Bump-Starts and runs great, won't start with key - P0335 - ECU replacement fixed

Well comparing yours to the known good @TnShooter posted it looks dead on, the cam trigger falls right in the middle of the 8th and 9th crank triggers from the sync notch.

Maybe we are looking at this wrong and it's not the cam and crank signals that is the problem, maybe we are losing a power when the key is in the crank position.
Do you have a test light so we can do some power checks?

 

Man that's perfect, I'll have to bookmark that.

 

That's normal, as I said lower RPM = lower amplitude.

I don't think there's anything wrong with our cam/crank signals at this point, they look perfect.

As I stated above I'm wondering if we are losing a power feed from the ignition switch when in the crank position, it's the only other thing I can think of that would be different between cranking from the key and popping the clutch.

Does your instrument panel stay online while cranking? Its on the same leg as the EFI system.

 

I have a multimeter I can use, no test light yet.

That makes sense although with the new starter they installed I'm getting pretty strong revs but still looks like about a third of when idling.

My instruments stay on (fuel gauge, check engine light etc.), the only things that's "dead" is the RPM reading while cranking.
*RPM catch right up when bump starting...

I tend to agree but feel not knowledgeable enough.
Any resources/electric diagram I can investigate?
What is different when turning the key from RUN (IGN1) to Crank (IGN2)?

 

Well that rules out that theory, hmm...
We have to be missing something...

Let's put scope ground on battery negative, Channel 1 to E1 (Connector E4 Pin 3 (Brown)), and Channel 2 to E03 (Connector E5 Pin 4 (White/Black) and see what our voltage does there while cranking.

 

Not sure what I just measured, Blue line is E1 and Red line is E03:

Around Midtime (2.75s) is cranking.
The E1 scale is super zoomed, not sure you can call that a reading or just noise..

 

If your connected correctly I think we just found why it won't start, those should both be grounds. E1 looks good but we have 10v+ on E03 during cranking, what's interesting is they where they ground they are right next to each other on the back of the cylinder head.
E1 is grounded at Ground Point EH and E03 is grounded at Ground Point EG.

 

That's odd, I couldn't immediately find either of those grounding points.
What I did see is one empty nut/threads at the location of EG, but only one in the vicinity that's immediately visible
Any Idea where the wire is coming from to try and trace it?

P.S. You sure that's the right diagram for me? I'll continue looking online for those grounding spots.
Here's a picture of what I'm seeing:

 

That's the correct diagram, they should be bolted to the back of the head facing the firewall. Should be multiple White/Black and Brown wires going to each of them.

With the amount of rust I'm seeing I wouldn't be surprised if one or more wires are corroded off.

 

Found/Saw both of them by crawling underneath.
Was too cramped to take a picture but they look in pretty good shape, not a spec of rust.
Couldn't see any damage to wires from the angle I was looking.

It's really cramped getting there, about an inch of clearance makes it difficult to even see the bolts, let alone try to fiddle with them and reinstall. How would you go about this task? Maybe run a continuity test?

Also, just for testing sake, maybe I could jump that ground with another wire leading to ground and give it a try?
Not sure if that could risk blowing something.

 

A test light from battery positive would be a better test as it would load the circuit.

I guess you could if you make dang sure your on the right wire, I try to avoid jumping directly to circuits. I feed stuff through test lights when I want to send voltage or ground to something that way it's low risk, if something is wrong the worst thing that happens is the light lights up.

https://www.tacomaworld.com/threads/2nd-gen-information-diagnostics.784008/

If you watch some of Ivan's (Pine Hollow Auto Diagnostics) videos you will see what I'm talking about.

 

Ordered one on Amazon, will arrive tomorrow sometime.

I guess that makes sense in most cases, however if we're adding resistance (via light) wouldn't that impede, although negligible, with grounding we're trying to improve?

How about I try to jump a wire from my negative battery terminal to the questionable grounding nut (EG).

 

I'm not sure how to explain it but we use different sized bulbs depending on how much current we want to allow to pass, for example a H11 headlight bulb will pass about 5 amps through it at 12v. If we are only passing say 2 amps through the bulb the voltage drop across it would be pretty low.

A standard incandescent test light is typically around 150 mA or 0.15 A.

 

I probably need to think about this another time as I'm fried for today.
I couldn't help myself so I tried jumping the Battery negative to E04 - still the same.
Maybe I managed to get a wrong reading again with the scope once more, I'll try it again tomorrow.

 

This my test light collection what I have at work, 150mA up to 5 amp.

 

So I seem to have mixed up earlier between E1 and E03, verified this time with a continuity test.
Here's a snip of me trying again to jump the negative battery via a test light to the faulty E1:


Still no start with same symptoms.
Will it be any different if I try connecting directly?

Looking at E1 it seems to lead to junction so maybe the problem is further down somewhere?
Here are the diagrams:

 

My Apologies, I wasn't paying attention and have back probed the wrong pin.
Instead of pin 4 I was probing pin 3 (forgot we're looking into the connector).
Here's the correct reading of the ECU grounds I was supposed to be measuring earlier (i.e. E1, E03 and negative to battery):


So I guess back to the drawing board? Any ideas where to check next?

 

Man I'm at a loss here, I can't see why it can't see the crank signal when cranking with the starter but it can when you push start it.

Can you get me a capture of the cam/crank signals cranking with the key and one of you push starting it?

Save the pico files and put them in a zip file so you can post them here.

I wana see if I can find any discernable differences.

 

I can't get my head around it either, will try getting you a scope reading when bump starting, not trivial in my situation.

While reading I stumbled upon this:

So I hooked up the Pico to that pin on the ECU:



And guess what, I got no reading!
Red line is reading STA and the rest is like before for reference:


Trying to peek at the starter I couldn't see much.
Maybe this is root of the problem? Or would that be a different error code?
Thanks for finding that IH1 sensor, I'll try looking there too:
https://www.tacomaworld.com/threads/connector-behind-glovebox.792651/

*edit: on second glance it seems not to be the issue since if I'm not mistaken STA is just a signal to the computer from the key switch, which is working fine since I do get cranking...

 

Set your timebase up to 1-2 seconds and it should be able to record around 30 frames which should give you plenty time.

I guess it's worth pursuing at this point although it shouldn't need that input to start.

That wire comes from Connector 2B Pin 5 (Black/Yellow) in the underhood fuse box, it should have battery voltage while cranking.