Backup Aid No Sound

[Chiefe9]

My backup aid appears to be working properly other than no beeping sound out of the speaker. When I put the vehicle in reverse the message center says it is "on" and there is no indication of failure. When I run the setup check the message center says backup aid is "okay". To check each individual sensor I turned on the radio and put the vehicle in reverse. I then ran my hand over each sensor approximately 12" away and each one caused the radio to go silent as described should happen. Yet, there is no sound from the speaker. I removed the speaker and did an ohms check expecting to get a reading but the needle didn't move at any ohms setting. However, I'm not sure if that is a true indication the speaker is bad. I think the speaker might be bad but not sure since I can't find any description how to troubleshoot it. (The fuse [27] is good)

1. Is there a way to use a voltmeter to test the backup aid module for a signal to the speaker?

2. Are there any other tests a home mechanic to perform to determine what component has failed? Of course, my final option is to pay Ford dealership $70 to run DTC checks and then repair. Thank in advance for any suggestions/advice.

 

[05expedeb]

You could put a voltmeter across the speaker commections and see if you get a reading when the system is in reverse and a sensor is blocked. Most likely you have a bad speaker or the speaker has bee disconnected

 

[Chiefe9]

I connected a voltmeter across speaker connections to do ohms check-no reading. When I started troubleshooting the wiring for backup module and speaker were connected properly. Is there a way to electrically check the module to see if there is a signal at the end of the wire that goes from the module to connect to the speaker? Once I know I have a signal going to the speaker I can replace the speaker. I just hate to buy a new speaker and then find out it wasn't the problem.

 

[05expedeb]

Have you checked the message center to see if the system is enabled or disabled?

 

[stamp11127]

If it is a regular coil type speaker it will have a low ohm rating. Is your meter auto ranging or manual set range?

Most car speakers are 4 or 8 ohms.

 

[Chiefe9]

Message center says system is on and okay and I used all ohms settings from highest to lowest which is Rx1.

 

[GAINMOB]

this is just my thought process cuz I don't know...have u tried putting an object behind the truck? another car...bike...big trash can to test the sensors? you hand may not trigger the response due to being on one sensor...maybe more that one sensor needs to be activated for the audible sounds ur trying to duplicate...I would suggest to use an actual object...make sure the speaker is connected and the wiring for it isn't crimped somewhere...im just guessing from taking that side off several times for my stereo system

 

[05expedeb]

this is just my thought process cuz I don't know...have u tried putting an object behind the truck? another car...bike...big trash can to test the sensors? you hand may not trigger the response due to being on one sensor...maybe more that one sensor needs to be activated for the audible sounds ur trying to duplicate...I would suggest to use an actual object...make sure the speaker is connected and the wiring for it isn't crimped somewhere...im just guessing from taking that side off several times for my stereo system

FYI any sensor being blocked will cause the alarm to sound unless its a bad sensor

 

[stamp11127]

Is the speaker built similar to a "normal" car speaker or is it a piezo buzzer?
If it is the "normal" type you can also take an Ohm reading on the leads that go to the cone.

 

[Chiefe9]

I found this info on a website related to this issue. "The parking aid system is disabled if a fault is detected in one of the 4 sensors, the parking aid speaker, or the parking aid module. This is indicated by the parking aid disabled warning. The parking aid module is on the international standards organization (ISO) 9141 network and can be diagnosed with a diagnostic tool." I truly don't believe I have a bad sensor. Hopefully there is a "backyard mechanic" way to troubleshoot the module and speaker but beginning to believe it can only be done with the Ford Diagnostic Tool. Hopefully I'm wrong. Ha! The only thing that confuses me with my Expy is the message center says all is okay instead of giving me system disabled warning. Just received a PM from Bob M. including wiring diagrams and Ford Service Manual section applicable to the backup system. Will spend time reading and hopefully learning. More to follow and thanks, Bob.