05 Tacoma, crank no start -SOLVED-

Hey guys long time scanner new poster!
I have a 05 Tacoma 4.0 that I've sunk a lot of mods into and money. But I've had a bunch of shops try to figure out what's wrong with the engine harness. But recently I gave up and decided to just replace the whole thing. My question is while looking up harness options will I be fine just getting one that has the same year a/t and 4.0 motor. Are they all compatible or is it going to give me trouble

 

What kind of problem are you having? I seriously doubt it's something that would warrant replacing the entire engine harness.
05-08 trucks are the same electrically for the most part but to ensure compatibility you really should go by part numbers on wiring harnesses as subtle changes from vehicle to vehicle can cause big headaches when swapping harnesses.

 

It won't deliver power to fuel system. Last I had it in my hands. Been to three dealerships. They all have up after about three days. And then sent to a specialty shop but he didn't have the time to dig into it heavily.
Replaced the ECM, still don't get 5v signal to the fuel system for some reason. I may personally try and get continuity through wires that revolve around that before I try and replace it. Removed the engine to rebuild with new internals, when I put it back in it started up and ran, shut it off to finish wiring up the electric fans and then it never started again.

I haven't been able to locate the part number on the harness, any idea where it might be hidden?

 

So you have no CEL, no communication, and don't have anything on the 5v reference circuit?

Interesting.

If you can use a test light, multimeter, and backprobes I bet we can find your issue.

I'm honestly not sure, it's usually a white tage taped to the harness somewhere. Being an 05 it may be long gone or unreadable by now, you may have to get a parts guy to look it by vin.
I've never replaced a whole harness except a few times small sub harnesses that couldn't be repaired, I've always found and fixed the broken/shorted wire(s) or worst case ran new wire(s) but I hate doing that.

 

Thought it was the ECM. Replaced it. Still same issue.
Had some wires repaired under dash from rodent damage. Still had same issue.

I have a good multimeter with continuity selection, and probably have a test light somewhere, but don't know what a backprobe is?

 

I'd much rather be able to fix it then replace it at this point. I did see where some other people had had some issues with wires rubbing together when they go through firewall and figured I may start there. It's been so long since I had it in my own hands I can't remember what I had done and what I had tested at this point haha

 

Essentially it's a small pin to stick into the back of a connector next to the wire to check a circuit with it connected. You can use a needle or t-pin as a substitute, just have to be careful especially when backprobing multiple circuits at once.

We need to start at the basics.
Does the CEL come on with the key on?
Will it communicate with a scan tool? If so any codes?

 

When I get off work I will hook the battery charger too it and get my scan tool out to see what it's currently doing. If I remember correctly it would run off starting fluid but wouldn't actually push fuel through the rail. But since I have it now I agree I should start at the basics and get a starting point. I'll give you an update once I get back over to it

 

So no check engine light when I turn the key on. And obd says it can't connect to ECM. At least I'm getting power to the obd

 

Ok so we need to start with checking powers and grounds, I'm in the middle of a evaporator replacement right now but I can get you diagrams and pinouts later this evening.
Just for grins swap the EFI Relay and Horn Relay, we recently fixed one that had abad EFI relay.

 

I have the actual Toyota electrical wiring book but I can't really make heads or tails of it since it doesn't tell me where voltage should be and where it shouldnt

 

I can walk you through it later, meanwhile swap the relay. Maybe we will get lucky.

 

I feel like we’ve been here before.
Somewhere, there is a post with this information already in it.
We both posted in it.

 

I wish. I had replaced all the relays after Toyota tried to track everything down by feeding 12v through everything. Got it back without paying a dime and thought it was odd. Every relay and fuse in the engine bay was blown.

 

Yeah, I remember this similar thread.
Pin out here
https://www.tacomaworld.com/threads...-not-start-solved.799571/page-2#post-28660100

OP, you might glance over the whole thread.
It has good information in it.
Might even help you with the checking process.

 

So I've already found I don't have power to ECM 1+2 on 5th plug. But have it at 3. Glad I'm not alone on this

 

Well, those are powered by the EFI Relay.
You do have the key on when checking, right?

The ECM controls that really. If the 20A EFI fuse is good, we need see why the relay isn’t working.
Bad relay?
Not being commanded on?
Wiring not intact?

We will get there. Just hang in there.

 

So I'm working through the other discussion and I'm looking at my 5v reference. But I'm not getting any 5v out of the ECM. When I back pinned it and ohmed it to ground it was some stupid high number like 500. But no continuity between wire and ground when I have it u plugged from ecm

 

I'm sorry if I post a lot. I was reading the other post but I don't understand a ton of it. It seems like him and I have a lot in common though haha

 

The answer to that question is, you won’t see the 5v if the ECM isn’t getting correct powers to the correct pins.
Keep reading that thread, we addressed that question. See post #212 in the link

That thread was a good one. We learned a lot on that one.
Yours might be another good one for us