5.0 Harness Questions

I picked up a 5.0/4r70w combo to use in a project vehicle. Came out of a 98 (PATS I know) and got a steal on it. I plan on using the power steering pump, alt and thats pretty much it. I got the complete harness with computer. When I say complete he even brought my the steering wheel and fuel pump, wiper motor etc.

Question is I need to thin out this harness big time. I really just want the essentials to install the engine and trans into my project and I will figure out wiring it into that vehicle from there.

Anyone have anyone insight as to what the basics I need to keep are.

I would grab a 97.5 pcm and use it, it's basically the same pcm without pats. It must be from a truck with external egr which is build dates 11/96 - 03/97.

There isn't much you can thin out of the engine harness, you can delete a good bit of wires going to the body harness though. All a/c connections are on the body harness in the v8s.

And the big question...... Whatcha putting it in?

boominXplorer said:

I would grab a 97.5 pcm and use it, it's basically the same pcm without pats. It must be from a truck with external egr which is build dates 11/96 - 03/97.

There isn't much you can thin out of the engine harness, you can delete a good bit of wires going to the body harness though. All a/c connections are on the body harness in the v8s.

And the big question...... Whatcha putting it in?

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Thats some awesome info, thanks for that! Do I need to make sure the codes match or does that not matter much?

Its going in my 93 YJ, HP 60 front, fabricated housing 9" rear and 40 trepador radials on creeper locks I thought about putting it in the explorer but it works great with the sohc.

Here is my solution to the harness wiring for my swap.

http://forums.turbobricks.com/showpost.php?p=4038594&postcount=2

There was a transition from the early to late configuration in mid-97 but I am unsure what was changed. Wishful thinking would be that PATS was not implemented but that the later fuel system that is on your engine was.

More information is available here:

http://www.explorerforum.com/forums/showthread.php?t=364540

The 98-01 computers have much different wiring than the 96/97's. The PCM's don't swap across that major wiring change.

The EGR didn't affect the computer, the same 96 PCM will work in a late 97 302 with external EGR. There is one 97 computer, they all swap.

1998 is unique in the PCM, the wiring changes are exactly like the 99-01's, but without the fuel system changes. So by altering things for the fuel systems will let you swap a 98 PCM into a 99-01, and vice versa.

Here's the big key for swap into non Explorers; The 98-01 Explorer PCM must have a conditioned VSS signal, and that is done by the Explorer ABS module.

If you don't want to mess with the VSS issue, use a 96/97 PCM, and the matching 96/97 engine/trans/PCM wiring harness. That is the best system to use for controlling any Ford pushrod V8, in a different vehicle.

I agree with boomin that's what I have in my sport, and no the computers don't act right with the wrong egr ,

XDT2 is the one you want

Ford seems to think that the transmission OSS provides input to the PCM for shift management.





My Volvo does not have a VSS and shifts just fine with only the OSS and an unmodified '00 harness. I have come to believe that the VSS provides information through the ABS module for 4WD management.

Your sorta right, the v8 trucks , electronically speaking think they are 2wd , but yes the signal in the 98 up trucks is from the the rear tone ring and goes through the abs to the pcm ,

I would really like a clear and definitive answer to the OSS v. VSS question and do not respond to be argumentative but my '82 Volvo thinks it is a 2WD truck, does not have a VSS or ABS and shifts just fine.

This series of Explorer 302's is used in many swaps into lots of different vehicles all without a VSS.

delexploder said:

I agree with boomin that's what I have in my sport, and no the computers don't act right with the wrong egr ,

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delexploder said:

XDT2 is the one you want

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I spoke with my Ford parts man, and the 97 302 computer is the same for any build date. I bought two 97 PCMs, both happen to be that XDT2 calibration catch code. The others I saw on eBay had the same part numbers when available, and the same XDT2 code when shown.

My parts guy is very very good(40 years at the same dealership), I do not doubt him one bit. He says there is one 97 PCM. If there is another 97 unit, then Ford doesn't know about it.

Now, beyond all of that, the 1998 wiring harness will not work right with the 96-97 computers, which is what the OP has.

The physical PCM is the same over many years and several models of Ford vehicles but there must be 200 or more software loads. I had a list of all of them at one time but cannot find it at the moment.

TestPoint said:

The physical PCM is the same over many years and several models of Ford vehicles but there must be 200 or more software loads. I had a list of all of them at one time but cannot find it at the moment.

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PCM's change physically for the actual hard wiring changes. You have seen and analyzed those 96-01 schematics thoroughly. Tell me how the wiring changed through those six years? I see two versions only, 96 to 97, and 98-01, with no mid year changes. The 97 wiring did not change when they altered the EGR system to be external. That is the same wires perform the same functions. Connectors might differ with that EGR change, but the PCM uses the same wires and circuits.

I have plenty of Explorer wiring now from the 302 in 1997, and my 98 truck. I can compare the EGR wiring etc, I just haven't needed to yet.

That's because the early 97 uses the same pcm as the 96 , the change coin sides with the switch from internal egr gt40 heads to external egr and the p heads, As for the vss I'm not sure why your setup is working unless its in some sort of limp mode , this is also why I set my sport up the way I did , it started as a 97 , no pats already return fuel and vss in the t-case , when I first put it together all I had was the 99 drivetrain and the awd case without a vss , when I switched the case to an early one with the vss it killed half my trouble codes

If you keep the 98 PCM you won't have to deal with any speed signal for the PCM, just Pats. Any 96/97 PCM requires an VSS signal to shift correctly where the 98+ uses the OSS sensor in the tail shaft of the transmission

All my info comes from comparing 97.5, 98 and 00 model year harnesses. I do know 98 and 97 share the same 02 sensors, fuel and ignition system where 99+ is uses different sensors and plugs but the overall wiring diagram remains close to the same

boominXplorer said:

If you keep the 98 PCM you won't have to deal with any speed signal for the PCM, just Pats. Any 96/97 PCM requires an OSS signal to shift correctly.

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boomin,

You seem to have 'been there, done that'. Would you comment on the note on the schematic above stating that the OSS provides the shift management input to the PCM?

TestPoint said:

I would really like a clear and definitive answer to the OSS v. VSS question and do not respond to be argumentative but my '82 Volvo thinks it is a 2WD truck, does not have a VSS or ABS and shifts just fine.

This series of Explorer 302's is used in many swaps into lots of different vehicles all without a VSS.

Click to expand...

No abs or vss , is why I said that

TestPoint said:

boomin,

You seem to have 'been there, done that'. Would you comment on the note on the schematic above stating that the OSS provides the shift management input to the PCM?

Click to expand...

The 98-01 trucks use a digital signal from the rear abs sensor and convert it to analog for the speedo to work. The OSS signal inside the transmission is only used by the computer to determine shift points. If your using a 00 pcm/wiring setup you shouldn't have a shifting issue, it doesn't require a VSS input.

96-97 trucks use an analog VSS signal located in the tail shaft of the trans (2wd) or t-case (4wd) for shift points and speedo.

My 01 ranger also used an analog input for the speedo factory, that was another reason I used a 97 computer for my swap. Well that and the fact I had 2 late 97 parts trucks.

Great answer!

Now, my though is that each and every one of the PCM's of this era are physically identical. The differences being the software load.

I use the Cam Position Sensor of the early/late model years as an example. The early, '96-'97 used a powered sensor with a three wire connector. The later '98-01 used a 2 wire non powered connector. Both designs delivered the timing pulse signal to exactly the same C202 pin on the PCM.

The difference being the software load.

To me that says the PCM is just a little computer with 104 pins that can be defined, to a large extent, by software.

What say you?

All the v8 pcms 96-01 are very similar but all have their differences defined by the calibration code. You just can't throw a 99 computer in a 97 and hit the key, it wont work. Now with some re-pinning of the harness and a custom tune anything is possible. The fuel system change between 98-99 is where the big change between the computers is.

Oh and back to the original post, you have 2 relatively easy options for computers....

- Use the 98 computer, delete PATS and your done

- Use a 97 computer and add a VSS input by using a 97-98 F150 4406 T-case. You may also have to move a few pins in the main connector, I never compared a 98 PCM pinout to a 97.

The only difference between the 2 is the VSS and PATS. Going with the 97 pcm might help you get a working speedo if your interested in one.