converting 99 24 valve to 12 valve problem

Well, here is the thing. the title says 98 but the tag I on the block says 96 so I guess your right.
so you think it will be best to go with my 98.5 harness and 98.5 pcm?
If that is the case can you offer suggestions on where i should start and where difficulties may arise?
 
ninerqb8 said:
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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Yup the pic you posted is not a 98, looks like my 96 plugs. A true 98 engine harness will plug into your existing fuse box in that square plug. I just went through a bunch of wiring, no bus, instrument cluster, sensor crap swapping a 00 cab onto my old 96. There's only a couple wires you'd have to adapt to your existing fuse box and the 12v will come to life. Granted that's if you have the 98 12v pcm and engine harness otherwise I see lots of harness splicing in your future.
 
slrrls said:
Well, here is the thing. the title says 98 but the tag I on the block says 96 so I guess your right.
so you think it will be best to go with my 98.5 harness and 98.5 pcm?
If that is the case can you offer suggestions on where i should start and where difficulties may arise?
Click to expand...

Look into p pump 24 valve wiring. The hardest part is going to be getting the 24 valve sensors to fit on the non STORM 12 valve block. You can either adapt from NPT fittings on the 12 valve to the metric o ring fitting on the 24 valve sensors, or try changing the plugs on the 24 valve harness to use the 12 valve sensors.
 
Being this is a 96 motor will it still be a plug and play with the 98 harness or will I still be in the same place I am at the moment swapping wires and plugs?
Because I may be able to get the 98 harness but it will sure cost me.
And i should add for the record that my truck is a 99 24 valve but made in 98. I add that just in case being a 99 is another game changer.
 
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With my 96 engine and the 98 harness the oil pressure, coolant sensor, and crank/engine speed sensor plugs were all different. I swapped them all for the 98 sensors. My 98 harness was missing a extension pigtail for the coolant sensor or something cause the connector was way too short and the wrong style so that's the only one I had to completely change. The fuse box will have no wire for the fuel solenoid relay power in it so you'll have to pull that out of the engine harness and snag power off the fuse box. Also my v10 fuse box had no starter signal wire to turn the fuel solenoid relay on, should be same issue for your 24v fuse box, so you'll probably have to pull that out of the engine harness and tap it in also. Those should be the only 2 you'd have to cut and "adapt" out of the engine harness.

I also ran into an issue with no bus error on my cluster using a 00 v10 auto cluster and 98 12v manual pcm. I ended up getting the cluster from the same truck the pcm came from and all was well. Not sure if yours would work or not, seems to be hit or miss for some reason.

98 harness's and pcm's are out there for good prices, you just have to look for 'em.
 
slrrls said:
Being this is a 96 motor will it still be a plug and play with the 98 harness or will I still be in the same place I am at the moment swapping wires and plugs?
Because I may be able to get the 98 harness but it will sure cost me.
And i should add for the record that my truck is a 99 24 valve but made in 98. I add that just in case being a 99 is another game changer.
Click to expand...

Being a 98 or 99 wont matter all of the new interior 2nd gen trucks use the same wiring and plug for the cab, they just changed it from the firewall out. If your 96 engine happens to have a storm block then it would be pretty easy to do either the 24 valve harness or the 98 12 valve harness. If it is not that where it can get interesting because your 24 valve sensors will not thread into the 12 valve block without adapters, and buying a 98 harness will not help much because most 98's had a storm block so you would be back to finding adapters for the sensors.
 
I think we determined this 96 is non storm but how do you tell if it is s storm block?
Is one of the factors that it has the 3 bolt holes for the motor mount?
 
From a engine ID link off google....

The second design block, the Straight Thread O-Ring Metric (or STORM), was used beginning in 1997.5 through 2002. This block was also used in 2003 and newer off-highway applications.
 
slrrls said:
I think we determined this 96 is non storm but how do you tell if it is s storm block?
Is one of the factors that it has the 3 bolt holes for the motor mount?
Click to expand...

Easiest way to tell is if it has 2 places for the turbo oil drain to go back into the block. 1 where the stock drain is and one further back.
 
both blocks only have one oil drain back into the block and both in the same place.
But the 24 valve has another oil port further back that is undrilled or plugged so the 24 valve has two ports.
Date on the 12 valve is 9-20-96
 
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I would recommend keeping the 24 valve harness and adapting the sensors to work on the 12 valve. The you only have a small amount of wiring for the 12 valve to work.
 
So I don't see the cam timing sensor on the 12 valve and I don't see the crank sensor.
Do you know what sensors I need to concern myself with making work?
Actually if I had a list of the items I need to get connected it would be most helpful.
 
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slrrls said:
So I don't see the cam timing sensor on the 12 valve and I don't see the crank sensor.
Do you know what sensors I need to concern myself with making work?
Actually if I had a list of the items I need to get connected it would be most helpful.
Click to expand...

I have not done this with a 24 valve harness, so my advice would be to look into p pump 24 valve threads. And for the sensor adapters I would find out what sizes you need to adapt from and to and call the parker store.
 
I read on Bigpapa's thread he linked that there is no cam gear sensor requirement with the 12 valve so I take it I don't have to even deal with that plug except to tuck it out of the way
With all said, will you guys weigh in on which pcm I should use?
I have the 12v pcm that came with the motor and then my 24 valve that is in the truck.
the guy that bought the cab is sending me the fuse block from engine to cab harness and cluster today and maybe what ever else he decides to throw in the box.
So I'll have these items if I need them.
I'm following everyone opinion here and zooming in on the 24 valve harness to the 12 valve block.
But, it seems to me that I should be using the pcm that came with the motor because that pcm would only require what is found on the engine to run.
However, this means I need to consider that pins that are missing in each plug on the pcm. Each harness has a couple pins the other does not.
But using the 99 pcm seems to request information from sensors that are not present on the 96 motor.

I have the 2001 manual which provides schematics for the 99.
Does anyone have wiring schemeatics for the 96 12v?
 
when i put a 12v in my old 01 i used the 24 v harness, ecm and 24v sensors and used bushings and such to make them able to screw into the block. used a 24v tappet cover and located the ecm where it would be on the 24v with case breather covers for ccv. shutoff solenoid wired up like factory everything worked as should just had a check engine light on but unsoldered it from the instrument cluster
 
The 96 pcm won't run the newer gauge cluster, you'd need the 98 12v pcm. I agree you're probably better off using the 24v computers and adapting it like a p pump 24v.
 
The whole premise here is to make you're truck think it has a 24V engine in it, not to make the engine think it's in a 12V truck.

We did the same thing Sigal did except for the tappet cover. Currently my ECM is hanging from the hydroboost on a piece of wire until I get a bracket fabbed.
 
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I'm glad no one bought my 24 valve. I took it off sale today so I can retrieve the sensors I'll need
 
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