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Tim Mohr
Tim Mohr, ASE MASTER TECH
Category: Nissan
Satisfied Customers: 560
Experience:  30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
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03 Nissan Altima. Car turns over but will not start. Tried

Customer Question

03 Nissan Altima. Car turns over but will not start. Tried connecting a scanning tool to pull codes but get the message "cant locate ECM" on scanning tool screen.
Submitted: 12 months ago.
Category: Nissan
Expert:  Jay replied 12 months ago.

Hello my name is ***** ***** thank you for your question.

When you turn the key to the ON position, are the engine cooling fans coming on?

Customer: replied 12 months ago.
Car is vold. Fans only run when vehicle is hot.
Customer: replied 12 months ago.
Check engine light on
Expert:  Jay replied 12 months ago.

The reason I asked about the fans, is if there is a Ecm failure, the engine fans normally come on when the ignition is turned on.

Do you have a test light or volt meter?

The Service Engine Soon light should come on when the ignition is turned on, that is part of Bulb Check.

Customer: replied 12 months ago.
Fans do not come on when the ignition switch is turned on. Car was running fine with no issues last night. everything was working.
Customer: replied 12 months ago.
Is there a fuse or switch that could be the issue?
Expert:  Jay replied 12 months ago.

ok. When you turn the key to the ON position, there is a security light on the top of the dash. Is that light out or ON solid when the key is turned on?

Customer: replied 12 months ago.
Expert:  Jay replied 12 months ago.

Well if your scanner can't communicate with the cars computer, the first thing I always do is go through all the fuses.

Oh! That security light is ON Solid when the key is turned on?

Customer: replied 12 months ago.
Everything works on the car. There is power to the ODB port. Id have to dbl check on the security light... what if its steady on or off??
Expert:  Jay replied 12 months ago.

Off means it can read the key. ON solid means it can't read the chip in the key.

The OBD2 port should have 3 power sources. Do you have a Test light and Volt Meter?

Customer: replied 12 months ago.
Security light is OFF when key is in and vehicle is turning over). All fuses under dash and by Battery are ok... There is power to the ODB port under dash.
Expert:  Jay replied 12 months ago.

Do not check security light with the engine turning over. Key in the ON position only

Did you check the fuses with a test light?

Customer: replied 12 months ago.
Only reference I can find for an ECU fuse is a relay switch by the left front by fluid reservoir... should I check that? That relay is not available for purchase... per dealer.
Customer: replied 12 months ago.
Checked all fuses, both sides with check light. all fuses ok.
Expert:  Jay replied 12 months ago.

These IPDMs don't have Ecm relay issues like the Pathfinders or Xterra's.

Does the scanner you have work on another car? It is interesting that it won't communicate.

Let me know.

Customer: replied 12 months ago.
The scanning tool (Diablo ITune) works on both the Chevy truck and Nissan Maxima.light goes out with key in ignition and turned to start. Scanner tool on, does not locate ECM.
Expert:  Jay replied 12 months ago.

That is not good. Did you check to see how many power sources you have at the OBD2 connector?

Customer: replied 12 months ago.
I would have to go check.. should I have power to how many? I think there are 16 pins.
Expert:  Jay replied 12 months ago.

You may have a 16 pin OBD2 port, but it doesn't have 16 pins in it. I just quickly hook up a volt meter and ground the negative lead and with the positive lead just quickly go through the pins. You should have 3 power sources.

Customer: replied 12 months ago.
2 on top row, 1 on bottom row.
Expert:  Jay replied 12 months ago.

Ok, So you do have 3 power sources.. That is good.

We may need to do a ECM terminal layout check to see why there is no communication. The fact there is no communication can be the reason it's not starting.

Hang on while I get that for you.

This is a 2.5 correct?

Expert:  Jay replied 12 months ago.

is this a 2.5 Altima?

Customer: replied 12 months ago.
it is
Expert:  Jay replied 12 months ago.

That is the Ecm terminal layout. The way I do these checks is I print it and take it to the car. I do all the Key ON and Key off or Engine Turning over checks. I will take a pen and write down my readings as I take them so when I am done I can review them and see where it looks incorrect .

Customer: replied 12 months ago.
looks like it will take a while. Can I get back to you?
Customer: replied 12 months ago.
Do I check it all? The car turns over but does not start.
Expert:  Jay replied 12 months ago.

Yes, it will take maybe 1/2 hour or so. Sure, take your time. I will be online till late tonight.

I check them all. Cause if you find more than one that is out of spec, you can reference to see if they have something in common.

Customer: replied 12 months ago.
ok
Expert:  Jay replied 12 months ago.

Let me know what you find when you are done.

Ecm is located behind the glove box.

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