1990 Montero 3.0 Crank, No Spark

If this car has a fuel pump prime at key on, pin 13 should momentarily get voltage.

[strike]Pin 46 is low voltage so is this car a manual transmission?[/strike] never mind, 46 is only hot on start

Also check the female terminals visually and see if any looks weird at all.

Here's updated image with your voltage readings, because I know for sure that image is upside down for you all lol.

Here are the next set of voltage readings with key on and sensors unplugged.

Just to be sure when I test grounds, red should be to battery positive and ground to connector or ecu?
Or should I be looking for voltage drop down the wire?

No power yet coming from 13 on initial key o position. I currently have the fuel pump disconnected at the pump due to with the other ecu the engine stopped rotating on cranking do to the excess fuel Pressure in the cylinders with no spark.

Still 2.7 v at tps and air flow sensor connector unplugged and same at ecu.

Time to ohm check the 5v reference wire for a short to ground. The fastest way to check is to cut the wire at the ECU harness and check if voltage returns to 5v.

The longer way, if you don't want to cut wires, it to unplug the ECU, TPS, and Airflow Sensor. That way the wire is completely isolated. Take your multimeter and set it to ohms (the icon looks like a horse shoe) (if you don't have an auto-ranging meter, set it to the highest scale). Connect one end of meter to ground (battery negative is best) and the other end to the 5v ref wire you just isolated. It doesn't matter which end goes where. Please report your meter readings. "OL" means no short to ground. It also means your computer's bad.

I did the ohms test to ground with the GY and reading was OL. Doing some more hunting through the harness. Hard to think the Ecu is bad this is a freshly refurbished one and I haven’t tried cranking yet. If they are frying on me I would like to understand the why.
Any thoughts?
Thanks

I GOT SPARK!!! Don’t know why...

Thanks for the help

Minivandan wrote: I GOT SPARK!!! Don’t know why...

Thanks for the help

So you cranked it? Any more signs of life from this ECU? What about injector pulse during crank? Can your hear the IAC moving when you cycle the key on and off?

I would open up the ECU and look for visual clues like leaking capacitors. Did the original ECU also have 5v ref issues?

I rechecked the 5v reference wire and it’s still pumping out 2.75 V but seems to start up now. Not sure if it was the same with the old ECU. I didn’t know about that before this issue. As far the original ECU I sent it to a repair shop 3 times. They said it was fixed the first two times and the third time that said it was unrepairable. It still doesn’t idle very well I need to keep pressure on the accelerator to keep it running once it’s warm. I could not hear the IAC cycling on start up. Reset the distributor but had to take a few days off due to snow storms. Any thoughts on idling adjustments?
Hope y’all are well and thanks again for all the info.

I missed an important step to inform you of when checking 5v ref circuit. Did you cycle the key after you disconnected the TPS and Airflow sensor? Recheck voltage with both sensors disconnected after you do that step.

I did that and it worked. I now have 5v on the volume airflow sensor and the TPS.
Thanks for that!! Idles nice while cold but as soon as it warms up it idles down and stalls out. I need to use the throttle to keep it running. Any ideas with that?
Cheers

Check your fuel trims before and when that is happening.

Are you able to restart it or is it still bad because it's hot?

Nissan Technician

That's great but which one of the sensors is the bad one? You should still have 5v on that wire with both sensor plugged in. If you don't, then one of the sensors must be pulling the 5 volts down to 2.75V. Test each one at a time, cycling the key, and find the one that's pulling the voltage down.

So it finally runs pretty good I have 5 v on both sensors with them both plugged in and back-probing them. It might have been cheating but by adjusting the accelerator cable at the throttle body while it was hot to adjust the idling and it seems to have worked. Idles nicely now At 750 rpm.

:DDDDDDDDDDDDDDDDDDDDDD

Amazing thanks for all the support!!
Ghost chasing done for now

Lol I have that same multimeter !!!!!!!!!!!