PRE-COLLISION SYSTEM UNAVAILABLE

You’re welcome.

Like all modern cars, a Prius has several computers, called electronic control units (ECUs), each designed to perform certain functions. The radar sensor assembly is one such ECU. When a technician uses the Health Check feature of the Toyota Techstream diagnostic system to produce a report like the one you shared, Techstream communicates with each ECU in the car and asks it to report the DTCs recorded in its memory.

None of the DTCs listed in your report came from radar sensor assembly itself. This may be significant: if the radar sensor assembly’s self-monitoring feature had detected that it was malfunctioning or misaligned, it probably would have recorded DTCs C1A10, C1A11, or C1A14, none of which are in the report.

Two ECUs, the forward recognition camera (LKA/LDA and Front Recognition Camera in the report), and the driving support ECU assembly (Pre-Collision 2 in the report), recorded DTC U0235, meaning they were unable to communicate with the radar sensor assembly. These are history DTCs, indicated by an X in the Hist column, so the communication problem occurred some time in the past, but the report doesn’t tell us when or how often.

During the Health Check, Techstream was able to communicate with the radar sensor assembly, since it was able to retrieve the Calibration ID from it. This is the software version code, 8821F4702000, shown in the Calibration column, in the row for the “Front Radar Sensor” system. This proves that the radar sensor assembly wasn’t disconnected or completely dead.

FFD stands for freeze frame data. When ECUs record a DTC, they might also store some additional information about what was happening at the time; these snapshots can be useful for diagnosis. YES in the FFD column means that Freeze Frame Data were available from the ECU when the Health Check report was run.

The battery voltage was probably fine immediately after the car was parked. Remember that the auxiliary battery is always discharging, though, even when the car is off, since the ECUs and other components continue to draw current, called the parasitic load. If there weren’t any aftermarket accessories or other unusual conditions, I wouldn’t expect the battery voltage to have dropped enough after 12 days to cause trouble, but it is one possible explanation when there are several seemingly-unrelated electronic problems.

If the car has been in a body shop, it’s also possible that the DTCs are from that work. Toyota asks body shops to check for and clear DTCs (PDF), but if the shop that repaired your car was as clueless as you describe, they may not have followed this recommendation.

It’s possible. I think you’re unlikely to get a warranty repair for the radar sensor assembly with any nearby damage, no matter how it was caused, or if the car has a history of body repairs.

If you’ve tried waiting, then it’s time for proper diagnosis and repair to restore the pre-collision system, an important safety feature.

The first problem is the history of communication failures (U0235). If the DTCs weren’t cleared after the Health Check, the dealer should do this and road test the car. If U0235 or any other DTC returns, then they should follow the diagnostic procedures in the Repair Manual, starting with checks for CAN bus or wiring problems.

If the radar sensor assembly is loose, there’s no sense adjusting it if it will drift out of alignment later. Hopefully this can be fixed just by tightening bolts or screws or by replacing the bracket (88201-60010, list price $12.35), not the entire assembly (88210-07010 or 88210-47090, list price $791.20).

The next step would be to do the millimeter wave radar sensor assembly adjustment procedure, which the dealer called “calibration.” If the adjustment is successful, the problem should be fixed; if not, the radar sensor assembly may have to be replaced.

Some tips for negotiating for the repairs:

• Ask that you’ll only be charged once for the adjustment procedure, even if it fails the first time and they have to stop and replace the radar sensor assembly and adjust the new one, too.

• If you’re paying for the work, it could be done at an independent shop, if they have the necessary tools and knowledge. If you call any shops, ask if they have the “Reflector C special service tool needed to adjust the radar cruise control on a Toyota”—I’d be surprised if anyone other than a dealer says they do, but if so, it’s a very good sign they could do the job.

• If you have to buy a new radar sensor assembly, they are available from Japanese exporters (¥39,100, no U.S. warranty) and from dealers selling online ($540 or so from one near me) for much less than the list price—though it’s also reasonable for a dealer or shop to insist on furnishing the parts if they are to make a warranty for the repair. Nothing says they can’t give you a discount, though.

 

Hmmm, Glad to hear it. Mine did the same thing. It might be operating time instead of total days for a reset. It has happened to me 3 times I think, and each time it "reset" after a while.

 

Next time it happens to me, I will record miles and run time until the reset to see if there is any correlation.

 

It's the squirrel in your picture. He likes the wires in your car.
I had a "sensor dirty" message one day and the radar cruise would not work. It eventually went away.

 

I have the same problem now :/
no damage, but massages appear - precollision, LDA and DCC are unavailable.

OBD shows C1AA9 code.
did you check your with any scanner?

Hope it can goes off as in yours

 

thanks for reply.
I can see mine code is different than yours but in overall you had 10 diagnostic codes (DTC)?

so, you just did nothing apart from this whipe you mentioned earlier and it just went off?

 

DTC C1AA9 (Front Camera Module Beam Axis Not Adjusted) means there is a problem with the forward recognition camera; it’s unrelated to the millimeter wave radar, except that both are sensors used by TSS-P.

Specifically, the Repair Manual (available by subscription to techinfo.toyota.com or toyota-tech.eu) says DTC C1AA9 is stored when “2 seconds after the power switch is turned on (IG), the forward recognition camera detects that Forward Recognition Camera Learning has not been completed.”

The Repair Manual says to do the forward recognition camera learning procedure (about which I’ve written before, on April 29, April 30, and September 21), and if that doesn’t work, to replace the camera, and then to do the learning procedure with the new camera. I don’t think the code is likely to go away on its own.

 

If it's under warranty, it should be covered.

 

This is just great!
The car is out of warranty now thats why i am looking for own solutiona. Much appreciate contribution!
We talking about front camera that is in the whindshield?
I have tss-p package. Three things are unavailable - LDA, DCC and Precollision.

What might be the reason for this? I know this is quite open question, but there was a time a month ago that front bumper needed to be taken off. Can it be that somehow guys at shop moved it or touched?

Calibration now might be solution.

 

Well, I have a variant. Someone stole the Toyota logo from my Prius - God knows why, they just pried it out. Toyota said I should pay $500 to replace the radar unit - seemed a bit much. Especially since when I bought this car, I declined the multi thousand dollar PCS system, and didn't pay for it. But with the logo gone, guess what was behind it? A radar unit!
I bought a new logo (Also called the grill garnish some places) from ebay for $20. But it didn't have the tabs that fit my car, even tho it was supposed to fit my VIN #. so I broke off the tabs and glued the logo in place. Worked fine for 2 months, now the PCS light is on. Didn't come on when logo was taken, or when I replaced it.
Any thoughts on where to go? Just learning that replace is first option before calibration gives me some leverage.

 

I’d suggest checking for DTCs using a Toyota Techstream diagnostic system or equivalent. If a warning light is on, there should be one or more codes, for which you can then follow the Repair Manual troubleshooting procedures. Without this information, repairing the pre-collision system is an expensive guessing game. Indeed, the trouble this time might not be with the millimeter wave radar unit at all.

 

rent one for the weekend and take the parts you want... put your defective ones on the rental.. if they didnt see it you didnt do it.. ... now ive never done this myself but I did see it in a movie once.

 

Moved to a new house recently and it auto stops at the flowers near the drive way when backing up. My wife is happy.

That squirrel is getting fat on your Prius wires.