Non stop pinging sound car on or off and backup lights on issue

[Hercar]

My wife's 04 LS V8 Sport started a new issue last week. There is a Non stop pinging sound car on or off and backup lights stay on all the time issue. Code reader says 0 faults. The beep beep beep is not the same as the door or seat belt chime. It sounds to me like it comes from the rear deck behind the back seat. I pulled the speaker wires and it still has the pinging. I disconnect the battery and reconnected. Same bit. In the relay box next to the battery if I pull the second relay from the right it stops. I tried switching relays but it does that with all of them. For some reason the other day I decided to unplug the the electric trunk release and that stopped the ping and the back-up lights went back to normal operation; just had to use the key to open the trunk. The next day I decided to wash out the trunk release with electric contact cleaner, then lube it, plugged in the release wire and all was fine. Today back to the same crap but unplugging the trunk release wire did not stop it. I had to take out the backup light bulbs to turn them off to save the battery (2 months old). It has sat in the garage beep beep beeping for hours now. Garage kept, have owned it 20 years, 79,000 miles now, never driven in the winter so it has never seen salt. Any ideas?

 

[Hercar]

Wife tells me to take it to St, Louis and trade it for a Jaguar. I asked what 75 year old woman drives a jag? She tells me the Jag forum people were always helpful.

 

[Hercar]

Replacing the trunk latch/release mechanism seemed to fix it for 1 day. Back to the reverse lights stay on till the battery is dead and non stop pinging like a quiet backup alarm till the battery is dead again.

 

[Action]

Wife tells me to take it to St, Louis and trade it for a Jaguar. I asked what 75 year old woman drives a jag? She tells me the Jag forum people were always helpful.

Age has nothing to do with it!

Drive what you wanna drive.

As to electrical issues, those require a diagnosis. That means getting a wiring diagram, may be a shop manual, along with a test light or a meter.
In addition to inspecting for poor connections and bad grounds. Plus having a fully charged battery.

The alternative is throwing parts at the problem. It gets rather expensive because this is a guess.

Action

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[driller]

I'm not familiar with the LS platform, but just some generic thoughts...

Is the beeping constant or is there a pattern? If a module fails, many times they will beep an audible trouble code. Like 5 beeps, a pause then repeats 5 beeps and so on.

Do all the dash lights illuminate upon key on or shortly after startup? Often a burnt out dash indicator bulb is accompanied by beeping as an audible warning.

My thinking is either a failed/failing module or there's a short somewhere. A short seems more likely since the problem continues even with the car off.

Since the backup lights are involved, perhaps there is a problem with the reverse sensing feature? Perhaps a bad sensor? A short?

Finally, it seems at one time you isolated the problem to a single relay. Which circuit is that relay associated with?

 

[ArloHenry]

Good points! you’re right that a repeating beep pattern can be a code and a short does sound likely if it continues with the car off. Tracing that relay’s circuit should help narrow it down.