No start issue

Bought the truck from a woman who had it worked on by an individual they replaced the starter and the steering column I have no clue why.
I’m a certified mechanic I work at a Dodge dealer but I can’t for the life of me figure this truck out
I’m not getting 12 volts to the signal wire at the starter but I do get 12 volts at the switch with the key held in the start position all fuses and relays are known good and the starter is good
Also not sure I’m getting power and ground to the ECU due to the fact of the check engine light not popping on and my Autel scanner not communicating with the ECU but communicates with every other module on the truck
I’m almost certain I have a bad wire or ECU or both but wanted to come here for some ideas
Thanks for your time

 

05 is ECU sent start signal.

If the ECU isn't powering up, you'll never get anything at the starter signal wire.

 

fuck. This sounds like you're gonna be following wires for a while.

I hated fixing peoples mistakes

 

Yea I know the ecu sends it to the starter if I remember correctly it’s pin 11 on the e5 connector and it’s pink I’ve chased every wire and checked continuity all over the truck I haven’t load tested wires so the only thing it can be is a bad ecu or broke wire somewhere that reads good continuity but won’t carry load

 

First off, we've seen a shitload of aftermarket (i.e. non-Denso brand) starters on here that were DOA. I take it you tested the relay to ensure it's OK? And did you jumper the pins in the starter relay socket to see if the starter kicks up on its own?

2nd, I take it you already checked for an aftermarket alarm? Or remnants thereof? Do you see any spliced wires bullshit quicktaps, t-taps or other hackish BS under the driver side of the dash?

3rd, some DC models used immobilizer (via BCM, if I recall), are there ANY codes at all to indicate immob might be kicking in? Are you sure whether the truck uses an immob/chip key?

4th, you verify the park/neutral switch yet?

You've got a copy of the FSM for that truck from the sticky "So you just bought a 1st Gen Tundra" thread, right? Download link to it, and another link to the electrical wiring diagrams is in that sticky thread.

Additionaly, these trucks are pretty notorious for corrosion inside the larger wires and battery cables, and sometimes melting contacts under the fuse/relay block in the engine bay.

Beyond that, some folks have found that forcing ground to the ground pin of the starter relay will allow you to start. But I've never fully understood why that is. It's gotten a few people out of a bind, though.

 

Yeah I jumped the relay and starter does work with the relay jumped all the lights come on with the key I’ve traced all wires and checked everything from the fuse box to the ignition and the ecu the key I’m not sure about it’s just a black tundra key doesn’t appear to have a chip I’m getting 12 volts from one power side of the relay and 8.5 from the signal side of the relay coming from the ecu and both ground sides of the relay pins have good ground so my assumption is that the ecu isnt engergizing the signal side of the relay properly hence the 8.5 volts going to it or the wire is corroded or broke from there to the pcm and can’t hold a load I’m gonna try and source a used ecu and see my results from there

 

If you jumper from ECU pin to starter relay trigger does it crank?

 

This is where I was thinking also.

And while you have the ECU hands-worthy, I’d jot down the 10-digit hyphenated part number on its sticker and consider reaching out to FS1 (Flagship One) to source a verified replacement.

 

I’m gonna do some more diagnostics this weekend and keep yall posted about what I find and what’s bad

 

Key to Junctoin box to ecu to starter. I'm guessing fried in the Jbox. I don't envy you.

 

So your thinking between the starter and ecu at the fuse box inside the truck there’s a bad wire?

 

There is a well known and documented issue of water leaking from the a-pillar and/or winsdshield, down the harnesses and straight into the back of the fuse box in this gen of Tundra. There are pics of several cases linked in the “So you just bought a 1st gen?” megathread sticky. I think it’s the last bullet point in the “electrical issues / keys” section. That may be what he’s referring to.

You don’t need to pull the whole firebox to validate. Sometimes you can see green staining inside the rear connectors or even on the rear of the housing which would indicate this is your problem. If you’ve ever had your windshield replaced, or you’re the type of irresponsible person who lets your windshield get cracked and does nothing about it, it’s entirely possible it could be the case, but I don’t typically associate this problem with that. Still. It’s worth investigating. If you need help getting to the sticky thread I’m referencing, LMK.

 

Are you sure all of your grounds are good? Poor grounding will limit current.