Dash lights in rain (four separate Lexus dealerships have failed to solve this)

[JPClx470]

Hi. I have an 04 LX470 with 135,000 miles. I have known this car and it has been excellently maintained. Was great til it hit 105,000 miles. Since then I've put ~15 grand into it. 9 grand since July... it's my worst nightmare. Anyhow, I have had various Lexus dealers across New England fail, after hours and hours, to diagnose this issue (or, god forbid, multiple issues...) and it is now preventing me from being able to trade it in because it's literally always happening.

So,
When I drive in the rain, my CEL and VSC lights always come on. This has been happening since 2015. They used to go off the next day (if it was a dry day). It has gotten progressively worse over the years. Now, if I drive in the rain--usually within 10 minutes on the highway--the ABS, BRAKE, and VGRS warning lights join in on the fun. It's a literal christmas tree, and now it takes a few days after for the VGRS/BRAKE/ABS lights to go off, and almost a week of dry weather for the CEL/VSCs to shut off. Nothing is actually wrong with it (well, things are always wrong with it, but I get them fixed/they're unrelated...)

I once had the codes read, and a catalytic converter situation came up. However, it wasn't real.

I've had the windshield and the windshield attachment pieces replaced, my sunroof lines cleared (like 3 times unnecessarily by adamant mechanics), and I believe one of them changed some 02 sensors.

Can someone please help me!!!???!!! I need to send "Lexi" on her way to ruin someone else's life. I am on a short break from grad school and need to get her outta here asap--I need to "fix" this problem in any way shape or form, no matter how janky. Right now I'm getting the U-joint replaced because my power steering randomly started failing, so they're gonna clear the lights. Was going to be all set to ditch her, but rain is in the forecast all week/weekend/next week. I'm totally roasted.

Is this all happening in one area? If so I'll just bring a hair dryer with me lol. I literally want to just like cover some s*** in a plastic bag to be able to roll through this Volvo dealership with the lights off so I can ditch her and get 8 grand for trade in / never look back!!! (Though I love the car in all other respects)

Or any tricks to simply reset the lights? Literally anything? Please help!

I've heard people have needed a new "sunroof gasket," but the Lexus man looked at me like I had two heads when I said that. Also the lights only come on when I'm in motion...

I've also heard that it is an 02 sensor(s), which has been fixed/replaced/handled. Also I have read that it could be a wheel bearing sensor? That seems like a trivial thing to cause 6 dash lights to come on, and one would assume at least one of these "expert" mechanics would have considered that. It hasn't been mentioned to me ever.

Also, my height control sensors all had to get replaced for the same reason ... the car randomly started dropping and lowering in the front and back (separately--so dangerous lol) while driving in the rain a few years ago. Those were replaced and that issue was resolved.

Any insight would be much appreciated! Thank you!!!

**why the frick is this quasi-landcruiser not capable of driving in casual rain... Shouldn't I be able to like ... drive through a flood? Honestly embarrassing...

 

[westwardCruiser]

I'd suggest getting a code reader or going to an auto parts store and having them read them.

The only thing I can add is that when my O2 sensors were on their way out I noticed I would go the P0420/P0430 more frequently in wet weather. FYI - there are 4 O2 sensors. A pair in the front and a pair in the rear. If these are the codes you're getting I'd suggest getting a set of rear Denso sensors off Amazon and installing them yourself. It's a trivial process. There is a whole thread on that topic as you have probably already seen.

(I replaced my front ones first, turns out the rears were the ones that were bad)

 

[JPClx470]

I'd suggest getting a code reader or going to an auto parts store and having them read them.

The only thing I can add is that when my O2 sensors were on their way out I noticed I would go the P0420/P0430 more frequently in wet weather. FYI - there are 4 O2 sensors. A pair in the front and a pair in the rear. If these are the codes you're getting I'd suggest getting a set of rear Denso sensors off Amazon and installing them yourself. It's a trivial process. There is a whole thread on that topic as you have probably already seen.

(I replaced my front ones first, turns out the rears were the ones that were bad)

Thanks! Yeah, the 02 codes have come up with the catalytic converter issues when the codes have been read while they were on due to rain. The exhaust was replaced in full last year, and I am unsure of what actually went down with the 02 sensor(s), but it's been repeatedly deemed to be some sort of "mystery water leak" with me shelling out thousands of dollars to diagnose ... multiple Lexus service departments have determined that "everything should be good." Honestly Lexus is trash now anyhow and although the car is iconic I've really just had it with them. I like your front bumper/grille guard!
I might just put a rock on the gas pedal and send it over a cliff.

 

[Octous]

Have you inspected the firewall wireharness boots for tears or other leaks? The ECU is behind the glove box on the passenger side. There is a big wire loom that goes through the fire wall there. If there is damage to that bulkhead seal, water gets in there and onto the ECU which can be no good . . . .

 

[JPClx470]

Have you inspected the firewall wireharness boots for tears or other leaks? The ECU is behind the glove box on the passenger side. There is a big wire loom that goes through the fire wall there. If there is damage to that bulkhead seal, water gets in there and onto the ECU which can be no good . . . .

Perhaps it got f***ed up permanently ... if the windshield was at any point improperly installed / the sunroof drains were at one point actually clogged? I know those are the two classic problems causing water to leak right down in there. I just don't get how multiple Lexus dealer mechanics can spend (/bill me) ten hours of "checking time" (for this one issue only) without checking all the basics... I'll ask my guy (he's my favorite ... I'm visiting my parents and he knows the car best) to look at it in the AM before he calls and tells me it's ready to get picked up. Thanks! Good to know!

 

[CorporalClegg]

Get the water hose out, start spaying isolated areas. These type issues are a huge pain to diagnosis but its seriously about the only way to sort it. If your lucky it's not just high humidity and something is actually getting wet

 

[2001LC]

Likely a short.

Most common is water leak into cabin electronics inside dash and side panels. All sorts of strange stuff can happen. Number one location for water entry is from under windshield, "if," windshield has ever been replaced.

It's rare that I find windshield properly installed. Most common, rivet holes are left open (passage for water to enter cabin) or factory holes/mounting points along roof line open. The installer either drills new holes (bad) or doesn't replace all four rivets that hold side molding or doesn't fill factory hole/mount point.

Installers also nick the paint all too often, under the rubber seal along the top roof line and along the "A" pillar. Bare metal eventually rust thru, creating a hole (passage for water to enter cabin).

You can remove inside molding and look for leak while spraying with water.

Also pull the inner molding form side molding (outside of windshield) and look for the four rivets.

One of the factory mounting holes

Unless you've a rust buck or the 04 is beat up. It's worth more than $8K.

 

[fng36]

Wheel speed sensors....

 

[2001LC]

Cracked wheel speed sensor or loose wheel bearing are possible causes.
Clues are rain, improves after time (drying), worsting duration over time and varying DTC/diagnoses. All the ear marks of water entry.

 

[JPClx470]

Likely a short.

Most common is water leak into cabin electronics inside dash and side panels. All sorts of strange stuff can happen. Number one location for water entry is from under windshield, "if," windshield has ever been replaced.

It's rare that I find windshield properly installed. Most common, rivet holes are left open (passage for water to enter cabin) or factory holes/mounting points along roof line open. The installer either drills new holes (bad) or doesn't replace all four rivets that hold side molding or doesn't fill factory hole/mount point.

Installers also nick the paint all too often, under the rubber seal along the top roof line and along the "A" pillar. Bare metal eventually rust thru, creating a hole (passage for water to enter cabin).

You can remove inside molding and look for leak while spraying with water.
View attachment 1978526
Also pull the inner molding form side molding (outside of windshield) and look for the four rivets.
View attachment 1978519

View attachment 1978524

One of the factory mounting holes
View attachment 1978529

Unless you've a rust buck or the 04 is beat up. It's worth more than $8K.

Thanks so much for these photos! The windshield has been replaced twice in the past 5 years. First one was just because it was like 10 years old, and then two years ago I accidentally cracked it with my foot (lol). I've had them take it off and check everything (at the glass place Lexus recommended) and Lexus gave me a print-out diagram with the areas all highlighted for the glass people to check. It's very cool to see for myself--I'll probably do some checking tomorrow after the rain--I'll pull it in the garage, wipe it down, and see if there's any water inside the side molding etc. Thanks a bunch.

 

[Hokie LX]

Another item to check is the sunroof seal itself may be leaking. The drains are one culprit but on my truck, the seal itself was leaking and had worn out which caused by VSC among other lights to come on during rain storms. I replaced it and no more water causing my lights to come on during rain storms. You can diagnose this when it raining by the following...

1. open the sunroof cover
2. pull the black plastic covers that form a rectangle inside the sunroof glass and cover the mounting brackets. They just pop off when you pull them.
3. If there's water/moisture in these black plastic covers, your seal is leaking.

 

[JPClx470]

Another item to check is the sunroof seal itself may be leaking. The drains are one culprit but on my truck, the seal itself was leaking and had worn out which caused by VSC among other lights to come on during rain storms. I replaced it and no more water causing my lights to come on during rain storms. You can diagnose this when it raining by the following...

1. open the sunroof cover
2. pull the black plastic covers that form a rectangle inside the sunroof glass and cover the mounting brackets. They just pop off when you pull them.
3. If there's water/moisture in these black plastic covers, your seal is leaking.

Thanks! Seems like a super simple thing to check--I'll look at that first tomorrow when I garage it after driving in the rain.

 

[kruisinkid]

roof rack bolts might be loose. water will come in over drivers door and run down A pillar and soak the junction box left of drivers left foot. have you ever noticed water on the floor mat in drivers well? look up and behind hood/gas door release and see if some metal looks rusted more than others or at all.

 

[Zero Emissions]

our Toyota sienna would have 3 lights come on during a turn and turned out being a new steering rack and the lights went away

 

[wsmiller]

I had nearly this exact same issue a few months ago. Combo meter started acting really weird one day. First the oil pressure gauge started jumping all over the place. A few days later it lit up like a christmas tree. VSC light, CEL, Airbag light. I had the windshield replaced a few months before and symptoms didn't show until it started raining on and off. Turns out the windshield was not installed correctly. I found water saturated the passenger side carpet and narrowed it down to the windshield. It had obviously been dripping on the fuse box. Had the dealer look at the windshield (which they all use 3rd party windshield guys that also don't know what they are doing) and they confirmed the leak was the windshield molding. They replaced the molding and also didn't do it right a second time ($350). The rivets must be in place to prevent the leak. This or they need to polyurethane over it to keep it from leaking again. I fixed the molding myself, I hate dealing with incompetent techs. Let the area dry out and it will not come back.

 

[JPClx470]

I had nearly this exact same issue a few months ago. Combo meter started acting really weird one day. First the oil pressure gauge started jumping all over the place. A few days later it lit up like a christmas tree. VSC light, CEL, Airbag light. I had the windshield replaced a few months before and symptoms didn't show until it started raining on and off. Turns out the windshield was not installed correctly. I found water saturated the passenger side carpet and narrowed it down to the windshield. It had obviously been dripping on the fuse box. Had the dealer look at the windshield (which they all use 3rd party windshield guys that also don't know what they are doing) and they confirmed the leak was the windshield molding. They replaced the molding and also didn't do it right a second time ($350). The rivets must be in place to prevent the leak. This or they need to polyurethane over it to keep it from leaking again. I fixed the molding myself, I hate dealing with incompetent techs. Let the area dry out and it will not come back.

I'm sure you're right. At one point the lines in the sunroof needed to be cleared, and water was dripping on the floor. Otherwise no issues with water inside. With the photos the person provided above, I'm going to take some stuff apart and check myself. The windshield people were specifically instructed by Lexus but I'm sure they just did a bad job / didn't listen. It seems like the most common thing.

 

[staggrlee]

Some suggestions to try and isolate the general trouble spot if not the root cause...

• OBD code readers are not going to tell you anything or it would already have been fixed, but you can also check the ABS/VSC "blink codes" displayed when you jumper Tc and E1 inside the terminal block under the hood on passenger side fender well. Read the cluster light blink error codes and decode using the field service manual. I'm sure the procedure is here somewhere but Search doesn't readily find it for me.
• Replace all of your fuses. Check each for corrosion, green deposits on the spade contacts. Remove and inspect relay contacts at the same time.
• Remove all your trim in your driver/passenger footwells and wait for it to happen again. Feel around fuse panels for any moisture/damp carpet. Try running a hair dryer over the panels and see if the lights go out on your next drive. Check the backs of the footwell fuse/relay panels for corrosion too by unbolting them and pulling them away from body. Leave them like that if you can, and drive it a bit to see if the issues stop.
• Remove gauge cluster and lightly coat the contacts of the multi-pin connectors with dielectric grease. Use a Q-tip and apply sparingly, you don't want to smear it all over. Do the same on the harness connectors down in the left driver's footwell. Both connectors are of a type that have a captive screw that prevents over-tightening but this can also mean intermittent contact if there's corrosion since the couplers are designed to "float" a bit.
• While you have the cluster out, replace all serviceable lamps with OE bulbs. Especially if you (or the PO) have done an LED "upgrade". Do the same in the center stack. In some cases a circuit's fault detection logic (like the CDL) factors in indicator bulbs. Resistance and impedance differences with a marginal bulb/contact or LED can be enough to set DTCs.
• Check all your main grounds for loose/corroded connections, battery/engine/chassis, footwell fuse panels etc. You're in salt road country and a little water/humidity can be enough to mean the difference between an OK ground and a bad one, and everything references ground.
• If you have an aftermarket stereo, remove it and its fuse(s). Nothing worse than dodgy tap connectors put in by idiot installers.
• Look for any sign of rodent nesting and damage to wiring by checking connectors/wires for ABS, wheel speed sensors, ABS, CDL solenoid etc. Don't ask me how I know this.

Good luck.