Paulschutz

I have an 02 Maxima SE that will not start. The fuse "Eng Cont 2" blows out everytime the key is switched to "on". I've read all over and have not found anything similar to mine. I turn the key to on, the fuse blows, and the AT Check light blinks several times. Ive checked the wires and sensors to the trans, followed the O2 sensors, and checked the relays, all of which checked out. I cant check for codes, it just reads back error. I've looked at wire diagrams and the fuse leads to the NATS and and ecm relay, but im sure it could also lead to other things.

DennisMik

iTrader: (2)

That is a nasty fuse to have problems with. Like most fuses in the car, it supplies power to more than one thing. In the case of the Engine control 2 fuse, it powers 13 different things/circuits. They are:

The ECU (main)
The MAF (MAFS)
The crankshaft position sensor-POS (POS)
The ECM relay energizing coil (PGC/V)
The ECM relay energizing coil (IGNSYS)
The Intake Valve Timing Control Solenoid Valve Bank 1 (IVCB1)
The Intake Valve Timing Control Solenoid Valve Bank 2 (IVCB2)
The Camshaft position sensor Bank 1 (PHASE)
The Camshaft position sensor Bank 2 (PHASE)
The front electric engine mount - auto transmission cars (EMNT)
The rear electric engine mount - auto transmission cars (EMNT)
The ECU secondary power input (ECM/PW)
The NATS IMMU module (NATS)

In the above list, I would start with the electric engine mounts. They are known to short out and sometimed cause the ECU to short out, too. Start by unplugging the engine mounts and see if the fuse blows. If the fuse still blows, start unplugging all the other things in the list. Hope you don't need too many fuses before you find the problem.

Paulschutz

I checked the mounts, but i inly seem to have 1 electronic mount. Are you sure theres more than one? And ill start down the checklist now i guess haha

Paulschutz

Also, my ses DOES NOT come on. I should have a code for intake timing control for BOTH banks, which i found online to mostly be solved by an oil change. I did this the other day and 2 hours after is when i could not start the car. AKA the first ride after doing the oil change, something happened. Hopefully this helps narrow the options?

george__

iTrader: (1)

Is your ECU okay? Something didn't melt or break in there?

I heard with automatics the motor mounts can fry parts of the ECU...

QueensMAX

It looks like ECU..unplug both your engine mounts. I came across a 2003 recently with a burnt out ECU due to a bad engine mount. Check engine light was not working as well.

DennisMik

iTrader: (2)

The close timing to the oil change doesn't mean squat, just unfortunate timing. The only thing that has meaning is the fuse blows.

In a effort to save fuses, unplug several things at a time and see what happens when you turn the ignition switch on.

When you first turn the ignition key to the ON position, the SES check engine light should come on. If it doesn't, you have a problem with the check engine light.

As far as the electric engine mounts, I don't know if you have two or only one. The is conflicting information on that.

Paulschutz

Okay guys ill get onto the mounts when i get home from work today and let you know

Paulschutz

Ok i have my ecu and NATS module out. Ive unplugged and tried everything EXCEPT the "ecm relay energizing coil" and secondary power input. This is only because i dont know what those are, lol. I opened the ecu and i dont see anything burnt out, no blown up capacitors, everything seems in check. The same goes for the NATS. So what are those other things? How do i test/unplug/find them??

DennisMik

iTrader: (2)

Since you removed the ECU, that would mean that you unplugged the big connector on the end. That disconnected both primary and secondary power input wires. Does the fuse still blow with the ECU out of the car?

A relay energizing coil is a part inside of a relay. So you need to unplug the ECM relay. As a point of clarification (just in case you weren't aware of it) the terms ECM and ECU are interchangeable.

The ECM/ECU relay is under the hood, in the box in front of the battery. It is in the front corner by the radiator, the cover labels it ENGINE CONTROL.

Are there any other things you are not clear on?

Paulschutz

Ah didnt see your post! I didnt think to check the fuses when the ecu was out, i just took it apart and put it back in. Ill do that tomorrow. Ive check the relay, its fine so it must be the nats or ecu then? Everything else seems fine, like i said i unplugged pretty much everything on the list you made.

Paulschutz

Ok i tried it without the ecu or nats plugged in and it still blew out. That leaves the ecm relay energizing coil. I tried that as well, but im not sure which one i tested. You have two listed, i unplugged the one labeled "engine control" in the relay box. The fuse didnt blow, but if i plugged in another relay (i used the "rad fan 3" relay) it would still blow. Any thoughts?

Paulschutz

Also, when i had the ecu and nats unplugged, the ses light WOULD come on, but it would dim out. I turn the key on and it lights up but just as it does that it sort of "dies out" i guees you could say. The AT check light also did NOT come on. Does this mean anything or is it purely because those two things just werent connected?

Ephraim

iTrader: (15)

I had a similar issue, try unplugging o2 sensors then starting the car.

if that fixes it, replace the sensor

https://maxima.org/forums/5th-genera...s-blowing.html

**thread cliff notes edit
-for me it was 'Engine Control Fuse 1' dying. Progressed to where it died when I turned the key
-should be obvious, but by 'unplug sensor' I mean electrically unplug it, dont take it out of the exhaust. Unplug it from the wiring harness. super easy to test/troubleshoot

DennisMik

iTrader: (2)

Since the SES light is turned on by the ECU, having the ECU out or disconnected will not make the light work properly. I'm kind of surprised that it lit up at all. Evidently some kind of back circuit in the cluster.

You can try unplugging the O2 sensors while you are at it. I don't see the connection with the fuse that is blowing, but I'm always willing to learn something.

There have been a few instances of the bottom side of the fuse block coming apart. I remember another thread where a guy's car was blowing headlight fuses and he discovered that the screws on the bottom for the fuse block were loose or fell out and things were touching. This is another possibility.

Paulschutz

Well it's not my O2 sensors, but 3hich relay is IGNSYS and which is PGC/V??? Those are the only things left to disconnect

DennisMik

iTrader: (2)

I need to clarify my first post where I listed things that use the Engine Control 2 fuse.

At the end of each line is some esoteric junk enclosed in parenthesis. This "junk" is the name of the wiring diagram that shows that particular electrical circuit. The 2 things that are still confusing you, IGNSYS and PGC/V, are the same one single relay. Electrically, the relay is 2 things built into one package, and each of those parts end up with a different schematic.

So you have tried unplugging the ECU relay. Again, there is only one of these critters.

With the relay unplugged and the fuse not blowing says you have eliminated most of the other possible causes. But when you plugged in the RAD FAN 3 relay and the fuse blew, Exactly when did the fuse blow? Was it as soon as the relay was plugged in or when you switched the ignition key on?

zachpark17

OP, did you ever figure out what was going on with the engine control 2 fuse?? I'm having the same issue, except the fuse blows whether the key is in the car or not. Immediately when I try to replace is, even with the car completely off, the fuse blows. I'm driving myself crazy trying to figure this out. Any help would be appreciated.