Same here. My RX TS does not interact with cruise.

 

Tried it in my RX300, turn signals do not cancel cruise control

 

Thanks everyone.
Conclusion: It is unexpected beviour [cruise cancelled by turn signal].

Seems like a wiring issue or a bad ground [suspect].

Salim

 

The hatch wiring, light bulbs, and and all socket grounds on the affected side would be a good place to start. Pull the affected side light tail light bulbs and go for short drive in order to verify. That will rule out downstream grounds. A high resistance or open light ground will feed back into other filaments. If no change, inspect the wiring where it enters the hatch. Potentially an area for flex damage.
Previously replaced tail light fixtures (and maybe headlight) and trailer wiring damage could cause same.
Any rear or front impact history, under dash repairs, aftermarket alarms are suspect.
Factory manuals '1' and '2' offer minimal hard wiring data. Found a factory Lexus electrical printed manual for $36 bucks. Figured I'd need it given time. Might offer insight onto how the the cruise and TS interacts?
Imported vehicles have stand along turn and brake light wiring. In order to minimize light bulbs and allow flat 4 trailer light wiring, a priority box is mounted in the L rear (I think) cargo compartment. Never seen or heard of one failing, but?
Pulling lights and operating the car will light the dash up with warnings, but as the bulbs are replaced, all returns to normal.
*When poking around under the dash, steering column, or front bumper area avoid molesting air bag yellow wrapped wiring and connectors unless the airbag system has been safetied

 

Update with no real update.

Checked wiring assemblies, replaced turn signal bulbs in front to see any impact.

Went to go for a test drive aaaand she turned over but wouldn’t catch unless I gave it gas, then stalled again after release.

Got in other car, bought throttle body cleaner, cleaned IACV. Starts and runs again.

And I’m done for the day. Will see if any change driving to work tomorrow.

 

Latest recommendation. (??) There appears only one location where brake and turn signals communicate. In the left rear side near the spare there's a priority box for factory, or aftermarket, trailer lights. If your RX isn't factory tow equipped, yet has a trailer connector, an aftermarket box could be anywhere inside or outside the left rear body.
Remove the two connectors, check the witing for faults, and verify that the cruise problem is resolved. For sure the trailer pigtail can be left disconnected. Probably both connectors could remain disconnected. Unless you are pulling a trailer? Still, resolution is the goal.
if that doesn't resolve, back to the tailgate and left left tail/brake/turn light grounds. A bad ground could backfeed and per the wiring diagram, there's nothing stopping a backfeed until it finds the brake switch backside.
if it isn't one of those...bummer...

 

Sometimes the cure is worse than the problem. Personally I would not loose sleep over this, unless I use cruise control most of the time.

Salim

 

I agree Salim, not worried about the loss of function, now I want to understand the relationship b/t cruise and turn signal.

So update: Switched out all four turn signal bulbs, checked wiring (no obvious issues), no change.

Facts about the car/ issue

- All bulbs work (they did before I swapped the turn signal bulbs too)
- I haven’t changed any bulbs otherwise sonce purchase in 2015
- Cruise drops out with both left and right turn signal
- No tow package or aftermarket add ons
- No battery drain issues (I would suspect (?) that a short to ground would also cause battery drain over time without running over several days). She stays parked for days at a time depending on which car I’m driving.


Can anyone think of a potential wiring interaction or common junction box b/t lights and cruise?

Any other troubleshooting steps to recommend?

 

I will check this out and update.

 

Good idea RE hazards, will check and update.

 

my 2006 RX400h does the same thing. Cruise control shuts off when turns signal is activated. 220k miles