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Hello - I'm new to this forum, glad I found it.

I have a 2005 Freestar (4.2l) minivan which all of a sudden has an issue with the backup lights on all the time, even when the key is out of the ignition.

I have the troubleshooting flowchart from AlldataDIY and I've checked all the obvious items, and the correct bulbs are installed. The last thing I did was to unplug the transmission range selector (most sources identify this part as the root cause of reverse lamp issues). The backup lights are still on. For now I am unplugging the battery every night.

The SJB looks just fine, and I'm not about to disturb it much. The next big thing to try would be to unplug the PCM.

The big question is why did this issue suddenly pop up? And any ideas how to resolve are welcome. Thanks for looking.

MitchellT
 

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I removed and reseated the PCM - no change and no issues observed with it. Reverse lights still on all the time.

Considering that after unplugging the transmission range sensor and the backup lights remained illuminated, what exactly does the transmission range sensor do!?
 

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Did it rain a lot before this issue popped up?


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There was a TSB on water getting into the PCM and causing all sorts of problems with electrics .


 

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Thanks @R.S.LOGAN I saw that video and I pulled out the PCM and it was dry and clean. No corrosion. But somewhere else along the way something must be going on. Any ideas welcome.
 

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This is for a 2005 Ford Freestyle with the same fault , whether it could apply to your vehicle or is same set up , I dont know

Reverse lights are stay on from the moment I start the car.


" There is a reversing relay in the fuse panel that may be stuck closed and would need to be checked by tapping on i.t to see if it is just stuck all the time. "

" So inside the fuse box, where is the reverse relay that I need to tap on?

The reverse lamp relay is built into the smart junction box. It can not be touched, or replaced. If the relay is faulty then a new SJB is needed. "
 

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I was about to suggest checking the sjb myself. That’s a common problem in the 05-14 Mustang world. Water intrusion into the sjb and all hell will break loose lol.


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At first I thought it was odd that SJB has hot current to it when the ignition switch is off, but then I realized - duh! - the running lights, horn, and emergency flashers operate with the switch in the off position. If anyone else wondered this, you don’t have to embarrass yourself by admitting it. I fell on the sword for all of us.

As for getting water out of tight places, compressed air usually works. But not always. Sometimes liquid needs to be displaced by another liquid. You can spray WD-40, or a product such as Wire Dryer, in the suspected problem area, and hopefully that will take care of any water in there. This suggestion is based on my many years of riding dirt bikes, sometime for long periods in the rain, or in and through deep creeks.
 
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