98' to 03' motor & Transmission SWAP HELP!!!

[BAttitude7689]

1998 Mustang GT (Auto) swapped to 2003 Mustang GT (Auto) *Motor and Transmission* currently using the 1998 computer and harness

just cleaned up and we had to roll my car out of the shop, but the motor fires up just fine, but now here is the issue

on the left side of the transmission (towards the middle) there is a sensor, my mechanic said it was some type of transmission speed sensor. now with sensor from my 98' inside the transmission it would plug in of course because im using the 98' wiring harness and computer, but with it inside the transmission it would not allow the output shaft to turn. so we removed the sensor and put the 03' sensor in the transmission and the it turned just the plugs were completely different plugs.

what are my options? list my possible ones if you can? if i cut the plug off the 03' harness and just solder the 2-pin connector to it then i can use my 98' harness will that work? if so will it work correctly?

now with the extended rang speedcal from dallas mustang...would that fix my speedometer problem? im kinda confused with all of this so could you just help explain it out a little for me with this whole swap i have so much stuff running through my head im gettin confused some so that would be great!! thanks alot again for all the help! i really wanna get the car running and driving and shifting properly ASAP

 

[wmburns]

OSS/VSS sensor differences

The 98 uses a vehicle speed sensor (VSS).

The 03 uses an output shaft sensor (OSS). The OSS is like the crank position sensor.

The VSS is not compatible with the OSS. The signals generated are different. A Speedcal would have to have the ability to convert the OSS signal to a VSS signal.

It may be possible to retrofit a VSS on an OSS transmission. However, it is almost certain that some level of disassembly will be requried. Best to consult a transmission expert if going this route.

Note, Ford has even changed the number of teeth used in OSS applications. For example, a 2000 and 2003 both have OSS sensors. However, the number of teeth is different between the MY. It is possible to change the OSS tooth wheel to resolve the differences. Again, some disassemble required.

I have read that it is possble to re-program/tune for a change in OSS teeth.

It is not reasonable to re-program the PCM for the OSS/VSS differences because the analog/digital converters are different for the different sensor outputs.

 

[BAttitude7689]

would my best option be to buy an 2003 GT computer and interior harness and instrument cluster to fix the issue? would the 03' fit in my stock 98' dashboard?

 

[wmburns]

In 1999, the Mustang was heavily updated. The electronics are MUCH different. Electronic cluster, completely reworked fuse panels, CCRM, fans, wiring, PATS, GEM, the list goes on.

Return fuel system ditched for a return-less system. Fuel pump driver module (FPDM).

Just swapping PCM and cluster will not give you the easy results you are looking for. Replacement of the entrie body wiring harness is needed. And even then, you will run into the differences in fuse panels (location and number of circuits).

 

[BAttitude7689]

i was going to have a custom tune, to help me with alot of the changes. what else does it entail for a entire body wiring harness, i already have the 03' engine harness and i was going to change the interior harness, what other harness would have the to change if i have the motor,interior and transmission rewires with all new harness and computer. also alot of people have done motor swaps with my year mustang to newer style motors? only thing i did was change the transmission as well, so its going to throw off my speedo and odometer and fan speeds until i switch the harness and computer with cluster....what other harness is there. and the fact about returnless fuel line i used my stock 98' fuel rails and setup and with the tuner i know you can tell it if you have return less or a return

 

[wmburns]

So how did this grow from a transmission modification into a complete car re-wire.......

Have you spoken to a transmission shop? This may not be any harder than swaping the tail shaft from the 98 onto the 03.

Is there anything wrong with the transmission from the 98?

Have you researched the Speedcal option?

I guess it would never occur to me to transplant an entire car's wiring harness from a 03 into a 98. I would be too daunted by the fuse panels being in different locations. The fuel pump relay in a different location. How does one re-do the wiring in the dash? Remove the dash perhaps. What about all those relays and controls in the dash? You must have access to a complete donor 2003 to be thinking about doing it this way.

Anyway, listing exactly what it would take to transplant the wiring harness from an 03 into a 98 is way above my head.

Anybody out there have a good idea what it would take to transplant the PCM, Cluster, ect from a 2003 into a 1998?

I really can't offer any more help down this path.

 

[BAttitude7689]

So how did this grow from a transmission modification into a complete car re-wire.......

Have you spoken to a transmission shop? This may not be any harder than swaping the tail shaft from the 98 onto the 03.

Is there anything wrong with the transmission from the 98?

Have you researched the Speedcal option?

I guess it would never occur to me to transplant an entire car's wiring harness from a 03 into a 98. I would be too daunted by the fuse panels being in different locations. The fuel pump relay in a different location. How does one re-do the wiring in the dash? Remove the dash perhaps. What about all those relays and controls in the dash. You must have access to a complete donor 2003.

Anyway, listing exactly what it would take to transplant the wiring harness from an 03 into a 98 is way above my head.

Anybody out there have a good idea what it would take to transplant the PCM, Cluster, ect from a 2003 into a 1998?

I really can't offer any more help down this path.

Well I was told that would be very expensive to tear apart two transmissions but besides that the problem is just not the speedo gear itself its the transmission speed sensor that does not plug into my 98' harness, so my solution was to use the 03' engine harness and computer take out my dash board n swap the interior harness with the 03' then get a new instrument cluster to use that is digital n controls my speedo and odometer, and of my other minor issues have fixed in a tune.

About the speedcal I did some research on the extended range speed cal and all I found that it won't work correctly bc I have an auto and not a 5 speed, but my next phone call tm will be to Dallas mustang about the speed cal if that will fix my speedo gear prob and my transmission speed sensor.......

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[patman0911]

Tearing the whole car apart and swapping out harnesses is the best option you've got? This doesn't make any sense to me. I think you're just asking for more headaches and are bound to run in to more problems by swapping harnesses. Either there's a reasonable process for converting the transmissions, or just reuse, or have it rebuilt if age is an issue, the old transmission and sell the '03 trans to offset that costs of this project.

I'm no transmission expert so you should follow up on this with someone who really knows these transmissions but a little searching turns up the following options if reusing your '98 isn't an option.

• Inspect the '03 transmission and see if you can find a cover plate in the same area where the VSS sensor would go on your '98 transmission. If there is a plate, then it's very likely that the teeth are there and you can simply transfer your VSS sensor over from the '98 trans.
  
• If the cover plate isn't there then the transmission will have to be opened up and the output shaft will need to be swapped for one that has the teeth for VSS and you'll need to swap tailhousings or possibly modify the current one to accept the sensor. It's not clear if the '98 tailshaft and housing will work or not, there may have been some changes in '99 that may affect that. It will require a tear down of the transmission to get to the output shaft.
  
• If that doesn't sound palatable then you may be able to correct the signal with a Speedcal. You'll have to figure out the multiplier and see if that's within the range of the Speedcal. I didn't dig any further to see if anyone had successfully done that but if the multiplier is within the range of what the Speedcal can correct, then that is what the thing does

 

[BAttitude7689]

the speed cal with not work for my application, i contacted dallas mustang and talked to the guys over there and they said only on manual transmissions it will work NOT on the automatics...

but i did alot of reasearch and call alot of people today and i found a donor car, its a 2002 GT and its and auto... i was gonna get the computer,speedo and dash harness and swap with mine and have sniper tuning adjust my PATS and fuel line setup.

but one thing i was told that for the computer i can use an 02' computer as long as its an automatic, but my motor and tranny are 2003

and someone told me to rather get all my parts from the same car and not all different cars because sometimes the speedo's wont work with a different harness even tho 99'+ are the same but a lot of people said find an 03'-04' computer but like i said i found a 02' with 25k miles on it to use for my swap

this seems like a lot of work but easier than swapping a tail-shaft which i was told that's not worth it!

 

[wmburns]

Just wondering which wiring harness is currently installed on the 03 transmission. The reason has to do with how the transmission, harness, and PCM have to work together.

As stated before, the VSS and OSS signals are not compatible. The VSS wiring harness supplies 12 volts to the VSS sensor. The PCM supplies the grounding signal return. The transmission harness is configured accordingly.

In an OSS application, the sensor generates it's own voltage. The PCM needs TWO wires (same as the crank shaft CKP sensor). The wiring harness has been altered to match.

Other wiring differences exist between 96-98's and 99+'s. The 99+ 4R70W uses a digital transmission range sensor (DTR). The 98< do not. The way the transmission communicates with the PCM is very different between the two versions of the transmission range sensor. The wiring harness is configured to support this.

The trans will need to have the correct TR sensor for the application.

The 4R70W transmission is an electronically controlled transmission. There is a lot of integration/communications needed for the PCM and the transmission to work. This needs to be taken into consideration when mixing/matching components from different Model Years. Some swaps are easier than others. IMO, swapping to/from 98</99+'s is harder because of the huge changes made in 99.

On to the cluster question. A 99/00 MY cluster will work only in a 99/00 car. The later MY's do have better interchange. There are fewer differences between MY=02 and MY=03. However, that is not to say there are none.

Advice time. When mixing/matching major components, there is always some risk. Often there are varying degrees of difficulties in resolving. IMO, a lot of this depends upon the access to the detailed diagrams of the various MY and the willingness/ability to understand the differences (IE, what can be easily changed vs what requires a re-design).

Keep us posted. It is likely to be a wild ride. Good luck.

 

[BAttitude7689]

right now its using the 98' harness and computer and it all plugs together EXCEPT for the transmission speed sensor the plugs are different so it dosent plug in and i check to swap a tailshaft and i was told its $$ and may not fix my issue to be perfect again

my other thing i looked into was the speedcal option and i was told that wont work either.

so my last option was to turn my 98' stang into a 03' like i said i found a 02' GT with a computer and cluster with 25k and the dash harness.

Im planning on swapping the dash harness but as well using the 03' engine harness then change the cluster and computer and then put the dash all back together, and i have sniper tuning helping me with a tune to turn off the PATS, and change the fuel system to have a return instead of return-less, but that just for now to get the car running and shifting good and down the line i will make the swap and see whats involed in making it a return-less system, like it should be!!

 

[wmburns]

At the risk of beating a dead horse. If it were me I would make sure I also had a line on the Fuse panel (BJB and CJB), The harness to/from the CCRM. The CCRM itself.

In the dash there are various new control devices such as the GEM, seat belt minders, electronic flashers. The air bag system is different (clock spring vs capactior discharge).

The engine harness (Coil pack vs COP). The transmission harness. The right side body harness. The fan harness. The fan (two speed vs single speed).

This is going to be harder with the engine in the car.

I would get the fuel pump harness and FPRM for future. OBTW, converting to return-less will also involve changes in how the vapor management is done. The later model cars have a different vapor hose set up. The charcoal canister is in a different location. The evap purge solenoid is also in a different location.

Are you doing the work yourself or paying someone to do it?

Is it actually cheaper to buy all of those donor parts as opposed to rebuilding your 98 transmission? Live and learn because I would not have guessed it.

I have to tip my hat to you. When completed you will really have something to be proud of. Besides, this will make a great build post. Looking forward to reading it.

Some consideration should be given to buying a full set of wiring diagrams from the 96 MY and the 02-03 MY. Ebay has multiple sellers for the Ford factory service CD's. Should make the troubleshooting easier. It will be the some of the best $$ spent on this project.

 

[BAttitude7689]

At the risk of beating a dead horse. If it were me I would make sure I also had a line on the Fuse panel (BJB and CJB), The harness to/from the CCRM. The CCRM itself.

In the dash there are various new control devices such as the GEM, seat belt minders, electronic flashers. The air bag system is different (clock spring vs capactior discharge).

The engine harness (Coil pack vs COP). The transmission harness. The right side body harness. The fan harness. The fan (two speed vs single speed).

This is going to be harder with the engine in the car.

I would get the fuel pump harness and FPRM for future. OBTW, converting to return-less will also involve changes in how the vapor management is done. The later model cars have a different vapor hose set up. The charcoal canister is in a different location. The evap purge solenoid is also in a different location.

Are you doing the work yourself or paying someone to do it?

Is it actually cheaper to buy all of those donor parts as opposed to rebuilding your 98 transmission? Live and learn.

I have to tip my hat to you. When completed you will really have something to be proud of. Besides, this will make a great build post. Looking forward to it.

Some consideration should be given to buying a full set of wiring diagrams from the 96 MY and the 02/03 MY. Ebay has multiple sellers for the Ford factory service CD's. Should make the troubleshooting easier. It will be the one of the best $$ spent on this project.

Well I will be using the 03 engine n tranny harness along with the dash harness n fuse panel and computer as well as cluster.

As for the coil packs vs cop I have the 03 engine in the car with the coil packs with the 98 computer so once I switch computers n harness I will be able to use the cops

Will my air bags not plug into the 03 dash harness?

I'm confused about what you said about the fuse panel can you explain.....

With the new harness n cluster will my head lights and tail lights Along with blinkers work properly?

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[wmburns]

1996-1998 fuse panel overview.
Engine compartment: number of circuits=17
I/P panel: number of circuits=18

1999-2004 Fuse panel overview.
Battery Junction Box (BJB): number of circuits=28
Central Junction Box (CJB): number of circuits=38

35 increased to 66 circuits. 31 additional circuits. Almost double.

Will it work.. However, I suspect success more depends upon your ability and determination.

Just knowing how car projects usually pan out for me, it is usually the little details that are the biggest PIA. Everyone knows what I am taking about. Some tiny little switch or $1 part that has to be special ordered. The transmission sensor difference is a sample of things to come.

 

[BAttitude7689]

well im stuck and totally fcked!! im lost and dont know what do to do, im going to call another transmission shop tomorrow and ask what they say, but when people say to swap the tailshaft will that correct the transmission speed gear because if i remember correctly on the tail shaft was a blank plastic plug. and on my transmission thats where my mechanical gear inserted in the transmission. but my biggest issue is, about midline of the transmission on that left side is a transmission speed sensor that plugs into the transmission and the other side has a pigtail connector that plugs into the tranny harness, well that plug that plugs into the harness is a different connector. and the only way i got the tranny to turn was to put the 03' sensor inside because with my 98' sensor inside it was to long i believe and it wouldn't allow the transmission to turn properly and get out of park. so would a tailshaft swap be able to fix that problem? and if not WTF!? do i do next?

swapping the harness sounded easy until you brought up the fact about the fuse panel under the hood and different circuits and to be honest after swapping the harnesses and it not working i wouldnt have the slightest idea where to begin....