Truck cranks but won't start after new stereo install. What the $%*# is going on?

Hey guys, long time lurker, finally bought a Gen 1 about a month ago so I made an account. I didn't expect to be posting a "help me" thread this soon but here we are. Before I go any further let me just say HUGE thanks to the people on this forum and specifically Shifty for that intro write up (among many others). I was able to shop for and buy a truck with so much knowledge in my back pocket. And in the month I've had it I've been tinkering away at many of the common upgrades. So THANK YOU ALL! Now, on to my problem:



TLDR: My truck cranks super strong (bought a new battery) but isn't starting. Not even a little bit. Red Battery light is illuminated on the dash. But even if the alternator is toast, or the leads going to it, how would that prevent a start with a fresh battery?

Additional Facts:
- When headlights switch on with key in ACC, tailights do not come on.
- Brake lights are functional, reverse lights are functional
- With Key in ACC the fuel gauge is not coming alive (I can't remember but I assume it should show the proper fuel level with ACC on)



Full story:

The truck has started up and run absolutely fine since i bought it (although I haven't been driving it because I'm about to do timing belt, water pump, etc). This last week I decided to do a backup camera and new head unit that I had ordered from Crutchfield. I will link what I bought at the end for anybody interested.

Before everything I started the truck up and let it idle for 20 minutes to make sure the battery was charged up as it had been sitting for a week. I then disconnected the battery before beginning. The backup camera went to the license plate, and then per Crutchfield's customer support I attached the power and ground to the head unit's power and ground. So I ran power, ground, and RCA from the camera alongside the truck's taillight harness, into the cab, behind the driver's kick panel, up and behind the gauges, and to the head unit. There I spliced and soldered the camera power into the stereo harness power, the camera ground into the stereo ground, and plugged the RCA cable into the unit.

Then all that was left was to wire in the parking brake cutoff and reverse trigger. Parking brake was easy, I just went to the switch itself. There is a single light-green wire there so its obvious. I cut it, and spliced and soldered in the wire for the head unit.

Now the reverse trigger was a little less obvious. The info from Crutchfield as well as many of the posts on this website did not match up exactly with my truck, either with pin location or wire color. Not wanting to make a mistake I went to the right taillight assembly, identified a red/black wire running out of the reverse light, then went back to the harness on the floor of the cab by the driver's kick panel and found the same wire. Then cut and spliced in a wire for the head unit's reverse trigger.

So, all done, everything should be happy days. I reconnected the battery and turn the key to ACC to test my work. The head unit starts right up. Great! It then takes me to a couple menus and a backup camera configure menu where I see the backup camera working perfectly. Then, once setup is complete, I shift the truck into reverse and the screen switches to the backup camera, and shifting back into park or Drive it shuts off. Perfect, a job well done.

I then attempt to start the truck and it cranks powerfully but won't start. I try again, nothing. Things I noticed right away:

- The fuel gauge is indicating empty. There is definitely fuel in the truck and it was functioning before.
- The red battery symbol is illuminated on the dash.
- The taillights no longer work. The headlights, blinkers, brake lights, and reverse lights all function normally.


I begin a series of troubleshooting steps over the course of the next two days:

- Pull and check all fuses, under hood and inside cab.
- Jump up and down on the rear bumper to slosh fuel around
- Smack on the fuel tank to dislodge the float
- Disconnect the new head unit (now only the reverse trigger and parking brake cutoff remain connected)
- Attempt to start the truck while applying some throttle, then a lot of throttle. Supposedly this can help reset the ECU.
- Buy a brand new Costco Interstate battery. Red battery light still illuminated.
- Replace 120A main fuse
- Use test light to re-test every fuse


So here I am. Out of ideas. I take it that the alternator or the leads connecting the alternator to the battery may need replacing, but how could that explain the truck not starting? Doesn't ignition come from the battery at least initially?

How could the truck start and run FINE before the head unit & backup camera install but now its silent? I've seen this said on many similar posts, but its as if an immobilizer has been tripped. Occam's razor says that somehow this is related to the head unit install. But how could that problem persist once the head unit was disconnected? The parking brake cutoff and the reverse trigger are not pulling power until activated. So they shouldn't affect anything right?


Massive write up but I wanted to get out everything I could. Any help is appreciated.

 

For those who are interested:

The Head Unit: https://www.crutchfield.com/p_113DMX8709/Kenwood-DMX8709S.html

The Backup Camera: https://www.crutchfield.com/p_113CMOS240/Kenwood-CMOS-240U.html

 

Does it start with the factory unit in, or the new one unplugged?

 

I haven't tried plugging the factory unit back in, but no it does not start with the new one unplugged. I will try the factory unit in the morning.

 

Did you remove the negative battery cable before starting to install the radio, as you always should, to avoid arcs/shorts?

Did you cut *any* wiring during install? You're not one of those fucking savages who cuts factory harnesses to save $8 on adapters, are you?

Did you check all fuses in the dash, and fuses in the engine bay?

Have a local store test battery for CCA, not just voltage? (Batteries tend to exhibit less CCA performance in cold weather, and voltage verification is a bullshit, inadequate way to test a car battery)

Loosen your terminals to verify their integrity, check for any cracks, loose shims, andclean them up? This is one reason why right here.

Verify there isn't corrosion inside the cables? Here's why I bring it up.

Verify all grounds in the engine bay are OK? (And maybe consider running a temporary ground direct from the battery to the block)

The circuits you've indicated are impacted would suggest you've blown a fuse, which is highly likely if you didn't remove the negative battery cable during install. All it takes is one arc, and you may not even realize it happened.

The only other explanation for all of those circuits you listed would be you having a cracked and/or poorly sealed windshield and/or a-pillar, and you've got the classic water-into-the-dash-fusebox damage (pics & pics & pics, it happens a LOT).

But start by checking fuses. It's highly likely it's going to be one under the hood, either the square window-top fuses, or one of the blade fuses in there.

 

A lot of good has already been said here but just for reference, this light should be on if the truck isn't running.

 

UPDATE INFORMATION:
- Truck did not start with factory Amp and Stereo reinstalled
- The only wires I spliced into was the reverse wire and the emergency brake wire. Both splices have been cut out and fresh, bare wire twisted together. In other words the truck is now fully back into it's stock state. Still no start.

Responding in order:

- Yes I disconnected the negative battery terminal during install.
- I purchased a harness adapter for the head unit from crutchfield. The only wires that were cut was the parking brake switch, and reverse trigger. Both were soldered and shrink tubed.
- I have checked every fuse multiple times now. I can start replacing them anyhow to rule it out with finality, but they are very clearly not blown.
- Battery is brand new from Costco yesterday
- Terminals are clean, wires appear quite new, no indication of corrosion anywhere.
- No indication of water leakage and the truck has been inside a garage the whole time since the last time it ran.

- I will look into verifying the grounds. I've never done that so that will take a google.

 

Ok that's good to know, I didn't realize that. So I suppose that can be ignored and the charging system is probably fine. At this point I'm going to pull a spark plug and check for spark....

 

I'll tell you this: The fusebox in the truck dash has a lot of stuff routed through it. If you haven't had rain recently, I'm thinking nothing of it. But that issue I pointed out in my last reply, 2nd to last paragraph, is pretty common. Whenever we have multi-circuit issues for something that passes through that in-dash fusebox (radio, ignition, tail lights, etc. - i.e. lots of items on different fuses/circuits) it can be the cause. I am not saying that's what it is, just saying "multi circuit failure, where circuits pass thru dash fusebox" raises my eyebrow to that.

That said, if I'm not mistaken, two things caught my eye here, reading back over this and I think the following is your most likely problem.

1. Fuel gauge not working
2. Crank but no start (i.e. almost like it's not getting gas).

What does that tell me?

Both of those things (fuel pump, fuel sender) are wired running through the same harness. And if that harness is compromised, the truck would turn over, but not fire, because the fuel pump is getting no power.

Obviously, the first thing I'd be doing, knowing that's one of two place rodents LOVE to make nests on these trucks, I'd be looking on top of the fuel tank for signs of harness chewing, nesting material, etc. Since this truck has been sitting so long.

Got a can of starting fluid (ether)? Try this. Squirt some in the manifold. Turn the truck over. If it fires, I'm right. Something has fucked up your harness.

But the fact the fuel pump harness AND the tail light harness both pass through the driver's door sill, and both run down the driver framerail of the truck, I'd be inspecting the harness the whole way down also to look for signs of damage. I'd be unplugging/replugging. You may need a mirror and flashlight to look on top of the tank from underneath.

I was going to say a bunch of other shit, then I read back over one more time and the gas gauge thing jumped out at me as I was thinking, "Fuck, wonder if this guy checked for fuel pressure?" My next thought was, "Wait ... turns over, but no start could be no fuel pumping. Wait ... no gas gauge .. both of those are in the same harness/plug!"

 

Does your ignition key have a dangling FOB? Do you have a 2nd one in the closet in the key box that you've tried?

 

OP has an AC. AC and RC didn't have immobilizer. Sequoia did, and some DC did. I don't know if I've seen an '00-'02 (in Sequoia) with immob.

 

OP said something about the reverse wire. Hasn't that bitten people in the ass before? Something like it got grounded out so the truck thinks it's in Reverse and won't start?

 

I don't remember seeing it, but if you do, there's probably a reason. I'll sometimes see a post from 2016-2018 pop up, before I started lurking in early 2019 around the time I started considering a 1GT as my 'new' truck, and I'm like, "The hell? That info would've been nice before!"

But yeah, the fuel gauge thing is what's got me saying "hmmm....", but I'm still chewing on this:

• Tail lights aren't working, but brake lights are - tail lights are on a separate wire in the bundle going down the driver framerail
• Fuel gauge isn't working - fuel gauge is sent to dash on a wire in the bundle going down the driver framerail
• Truck is cranking but not starting, which can be a symptom of no fuel delivery - fuel pump is fed by a wire going down the driver framerail
• OP was obviously dicking around with and/or near the wiring bundle going down the framerail, he was cutting and splicing wires to trigger the camera

Best case scenario: While OP was fucking around with the reverse trigger wire cut, he dislodged a harness OR maybe pulled a couple of pins out of a harness. Or if he pulled up the sill plate on his driver's side, he ran a screw through a wire, pinched a harness, or tightened down and pulled some wires.

But generally speaking, I'm concerned that 3 wires that deal with fuel pump power, fuel level sending, and tail lights all being in the same general bundle headed to the rear of the truck are now non-op after OP was dicking around with installing a reverse camera. If he used a razor knife anywhere, like to trim zip-ties for example, I'd be looking for loom cuts anywhere near zip ties. If he dicked with sill plates and kick panels I'd be pulling it all up again and carefully inspecting my wire looms. etc....

 

I have a suspicion you bumped, nicked or damaged wiring or connection to the fuel pump/sender. I assume you don't have the fittings necessary to test the fuel pressure on the 2UZ so to test this theory I would open up the throttle body butterfly and spray a little bit of starting fluid into the intake then attempt to start the truck as @shifty` suggested. If it coughs or shows any sign of attempting to start its safe to assume the fuel system wiring needs to be looked at.

 

Hey guys. I've been away for work for some time and haven't gotten around to replying to this post. But its with my tail between my legs that I have to come back and tell you all what it was...

The connector under the drivers seat was unplugged....

I say "tail between my legs" because this is such a glaringly simple oversight. That said, I was never anywhere near this plug. I had to remove the driver's seat to get to it and it's a solid 8+ inches away from anything I touched, but it was fully unplugged and obviously the problem the second I saw it. The only thing that makes sense to me is that it was not fully clicked closed when I bought the truck and was barely hanging on. Then my repeated adjustments of the seat position and the little tugs on related but distant sections of wiring harness was enough to pop it off.

Anyhow, I really appreciate all the advice of the community. As is so often the case it troubleshooting, ALWAYS work from simplest answer up. Thanks everyone.

 

Appreciate the circle back. So many figure it out with or without the helpful advice here and never return to let us know what worked. Now we’ll all add this experience to our knowledge base. Or, who knows, maybe you’ll stick around, get involved, and end up helping the next guy.

 

Glad it was simple. I hate wiring!