A dead battery, a leak, and CEL/4LO/VSC issue all in one week

[Undefined]

This has not been a good week.

First, the battery in the new to us 2008 LX died. Strange, considering it is only a 2 year old battery. It read 3.9 volts, so I went down to Costco and bought a new Interstate 27F. Put it in and everything seemed good...

That was last night. This morning I started up, backed down the hill of a driveway, and when I came to a stop I was greeted by a cup or so of water splashing down from the driver's side A pillar.

Figured I'd check the sunroof drain later, I kept going. Drove 30 miles to the other side of town, and as I'm pulling into a parking place the 4LO light starts flashing.

Thinking my wife might have bumped the switch when grabbing her cup, I put it in neutral and tried to engage 4LO (so I could then disengage it)...

The vehicle did not like that. You can't see it in the photo, but 4LO was still flashing.

Parked, turned it off to carry stuff inside, and noticed the fog lights stayed on. After some testing I've found that with the fog light switch turned off, the fog lights stay on with the vehicle off unless I switch the light position to a non-off position and then back to off...

Starting to think this may be why the battery was dead.

Grabbed a code reader and it showed only one code P0705.

Cleared codes and warning lamps went off. Tried to engage 4LO and all seemed good - solid 4LO light. Tried to disengage 4LO and the dash lit up like a Christmas tree again. Code reader said no codes, and turning off the vehicle and then back on again cleared the dash.

I could really use some guidance on where to begin troubleshooting this.

 

[highfructose]

I don’t have any advice to offer except that you might consider purchasing a tech stream and spending 400 or so on a full set of shop manuals.

 

[Sandroad]

I’ll guess the problems are all connected to the water leak. You’ll need to find and fix the leak and then see where the water has been running and accumulating. The water damage to electrical connectors may be inside a junction box or fuse Panel. With those thoughts, do some searching on here to find potential solutions from others.

 

[Undefined]

New symptom.

Even after getting the fog lights to turn off, they are coming back on on their own after a few minutes.

 

[Sandroad]

That new symptom indicates water damage somewhere, and not just a bad sensor related to the code. Here’s a thread on the code, but I’d fix the water issue first.

Neutral safety switch - https://forum.ih8mud.com/threads/neutral-safety-switch.1231241/#post-13470577

Edit: Has the windshield been replaced? That and the sunroof drains are the usual suspects for leaks.

 

[Undefined]

New plan....

Pulled the fuse for the fog lights so I don't need to disconnect the battery to leave it parked.

 

[Undefined]

That new symptom indicates water damage somewhere, and not just a bad sensor related to the code. Here’s a thread on the code, but I’d fix the water issue first.

Neutral safety switch - https://forum.ih8mud.com/threads/neutral-safety-switch.1231241/#post-13470577

Edit: Has the windshield been replaced? That and the sunroof drains are the usual suspects for leaks.

Windshield looks OEM and says Lexus.

 

[linuxgod]

If the fog lights are staying on, then there's something shorting the connection. Water most likely, though it's possible if it's been leaking a while there some corrosion.

I had this with some aftermarket lights and it was some water that had splashed into the relay, which I'd not mounted vertically. Swapped the relay and mounted it so water would drain out and it was fine since. However with your factory fog lights it's more likely water infiltration into the connectors inside the vehicle.

 

[Markuson]

This has not been a good week.

First, the battery in the new to us 2008 LX died. Strange, considering it is only a 2 year old battery. It read 3.9 volts, so I went down to Costco and bought a new Interstate 27F. Put it in and everything seemed good...

That was last night. This morning I started up, backed down the hill of a driveway, and when I came to a stop I was greeted by a cup or so of water splashing down from the driver's side A pillar.

Figured I'd check the sunroof drain later, I kept going. Drove 30 miles to the other side of town, and as I'm pulling into a parking place the 4LO light starts flashing.

Thinking my wife might have bumped the switch when grabbing her cup, I put it in neutral and tried to engage 4LO (so I could then disengage it)...

View attachment 2577434

The vehicle did not like that. You can't see it in the photo, but 4LO was still flashing.

Parked, turned it off to carry stuff inside, and noticed the fog lights stayed on. After some testing I've found that with the fog light switch turned off, the fog lights stay on with the vehicle off unless I switch the light position to a non-off position and then back to off...

Starting to think this may be why the battery was dead.

Grabbed a code reader and it showed only one code P0705.

Cleared codes and warning lamps went off. Tried to engage 4LO and all seemed good - solid 4LO light. Tried to disengage 4LO and the dash lit up like a Christmas tree again. Code reader said no codes, and turning off the vehicle and then back on again cleared the dash.

I could really use some guidance on where to begin troubleshooting this.

Pull out the driver door jam on floor. Look forward of it. Good chance there is water pooling there, possibly fouling several LARGE wire harnesses at floor level.

**Important that you immediately dry that out if water is there.

 

[Undefined]

Pull out the driver door jam on floor. Look forward of it. Good chance there is water pooling there, possibly fouling several LARGE wire harnesses at floor level.

**Important that you immediately dry that out if water is there.

Here?

Looks pretty wet. Hair dryer?

 

[highfructose]

New symptom.

Even after getting the fog lights to turn off, they are coming back on on their own after a few minutes.

With a shop manual you can track the wiring from the fog light to the dash and find where in between your issue lies. There will be water most likely.

 

[Undefined]

Used a hair dryer in the door jam for about 15 minutes. No more obvious signs of moisture, but fog light issue persists (reinstalled the fuse to check).

Have not rechecked going into 4LO.

Also noticed the rear driver side door auto unlock feature isn't working (when you just grab the handle to unlock).

I may end of breaking down and taking it to Lexus for them to check it out, but that won't happen until sometime next week at the earliest (and I won't be bringing in anything on a Monday morning when the techs are still hungover from superbowl parties).

 

[nwfl4runner]

I recall somewhere that there was a faulty seam seal that was causing water to get into the driver's side - I would check there as well as the sunroof drain. I think (could be wrong) it was found by removing the plastic fender liner and looking around there near where it joins the cab. Chances are the issues you're having are moisture on connectors. I'd disconnect and pull the battery, dry as much as you can, and leave it to air.

 

[Markuson]

Here?

Looks pretty wet. Hair dryer?

View attachment 2577466

Remove panel to left of driver poor well. you can then remove a couple of small screws that hold white plastic that secures large wiring harness. you can then move the harness inward a bit toward foot well and look for moisture around it. Get to metal floor level directly below a pillar. Look for standing water. Dry what you can. Run house or carpet fan on high into that space overnight.

PS. If you can, open a crack at the top of a pillar so air moved up and through.

 

[highfructose]

There is a bundle of wires that goes underneath the door jam on the drivers side...it’s the panel with the light up Lexus logo on the floor. It pops up really easily. I’d guess there’s an issue in that “vein” of wires.

if you don’t see something obvious in that vicinity and you don’t have a wiring diagram to look at, the dealer may be your best bet.

 

[highfructose]

If you’ve got the leak squared, a dehumidifer will get all the moisture out of the car if you let it run over night a couple days in a row.

gettin it all dry might solve all your problems.

 

[linuxgod]

Note btw that once you get a flashing 4Lo or CDL light, I’ve found it won’t go away unless you turn the vehicle off and back on.

 

[Sandroad]

Make a serious, extended attempt to dry it out yourself, removing whatever you need to and using guidance from @Markuson, before taking it to the dealer. A dealer working through electrical issues due to water intrusion like you have could lead to sticker shock.

 

[Markuson]

PS. Another great way to make sure you dry out the entire route between the roof and the a pillar is...

Open the sun shade on the sun roof (but NOT the glass). Point a fan directly UP from the center console arm rest... The harder the better...like a carpet/floor blower pointed up at the glass. If the footwell panel is off, this creates a stream of air moving through that entire leak path.

Leave that on over night. Does wonders.

 

[DCOVIEL]

I had the same issue in my old '11 LC. Clogged sunroof drain in the A-pillar caused fog lights to stay on. drained a battery before I finally pulled a fuse to stop it. if you search threads here you'll find other examples of this issue. I was literally at the dealer in the service lane ready to get bent over on fixing the issue when lo and behold a '14 LC had come in as a trade-in. Made a quick deal and drove off in that.