Sometimes Taco won't start, bad accessory wiring??

Did your truck actually start? Even with the check engine light not showing?

I wondered about that with the alarm as well, I think it's possible that it could be cutting off the ECM. I am still curious what access it had to the truck's systems. If I can find the dash wiring diagram in the FSM I'll see if I can figure out what the wires it was spliced into go to.

Yes, when those are removed from the fuse panel that circuit is disconnected. You could just tuck them up behind that drawer by the fuse panel.

 

No the truck will not start at all when the check engine light is not showing and the key is in the ON position. NOW, this is how I can tell if the truck is going to start or not. When the CEL comes back on, then I know the truck will start, and sure enough, every time, that is the case. I've read aloe of people with that Gut State alarm have problems like this, but it is way too much of a mess for me to remove, so I probably won't LOL, unless I 100% know that it is the culprit that is killing the ECM.

 

It really wasn't that difficult to remove, pulling the panels around the steering column was about the hardest part. If you wired in cameras you can pull that alarm.

I imagine you need your truck up and running sooner rather than later but, if you have time and you're anywhere between West Texas and Montana I'm taking a trip the second week of September. I could make a stop and pull the alarm for you.

 

Thank you, I appreciate the offer. I am in East Texas, but I will look into removing it myself.

 

Jimmy, please explain. I've used wire nuts for years and never had a problem. I use only metal spirals on the inside, no all plastic. Also wires a stripped to the proper length.

 

So close but still so far

I'll be curious to hear updates!

 

I have seen way too many wire nuts come loose from stranded wires where the nut is tightened and cutting the strands, this is especially true in environments where there is vibration ( like in the truck ). I also use wire nuts on stranded wires for electric motors etc inside of the motor peckerhead, but I always tape them with rubber tape, electrical tape, and Friction tape. In my opinion if you need to join stranded wires best is to solder and heat shrink, second best would be the newer Wago Connectors. (see below). Wire nuts in a vehicle is never a good method. Granted as in anything else there are lots of opinions.

https://www.wago.com/us/c/wire-splicing-connectors

 

Did you just call me a peckerhead?!
Again, I've never had a problem with wire nuts. I do agree that solder and heat shrink is the best way to go.
These are the worst

 

Those Wago connectors look really fast and easy.

 

i read UR post not knowing what a ' piggyback ' is

being a trained technician i recommend NEVER to compromise the OEM wiring harness

come directing of the battery to a device like a ' Centech ' that can handle quite a few AMPS & accessories

if there IS an issue simply disconnect all voltage going to Centech
a direct process of elimination..................no less preserving the integrity of the OEM wiring harness

that way U can trace all issues & troubles toward the OEM vehicle or towards the Accessories on the Centech

no less ALWAYS better when taking to Dealer
he cant throw blame or fault towrds U & the accessories connected when they are NOT in the loop

 

all those convenient connection devices will fail with heat moisture vibrations

only a matter o time

wire nuts were designed for AC current.............. not DC current

they can easily result in what s technically known as
correctly known as
HI resistant trubles
HI resistant opens

 

They are bulkier than a wire nut, but are great if you have the space for them.

 

So I think I found out WHERE the issue is coming from. Its the wire connection in the picture attached, right next to the fuses. I can push on this connection with the keys in the ON position, and the check engine light will come on and turn off, like there is a bad wire connection, I assume. I unplugged this connection and there are no burn marks, so thats good. Any ideas, or anyone ever had issue with this wire connection before?

Also, when I push this connection and hold it so the CEL stays on, I start the truck and when I let the connection go, the truck turns off (assuming because the power to the ECM is cut due to this wiring issue).

 

That's a new one, good catch!

Is the whole plug loose in the socket or do you only need a smidge of pressure on it?
Any of the individual wires loose from the back of that connector?

If you haven't maybe try pushing in on each individual wire and see if just one of them turns the CEL back on.

You could get it repinned.

An odd issue for sure! I'm still shuffling through the FSM for that wiring diagram. My copy isn't labeled properly so it's a fun experience.

 

ill mess with it more tomorrow, but yea I have been looking for the fuse box diagram (that shows what the harness and other big connectors go to or do) and can’t find it anywhere, so I am not even sure what that wire harness is even called, or goes to but I know for sure it’s something in that which is causing the check engine light to show/disappear.

for the most part everything seems pretty solid, nothing loose that I can tell but I’ll look more tomorrow.

 

That’s connector 1B. The black/red wire in that connector feeds power from the ignition switch to the 15A IGN fuse and the 7.5A GAUGE fuse. Put a multimeter on the IGN fuse while you futz with that connector. If the meter reading drops, you know which wire is the culprit.

 

And the body ECU is on the back side of the fuse panel.

 

Alright I was able to track down the correct FSM diagrams and trace the wires off that connector.

It is designated B1 as @Muddinfun said and @Jimmyh is correct that the body ECU is on the back side of the fuse panel.

Here's the connector and numerical pin locations circled in green.




B1 wire pin locations, colours and supported vehicle systems

1. Unused
2. Blue ------------ Stop Lamp Controls
3. Pink ------------ Windshield Washer Motor
4. Black & Yellow - Turn Signal Hazards
5. Red & Yellow --- Front Turn Signal RH
6. Black ----------- ECM, Electronic Fuel Injection
7. Red & Black ---- Front Turn Signal LH
8. Blue ------------ Windshield Wiper Motor
9. Black & Red ---- 15A Ignition, 7.5A Gauge ---- *See Below \/
10. Black & Red ---- Ignition Coils
    
11. Black & Red ---- Fuel Injectors

Several of those lines run through the ECM so if it is loosing signal/power that could be causing issues with the check engine light and the truck starting. The only wire from B1 that interacts with the Engine Immobiliser System that I saw is #6 for the electronic fuel injection.

I attached a PDF with the fuse panel locations and layouts.


*From Above ^
Location ------ Use ---- Fuse -- Description

1. ---------- IGN ---- 15A --- Multiport fuel injection system/ sequential multiport fuel injection system, anti-lock brake system, traction control system, vehicle stability control system, SRS airbag system, front passenger occupant classification system, engine immobilizer system
2. --------- GAUGE - 7.5A -- Meter and gauge, emergency flashers, front passenger’s seat belt warning system

 

Very nicely done. Also worth mentioning, the 7.5A gauge fuse feeds the CEL. This gives further evidence that the pin 9 black/red wire is probably the issue.

 

YES! You guys rock! I was just out there and noticed that one of the wires (around the #9) seemed to be a trigger, then this confirms that. So I still am not sure what the issue is. The wire doesn't seem loose, and I cant get the CEL to stay on, it will turn on, then eventually turn off, like the connection broke again.