2008 f150 no audio in reverse

I put a 4113 One button remote start in a 2008 F-150. On these trucks I always grab my parking lights/brake lights at their respective switches and grab ignition wires in the loom coming out of the bottom of the steering column. No need to take of the steering wheel shroud. I also grab my data wires in that same harness for Idatalink TB unit I installed as a bypass. I didn't run a tach wire as the F-150 had under/over crank. Its a pretty basic and easy install that I've done many times.

A week after I installed the remote starter, he's telling me that sometimes the car wouldn't start(crank). First he told me it wouldn't start with the remote starter. So I adjusted the crank time up on the 4113 and turned off engine checking. Then he tells me it won't start with the key sometimes and still the remote starter. I couldn't duplicate that yet, but heard it over the phone. It literally will not crank. The security light goes out, so I know its reading the key. I told him to move the shifter into neutral and to try to start it, but that didn't work. The only way he can start it is to disconnect the Battery and reconnect it. I'm trying to figure this one out and figure its related to the Radio Muting problem.

So the Radio problem he started by telling me he would be driving down the road and the radio's audio cut off and didn't return for about 10 minutes. It doesn't actually say "mute" or "phone" on the screen. Then he was telling me while plowing every time he put the car in reverse the audio would cut off. I played with it and again could not duplicate it. He called me later after I was looking at it and it was happening again. So the problem is intermittent right now.

Some info on the truck:
Its a factory Radio
He has a plow
He had the transmission replaced recently
He had the remote start installed recently

I'm stumped... anybody have any ideas out there on this one?

is the whole audio system factory? is it premium factory amplified or just base? no amps or converters of any kind?

it sounds like something could be activating the neutral safety of the truck even though it is in park or neutral. the truck is not seeing that it is in park. there could be a shifter position switch that is getting stuck in the wrong position, might need to be replaced but its had to say that if you cant replicate the problem. you could try it and hope it works.

the audio problem is what is truly strange. is there a back up camera or maybe a backup siren that could be hooked up behind the radio to a power wire and drawing enough current to make the audio turn off but not the radio itself. this could also be related to the shifter position switch being messed up because while driving it might be possible for it to randomly jump out of position and make the truck think that its in reverse and kill the audio.

those are just my thoughts and i have never had this problem before.

I believe the ford radio has a start input wire, which mutes the radio during cranking. It would be terminal 15 in the main radio harness (two positions away from the ground terminal). Owners manual shows fuse #07 (5A) radio, start signal. Pull that fuse and see what happens. Perhaps the remote start is somehow activating? ignition switch issues? transmission logic? With the vehicle having overcrank protection, probe the start wire for voltage. Shift into reverse, check for voltage.

i think my point might still stand but i think weens point is valid too. its all about troubleshooting and eliminating all of the various possibilities however wild they might be. but honestly if you cant get the truck to replicate the problem under controlled conditions it might be hard to pin down the issue to any one thing without just trying random possibilities.

Thank You Guys. I spent 45 minutes trying to duplicate either one of these problems but couldn't. Ween I've also heard of the muting circuit from my google searches. It seems to happen enough that I can find it by googleing it, but nobody ever posts a solution, or even specifics. I will try to pull that fuse for a few days to see if the radio works from there. If pulling the fuse works, I'm leaning more toward the signal it gets from the transmission. Do you know where that comes from, since you mentioned transmission logic? I read in one google article that it might be the transmission range sensor?

SoundSecurity, Thats what I was thinking, the neutral safety switch might be bad or mis-aligned after his transmission switch out. I will have him bring his truck to his mechanic to realign it/change it out.
I'll keep you guys updated.