How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Shawn Your Own Question
Shawn, Auto Service Technician
Category: Ford
Satisfied Customers: 3756
Experience:  16 years experience Ford,Nissan and Honda dealership in all areas
Type Your Ford Question Here...
Shawn is online now
A new question is answered every 9 seconds

!.I have an 86 F150 w/a 302EFI engine. where can I find the

This answer was rated:

!.I have an '86 F150 w/a 302EFI engine. where can I find the modulator valve on this $X$ Auto tranny? I CAN'T FIND IT!
2. the engine runs really rough at idle and is running extremely rich. It lopes so bad that I cant check the timing. Once you get it up to speed, (25 or more) it runs great!

Hi Customer,


Thanks for using Just Answer, your vehicle's transmission modulator valve is located on the driver's side of the transmission.





As far as the rough idle, the most common cause is a stuck or defective IAC (Idle Air Control) valve mounted on the side of the upper intake.








The idle air control valve (IAC) control the engine idle speed and dashpot functions. The valve is located on the throttle body on. This valve allows air to bypass the throttle plate. The amount of air is determined by the Powertrain Control Module (PCM) and controlled by a duty cycle signal.



  1. Make sure the ignition key is OFF .
  2. Disconnect the air control valve.
  3. Use an ohmmeter to measure the resistance between the terminals of the valve solenoid.


Due to the diode in the solenoid, place the ohmmeter positive lead on the VPWR pin and the negative lead on the ISC pin.

  1. If the resistance is not 7-13 ohms replace the air control valve.




1. Unplug the connector at the IAC valve.


2. Remove the two screws retaining the IAC valve


3. Remove the detached IAC valve from the throttle body


4. Remove the gasket from the throttle body and discard.







To install:

  1. Clean the area of old gasket material.
  2. Using a new gasket, attach the IAC valve to the engine. Tighten the retaining screws to 71-102 inch lbs. (8-12 Nm).
  3. Connect the IAC valve wiring to the unit.





Customer: replied 8 years ago.
I tested the unit, and got and open circuit. so after having to cut the screws out, removed the unit and bench tested it. I got 10 ohms, and reinstalled it, again getting 10 ohms

Hi Customer,


The IAC is more than stuck shut due to excessive carbon build up, the IAC is relatively an inexpensive part and is in need of replacement. The IAC can be purchased at any local auto part store.

Customer: replied 8 years ago.
OK, I'lll go get anouther one, and get back to you.
No problem

Hi Customer,


I was just re reading all the posts and I noticed that you said that you've cleaned the spark plugs.


I would recommend using the proper plugs, such as Motorcraft SP-450.


Also double check the spark plug Gap .044 (In thousandths of an inch).


And finally, inspect all vacuum lines making sure that there are no splits or cracks, or even disconnected. Try spraying carb spray around all vacuum line fittings as well as the intake manifold and monitor for any change in the idle. If idle increases when spraying then you've located the leak. Hope this helps you out.





Customer: replied 8 years ago.
I thru the guys at Advance Auto a curve, the part that I took in was half the size of the one they had to sell. I came home & dicovered that I had only taken off the electronic part! But I put on the new one(the whole one)and it does'nt run super, but it is 90% better. I'll probably need to blow it out a little to get the carbon build up down. I'll spray a little water into the intake, that used to work. Let's call that a success! Now where can I find the transmission modulator? I bought one a few weeks ago, but I can't find the old one!It's an automatic 4x4, but I don't know if it's c4 or c6.

Hi Customer,



More than likely the transmission that you have is an AOD. The modulator is on the driver's side of the transmission.



This is for the AOD





And this is the C6








Thank you for using Just Answer, if you are satisfied with my response please click the ACCEPT button so that I may get credit for my work. Positive feedback and bonus are very much appreciated, if not satisfied ask more questions.Thanks

Shawn and 4 other Ford Specialists are ready to help you
Customer: replied 8 years ago.
Thanks, XXXXX XXXXX screwin' around with this thing off&on for two weeks. Luckily,it's my backup unit(iput about 1000 miles on it last year). You'll get another notch in your positive feedback belt.
   Thanks again, Customer
Thanks Customer
Customer: replied 8 years ago.
Shane, Still looking for modulator. Vin#1FTEX14N3GKA77862 Trans "T".
Pan is almost square(tapers at rear corners)and has a sump near the middle. Customer
Customer: replied 8 years ago.
Shane, Still looking for modulator. Vin#1FTEX14N3GKA77862 Trans "T".
Pan is almost square(tapers at rear corners)and has a sump near the middle. Customer

Hi Customer.


We need to find out if this transmission is an AOD, if it is then it does not require a vacuum modulator.


Transmission Identification

All vehicles are equipped with a Vehicle Certification Label, affixed to the LH (driver's) side door lock post.

Refer to the code in the space marked TR on the Vehicle Certification Label for proper transmission identification


Hi Customer,


For additional information such as: model, service ID level or build date, refer to the transmission ID tag which is attached to the transmission case.






Customer: replied 8 years ago.
My label is not like that. It has a trans code of T. is there a way that I can send a photo of the label to you?

Hi Customer,


The "T" only indicates that the transmission is an automatic.








Hi Customer ,


From the description of the pan, it seems like the transmission that is in your truck is an AOD and uses the Throttle valve, instead of a vacuum modulator.



Throttle Valve (TV) Control Cable Adjustment


Service Adjustment Procedure

Two methods of TV system adjustment are available.


1. TV cable adjustment with engine off.


2. TV control pressure check and adjustment procedure with engine on.

The Throttle Valve (TV) Control Cable System consists of a cable attaching stud on the throttle body throttle lever, the TV Control Cable Assembly, the External TV Control Lever on the transmission, and the Cable Mounting Brackets at the throttle body and transmission. As the throttle body lever is moved from idle to wide open throttle (WOT), the TV control cable pulls the transmission TV control lever from idle to WOT. Return of the cable and transmission lever towards idle is accomplished by the return spring on the transmission end of the cable assembly. This spring and the end of the cable assembly is protected by a flexible rubber boot. The transmission external TV control lever actuates the internal TV control mechanism which regulates the TV control pressure. The travel of this lever is controlled by stops internal to the transmission.

The TV control cable is set and locked to its proper length during initial assembly by pushing in the locking tab at the throttle body end of the cable assembly. When the tab is unlocked, the cable is released for adjustment. The take-up spring at this end of the cable automatically tensions the cable when released. With the slack taken up and the locking tab pushed in, the take-up spring plays no part in the operation of the system.











Hi Customer,




Here are some diagrams








And Click Here









Customer: replied 8 years ago.
I removed a tag from the tranny and it reads as follows;
044631 A20
In responce to your last post. other than checking the springs, this is over my head I have'nt driven the truck since replacing the IAC,
I have checked the cable and springs, and everything seems good.
By the way I used my beadblaster cabinet to clean, then regapped the plugs.I stillneed to get a can of carb cleaner to check the rest of the vac system. before I contacted you, I found two short hoses that were dry rotted. I have printed hte diagrams that you sent and will file them for future reference.