johntkha

Hello all,

My mom has a 1994 LS400 with 109,000 miles on it. The other day she was driving home from work at night and all of a sudden she lost all electrical power like if the car didn't have a battery hooked up to it. At first, the power was lost for about two seconds and then like a minute later, while the car was moving it just lost all electrical power. So she pulled over and called for a tow truck to tow it home. The next morning, the car started up and runs like normal, and it's running like normal for the last few days. Five years ago, the car had a common sputtering, rough idle, etc. problem and was fixed by sending the ECU to Auto Computer Exchange. (That place has horrible customer service by the way.) So we thought it was the ECU again, so we sent it to them for warranty and they sent it back saying nothing is wrong with the ECU. Has anyone ever had this problem where the car completely has no electrical power? Please let me know because it is dangerous for my mom to drive the car like that. Thanks.

John

LScowboyLS

well yamae and I are the ECU guys here at Club Lexus, and while sputterring, rough idle etc. can very well be failing ECU caps, however, complete loss of all electrical power is *not* an ECU issue.

complete loss of power can actually only be caused by very few things, battery connections (I know, it sounds too simple, but corrosion can be a very stealthy lady) or a critical fuse link or critical main fuse. - also a failing alternator can fail to charge the battery and then eventually the battery voltage drops below a threshold level where suddenly nothing works.

long story short, this will be a much easier problem to find than an ECU problem and other intermittent kinds of problems to locate and pinpoint, because so few causes can cause a total "blackout"

do you have the factory service manual? - or the factory wiring diagram? (very cheap on ebay)

link is to a 93 which is essentially identical to 94, and $29 is a steal for the real factory diagrams!!

the very first thing I would do in a case like this is replace the positive battery terminal, just go to any Toyota dealer (cheaper than the Lexus dealer) and pick up part number 90982-05037 (about $15)

PureDrifter

iTrader: (10)

check main cable connections, fuses, and fusible links. incl on alternator.

RA40

iTrader: (6)

Welcome to Club Lexus.

The basics first. Check the battery cables. On older cars, the corrosion migrates down through the cables so preventing this is important early on. First signs of any build-up at the terminals should be cleaned off.

In this situation, check that the battery cable insulator condition. Corrosion causes it to swell and split open. If so, there is the starting point and if caught early, you can deal with the top portions of the cable. Check the harness that connects to the engine compartment fuse box.

Legender

Cables and connection... almost the same thing happened to my dad's 93... thought it was the battery, but mechanic found corroded cables and terminals... the mechanic re-wired a new negative cable instead of buying an OEM and it's worked fine ever since. His only had 105k on it when this happened, but believe it's more the years than the miles that factors into this mostly. Good Luck...let us know what you find.

LScowboyLS

it's funny how there is often an echo in here


I don't see as how he had any choice, I know of no OEM negative battery cable available from the dealership. - The positive battery terminal is available and highly recommended, but the neither the negative battery terminal nor cable is available

johntkha

The car died again today while my cousin was driving it. Somehow he actually made it home while the car was turning on and off. It was indeed the positive battery cable. The corrosion wasn't really visible until I removed the connector and saw nothing but corrosion between the connector and the battery terminal. I cleaned and rinsed it baking soda and sprayed some battery terminal protector on it. Everything is running like normal now. Thanks everyone for your help.

LScowboyLS

I would still pick up that $15 terminal end piece at any Toyota dealer (it was used on zillions of them) if you don't want the problem to return soon.

part number 90982-05037