I hope I can get some input on what might be causing some issues with my 2000 Maxima GXEL. It's an automatic with about 140,000 miles. No major mechanical issues until now.

About a month ago, I drove it about 650 miles across Texas, then back again (about 1,300 miles in total). A few days later, I drove another 650 miles back. No major issues during that time.

A week ago, I noticed that the Cruise Control was no longer engaging while driving on the highway. I assumed I had a brake light out, so I bought new brake lights. I was going to replace all three bulbs, but later found that all three bulbs were still working. I thought it was odd, but did not have time to troubleshoot it further. A few days later, I ran an errand and came home. When I turned the car off and got out, I noticed that all of my brake lights were permanently on. Now I was very confused, but still did not have any time to try to diagnose the problem. I decided to pull the brake light fuse and come back to it in a few days.

Last weekend, I put the fuse back in to test it and try to figure out the problem. I could not figure it out, but I also forgot to pull the brake light fuse back out. This caused the battery to completely drain. In the meantime, I did some research here on the forum and found that the probable fault was the rubber stoppers (Part # 465845P010, shown below). I looked around under the dash and, sure enough, both of the rubber stoppers were missing. I also noticed chunks of one of the stoppers on the floor. I ordered a replacement and replaced both stoppers.



They arrived on Tuesday 07/12/2022 and the installation was easy enough. At that point, I also found that I let the battery drain out and had to replace it. The auto part store covered it under warranty and gave me a replacement. I started up the car and tested it on the highway. Sure enough, the brake lights now worked properly and the Cruise Control is now working again. But, I also noticed that the brake pedal seemed more firm than usual.

Today, I drove into town and started experiencing issues. When I pulled out of the driveway, I found that the brake pedal was now even more firm than before. When driving on the highway, I noticed that the car seemed a bit slow to accelerate. I went into town and ran a few errands. When coming home, I had more serious issues. I could not get the car to accelerate beyond 48mph. I also noticed that the engine was revving upwards of 4,000 RPM, which is unusually high. It's usually around 2,800 RPM at that speed. At that point, I also smelled a burning smell.

I pulled over into a parking lot to examine the car. When I looked in the engine bay, I could smell some kind of burning smell, and there was a light smoke coming out of the engine bay. I checked the fluids, and found that the engine oil was fine. The transmission oil was a bit low, but I doubt that would cause a sudden onset issue like this. No fluids were noticeably dripping. Eventually, the smoke stopped. I turned the car back on and idled it. The engine temperature was normal, and the Check Engine light off. After a minute of idling, I went back onto the highway. This time, the car ran perfectly. I was able to get up to the 75mph speed limit with no issues.

I drove for another 20 minutes towards Lubbock for another errand, then went back home. When I was getting out of the city and accelerating up to 60mph, I noticed that the car began to shake violently. I suspected that this was probably another electrical issue, so I pulled over, turned the car off for about a minute, then started it back up again. When I got back onto the highway and got up to the speed limit, there was no more shaking. I drove for another 25 minutes without issues.

Almost right when I pulled into the driveway, the Check Engine light turned on. However, despite using two different scan tools, I could not find out what the DTC code was. Both scanners showed "MIL Light On", and all tests as "Ready", but no actual codes.

Now I am left scratching my head. Does anyone have any idea what is causing this? Did I screw it up?

Also, while it may be a moot point, has anyone else experienced both rubber stoppers failing within just days of each other?

 

I had another look at it yesterday and noticed that the ground terminal connector was a bit loose. Not significantly loose. But I decided to replace the terminal connector as a precaution. Also sprayed rust remover on some of the points where the ground cable connects to the chassis. I reinstalled the battery and started it up. Didn't have time for a test drive. But, I noticed that the unexplained Check Engine Light went away. Will drive it later and see if it's any better.

 

It's awfully quiet in here.

Anyways, I think I solved the problem. Turns out that my suspicion about an issue with the ground terminal connector was correct. As soon as I replaced that connector, no more issues have occurred. It was only slightly loose and could twist back-and-forth with some effort, but was not in danger of falling off. turns out that was not good enough. The new connector is tight enough that it will not move.