IS 250 PCS and DRCC (Dynamic Radar Cruise Control) Retrofit

waquidvp · September 17, 2023

After seeing a few examples of folks in the community attempting to retrofit PCS (Pre Crash System) + DRCC (Dynamic Radar Cruise Control), some successful and some not, I thought I give it a go on my 2015 IS 250 base model. After figuring out all the parts required, I started on the adventure of trying to get them. Here are all the parts that are required:

Cruise Switch (84632-30020) + Wire (84633-76020) for DRCC
Steering Controls (84250-53231-C0)
Lexus Emblem for Radar (53141-48050)
Radar (88210-53140) + Bolts (3x 90119-06782)
Buzzer (86652-50010)
Network Gateway ECU (89100-30221) + Bolts (2x 90159-50327)
Driving Support ECU (88150-53052) + Wire (82143-24020) + Bolts (94151-80600)
PCS Cancel Button (84770-50010)
Engine Wire Harness with Radar Connector (82112-53340)

Most parts were available in the used market, mostly eBay. Some from within the UK and some from the US. The parts that proved to be more difficult to find were the Driving Support ECU and a matching Radar.

The Driving Support ECU part number that is required is 88150-53052, however from a quick Google search, the only place this part number appears are in parts catalog websites. Digging a bit deeper I first found it on sale in Vladivostok, on a Russian site called wiweb(blocked word). Here is the full link: https://www.wiweb(blocked word)/goods/elektronnyiy_blok_lexus_is250_8815053052_gse30_4gr_8815053052-198031S2997547103.html. I reached out to the seller however he wasn’t sure about how I would pay him and also how he would ship it to the UK with the current restrictions in place. After looking at the parts catalog, I found two other part numbers, one for an older part (88150-53051) used in a previous production batch (2013/06 - 2014/07), and one for a newer part (88150-53053) used in a later production batch (2015/08 - 2016/10). My vehicle was produced 2014/11 and the part I am looking for is from the 2014/07 - 2015/08 production batch. I thought I start looking for these parts in the hope of widening my chances, keeping in mind that these might not actually work in the end. I ended up finding these in Japan, on Yahoo auctions, and bought them through ZenMarket since Yahoo auctions is not available outside of Japan. At first, I found the newer part (88150-53053), and ordered it.

As I waited for the Driving Support ECU, I managed to get the rest of the parts. I fit the Network Gateway ECU, swapped the steering controls, changed the engine wire harness to the one with the radar connector, the radar itself, swapped the emblem in front of the radar, and finally fit both the PCS cancel button and buzzer. The only thing now remaining was the Driving Support ECU. It’s worth mentioning that the new cruise switch, even though it’s the one for using with radar, works with standard cruise control.

Once the Driving Support ECU arrived, I plugged it in and hit my first issue. I got the following DTC: C1A0A - Front Radar Sensor Region Code Mismatch. Using Techstream, I found that the Radar had the country code set to NA (for North America) and the Driving Support ECU had the country code set to JPN (for Japan). This made sense since the Radar came from the US and the ECU from Japan, so then I ordered a Radar from Japan, again through ZenMarket.

After I got the Radar from Japan and replaced the US one, through Techstream, I used the initialisation utility on the Network Gateway ECU. After clearing all the previous DTC’s, started up everything and no errors. I can now see a cruise control tab in my instrument cluster and when using the cruise switch and the distance switch on the steering, everything seems to react accordingly. When turning on the cruise switch, I can also see “Radar Ready” in the instrument cluster. I went for a test drive, got the car to around 35 MPH and set the speed. For around 1 second, I see the set cruise speed in the cruise control tab but then get an error: “Check Cruise Control System”. Using Techstream, I get the following DTC: C1A52 - Driving Support ECU Communication Abnormal. I will try to record the exact behaviour and post a video soon. My first conclusion was that maybe since it’s a newer ECU, it’s not fully compatible with the rest of the system.

After resetting all the ECU (by disconnecting the negative Battery terminal for around 5 minutes) and trying again, I get the same DTC. Currently I have few theories, but no way to test them:

Even though there is no region mismatch error being shown in Techstream, since all the other ECU’s, mainly the ECM and the multiplex ECU, in my car would be set to EU (Europe) I suspect that might still be problematic. This is hard to correct, since I can probably never get a Driving Support ECU with the correct part number and region.
Since the ECU I tried is newer than the one needed and doesn’t match the exact part number, I thought I give the older ECU a try, this was in the market at the time on ZenMarket, so I went ahead and purchased it. Unfortunately that also leads to the same DTC.

Other examples from the community:

If anyone has any ideas or thoughts about how to go forward, feel free to respond to this thread.

DTC C1A52.pdf DTC C1A0A.pdf

Linas.P · September 18, 2023

Wow... that is massive undertaking, well done on that! Can't really help you with the issue, I would suspect maybe one of the units is slightly out by one number... and even if they are correct PN they may still refuse to communicate.

I believe there should be second step of DTCs for radar in Techstrem which shows connectivity between modules, I just cant access it as my car does not have radar cruise... I would suspect something along the lines "module stopped communicating".

I was actually surprised when I discovered that wiring harness for Distance ECU is already there on my car as well. Was almost tempted to see how it would go retrofitting it.

waquidvp · September 18, 2023

It would be quite straightforward if Lexus still sold the Driving Support ECU, since this is the only part that is very specific to the vehicle, the other parts are somewhat shared with other models, however after asking multiple suppliers, it’s been discontinued by the manufacturer and no one has any old stock.

And unfortunately, from the research I have done so far, I can’t find any cars from this production batch that has the PCS & DRCC option in the UK, so chances of it turning up at the breakers is near to zero.

waquidvp · September 24, 2023

Just to update this thread, I managed to find another project that seems to be experiencing the same issue. Haven't managed to get a response on if it was resolved. See their post: https://www.clublexus.com/forums/rx-3rd-gen-2010-2015/935954-lexus-rx450h-2009-cruise-radar-retrofit.html.

waquidvp · September 24, 2023

While writing up this post, it required me to review all the work I had done so far. I found that I was using the wrong Network Gateway ECU, I thought this could be the root cause, so I got the correct part, which was 89100-30160 instead of 89100-30221 which is from a newer production batch. However after trying it out, the same issue persists.

waquidvp · September 24, 2023

Another example of a project out in the wild, this time for a CT200H. No confirmation on if it was successful or not: https://www.clublexus.com/forums/ct-200h-model-2011-2017/928713-retrofit-radar-cruise-control-2.html.

waquidvp · September 25, 2023

I managed to get in touch with the CT200H owner, looks like that was a successful project.

With regards to my status, it seems like the PCS side of things are working. Yesterday I was surprised with the "BRAKE!" warning when I came a little close to someone at the lights. So the issue seems limited to the DRCC part.

ganzoom · October 10, 2023

On 9/18/2023 at 2:07 PM, waquidvp said:

From the research I have done so far, I can’t find any cars from this production batch that has the PCS & DRCC option in the UK, so chances of it turning up at the breakers is near to zero.

We wanted DRCC on our IS300H when we ordered the car new in 2015. When the dealer checked on pre-reg stock they couldn't find a single one with that option fitted, so we had to a new order from the factory.

Good luck, the rear radar for cross traffic when parking is really useful.

SPC · March 30

With some help from this thread and EEPROM programming I was able to add DRCC and PCS to my 2014 US spec. IS350 AWD. What finally worked was pulling the Driving Support ECU & Engine Control Module and virginizing them, which caused the car to think it has a new ECM.

Process to get the DSU to allow Radar Cruise (disconnect Battery before uninstalling DSU/ECU):

1. Backup ECM and DSU EEPROMs before doing anything. See these photos of the modules: https://imgur.com/a/jU8Jtjv

2. Write the semi-virgin data to the DSU EEPROM. (93LC66 16 bit) See this original and semi-virgin example data for writing. Don't delete the Region information or Part number information. Blank out the information like the example. (Different years and models may look nothing like this). (I'm not 100% sure if this whole step needed)

3. Write all 00's to the Engine Control Module EEPROM (93LC86 16bit)

4. Reinstall virginized ECM and DSU

5. Reconnect Battery. Initiate Immobilizer/ECM learn routine. (Jump Pin 4 and 13 on the OBD2/DLC, Ignition on for 30 minute, then off and start the car

6. Write VIN using Techstream to Engine Control Module (It will show a VIN not programmed DTC). Mine still shows the DTC after writing the VIN, but the check engine light is now off. I'm guess it will disappear eventually)

7. Test DRCC. All seemed to be working well matched leading vehicle speed and braking worked well. No DTC's after 30 min of driving. Radar aiming will likely be necessary to ensure it's properly tracking vehicles in front of you. DRCC should look like this one the instrument cluster: https://imgur.com/a/InCNkBt

Notes: Be cautious with the ECM modification, there's always a chance of causing the car not to start if something goes wrong.

EEPROM Tools and Guides I used:

CH341A EEPROM Programmer I used: https://www.amazon.com/dp/B07R5LPTYM?psc=1&ref=ppx_yo2ov_dt_b_product_details
CH431A EEPROM Programmer modifications needed to support 93LCXX EEPROMSs: YouTube Instructions
EEPROM editing software I used: AsProgrammer_v2.1.0.13 (Windows driver included in the driver install folder): https://mega.nz/#!VMR0QQhL!wU4fYzCqjtHfXbD_tyOCRVnd3ahGgjprG_8RnVJ7N3o

Other good things to watch would be this YouTube video also showing modification of the programmer to work on 93LCXX EEPROMs used in Toyotas. The ECM and DSU both have a protective coating sprayed on the boards, so you may need to gently scrape the pins of the EEPROM for good contact with the programmer.

Please keep in mind that I'm not an engineer or an expert, just a hobbyist that enjoys working on cars. These modifications can have expensive/safety repercussions if something goes wrong.

waquidvp · April 28

After following the above instructions, big shout out to @SPC, it works! I also found that you don't actually need to do any modifications to the DSU, only the ECM. It just means for who ever tries to attempt this, it's one less step.

The setup I have working is with a Radar and DSU that are both Japan spec, even though my car is EU spec. I am also using a newer DSU than the one which is spec'd for the car. I am using Part No. 88150-52053 instead of 88150-52052 (which I never could find anywhere). This confirms that, you can use a Radar and DSU which is a different spec from the rest of your car, the important thing is to keep the DSU and Radar the same region. This should be helpful for anyone who is trying to get parts but can't find them in their same region. I have found some of these parts are much cheaper in the US.

I will keep testing it and report back if there are any issues or DTC's that come up, but so far it's been clean. I am also fairly certain that I need to get the radar re-calibrated/re-aimed, even though it seems to be working without it for now.

I am also planning to do a full write up for whoever want's to attempt this in the future.

ianhu · May 14

Hi Waquidvp

Read your earlier post with great interest and followed your progress. Having almost the same car I am equally instrested in adding this. I believe (but might be wrong) that the UK version of your car is the is300h which is what I have.

Being and IT techy and always tinkering with something I am keen to understand if I could do this to my car - but I have to say my starting point came about because I was looking in Comma 3 self driving which needs radar etc.

Ian

ianhu · May 14

Just now, ianhu said:

Hi Waquidvp

Read your earlier post with great interest and followed your progress. Having almost the same car I am equally instrested in adding this. I believe (but might be wrong) that the UK version of your car is the is300h which is what I have.

Being and IT techy and always tinkering with something I am keen to understand if I could do this to my car - but I have to say my starting point came about because I was looking in Comma 3 self driving which needs radar etc.

Ian

just noticed your location say Cambridgeshire so might the cars are different

waquidvp · May 14

Hey ianhu,

Yup, my car is a UK car, it's an IS250. However the DRCC/PCS systems aren't too different between them. You will roughly go through the same steps. It might even be easier to find part since the IS300h is more common in the UK, even when I was looking for parts for mine, I would come across alot of IS300h parts with very similar part numbers.

Happy to help with finding you the right part numbers etc. Would need your VIN for that, so feel free to DM that to me. I also have some left over parts which might be usable for you.

About Comma 3, I had also explored it for a while. In it's current state, I don't think it would work with our cars. You need to at least have the 2017 facelift version of the IS which has the updated safety system (Lexus Safety System+) that includes steering assist (I think the technical term is Lane Keep Assist - LKA) which Comma 3 relies on. However, if you find something else, feel free to put it on here.

ianhu · May 14

Hi.

I did have an email swap with some UK chap selling comma 3 and he even offered to 'try it's on my car if I drove to him.

"I had my Octavia retrofitted with Lane assist only to find out I didn’t need to as I could’ve reprogrammed my car!

Good luck with your car.

For me, the Comma 3 has been the best thing for long journeys making the drives less tiring."

Interesting because that's suggests it didn't use LKA. But since the Comma (from the videos I've seen) plugs into the forward facing camera for power etc it difficult to say for sure it isn't using some aspect offered by the car, besides the steering you have pointed out already.

Yes I'll DM you my Vin. I'd be interested what you have. I had a front radar never fitted but nothing else.

waquidvp · May 27

Small update on my experience so far:

TLDR; If you use JPN spec parts, mainly the DSU, your max speed will be capped at 73 MPH. If this is a problem for you, use NA (North America) or EU spec parts.

Most things have worked very well, however I noticed that the max speed you can set is capped at 73 MPH. After doing some research, this seemed to be a limit set on JDM cars due to local rules. This made sense, since the DSU that I had fitted was Japan spec. First I thought that resetting the DSU to it's virgin state would resolve the issue, however that didn't seem to fix it. What I ended up doing was writing the NA (North America) spec data onto the DSU, I got this from the screenshot posted by @SPC. I also had to swap the radar to an NA spec one, but I already had one spare from my previous attempts to get this working. Ideally, I would get EU spec parts, but I haven't found any EU spec radars on the market so I have had to result to either JPN or NA parts.

On another note: @ianhu I will get back to you with those part numbers as soon as I get some time on my hand to do the research.

ianhu · May 27

52 minutes ago, waquidvp said:

Small update on my experience so far:

TLDR; If you use JPN spec parts, mainly the DSU, your max speed will be capped at 73 MPH. If this is a problem for you, use NA (North America) or EU spec parts.

Most things have worked very well, however I noticed that the max speed you can set is capped at 73 MPH. After doing some research, this seemed to be a limit set on JDM cars due to local rules. This made sense, since the DSU that I had fitted was Japan spec. First I thought that resetting the DSU to it's virgin state would resolve the issue, however that didn't seem to fix it. What I ended up doing was writing the NA (North America) spec data onto the DSU, I got this from the screenshot posted by @SPC. I also had to swap the radar to an NA spec one, but I already had one spare from my previous attempts to get this working. Ideally, I would get EU spec parts, but I haven't found any EU spec radars on the market so I have had to result to either JPN or NA parts.

On another note: @ianhu I will get back to you with those part numbers as soon as I get some time on my hand to do the research.

I actually found a site selling most if not all the components and I put the order in. Days later they marked the radar not available, harness not available. They were about to send the rest of the part like screws and bracket etc which I promptly cancelled explaining there's little point when the main bit were all missing.

So back to square one. No parts. Apart from steering wheel with the correct buttons on.

Thanks for the help though that is much appreciated. I dm'd you my VIN

Regards

Ian

dugin · June 10

I have a 2010 USA RX450h hybrid. I also encountered error C1A40. I had to fill three eeproms with zeros - two(!) in the Power Management Control ECU (PMC) and one in the Engine ECU (ECM). Eeprom in DSU was converted using the @SPC method. After that I filled the VIN-number into the PMC using Techstream, then initiate Immobilizer/PMC learn routine and radar worked. (Part numbers: DSU 88150-48040, Radar 88210-48061, ECM 89661-48E21, PMC 89681-48052).

Then I did the same thing with the ECU from a restyled hybrid (2012-2015) from Europe and everything worked too. But the radar & DSU region remained North America. True, in this case the VIN had to be registered in the ECM. (Part numbers: DSU 88150-48040, Radar 88210-48061, ECM 89661-48G10, PMC 89681-48240).

Now the dynamic speed is set from 47 km/h and operates up to 180 km/h.
Thanks @SPC!

Dump.rar

dougaliscious · June 14

On 4/28/2024 at 9:17 PM, waquidvp said:

I will keep testing it and report back if there are any issues or DTC's that come up, but so far it's been clean.

What is the top speed of the CC? I've imported a Japanese car to the UK, and the DRCC tops out at 115km/h (which is 68mph). That is fine for the UK, but I drove in Europe last week and that makes tedious work of the 130kph sections. I would like to remove the speed restriction and I guess that it's coded into the Driving Support ECU.

Just wondering what your experience has been, considering you've also got a Japanese DSU. Thanks.

dougaliscious · June 14

Never mind - I've now read your later post about 73mph.

I will be interested to read your write-up.

waquidvp · June 17

On 6/14/2024 at 2:37 PM, dougaliscious said:

Never mind - I've now read your later post about 73mph.

I will be interested to read your write-up.

So the way I ended up solving this is by using a NA (North America) Radar and Driving Support ECU. Depending on which car you have, it might be easier to find EU parts.

dougaliscious · June 17

And with the NA radar unit, how do you find that working for you? I wonder if it's got any particular RHD programming, for example ignoring high speed differential traffic which is across the center line of the road.

waquidvp · June 17

I initially had these same concerns, but I have been running with them for a few weeks now and I haven’t noticed any difference from before.

Conrado · November 8

Hi @waquidvp, thank you for very detailed tutorial on DRCC retofit. I am trying to do retrofit in my NX200t and I also encountered C1A52 error. I already asked few local ECU tuners to help me with EEPROM but it seems that everyone in my country is doing only german cars and they either refuse or don't answer. Can you give me some tips how to open ECM/ECU without damaging it? Do I need any special tools or just sharp knife and automotive grade silicone to seal it after?