2005 Tundra 4.7 Help Needed

Hello, first time member on these forums. Recently purchased a 2005 Tundra for my father. Truck was a non-start. Brought it home and tried to diagnose some issues but to no avail thus far. Any and all help / suggestions are appreciated.

Symptoms:
No crank, key turns in ignition, dash board lights come on, but starter does not engage. When key in position 2, I can select any and all gears, position light in speedometer lights up (as I move stick shift) in all positions except neutral and drive. Diagnostic scanners are not able to connect to the truck either (All fuses, even OBD2 port fuse, is/are good).

Diagnosis:
So I went ahead and eliminated the starter as the cause of the issue, it works fine. I provided external power to the starter and the engine does crank but doesn't turn over. We figured out that there is power going from relay to starter, but no power going from ignition to relay. Ignition is fine and this truck does not have an immobilizer(from factory).

I pulled up some wiring diagrams and it turns out that the power goes from the ignition switch to the "neutral safety switch" which is mounted on the passenger side of the transmission, this module basically completes the circuit and sends power to the starter. I got under the truck, found the neutral position switch and it all looks intact, no corroded wiring on the harness, everything seems fine on it. If the switch was indeed faulty, it would still allow the car to at least crank / send power to relay, in the neutral transmission position.

So engine will crank if external power supplied to starter relay and OBD2 scanners fail to communicate with the vehicle. Is the ECU toast? Following is a link of the Tundra cranking for some relative context: https://youtu.be/pVDCJTnyLAA

Any and all recommendations / suggestions are more than welcome on how to get this engine fired up.

Thank you

 

First, are you absolutely positive that your OBD2 scanner is compatible with the truck? When I got my first electrical issue with mine I also thought my ECU was shot, because the OBD2 scanner I had, even despite it saying it was compatible with older Toyotas, was not compatible with mine. I learned that ISO 9141 protocol is not the same as ISO 9141-2, the former being the one my scanner was using and the latter being the one required by this truck

Have you tried looking at the wiring for that neutral detection switch on the other end, where it connects to the column shifter? And if that is all good, how about the column shifter itself? My truck loves to give me a little heart attack once every couple of weeks. The truck will be in park, but it won't even make an attempt to start when turning the key. The issue is that while the column shifter is in park, it is either just sitting too high or too low to be making good contact with the terminals for the neutral detection stuff. All I need to so is bump the column shifter up or down and it will fire right up. It's simple, but I wonder if this could be your issue.

 

Just to add to the above , I don't see any mention of fuel . Are you positive that you're getting fuel to the injectors ?

 

Hey, thank you for the reply. Yes so the scanners we hooked up should be all good. One was a generic scanner and the other was a $9000 Autel diagnostic scanner, so definitely they aren’t the issue.

That’s a good point regarding the column shifter, I haven’t tried bumping it and starting it, however I did try all different positions to try and start the truck.

Also not sure if this detail is important, but on the speedometer when the key is in second position, both 4Hi and 4Low lights are continuously on and the abs light flashes in and out every 2 seconds or so. Also the battery light is on statically, but I think that’s normal.

 

We actually have not checked if the fuel is getting to the injectors. Just been occupied with trying to figure out why we can’t even crank the engine from the ignition, why is an external power source at the relay required. The truck has only 180,000 KMs so I am not worried about the fuel pump being wrecked, but you really never know.

 

It might not be the fuel pump , could just be a clogged fuel filter or a fuel relay .

 

I was going to say check the fuel pump too

Also check the mass air flow sensor to see if it's getting power or needs to be cleaned and throttle body too

 

aftermarket alarm installed?


you can try leaving the key on the on position and disconnecting the battery then reconnecting the battery.. worked the last time i had something similar to this and didnt know an aftermarket alarm was installed

 

That's what I'm thinking. That or dead cells in the battery.

 

Okay so this is a good one, I had thought of this previously but just didn’t know enough about the alarm systems to be able to track it down. The tundra also had an aftermarket 2Way remote start kit that was installed, but it was cutout from the truck. I checked all the wires at the ignition that the remote starter had tapped into and they seemed fine,
I couldn’t spot any wiring for an alarm system near the ignition so I gave up.

 

I’ve actually bought a new battery so going to throw that in. Up to this point I had completely charged the old battery in there and also tried to jump start the truck but it was to no avail, so I discounted the battery as a potential cause.

 

Yes! That’s a good idea, I’ll try and diagnose those.

 

red alert, red alert

find the install manual for the system and see exactly what they effed up, then start uneffing it.

 

I actually called a guy who installs remote starters, he came and spent a few hours diagnosing it and couldn’t find any open circuits. He said the ignition is getting proper power, all the ignition wires are good, just no signal going from the ignition to the relay. And the only thing in between the ignition and the relay is the neutral position switch.

 

1) Did you test for voltage at the switch (NPS) when turning it over?
2) I assume that NPS uses an in-line relay, somewhere - check the relay?
3) Or maybe just save time and attempt to bypass the NPS totally, or apply voltage to the correct side of it as a test?

I want to say there's an IGN relay in the engine bay fusebox. Maybe a fuse for IGN both in that engine bay and in-cab fusebox. I guess I'd be swapping IGN fuses, or pulling each and testing for continuity (sorry if you said you did already above, I might've missed)

 

Yes so we tested the voltage at the switch and everything seems to be good. There is also power leaving the switch and heading towards the relay, but that power never makes it to the relay and so clearly something is in the way. The only thing left that could be in the way has to be the transmission neutral safety switch, if thats causing an open circuit then clearly no power can go to the relay.

I also noted a random empty plug in the dashboard below the passenger airbag, will take a picture of that and upload.

 

Sometimes the best way to isolate the problem is to create a conditional bypass to test whether a specific component in the system is causing your issue.

This is why I'm saying: If you can bypass the NPS and NSS, then it starts, you know it's potentially one of those two systems/switches which are causing your issue.

If you then remove one of those bypasses - either the NSS or NPS bypass - and and it still starts, obviously that one isn't the culprit out of the two, it must be the other. Now, if it won't run unless both are bypassed, that's another very worthwhile result to find, and may send up a red flag for someone here.

You should know: The Factory Service Manual (FSM) will tell you how to test XYZ system and/or part and/or function. But first you need to identify which part could be the culprit, BEFORE you can test it, y'know? There's a copy of the FSM somewhere 'round here...

Just exercise extreme caution when bypassing safety systems, use this tactic at your own risk.

And with that ... I'm out! You seem like a smart cookie. I have faith you can figure it out.

 

Ahh yes okay I will try and find the FSM. Yes, there is a way to bypass the NPS, I saw a bunch of youtube videos relating to it, that will be the next step. Thanks for all your input, really prioritized things for me

Cheers

 

(Tip: Click the smiley then click the download arrow in the top right corner)

 

I believe the 2005 Tundra uses the CANBus over ISO 9141-2. I cannot remember the year they changed.

CANBus has 120 ohm termination at each end of the differential bus so if you measured it, the resistance on the line with the vehicle unpowered should be 60 ohms (two 120 ohm resistors in parallel).

If you don't measure that, one of the modules connected to the differential parallel bus is most likely shorting it out.

 

@rangek1d

So did you ever figure this out? I’m dealing with the exact symptoms in my ‘05.

 

Pro tip: Usernames are underlined. Click on it. It tells you the last time folks logged in. This guy hasn’t posted in 4yrs.

 

Yeah I’m aware, but throwing a Hail Mary that he’ll get an email notification and maybe chime back in.

 

This kind of OP is the "hit it and quit it" variety. Take take take, and then bail without giving so much as a resolution of the problem to pay it forward or even just a thanks for the help. You'll never hear from them again.

 

Happens far too often. Selfish MF'ers, can't be bothered to contribute to the greater good.

 

Ya there seems to be quite a few electrical related threads that never find a solution, maybe they all went mad and rolled their trucks off a cliff haha.

 

I get it. We're all tempted. I have a knock sensor issue that's pissing me off lately and some days I'm tempted ... but I haven't bailed on anyone that's shared advice on what they'd do to fix it (yet)

 

Absolutely. It’s common courtesy to check back in with a follow-up and show some appreciation for the knowledge on this board. The cost of new trucks is great motivation to keep these old war horses going.