OBD Won't Connect?
 

'05 Maxima, daughter's car.

Using a little cheap bluetooth OBD reader from Amazon. It used to work on the Maxima and still works on my Rogue, but it won't connect to the Maxima now.

The car had blinking Check Engine while she was driving and then died. I had it towed back home but now it won't connect to the diagnostics. Battery is new, starter cranks strong, but won't start. I recently replaced all plugs and coils, so they should not be an issue - plus the car will start (badly) with just two or three cylinders firing so if it's spark problems, it's all of them I think.

Any ideas?

You may check your battery negative/ground cable at the transmission end.

Where does the ECU live in Maximas? If it is under the hood, then check the ECU housing for corrosion. There may be water damage. If it's inside the cabin, ignore me.

Inside the cabin, under the glove box.

So water damage should be ruled out. Give us more details. How long ago did you do the plug job? Did the engine run fine since? What did you have to disconnect in order to pull the intake?

I did plugs and coils about two weeks ago, and it ran for a week before dying. It has a blown ignition fuse and replacing it blows the fuse immediately.

As far as what I disconnected to remove the intake plenum, basically everything attached. Vacuum lines, sensor connections, etc.

Take the ECU out and see if it's blown. It could have taken a few more parts with it to the grave if it is blown. Throttle body and EGR valve come to mind.

Just to follow up, this was the root of all the problems.

Unfortunately I had to take it to a mechanic and pay several hundred dollars to figure it out. Floating ground was blowing coils open or short and was the problem from the very beginning. Shorted one of the coils I replaced which blew the ignition fuse - which was why I couldn't connect the OBD to the ECU. The mechanic blew three coils in the course of his trouble shooting, in fact. It's running like a champ now.