Hey all! Posting this here and Toyota Nation looking for help!For Context: 96 T100 3.4 4WD

Drove the truck up on a rough gravel road to go berry picking. (Lots of bouncing around)

Took the truck to work the next day (truck was running great) and stopped to get a coffee, come back out and it’s misfiring and throwing P0301.



So I change the spark plug, swap coils from another cylinder, and no change.



I let it cool off while trying to diagnose my issue by inspecting my ignition wiring (which you’ll come to see is a mess), go to start it back up and no misfire. I finish driving to work (bills to pay) then drive it to the grocery store. I put the under dash panels back on while the wife was shopping, then misfiring again.



So here’s where things get complicated, the previous owner must have had an issue with the key/ignition switch and decided it would be better configured with 2 household light switches and a push button with standard 12/3 (see pictures attached)



So trying to get some sort of fix in the midst of this, I tried to wire it back to a standard key switch from autozone. (Not sure I have the wiring right)



Also while trying to diagnose this, it starts to pop a P1300 code.



But anyhow, after changing this wiring out, my turn signals, dash lights, hazards, cig don’t work and when the hazards are pressed the parking/drive indicator light will go bright/dim. Note: The radio, headlights and taillights still work.



Also they had the hazard spliced in on the 15amp cig fuse



Also worth noting that months prior, I redid the timing belt and valve covers but the truck has ran excellent up until this point.



I have an absolute electrical mess and I’m not very wiring savvy but I can partially read a diagram and love to learn but at this rate I’m ready to try to rip the entire harness out and start over.



I’ll try to attach all photos that might be helpful.



Any ideas and assistance as to what’s causing the misfire and the majority of the accessories to no longer work would be greatly appreciated.


Ignition switch

Ignition switches

Push button start


My attempt at getting a key switch wired in


Current state of the dash

 

i can't believe that the p.o. put solid core wire in there! wow

it's hard telling what else you'll find.

 

Hey Guys, I’m just replying to this thread instead of making a new one cause I’m still having trouble and wanted to make a more detailed write up on what’s going on.

September 1, 2023:

Bought truck which was formerly a coon hunting woods truck.

Previously owner(s) had decided to hotwire the truck to 2 household light switches and a push button using 12/3 Romex. Amongst other modifications such as jumpering the CIG 15A into the Flasher Relay and putting the heater blower motor on a switch coming straight off the battery.



November 17, 2023:

Taillights not working, removed trailer harness and redid wiring harness amateurishly and taillights working again. I also removed the plugs from the license plate lights as both bulbs were broken.



February 3, 2024:

Redid timing belt, valve cover gaskets, and changed spark plug wires

Truck runs like a dream on daily commute until:



June 13, 2024:

Take truck up onto a bumpy gravel road to go berry picking.



June 14, 2024: THE DAY OF TROUBLE

8:30am

Stop into a coffee shop (truck is running fine on the way there), come back out and the truck starts misfiring in cylinder number 1.

8:45am:

Pull out the code reader:

P1300 + P0301

Head to the local parts store to buy a spark plug to swap. - No change

9:00am:

Swap coil 1 and coil 3 - no change

10:00am:

Test ignition coils and wires according to FSM and theyre within spec.

Clean up battery terminals and undo under steering wheel dash to inspect ignition wiring.

11:00am:

The truck has cooled off and attempt to start: no more misfire.

Drive to work with no issues.

Come back out after, still no misfiring.

6:00pm:

Stop by the grocery store and decide to put the under steering wheel dash back together while wife is shopping.

Misfiring resumes.

Drive home about 20 miles with the misfire.



June 15th:

I attempt to rewire the ignition switch onto an actual key switch from autozone and redo the wires using 12V automotive wire.

Still misfiring.

I also accidentally break the green wire on the fuse box as well as the one under the steering wheel.

I then proceed to have no function in the following things:

Clock, Cig Lighter, turn signal, hazards and odometer lights

I leave the truck alone for a few hours and it stops misfiring until it gets warmed and begins to misfire again.



June 16:

Continue to try to troubleshoot and understand what’s going on. Same behavior is occurring. Truck will start and run fine until it warms up then when restarted, will start misfiring.



June 17:

I go back to work and buy another vehicle because I need a reliable ride to work until fixing this.



October 12:

First time attempting to work on truck again. Had drove the truck to neighbors a handful of times in while it was misfiring.

I ordered an OEM ignition switch thinking this would clean things up.

Now the truck will only crank, start for a moment then die.





TLDR: 96 T100 3.4 Auto with P1300 + P0301 misfiring cylinder #1 starting and stalling



Here’s the things I’ve checked:

Every wiring diagram Toyota offers for this year it feels like lol not really

All fuses under hood, AM1/AM2 fuse

IGF Signal from Ignitor to ECU

IGT1-3 from Ignitor to ECU

Coils/Wires within spec

Checked Ignitor BLK/Red with AM2 continuity

Cam Position Sensor within spec

Checked Coil 1 connector Blk/Red getting 12V





Here’s the things that’s wrong:

-Currently refusing to crank as if the battery is dead, just clicking when key is turned even when being jumped.

-Starts then stalls after a moment

-Clock, Hazards, turn signals, and cig don’t work. Tested white/black wire according the FSM and states open circuit but no sure where



Not sure what else to do



Can upload pictures as requested because there’s a lot lol



Note: I’m an newbie when it comes to electrical stuff but this has been a learning experience.



My next step feels like ripping the harness out and inspecting for bad wires but I’m sending out my SOS here and everywhere to see if there’s a better idea.



Thank you in advance for help or pointing in the right direction.