TCCoA Forums banner
Not open for further replies.
1 - 1 of 1 Posts

· Super Moderator
97 Thunderbird 4.6, 98 Mark VIII LSC
12,542 Posts
Discussion Starter · #1 ·
If installing a 1998+ transmission in one of our vehicles with a 93-97 4R70W, you will either need to repin the vehicle's electrical harness or swap out the transmission bulkhead case connector and its internal electrical hardware. Both revisions of the bulkhead connector use the same castings, so a 93-97 connector will plug into a 98+ transmission, but the vehicle will be locked in second gear at max line pressure when "drive" is selected unless the connector is repinned.

Below are some notes about the signals shown in the pinouts:
  • "Vehicle Power" has +12V on it with the ignition key in the "Run" position. Vehicles manufactured through the 1997 model year use three seperate pins to supply +12V to the transmission. 1998+ transmission use one pin and split the +12V internally in the transmission rather than externally in the vehicle's harness like in previous years. If installing a 98+ tranny, the two unused +12V leads can be inserted into any of the three unused positions on pins 1, 9 or 10. They can be also covered with an insulator such as electrical tape and be placed inside the split loom tubing, but there is a risk of them chafing into other wires in the bundle through time.
  • Shift solenoid #1 and shift solenoid #2 are applied in the appropriate binary pattern to automatically switch gears when the vehicle is gear selector is placed in "drive". To actuate each solenoid, simply ground the appropriate pin. Be very careful not to actuate an inappropriate gear at an improper time (i.e. shift into first gear at 100MPH). The PCM monitors current flow through these pins when energized, and some later model PCMs use an "inductive signature" too. Additionally, the powertrain control module also monitors whether there an appropriate drop or rise in engine crankshaft speed when a gear change is commanded. It should be noted that shift solenoid commands are ignored in "reverse", "neutral" and "park".
  • Transmission temperature monitoring is accomplished through a resistive thermal device, or thermistor. Both the pre-98 sensor and the 98+ sensor use the same resistance-temperature relationship. One side of this device is connected to the "Transmission Fluid Temperature" pin. The other to the "Signal Return".
  • The torque converter clutch (TCC) solenoid is a pulse width modulated solenoid that infinitely varies the slip of the torque converter anywhere from 0% - 100%. Leaving this solenoid disconnected would result in 100% slip and a correspondingly poor fuel economy and elevated fluid temperature. Also note that TCC lockup is hydraulically disabled in first gear regardless of the position of this solenoid. The PCM monitors engine crankshaft and transmission output shaft speeds. If a lot of TCC lockup is commanded and the PCM senses too much slip between the two, it may command an unlocked condition to prevent torque converter clutch damage and/or throw a diagnostic trouble code (DTC).
  • The electronic pressure control (EPC) solenoid controls pressure in the transmission fluid pressure circuit, which in turn controls transmission main line pressure through the main regulator valve. Main line pressure controls the force that clutches are locked together with and also how firm/soft the shifts feel. The impedance of this device varies with temperature, but should typically be in the 5-10 Ohm range. The EPC solenoid is technically a "current controlled" device, but connecting a frequency counter or oscilloscope will reveal an oscillating waveform. Previously observed was 5 kHz for relatively low line pressures and 10 kHz for relatively high requests (wide open throttle, uphill type).
  • 4R70W transmissions do NOT use a mechanical TV cable previously found on the hydraulically controlled AOD, used on 1989-1993 MN12s and the Mark VII. This does not appear to deter some uninformed "mechanics" from looking for one then proceeding to somehow "adjust" the shifter cable that they will incorrectly insist is really the throttle valve cable in disguise.

Note connector pictured above is from a production 1997 4R70W. 1995 and older vehicles used a P/Y wire for pin 3 instead of the R/LB wire used on 96-97 vehicles.

Note: The connector pictured above is for a production 1998 4R70W. Some later vehicles used a R/Y power wire on pin 4 instead of a solid R one.

Below are some other notes about 4R70W controls:
  • When changing pinouts one will have to contend with weatherpack seal inside the bulkhead harness connector. Some <97 vehicles will not have "pin 1" open in the gooey weatherpack seal. Punching a hole with a nail or awl in this surface would allow a wire to pass through, but would not properly seal out moisture. Likely not a problem if you live in the New Mexico desert, but is a sure way to have tranny problems later on if you live in a location such as Chicago where tons of road salt and moisture exist. So, if the donor vehicle's transmission harness is not available or the plastic looks brittle, purchase a new 98-08 bulkhead pigtail ahead of time from your local Ford dealer for around $25. The part number is 3U2Z-14S411-VHA.
  • There are a few revisions of the output shaft speed (OSS) sensors used in the 4R70W. Make sure to us the proper output shaft speed (OSS) sensor for the PCM that your vehicle is running on. All 2003 and older 4R70Ws are compatible in terms of physical shape and size, but the sensors from 2000 and earlier have a different electrical connector than the 2001-2003 sensors. Also, starting in 2004, the planetary ring gear and its accompying OSS sensor were revised and the electrical signal they generate is completely different.
  • The 1998+ revision of the MLPS is not electrically compatible with a 1997 and older PCM. 1997 and older vehicles use a resistive multiplex setup to inform the PCM of the driver selected gear, 98+ vehicles use a "bullet proof" switch that has numerous normally open switches in parallel. You will notice if you have the wrong MLPS because the "old ones" have 8 pins, the "newer" ones have 12 pins. Make sure to properly calibrate the MLPS after installation.
  • The linkage on the transmission for the gear selector cable changed. Very early 4R70Ws, typically found only on the 1993 Mark VIII or 92-93 Panthers, use the "old style" shifter linkage on the transmission. 94-05 use the "new style" shifter linkage. If installing a later transmission into an early vehicle, you can either swap linkages on the transmission or replace the shifter cable with its 1994+ counterpart.
  • If the bulkhead connector in the transmission is still the original one installed by Ford during the vehicle's manufacture, the pre-1997 revision is white in color, the 1998-2008 version is black in color, and the 2009-2009 connector grey in color. Do keep in mind that there are numerous aftermarket suppliers of transmission parts, and not all follow the Ford color scheme.
  • There is a compatibility issue with certain 2001+ valve bodies and certain 1992-2000 powertrain control modules. Line pressure will be within spec, but the 3-4 shift will slip into neutral for 2-3 seconds with very light throttle application. Reprogramming of the PCM line pressure curve or alteration of the valve body will be required to correct this problem. Reach out to a trustworthy Ford PCM tuner for more information.
  • In the 2003 model year, a new revision of the output shaft without vehicle speed sensor (VSS) teeth present was introduced into production. If installing a 2003 or later transmission, make sure that the VSS teeth are present on the output shaft as you will need a valid VSS signal to supply both the speedometer and the PCM. On later vehicles, such as 1998+ Lincoln Town Cars, 1999+ Mustangs and 2003+ Crown Vics, vehicle speed is calculated by the PCM from output shaft speed data. Do keep in mind that some 2003+ vehicles still have the old style output shaft in them complete with VSS teeth even though the teeth don't drive a sensor. If in doubt, remove the plug in the vss sensor hole or better yet, the entire tailshaft housing for inspection.
  • All Mark VIII and Thunderbirds/Cougars use the 7-tooth VSS drive gear on the transmission output shaft. Most other applications used the 8-tooth VSS drive gear. For 3.27 or numerically lower rear axle gears, either output shaft will be acceptable with the appropriate speed sensor gear. If you're running 3.73 or higher gears, you'll want the 7 tooth variety. As another option, the speedometer signal can be modified with a speedcal or electronic ratio adapter (era) device before it is sent to the PCM and instrument cluster. See also: and Abbott Enterprises Note: A global positioning sensor (GPS) device may be useful to accurately calibrate your speedometer.
  • EPC frequency range will vary somewhat depending on model year PCM strategy in attempts to minimize the hammer wear affect on valves and their bores. 1992-2000 Crown Vics all use a solenoid with the same current flow/line pressure relationship, 2001+ Crown Victorias use a revised solenoid first introduced in selected 1999 5.4L trucks which slightly raises the maximum allowable line pressure. Note that if this device were left disconnected, the transmission would revert to maximum line pressure. This may be acceptable for temporary testing or some runs at the local drag track, but running a tranny in a daily driver at full-time max line pressure for a few weeks will result in some sort of transmission failure.
  • The dimensions of the two oil passage holes cut into the valve body for the shift solenoids has NOT changed between the model years.
  • The valve body guide pins on pre-1995 transmissions are larger than on 1996+ models. If a newer valve body is installed into an older transmission case, make sure to use the proper guide pin spacers. A valve body that is improperly aligned to the case will cause a variety of difficult to diagnose transmission problems. Refer to the appropriate TSB for details.
Pre 1995 specific notes
  • Pre-1995 model year vehicles use a low impedance torque converter clutch (TCC) solenoid. 1995+ vehicles use a higher impedance solenoid. Use of a high impedance solenoid with a 1994 or older powertrain module will result in no TCC application. Use of a pre-95 low impedance solenoid in a 95+ vehicle will result in powertrain module and/or wiring harness damage. A low impedance "hardwire" circuit board type TCC solenoid is not available from Ford or the aftermarket. However, a 1992-1994 solenoid can be modified to physically fit inside a transmission with a hardwire case connector system by removing some of the plastic around the connector with a tool such as a hacksaw blade, sawzall blade, Dremel rotary tool with cutoff wheel, etc. The dimensions of the oil passage hole cut into the valve body has NOT changed between the model years.

Shift Solenoid Application Pattern
(with steering column gear selector in "drive")

Shift Solenoid 1
Shift Solenoid 2


  • Shift solenoids are electrically commanded by the PCM either "ON" or "OFF". They are not modulated signals like the TCC and EPC signals are.
  • Shift solenoids more often fail electrically "OFF" than they do electrically "ON"
  • On 1997 and older vehicles, the wiring harness inside the transmission sometimes gets chafed. 1998-2008 vehicles use a circuit board internal harness and are not prone to this problem. However, starting in 2009 the Panther 4R70W again started to use a softwire electrical setup inside the transmission.
  • A leak around the 1-2 accumulator piston will cause the intermediate clutch to drag to some extent and reduce pressure apply pressure available to other transmission clutches. A really bad leak (i.e. missing accumulator piston) can in theory cause the vehicle to start out in "2nd gear" and miss "1st" entirely. But in actual practice, a large leak on this circuit may result in no 3rd and no 4th gear complaints due to lowered apply pressure on the other circuits and new fluid leaks created by the heat/debris generated by the slipping intermediate clutch. Connecting a mechanical pressure gauge to the clutch taps will confirm or deny circuit leaks without disassembling the transmission.
  • Partway into the 1997 production year, the 1-2 accumulator piston was upgraded from a cast aluminum design to a bonded rubber design which reduces the chances of pressurized hydraulic fluid leaking around it. On early models, the bore in the case is likely to be worn significantly after several years of use. This process will be greatly accelerated if one or more of the accumulator springs shatter in the bore. Sleeve kits to repair damaged case 1-2 accumulator bores are avaliable aftermarket from manufacturers such as Sonnax.
  • Kracker from has constructed an adobe acrobat pdf document about swapping out the earlier the electrical components inside the transmission so that the vehicle's harness does not have to be repinned. There is also an html version of this document available.
  • Flagracer on has constructed some documentation about repinning the vehicle's electrical harness.

This content has been adapted from 4R70W AODE Transmission Bulkhead Pinouts - Original work credit to the team at
1 - 1 of 1 Posts
Not open for further replies.