Jim Fulmer said:
I'm doing this with a 12V going into a 01', I couldn't find a 12V harness so I used the existing harness and converted the pipe thread 12V over to metric to use the 24V sensors, other have said it will work so that is what I did.....keep in ind it was a P-Pump 24V prior.

Jim
Click to expand...

Did you buy the adapters, or make them yourself? Im doing this conversion as we speak. Thanks!
 
slrrls said:
That is the harness that I have; the engine harness which also is the way I read everyones post that said you just need the pcm and the harness.
It has a couple of couplers where it coupled into the rest of the harness on the 98.
But my 98.5 sold in 99 does not have those couplers. It is a little bit different harness which feeds into the engine compartment fuse block.
It is looking like I need that engine compartment fuse block as well as the rest of the harness that feeds into the cab.
Unless someone has dealt with this before and can help me with the details of splicing this 98 engine harness into my 98.5 harness.

Another question that has popped up is if I get the fuse block from the engine compartment and the rest of the harness that feeds into the cab then will it just snap into the the harness inside the cab? or will there still be some type of splicing there?
The details are few and far between looking on the groups and the net.

I'm stuck and don't want to install the engine till I have this worked out.
Otherwise I'm going to have to look at getting another block for my 24 valve then installing the P-Pump on that motor.

Gonna be easier to install this 12 valve which is the motor of choice for me from all the reading and from what I understand about these motors, because it is mechanical with no electrics.

If anyone has experience with this your help will be much appreciated.
Click to expand...

You are gonna need the fuse block and harness to the cab plug as well. The big plug at the fire wall is the same though so you will not need the cab harness. Should have 2 other connectors that go up to the dash fuse block as well. I did a 98 24 valve to 98 12 valve conversion and thats what it took, PCM, engine harness, and under hood harness. With that it looks like a 100% factory install, and everything worked perfect.
 
here are photos of the plugs on the harness and the fuse block.
the fuse block is the one that came with my 24 valve cummins. The large white recepticle in the right corner of the box that has a philips screw in it is a recepticle plug that I'm not sure is on the 12 valve and it has pins lined on the left and right of the philips screw. I'm curious if it is on the 12 valve box.

the photo of the 3 plugs is how this 12 valve harness attaches to the harness running to the engine compartment fuse block on the 12 valve motor.
My 24 valve harness is absent of any connectors such as this.
The 24 valve harness looks to be one solid harness connected to the fuse block and then running through the firewall into the cab compartment.


Ok I see your post after posting these photos.
So I understand I need the engine fuse block and harness leading from it through the firewall into the cab to that cab fuse block.
It sucks I sold the cab and frame on thurs and the guy lives two states away. maybe he will return my messages.
 

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Your secret squirrel patch just reminded me to go tell my wife about the mysterious disappearance of our squirrels.
You see we have had a yard and woods in the back that has had numerous families of squirrels in the spring so the place has been over run with squirrels.
Well they have dissappeared in the last two weeks.
we have none period.
so I popped in on my wife just now while she was brushing her teeth and asked if she had noticed the squirrels had all dissappeared.
She replyed ell aybe it to hottt with her mouth full of toothpaste.
I said so what they all in the air conditioning???
"NO" she replied aybe eir n hols n na gound like abbits? as she hopped her other hand through the air.
:lolly:
 
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We did mine using all the 24V harness, ECM, and sensors. I don't know about using a '98 12V harness.

There are several threads around on this swap.
 
kleann said:
Did you buy the adapters, or make them yourself? Im doing this conversion as we speak. Thanks!
Click to expand...

Pipe thread plugs tapped to M14 x 1.5 for the sensors....at least mine were, took one down to match it up.

This harness was odd to me cause it had a temp sensor in both the rear of the head and the front, I took a brass nipple, Tee...tapped to metric and elbow then modified and used the 12V heater hard lines, looks a little odd but so do hoses draped across the motor and I've seen that too.....need a pic let me know!

Same goes with the oil pressure sensor, 1/8th pipe to a 45 tapped and sensor in there.....haven't worked on it in a while so I'm likely forgetting something.

Jim
 
I got the engine bolted in to the motor mounts on the frame today.
I don't know if this is common in a swap or not.
But, while the bottom of the motor is touching the bottom of the transmission case the top of the motor has a 1" to 1.5" gap.
I stopped at that point and decided to see what experiences were on this forum.
maybe I'm supposed to bolt the hoist to the front of the block and pull so the back of the motor drops.
So to refresh I have a 98.5 24 valve with 47re automatic.
I have switched out the 24 valve for a 98 12 valve.
Is this common to see this gap?
Is the 12 valve slightly shorter in length?
And now that I think about it I may have seen the bolts that bolt the trans on the cross member in the slotted holes were slightly loose because I switched out the trans about 100 miles ago and must not have tightened them enough, I'm not sure. But I don't have time to double check today.
Anyway did anyone else find the lengths in the blocks to be different or come up with
this scenario ?
 
Tranny mount needs to come loose and adjusted to mate with motor put in bellhousing bolts and make sure converter still spins freely then install converter bolts etc.. Sounds like your allignment is off no biggie blocks are the same length.. You can also jack up front of the motor to align but think the other way would be easier..
 
i would use your harness from the 24 valve. should be much simpler than trying to change all the other stuff out. you just need a pin-out of the ecm/pcm connections and corresponding engine sensors. i did this in my swap and it worked perfectly, granted mine is an older harness but the same concept. I have a 92 harness, 95 pcm and 95 engine and sensors. sit down with some manuals and trace everything out before you do it. solder and heat shrink is your friend!
 
I considered this and quickly was stumped by the three connectors that go to them pcm.
there are pins in holes on the 98 harness where some pins are not on the 98.5.
I am told that the 98 is a beast in itself as it was only made 6 months so it's wire harness is actually different from the 96,97 and 98.5.
So it seems I would still find myself dissecting the harness's under the dash.
secret squrrel in this thread said that the 98.5 should just plug into the fuse block with two plugs and will look like a factory install. So it is just the engine fuse block with it's harness and it has two plugs that run into the cab to the cab fuse block, the engine harness and pcm.
But like it says beneath my name I'm a rookie and this is uncharted territory for me.
 
slrrls said:
I considered this and quickly was stumped by the three connectors that go to them pcm.
there are pins in holes on the 98 harness where some pins are not on the 98.5.
I am told that the 98 is a beast in itself as it was only made 6 months so it's wire harness is actually different from the 96,97 and 98.5.
So it seems I would still find myself dissecting the harness's under the dash.
secret squrrel in this thread said that the 98.5 should just plug into the fuse block with two plugs and will look like a factory install. So it is just the engine fuse block with it's harness and it has two plugs that run into the cab to the cab fuse block, the engine harness and pcm.
But like it says beneath my name I'm a rookie and this is uncharted territory for me.
Click to expand...

I am afraid by the pictures you dont have a 98 12 valve harness but a 97 or older harness. So you could do a whole lot of wiring which may still not work, or better bet would be to use the complete 98.5 24 valve harness, ECM, and PCM and wire it to think it is a 24 valve still (would be the same as a p pump 24 valve).
 
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