morgfarm1

Hi Ya'll! I just joined in after having no good leads on where to look.

My 2WD Hilux with good ol' 3VZE with A/C and Auto Trans has begun throwing Code 12. I've found a few options for what, so I need to inquire:

How do I determine if it's G or NE signal is to blame OR if it's the engine not being able to get an RPM Signal (I've seen these turn up often in searches). It's not really a consistent fault, either. Sometimes it pops up right away, other times it takes 30 minutes or more of driving, and there are also instances it'll come up after being run 12 miles, shut down, and then started back up.

WE DID find there's a wire that comes from the firewall on the truck's right side, down the fender, across the timing cover and to the truck's left. It's a broken wire, yellow with blue stripe. We're not sure WHAT this wire was for, but it seems to be a sensor of some sort. We couldn't find a search online and have determined we need an example truck; which is hard for us to do in a smaller town where these trucks rarely die of natural causes (usually from accidents)

So, Recap: Yellow wire, blue stripe starts at the firewall and goes with a massive wire cluster to the wire guide atop the timing cover to the left side, and is broken before reaching its destination. If anyone has any clue where to look or knows what this wire is, I'd greatly appreciate the info. If it relates to Engine Code 12, that's even better.
The engine performance isn't affected, though i've noticed if i run it awhile and shut down, the engine runs pretty roughly for a bit until I've gotten air through the radiator to cool it down a tad. Seems that was posted here somewhere also, but this check code is the top of my list. I've had the head gaskets redone already (drove it for 2000 miles that way and didn't really know it, but was tipped off to the possibility when I couldn't find where my coolant was going - No oil/coolant mixing, no poor engine performance, nothing per the norm). THIS LITTLE SUCKER IS A TROOPER.

This is my 2nd 3VZE equipped Hilux and this is the first one I've had ANY sort of issues with. My first one never even had head gasket issues in the 2 years I had it. (It did break the clutch bracket though, which I didn't know was a thing)

I had this one for awhile and I was told about over heating issues, though when I drove it, I never got the temp gauge to get much above the 'COLD' mark, and the infrared temp gun wouldn't read above 180 at the hottest point. I ran it for the aforementioned 2000 miles before determining the head gaskets had blown because it was sucking down coolant like a race car sucks gas. Finally, I'd parked it one day and it started puffing steam out of the overflow tube which told me it was done, confirming the head gasket failure. Sure enough, the right side head was so warped I could feel it with my finger (ouch!)

Anyway, thanks for any information you might have. I'd like to get on top of it before it bites me in the tailpipe

old87yota

It looks like you are on the right track for code 12 as code 12 is loss of RPM signal to the ECU.

Can you post a picture of the broken wire in question?

A picture will help us see what you are seeing.

Co_94_PU

iTrader: (-1)

Ne, G, and rpm are all the same for this situation, don't fret over "which terminology" looking for sensors you don't have. It runs therefore your wiring is most likely flawed somewhere between the ignitor control and the ECU.

When I swapped the sr5 cluster into the 94 I had to add the RPM signal wire, I recall this being yellow with blue stripes and very long (it runs the full width of the cabin, serpentines around a bit, and still reaches the diagnostics box.. Long), and yes I pulled the whole dash apart on the donor in the junkyard, sliced open the harness bundle and unpinned the wire from the connectors while it snowed.

Definitely post pictures. An overview and points you can trace the wire to are much clearer than a description in words. Also start looking for the 93 FSM PDF file, it's not that hard to find.

scope103

The distributor contains 3 coils, which are brought out as G and NE. Both contribute to Code 12.

You can check the resistance of the coils directly. http://web.archive.org/web/201212070...12onvehicl.pdf Since you're looking for an intermittent problem, try rocking the distributor shaft (it should not move at all). While you could have a failing distributor, I'd look more carefully at the wiring; a more likely source of an intermittent problem.

My '94 EWD shows a handful of Yellow-Blue wires, including the fuel light, oil pressure sender, throttle position sensor, IDL line to the cruise control ECU, and Wiper motor (sorry, no RPM signal wire). I can't tell you (from the EWD) where these wires are physically found.