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Brian, Auto Service Technician
Category: Ford
Satisfied Customers: 1227
Experience:  5 years Ford Technical Hotline/Service Engineer. 2005 Ford Master Cert. Automotive Technology degree
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i have a 03 ford expedition with the two rear parking sensors

Customer Question

i have a 03 ford expedition with the two rear parking sensors and they dont want to work...
i put it in reverse and the info screen beeps and thats it...i ask a mechanic and he goes it suppose to have two way communication with the computer and it doesnt send any sigal out to the computer please help!
Submitted: 8 years ago.
Category: Ford
Expert:  Brian replied 8 years ago.
Start by checking the fuses that power the Parking Aid Module. The owner's manual or fuse box cover should describe which fuses power this module. To be certain the fuses are good, go ahead and pull the Parking Aid fuses out, and replace them with new or known good fuses and retest.

The park sensors are connected to a computer module known as the parking aid module (PAM). The PAM is networked in to communicate with the instrument cluster module, and with a scan tool whenever a technician plugs into the connector under the dash. If the tech can't communicate with PAM, and the cluster cannot seem to either, then the PAM is either bad, or there is a wiring problem affecting power, ground, or the network connection to the PAM. If the tech is not using a sophisticated scan tool, he may not be able to communicate with this module. A Ford dealer should check it to make sure, or at least a shop with a professional grade scan tool that has the apropriate software is needed.

So the first step is to establish communication with the PAM. To do that, the technician would need to gain access to the PAM, and disconnect it, then check for good power and ground to the PAM connector by using a test light. If a problem is found, then the appropriate diagnostic steps to isolate the root cause would be necessary. Then the technician would need to double check the network circuit. Usually, no communication from a module is caused by the module not turning on, and that is typically a loss of power or ground.

If you need more info, please reply. I hope this helps. If so, press Accept. Keep in mind that you can continue this conversation by responding, you can accept when you feel satisfied.
Customer: replied 8 years ago.
i was already notified of this when u see my question ...
i was trying to find a soultion to fix it at home
Expert:  Brian replied 8 years ago.
If you would like, I can post up the wiring diagrams, and pertinent shop manual info. I am not sure how deep you want to go, and how much testing you are able to do. It would require some equipment like a test light for some basic checks. I can show you the wires to check for power and ground on the diagrams. Then you would at least know if there was anything further that could be done, or if the PAM might need to be replaced. Let me know, I didn't want to start posting a bunch of diagrams if you didn't need them.

Have you taken off the panel to look at the PAM yet? I can help you with that too if you wish.
Customer: replied 8 years ago.
pretty much the info i keep getting is the same that i got at the dealer
thanks but i rather not accept didnt really help
Expert:  Brian replied 8 years ago.
I can offer more info, not sure what exactly is going to help you best. If there was a common fault or a "magic bullet fix", I would tell you. It is one of those problems that requires some diagnosis. If you are not ready for that, then the dealer or a competent independent shop is the next step.

Good luck on getting it fixed. Thanks for the question.
Customer: replied 8 years ago.
ya cause when i asked the question it was pretty much trying to get a magic fix cause i have delt with the dealer already
Expert:  Brian replied 8 years ago.
I was thinking about something to suggest for you to try at home, and the best thing to do would be to focus on the most vulnerable part of the system. The sensors in the bumper and the wiring to them are the most likely parts to develop problems, simply due to the exposure to water splashing and debris.

I would suggest unplugging each sensor, and cleaning the terminals of the plug and sensor, then reconnect after using some dielectric grease to protect the terminals from moisture. While doing this, you can look for damage to the harness that goes to the sensors, and possibly find a broken wire or other obvious fault. This requires removal of the bumper cover though, to access the sensors. Some of the harness should be accessible where the body harness connects to the bumper harness, and sometimes a bad connection there will cause problems. It might help to disconnect, clean and use dielectric grease on the harness connector.

The sensors themselves are pretty difficult/impossible to diagnose without a scan tool. If you find one that is obviously damaged or affected by water, it may be worth replacing and retesting. You may end up at least needing to get the codes from the PAM scanned, and then post back, I can give the pinpoint tests for any of the codes you may have. Also, if you want the wiring diagrams for the system, let me know.

Ford did issue some Technical Service Bulletins for this system. One of them says that you should replace the module if you have code C1983:

FORD:2003 Expedition
LINCOLN:2003-2005 Town Car
2003-2006 LS, Navigator

This article supersedes TSB 06-20-13 to update the model year coverage and Service Procedure.


Some 2003 Expeditions built 4/1/2002-1/31/2003, 2003-2005 Town Car and 2003-2006 Lincoln LS, and Navigator vehicles may exhibit an inoperative parking aid system and diagnostic trouble code (DTC) C1983 stored in memory of the Parking Aid Module (PAM).


Follow the Service Procedure steps to verify the vehicle has DTC C1983 in memory. If DTC C1983 is the only DTC present, it may be necessary to replace the PAM.



  1. Use the IDS to run PAM self-test.
  2. If DTC C1983 is the only code present, replace the PAM referring to the physical replacement procedure in the on-line Workshop Manual (WSM). If other codes are present, repair other DTCs before continuing with this TSB.

    Refer to the following for the correct WSM section:

    • Expedition/Navigator/Town Car: Section 413-13
    • Lincoln LS: Section 413-00
  3. Reprogram the PAM using the following procedure:
    1. Start vehicle and place transmission gear selector into Reverse (R), wait a minimum of 10 seconds.
    2. Shift the gear selector into Drive (D), drive the vehicle ABOVE 25 MPH (40 Km/h) for a minimum of 15 seconds.
    3. Stop the vehicle and cycle the key off, then back on.
    4. Repeat Steps a, b, and c, three (3) more times for a total of four (4) times.



4L7Z-15K866-ABPAM - 2003 Expedition built 4/1/2002-1/31/2003
4L7Z-15K866-ABPAM - 2003-2004 Navigator
5L7Z-15K866-BPAM - 2005 Navigator built through 12/9/2004
6L7Z-15K866-AAPAM - 2005-2006 Navigator built on/after 12/10/2004
3W1Z-15K866-ACPAM - 2003 Town Car
4W1Z-15K866-ABPAM - 2004-2005 Town Car
6W4Z-15K866-APAM - 2003-2006 Lincoln LS

Another TSB is for false activation of the chime (which I know is not happening here, but there may be useful info): TSB 05-6-4

The difficulty is, that the bumper cover must be removed to get to the sensors. If you want I can post instructions. And if the module ends up being bad, all the effort of removing the bumper is wasted.

Some people have had luck with replacing all 4 sensors at once (even though usually not all fail at once). This approach only makes sense if you get a killer deal on the sensors, from Ford they start at around $80 or more. There was a seller on eBay selling surplus parts for $8 each, that is why it made sense for them. Unfortunately, I see no eBay deals like that at the moment.

I think there is a possibility of a bad module, like the TSB for C1983 says, or one or more bad sensors. These are the most likely faults.I suppose you could buy one working sensor either used or new, and try installing it in place of one sensor at a time, and you might find the bad sensor this way. When the bad sensor was replaced, the system would work. Drawback, though, I believe you have a different part number for inner (by the license plate) and outer (by the end of the bumper) sensors. Some of the Ford shop manual diagnostics with the scan tool use a similar method, telling the technician to swap a bad sensor to a different spot to see if the code follows the sensor or not. If the code follows the sensor, the sensor is bad. If not, then the wiring to the sensor's original position is the fault.