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Infiniti Q45t: is there someone to help me with 2000 Infiniti

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is there someone to help me with 2000 Infiniti Q45 - 4.1l question?
Hello and welcome! I'm Billy and i will assist you with this.

My apologies for the delay, thank you for your patience.

All the problems started at the same time, this is frustrating indeed. However, let's take this step by step, and we should be able to sort them out.

As for the MAP switch solenoid, i would first check the connector if loose, and i would check the air passages (the hoses, from air side and vacuum side), make sure you have no leaks, disconnection or restriction. Having checked these, then you'll need to check continuity from the switch to the ECM (engine control module). I will include the details needed to track this and figure out whether it is a wiring problem, air hose problem, sensor problem or ECM problem (hopefully not).
click here for details

The first two codes are related obviously, as if you have a problem with the ignition signal circuit, you will get misfires. I would start by checking the resistance between terminals (3) and (2):

If you get 0 ohms then the transistor is faulty, and the coil requires replacement, if you get a resistance, then the transistor is good.

Having checked the coils, next you need to check the wiring between the ECM and the coils for continuity, for that i will include the diagram of the coils (ignition):
click here for diagram

If the coils are good, and you have continuity to the ECM, and the ECM connectors are good (i would first check those), then the ECM requires replacement.

Thank you for your trust! Get back to me if you need more assistance...Thank you in advance for the positive rating...

Regards, Billy
nabilc and 4 other Car Specialists are ready to help you
Customer: replied 3 years ago.

Appreciate your answer, yesterday was unable to wait 2 to 4 hrs.

I will do what you suggested and will contact you. It will take time as I have lots to check.

Keep u posted.


My apologies for the inconvenience... take the time you need, and get back to me with the results, or if further assistance is needed.

Regards, Billy
Customer: replied 3 years ago.

Thanks Billy.


Where is ECM located? Thanks

Customer: replied 3 years ago.

I posted this question yesterday and no replies i have seen. Repeating the question on the same car.


Thanks Billy.


Where is ECM located? Thanks


My apologies for the inconvenience, there must have been a fault with the system, as i did not get notified.

The ECM (engine control module), is in the passenger side foot well under the dash:

Regards, Billy
Customer: replied 3 years ago.

Thank you again.


One last question. Where is location of ECM relay.


One good thing came out was that the MAP/BARO solenoid valve had a broken tube and vacuum line disconnected. Got one from Dealer.

You're most welcome!
The ECM relay, is just above the ECM itself:

Customer: replied 3 years ago.

Hi Billy,


Got the MAP/BARO solenoid installed and hooked vacuum lines and put it back together. Ran beautiful for half hour and the only code came was of multiple cylinder misfire. Waited sometime again ran good for half hour than code pops up stating multiple misfire.

Seems like only when when it gets hot is where the problem exists.

Any suggestions.



So you still have the ignition issue... accordingly, you need to check the signal (trigger) from ecu to coils, using a scope. And if the trigger is hesitating, than the ecu (having already checked the connectors) requires replacing.
Customer: replied 3 years ago.

i don't have a scope but can multimeter be used


A multimeter cannot be used to check the ignition trigger signal, i'm afraid.
It can be used to check continuity, voltage etc...

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