Gill23

Hello Club Lexus members. I have a 2005 Lexus ES330 with 89,000 miles. The alternator went bad, and died as I was driving to the mechanic. After the alternator was replaced, I noticed the car slipping out of drive and into neutral. The issue became worse as I continued to drive. The mechanic I went to poked around, inspected the transmission for any wear. He noticed there was minimal metal shavings in the fluid, and that the transmission should be fine. I was thinking the issue had something to do with a surge to the Transmission Control Module/TCM when it died. Just towed the vehicle this morning to Lexus Woodfield in Schaumburg, IL and they told me there weren't any updates available and that the transmission needed replacement. $5500 + tax. I am almost positive its the TCM because the trans shifted perfectly fine prior to the alternator going bad, and shifted fine up until 10-15min into my drive after the alternator was replaced. Any help at this point would be more than helpful. My current plan is to take it to my original mechanic and have him replace the TCM to see if this fixes the issues.

Thoughts?

Oro

As long as your mechanic is really good. If not, find a talented one - they are out there.

How did your alternator fail? A bad VR board can send damaging ac voltage through the system and damage some electronic parts.

Also, slipping from D to N is kinda vague - do you mean the gear shift moved, or the transmission just started slipping and you have no forward gears at all, or what? Certain things indicated mechanical fault, and others electronic.

Gill23

Thank you for the reply, Oro. The battery light came on at first. I notice nothing different with the driving experience. I then began to contact a few buddies who are a little more mechanically inclined than myself. After about 20-30min, the traction control, VSC, brake light, etc all came up and lit the dashboard like a Christmas tree. Shortly after, the Lexus started idling lower than usual, as if it were about to die. I then parked the vehicle at my parents house, and advised my mom not to take the car out for any reason. She ended up driving it, misinterpreting what I had said I'm assuming, and the car died on the road. Once the alternator was replaced, and battery was checked to make sure it was still good, the vehicle started slipping into neutral while driving. The gear selector was still in drive, but all it would do is rev up without movement. This happened while driving, and when accelerating from a standstill. Reverse works just fine. What I noticed was when you let the car sit overnight, or for an extended period of time, it works fine for the first few minutes, and then begins to slip out of gear, or slam back into gear causing a very rough shift and the car launches forward depending on the RPM. I did tow the vehicle from Woodfield Lexus back to my shop. I am surprised that Lexus didn't charge me any diagnostic fees for the time it was there... As of now, we are looking to replace the TCM and go from there. He does not think its a transmission failure, which Lexus continued to persist that it was even after I had asked then for an explanation.

Oro

From that description, someone very familiar with these transmissions can likely give a good answer. I'm not expert enough and I don't know a really good transmission person on this board who is (maybe there is). What I would do is take that 2nd description with a little more info and ask in the appropriate Camry forum at Toyotanation where more eyes could see it and hopefully an expert. Double check what year Camry V6s and possibly Avalons, etc. used this transmission and ask in that forum. My Transtec app says the Camry used this (U151E) from 04 to 12.

They would also want to know what happens if you start in 1st, 2nd, 3rd, etc. and what happens if you shift gears manually.

The description could be a bad solenoid in the AT. If it works sometimes, it is unlikely, but still possibly, the PCM (I do not believe these cars have a separate TCM; it is an integrated PCM AFAIK).

The car is not "slipping into neutral". It sounds more like the PCM is commanding the shift but it is failing to be done - either through damage to the clutch disks or because the solenoid is not effecting the shift. If the fluid is not burned/dark and bacon-y smelling, I would consider looking at the solenoids 1st. That is my semi-educated guess, and it is much cheaper and easier than swapping a PCM from what I understand. I have rebuilt transmissions and understand basic principals, but am not an expert.

I have been told, but never experienced, that failed alternator VRs can send AC ripple voltage that can damage electronics. I am unsure how often that really happens. I don't see it damaging a solenoid, though.

These are some thoughts to point you in the right direction; sorry I can't be more helpful.

aaidenton

Did you ever fix this. I have the same issue. I can disconnect battery and it is OK for a few miles. then wammo...shifts terrible and slips.

daredeil95

It's an old thread but, if the trans shifts fine when cold and as it warms up, it begins to slip then most likely its a bad transmission. You could try changing the fluid and filter and it might work better-longer but, you need another trans. I use to spend the big money on trans rebuilds but, I don't/won't anymore. I would buy a used trans and they are around $350 to $500 and you could install yourself or have a mechanic do it. Total job with trans & mechanic install should be about a grand or less and the used trans usually come with a 6 month to a year warranty with unlimited mileage but, labor not covered. It's an option. good luck

aaidenton

Not a transmission problem. Alternator failed and now the car has an electrical bug. Need to see what the OP did to fix this. Where is Gill?

daredeil95

Ooops....I need glasses,

Gill23

Hi, haven’t been logged on in years. TCM was replaced with the alternator, also replaced the trans fluid. Issue improved slightly, but still has some hesitation under light throttle from 2-3. It’s been like this for years now but my mom drives the car now as she only commutes down the street for work. Super late reply but I guess this is something we’ve just dealt with and haven’t had any major issues since so we just deal with the sputter.