brain mpem ALL ELECTRICAL STOPPED - car speed dropped then stopped

[justridingalong]

Long time Lexus owner, owned too many to count and love every one of them. My standby GX470 showed signs of low power and rough running so I attempted to return home with it. I got off the exit. stopped, restarted the unit and headed home hoping that I reset whatever was the problem. The unit had very low power and at one point actually smelled like burning rubber. The dash went black and all electrical died. I was close to a walmart so I replaced the battery and none of the electrical every came back on. I had it towed to my warehouse and I thought I would try to find a blown fuse or track down the problem before I paid to have it towed to a lexus dealership. I had zero problems with the car before this isolated event and the time I drove it prior to this I had zero issues. Very sudden and very complete - zero electrical works.

Is there a main fuse that may have blown?

[pj8708]

Hi Skippy and welcome.

Most of the fuses are located on the left driver side kick panel and more located under the hood. on top of the drivers side fender. There is a large 140a fuse on top of the alternator. However, I can't recall ever hearing of the alternator fuse tacking out all of the electric system.

Try going to an Auto Zone store and have them read out the codes. They do this for free.

Paul 

[justridingalong]

Update.

 

I connected the battery charger today and show good charge. I am leaving it connected for a few hours. 

 

A lot of the electrical has come back to life, radio, fan, seats, locks, mirrors, but the entire dash remains dark except a red car with doors open icon and a key icon with a box around it. There is no power getting to the dash. I am getting a beeping noise.

 

I connected a scanner today to the port by the fuse box by the trunk release lever and turned the key to on position and the scanner was unable to connect to vehicle. I got "waiting for vehicle to respond" and I got "linking error".  There was zero nothing when I turned the key all the way to start, lights did not dim, etc. 

 

As I crawled around the car I did notice a steady yellow light steady under the passenger side glove box. The yellow light could only be seen while kneeling on ground with passenger door open. I popped off the large plastic cover and it looks like light wiring harness is connected to a computer tire pressure monitor and to a computer 4 wd drive control.

 

I am encouraged that most electrical has returned but am still looking for fault. I did pop out most small fuses and all looked good, I have not yet removed any of the larger fuses.

 

I appreciate your help. 

 

 

[Lexus_DK]

Sounds like your AC compressor is possibly locking up and causing a restriction on the drive belt (rubber smell?). Try disengaging the AC clutch. And have someone check your alternator charging output. Do you remember if your battery light indicator came on while your were driving?

[justridingalong]

Update 2

 

so I have spent a few hours on various Lexus blogs and the am2 fuse keeps showing up as a fuse that controls a lot of the things I am seeing. I found this fuse in the box location noted by pj8708 and it was blown. I replaced it and it blew again when I turned on key but did illuminate dash cluster for a few seconds. I replaced it again and tried to start car, it stated right up but blew again in 5 seconds. It also sounded like a had a blown exhaust gasget on passenger side. A little more time on various forums searching now for am2 blown fuses lead me to many possibilities including a faulty spark plug coil. I noticed a lot of soot on the second coil from the firewall on passenger side and when I removed the bolt the coil top popped off leaving everything else inside in hole. I pulled about 20 feet of wire out and then pulled the end cap boot out with the spark plug attached. The burning boot was the cause of the odor as exhaust was exiting spark plug hole with loose/removed plug. 

 

Lots of debris is at hole base so I plan to vacuume that clean today and install new iridium plug and coil today. I also plan to add new fuse and test in on position, if it does not blow in 5 seconds then the faulty coil may be it. 

 

I had my oil changed right before this happened and oil is very black, with new oil dip stick is usually yellow for awhile... hmmm.

 

and how did that spark plug get loose...

 

hopfully new coil fixes issue. 

[pj8708]

Wow! I feel your pain!

I have never heard of such strange cluster of symptoms. I wish I could offer more help.

Paul

 

[justridingalong]

Update with a happy ending...

So I posted this thread on many lexus blogs and several people responded that I should consider checking all the fuses. One thread suggested looking at the 30 amp AN1 fuse under the big cover in the engine area. That exact fuse was dead. I researched the circuit for that fuse and it controls the ignition including the spark plug coil. I replaced the AN1 fuse and the GX started right up but died in seconds and the fuse was blown again. It also sounded like I had a leaking exhaust manifold on the passenger side. I immediately noticed the spark plug #2 from the firewall on passenger side was coated in soot. I removed the 10mm bolt and pulled on the coil assembly and the top coil box broke away from the coil shaft connected with a tail of copper wire. I pulled on the wire and the rest of the coil shaft assembly came out including the spark plug. Thats right, the spark plug was not screwed in to the head. I replaced the coil pack with a NAPA part, added a new iridium plug, added another 30 amp fuse and it started right up and remained running. 

This fix ended up taking about 15 minutes and under $100, a big win win. But how in the hell did that plug get so loose. The odor I smelled was the exhaust melting the silicone boot and plastic housing. I ran codes and it came back as a spark plug coil.

How awesome is it that I know not a lot about cars and a few hours on the internet and helpful suggestions from people all over got me back on the road - THANKS to all who helped.