Hello All,
I'm driving a 2000 Excursion Limited with the 6.8 V10. Bought it used back in February from a reputable dealer and have enjoyed everything so far...except...I've had two problems, maybe related or maybe not...

The first problem I fixed thanks to posting on this site - but for background I'll describe it in case it's relevant to the 2nd problem. Whenever it rained *hard* the door-ajar warning and dome light would sometimes stay on after all doors were closed - it was sporadic and random and would appear and disappear within minutes -but was finally fixed by a good dousing of WD40 in each door-latch mechanism...

The second is much more of a worry from a safety perspective - regardless of rain or shine, the back-up sensor turns itself off...and when it's off I can't always turn it back on!

I ALWAYS leave it on since I have kids around and it has been unnerving to find it turned OFF some mornings (with orange dashboard button LED turned on indicating 'off' - go figure!)...and if I push the button it may or may not flicker back to 'on' (where the orange LED is off)...

Before I take it back to the dealer at $75/hr, any suggestions?

Thanks,
Tim.
evans9790@comcast.net

 

NOTE: The liftgate must be closed for correct operation of the parking aid system.

Navigator, Early Build Expedition
The parking aid system detects objects behind the vehicle when the vehicle is in reverse gear. The parking aid module does this by calculating the distance to an object by the use of two ultrasonic sensors and one radar sensor mounted in the rear bumper. The ultrasonic field is emitted in a semicircular area around the rear of the vehicle. The parking aid sensors can detect objects approximately 5 m (16.4 ft) when the vehicle is moving and 3 m (9.8 ft) when the vehicle is stationary to the rear of the vehicle, 50 cm (1.6 ft) to the rear side of the vehicle, and 16 cm (6 in) above ground. A 750 Hz variable warning tone is generated from a parking aid speaker attached to the parking aid module. The parking aid speaker increases its warning tone rate as the vehicle gets closer to an obstacle. When an object is detected within 45 cm (18 inches) of the sensors, the warning tone becomes continuous.

The parking aid system is enabled when the vehicle ignition is in RUN and reverse (R) gear is selected. The system can be disabled by pressing the menu button on the message center. The parking aid system will indicate it is disabled by illuminating the park assist off located in the message center. The system will always enable when the ignition is transitioned to RUN, or upon entry into REVERSE (R) gear is selected.

The parking aid system will be disabled if any DTC is active. This will be indicated by the parking assist off in the message center. The parking aid module is on the UART based protocol (UBP) communication network and can be diagnosed with a diagnostic tool.

Late Build Expedition
The parking aid system detects objects behind the vehicle when the vehicle is in reverse gear. The parking aid module does this by calculating the distance to an object by the use of four ultrasonic sensors mounted in the rear bumper. The ultrasonic field is emitted in a semicircular area around the rear of the vehicle. The parking aid sensors can detect objects approximately 1.8 m (5.9 ft) to the rear of the vehicle, 50 cm (1.6 ft) to the rear side of the vehicle, and 16 cm (6 in) above ground. A 750 Hz variable warning tone is generated from a parking aid speaker attached to the parking aid module. The parking aid speaker increases its warning tone rate as the vehicle gets closer to an obstacle. When an object is detected within 25 cm (10 in) of the sensors, the warning tone becomes continuous.

The parking aid system is enabled when the ignition is in RUN and the transmission is in REVERSE. The system can be disabled through the message center RESET switch located in the instrument cluster. The parking aid menu is displayed until the transmission is taken out of REVERSE. While the menu is displayed, pressing the message center RESET switch will change the parking aid system status to OFF.

The parking aid system will be disabled if a fault is detected in one of the four sensors, the parking aid speaker or the parking aid module. This will be indicated by the parking aid disabled warning CHECK BACKUP AID displayed in the message center.
"Ford service manual"

 

Thanks for the followup - I think 2 sentences in there may apply to me:

"The parking aid system will be disabled if any DTC is active. This will be indicated by the parking assist off in the message center. The parking aid module is on the UART based protocol (UBP) communication network and can be diagnosed with a diagnostic tool."

-and-

"The parking aid system will be disabled if a fault is detected in one of the four sensors, the parking aid speaker or the parking aid module. This will be indicated by the parking aid disabled warning CHECK BACKUP AID displayed in the message center. "

...from the first sentence, what is DTC? And from the second sentence, since my Excursion doesn't have the same message center as the Expedition (i.e. no CHECK BACKUP AID warning displayed) should I assume my dash-indicator showing 'off' to mean the same thing?

I'll doublecheck the wiring around the rear bumper to look for recent damage, but this is starting to sound like a trip to the dealer...

Thanks again!
Tim.

 

DTC- diagnostic trouble code. Used to determine what is at fault.
The parking aid system is enabled when the vehicle ignition switch is in RUN and REVERSE (R) gear is selected. The parking aid disabled indicator will illuminate for three seconds when the ignition switch is turned to RUN. The system can be disabled by depressing the parking aid switch on the instrument panel. The parking aid system will indicate it is disabled by illuminating the parking aid disabled indicator (in the parking aid switch). The system will always enable when the ignition is turned to RUN, or when the vehicle is put into REVERSE (R) gear.

The parking aid system will be disabled if a fault is detected in one of the four sensors, the parking aid speaker or the parking aid module. This will be indicated by the parking aid disabled indicator being illuminated.

 

Tenapster,

I just had this same issue with my backup switch. It keep turning itself to the off position as soon as I put the X in reverse. The problem was a bad sensor. The dealer did a test and found the right inner sensor was bad and I had it replaced. Everything is great now.

 

Alrighty - thanks again for the tip.

This problem has been intermittent over the past month (for several days it works fine and then for two days it'll be locked out/off like right now) and wasn't preceeded by a crash or damage, etc.

I tool a careful look but can't see any damage to the sensors, and the wiring inside the rear bumper looks fine (bundled, dry, etc.)...and I know the speaker sounded strong two days ago when the system last worked for a few hours... so I'm leaning toward thinking the module itself is the problem...

I'm pretty handy with this stuff but haven't got my hands on the Excursion shop manual yet - is this a user replaceable/serviceable part? If so, where is the module located? (Last question on this topic I promise...)

 

Hey Photomanz - hit post before seeing your reply - I guess it makes sense to have the diagnosis made by the dealer...

 

tenapster

My sensor was intermittent also. You can remove the sensor from the back of the bumper and replace it yourself if you can figure out which one is bad. The dealer only took a few minutes to put the new sensor in once the new which one was bad. Hope this helps.

Al

 

Thanks Al and Fordtech1 - will post results when I have them for the sake of future questions on the same topic...

 

Hi I'm a newbe on the whole forum thing and have been reading some of these older posts looking for help with my 2000 Excursion's "Parking Aid". Your posts and answers seemed informative. I hope you may be able to help me fix mine. It seems to be temperature related. When it cool 55 F and below there is no problem, but when the temp gets above 70 then the trouble starts. That is I get false indications of rear obstructions, mostly continuous tone. There is no light on at the disable switch at all. Is there a test I can do with a ohm meter on each sensor in the bumper? Do you have any suggestions on where I should start?

 

Seems they are sensitive to moisture. Especially after a carwash. I just recently had an immediate solid tone when backing up after a carwash and nothing was behind me. Next morning it was working fine.

Ive also read that the connectors arent built the best and can let water inbetween the connections. Id unplug each one and inspect the connections, maybe a light sanding if anything looks funny, and reassemble with some dielectric grease.

That would be first on my list.

 

I have done that to all of the sensor connections and have also checked and rechecked those going to the parking aid module as well. I had hoped to find some kind of bench test for the individual sensors where I could eliminate all the other variables and at the same time temperature cycle each sensor.

 

how do you test the sensors to see if they are good or bad

 

Hi excursion68. My "Parking Aid "problem still haunts my 2000 Excursion. I have yet to find a effective bench test for the bumper mounted sensors. Sorry. Help anyone?

 

My F-250 suffering from the same symptoms as soon as you put the trans. in reverse the off light illuminates assuming it is probably a bad sensor. From what I have read in the repair manuals you have to use a scanner to retrieve the trouble codes and each sensor has a different code so that would pinpoint exactly which one is bad. If anyone has a method for bench testing the sensors as I do not personally own a scan tool, the info be greatly appreciated.