Infiniti FX Forum banner
1 - 5 of 5 Posts

·
Registered
2005 FX45 120K miles
Joined
·
152 Posts
Discussion Starter · #1 ·
2004 Infinity FX45 with 115,000 miles

This "no start" would only happens once in a while, probably since it is always warm here in Hawaii. (Seriously. Apparently temperatures have something to do with an AC Amplifier problem in cold weather regions, but in these posts the owner can crank their engine vs. my "no start" where nothing happens when I turn the key to the start position and release.

I have not yet replaced my AC Amplifer as described in this video below, but I did clean the fuses in the box where my emergency brake is located. And there I found fuses to the BCM and AC Amplifier. So what do you know. Could a dirty fuse contact contribute to a signal problem? TBD.

Here's the how to replace your AC Amplifier video:

So I still need some more days to confirm that all I had to do is to clean a few fuses to fix my "no start" and “no crank” problem, but so far so good.

Note: When I do have a "no start" condition my starter does NOT engage at all, but a simple recycle of the key cylinder always starts the engine, and my starter is very strong and my engine always starts right away!!!

Personally, I think this no-start problem may be more Anti-theft related, but I definitely know temperature plays a roll.

The Infiniti dealer recommended I replace my starter when this “no-start” key recycle problem happened in the shop the other day. (They were changing the tranny fluids.) However, I really don't think my starter solenoid is suspect, but maybe the mechanic flagged the starter & solenoid as the problem, because there is no "click" when the key is turned. TBD.

Based on this AC Amplifier video, and the fact the symptom is related to colder temperatures, I everyone has confirmed they fixed the problem by changing out a $450 AC Amplifier, then maybe that’s the right approach?

But $450 is a lot of clams so I think you should first try cleaning your fuses (which is free) and then move on to diagnosing an Anti-Theft Antenna problem next.

I'm wondering if anyone has opened up their old AC Amplifier? Note: I have had a lot of success and saved a lot of money repairing old circuit boards. If you don't know how, then I suggest you go to a Radio-TV Repair Shop where they can probe for out of spec resistors and leaking capacitors and shorts to ground. Further, I think a failing 50 cent component may explain why some are reporting “no starts” on cold days! ... or a visual CB inspection might reveal you have a bad solder joint you can fix yourself with a solder iron for free if you know how to reflow solder? It's easy! YouTube it!
 

·
Registered
2005 FX45 120K miles
Joined
·
152 Posts
Discussion Starter · #2 ·
Months later, I can confirm cleaning the fuse fixed this problem and my car starts normally all the time, no matter how hot or cold it is outside. My guess is that other owners in hot weather may not be able to get away with just a simple fuse clean using a wire brush or sand paper if you don't have a wire brush. Also when you look at the fuse box next to your emergency brake pedal, you will see several BCM and even the ACC and Amplifier fuse. So you can ignore the other fuses if you want.
 

·
Registered
2005 FX45 120K miles
Joined
·
152 Posts
Discussion Starter · #3 · (Edited)
The AC amplifier is (I think) part of the HVAC system. I'm guessing there is a cold solder joint inside that is causing havoc with circuit that talks to the BCM which also services the security system. And when the security system see something it does not like, it disables the starter circuit. And that is why nothing happens when you turn the key to start your engine.

This no-start condition seems to cause more problems in colder climates. And you can buy this part on Ebay, but you might find a local TV repair shop can repair your AC Amplifier if the box can be opened? ...If so, I bet you will a cold solder joint with discoloration around that pin. And all you do is touch a solder iron to the existing solder and it melts and reflows a new (tight) solder joint.

In warmer climates, like were I live, I found cleaning BCM, ACC, and the AC Amplifier fuses in the fuse block located next to the emergency brake pedal did the trick for me, and now my car is starting all the time just like normal. So I did not have to replace my AC Amplifier. Note: It's also possible when you pull the fuse to the BCM and AC Amplifier the system "re-learns" or "resets" and that fixes the intermittent start problem. (Note: If you hear a click or your starter cranks, then the AC Amplifier is probably not your problem.)

Note: I looks like the AC Amplifier can be found either above or below your radio, depending on your car's year and/or if you have a navigation package.
 

Attachments

·
Registered
2005 FX45 120K miles
Joined
·
152 Posts
Discussion Starter · #4 ·
Update: Today my car would not start, but I confirmed the battery was NOT low. ...I then connected a Lithium jump pack to the battery and the engine started right away. ...So I'm wondering if I have a bad ground problem that supplies the BCM?

As a fix, I will be looking at ways to add a ground wire to the BCM circuit instead of trying to chase down the bad ground wire. However, if anyone has some ideas on the best way to do this, please let me and all of us know what is the easiest way to do this?

I'm also thinking I could have a "cold soldier joint" inside the AC-Amplifier as described above, but since I got my car started... for now I'm going to leave my Air Conditioning switch "on" at all times; and then I will wait to see if I have another problem.

Note: The engine failed to start with the key after I pressed the key fob "open door" button too many times. This caused all my windows to drop halfway, which is part of the key fob programming functions. So, this no-start condition may also be related to a BCM problem that rectified itself then the BCM got reset. (Just a guess.)

Whatever if going on, at least I know I will not be stranded so long as I carry a Lithium Battery Jump-Pack with me. I just wish I can figure out what the problem is: A) Bad Ground. B) Bad AC-Amplifier. Or C) Bad BCM. What do you think?
 

·
Registered
2005 FX45 120K miles
Joined
·
152 Posts
Discussion Starter · #5 ·
Just adding: I think all FX owners should carry a lithium jump pack. Why? Because for whatever reason you can't start the car, I have found that every time I just need to jump my battery and that will get you on your way. Or you can plan to spend hours waiting for a tow if you engine will not start after letting it sit for a while. (3-10+ minutes on average, if this works at all???)

You also clean a number of key fuses with a wire brush. I recommend you disconnect the battery first and you may need to do this anyway to access the fuse block where the battery is located.

Attachment: pdf
 

Attachments

1 - 5 of 5 Posts
Top