When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
New to LS430’s...purchased a 2003 LS430 UL with 112K on it around 01/18.
I really enjoy the car, other than a nagging parasitic drain issue.
The PO mentioned that a few days before I bought it he went out one morning to find the car had a dead battery. Thought he left something on in the car. Charged it up and no issues.
When we got it from NJ, I had the 2 year old battery checked and the tech said the battery had a bad cell (or 2).
Three weeks later the brand new battery was very dead.
Advance Auto charged it up as well as tested the alternator and starter. All were good to go.
Tested for a parasitic drain immediately after we turned car off; drain was 2.09a.
3 weeks later the battery was very dead again.
In the meantime the nav system has died. I am in the process of buying a used replacement. The shop unplugged it to see what would happen; a ABS light appeared on the dash, so they plugged it back in.
The radio now works intermittently. Sometimes no reception, other times the screen does not show the correct (or any station), other times it doesn’t work at all.
Not saying the nav/radio issue and the intermittent high parasitic drain are related.
This time 1 month has passed without a dead battery issue.
Took it to an Indie shop and battery tested fine. The parasitic drain was within normal limits.
I mentioned pulling all the fuses to the owner of the shop, but he said since there was not an abnormal parasitic drain, in his mind it didn’t make sense to.
He also mentioned the CAN BUS and said the systems don’t appear to be communicating properly.
My uncle had the same issue with is 2007 Acura RL. He took it to the dealer and after about $140, they said nothing wrong, if there is, can't find it. He took it to an indie who was methodical, and it was a faulty bluetooth module. I don't know the procedure for testing things one by one and finding the offending device, but since my uncle doesn't talk while driving, they simply unplugged it I believe, so now he has no bluetooth, but no drain. He said if he didn't drive every 2 days, his car would be dead...
The important first step is to distinguish which line is draining the current. In case of an intermittent problem, you need a patient to wait the timing of the duplication or to use an expensive current/voltage recorder with a memory function like this if you can't withstand it.
If you have a multimeter which can read down to 0.1mV, you don't need to measure the current removing any fuses, just attach test leads to those 2 metal points at top of fuses to measure the drop voltage there because fuses have some resistance. In accordance with the Ohm's law, you can check the draining current as a voltage drop of a few mV. The detail of the method is written at the LS400 FAQ page below. The post #7 explains it more.
Wild guess - it is possible that if your NAV is malfunctioning it might be the source of the parasitic drain. I am pretty sure the CAN bus on LS and SC is integrated into and runs through both the NAV and the Radio. It may not communicate properly if one or both systems are disconnected or malfunctioning.
Most cases of parasitic drain are due to added electronics - auto remote starts, alarms, amps, Bluetooth, audio adapters, radar detector power feed, dash cam feed, etc. Sometimes the current owner is unaware the item was added in the past by previous owner and also the item may have been removed at some point but some bad wiring or component remains.
Wild guess - it is possible that if your NAV is malfunctioning it might be the source of the parasitic drain. I am pretty sure the CAN bus on LS and SC is integrated into and runs through both the NAV and the Radio. It may not communicate properly if one or both systems are disconnected or malfunctioning.
Most cases of parasitic drain are due to added electronics - auto remote starts, alarms, amps, Bluetooth, audio adapters, radar detector power feed, dash cam feed, etc. Sometimes the current owner is unaware the item was added in the past by previous owner and also the item may have been removed at some point but some bad wiring or component remains.
The nav is what the shop owner suspects...had that happen to acustomers car awhile back.
Wild guess - it is possible that if your NAV is malfunctioning it might be the source of the parasitic drain. I am pretty sure the CAN bus on LS and SC is integrated into and runs through both the NAV and the Radio. It may not communicate properly if one or both systems are disconnected or malfunctioning.
Most cases of parasitic drain are due to added electronics - auto remote starts, alarms, amps, Bluetooth, audio adapters, radar detector power feed, dash cam feed, etc. Sometimes the current owner is unaware the item was added in the past by previous owner and also the item may have been removed at some point but some bad wiring or component remains.
Jabber, I thought the radio and Nav are accessories downstream of the ignition / accessory function of the column key switch? While those accessories are users of voltage, I understood that they can draw voltage only if power is allowed to them? If so, no power is directed to those units until the key is in the accessory position and a switch / ecu and/or CANBUS opens to allow current to those accessories. For example, if you leave your key in the accessory position without the engine running but leave the radio playing, obviously that draws voltage and will drain the battery. How do those accessories draw voltage without the key in the accessory position? My understanding is that there is an ecu, CANBUS or similar that acts as the main voltage switch directing/allowing voltage to those and other accessories, depending upon the key position. Of course there are other electrical features in the vehicle that are not dependent upon the key position and that ecu / CANBUS voltage switch. Example: flashers, headlights, parking lights, etc. that can draw voltage regardless of key and functioning ecu / CANBUS voltage switch. Perhaps you can confirm or clarify.
Electrical gremlins are tough to isolate and identify with so many ecu's in the vehicle. To me, it would seem that you'd want to first eliminate the possibility that something not dependent upon the key position circuit is drawing the voltage.
One way to find the parasitic drain is to utilize a "fuse buddy" pictured below with your multimeter.
As Tom57 said, you can probably skip the fuses that are only powered when the ignition is on (downstream of the red "X" in the diagram below), unless you have a stuck relay.
Test each fuse individually and record readings. The LS430 is full of automated electronics and never really shut down completely, so you will see some current flow. What you're hunting for are those higher-than-expected draws. Once you identify the fuse with excessive draw, we can help you dig a little deeper on wiring harness and/or electronics that may cause the problem.
04-18-18, 08:41 AM
Advice for intermittent battery drain?
