First let me say my journey trying to fix the Blind Spot Monitor (BSM) was educational.
I bought this 2015 LR4 with full disclosure that the Blind Spot Monitor (BSM) did not work. Looking through history of repairs, the previous owner reported problems with the BSM in 2020. The cost to diagnose and potentially fix the problem was thousands of dollars. He decided not to have it fixed but he did mechanically maintain the vehicle with receipts to prove it. The front cameras failed soon after.
Fast forward to 2025. Using an OBD II tool I had, the error codes indicated a faulty right side BSM ECU. The cost of a new module was around $1,200. eBay cost for a used one was $84. I bought 2. I took the rear bumper off.
Before taking off the rear bumper make sure you have replacement fasteners on hand. Especially for the wheel arches.
Here’s what I bought on Amazon $10.92
GOOACC - GRC-33 240PCS Bumper Retainer Clips Car Plastic Rivets Fasteners Push Retainer Kit Most Popular Sizes Auto Push Pin Rivets Set -Door Trim Panel Fender Clips for GM Ford Toyota Honda Chrysler
Rexka 20pcs Wheel Flare Moulding Clips DYC101420 Compatible with Land Rover Freelander Ranger Rover LR3 LR4 $8.99
Installed the eBay replacement module on the right side and it didn’t work. I bought the GAP IID tool and it did not detect the right side BSM. It did show the left side module was fine.
What I hadn’t realized is that the BSM ECU’s are flashed at the factory as right or left. I unfortunately purchased 2 left side BSM’s on eBay (they don’t specify which side they came off the donor vehicle).
When I swapped the original right side BSM, which was working, with the old left side BSM it was detected by the GAP IID tool. So, I knew that original right module was bad. But then I thought perhaps the mirror glass display LED’s were bad as well so I purchased an aftermarket mirror glass. But that didn’t work. I’ll get back to the aftermarket mirror glass a bit later.
I emailed the folks at GAP IID and they told me the module had to be flashed from a Side Object Detection Left (SODL) to a SODR. They sent me a series of flashes for the module which resulted in it becoming a right-side module. But it still didn’t light up the mirror glass led’s. I kept the original mirror glass so I thought why not try it out. It worked! The aftermarket led’s were not recognized by the BSM. Not sure why yet.
Flashing a module requires caution. The battery voltage has to be above 12.7. The only way to maintain this level is a power supply that is designed to flash modules. These power supplies are relatively expensive. I bought this one:
AUTOOL Flash Reprogramming Power Supply 120 Amp, Car Battery Charger with Battery Repair Mode, Flash Reprogrammer & Adjustable Power Supply w/ 6.5ft Cables, HD Display
$389.99
I plan to do some of my own programming on this vehicle so I will get some continued use of it.
Let me say that the folks at GAP IID were outstanding!! I received one updated flash after 9 PM one evening. After a few flash attempts the module appeared in the tool.
The Blind Spot Monitor now works!
I now better understand how these ECU’s function. There are 31 on my vehicle. I can now take off the rear bumper in about 10 minutes.
I learned how the Car Configuration File (CCF) works after making some changes using the GAP IID tool. I learned that there are 3 copies of the CCF stored in 3 different modules on the vehicle for redundancy.
Another thing I learned. I asked ChatGPT to help me with this problem. At one point it told me the way the BSM module determined what side of the car it was on was it used the Led’s in the mirrors. It used the Led’s in the right mirror to determine if the module was on the right side of the vehicle.
This made some sense to me because when I looked at the wiring diagrams, the modules are directly connected to their respective left and right side led’s. But obviously that was wrong. ChatGPT also told me the GAP IID tool couldn’t be used to flash the BSM module! Ha! Wrong again!
I use ChatGPT for a number of things but this is another example of how it can steer you wrong. ChatGPT answers are plausible banality. Answers that are plausible but not verified. Sometimes it responds with hallucinations, sometimes folklore, sometimes correct. But how can you trust the response? Beware of those machines offering advice! They don’t care if they give you the wrong answer. In fact they always provide an answer. They never say, “sorry I don’t have an answer to that”, unless you want to build a bomb.
Now onto my Park Assist problem!
I bought this 2015 LR4 with full disclosure that the Blind Spot Monitor (BSM) did not work. Looking through history of repairs, the previous owner reported problems with the BSM in 2020. The cost to diagnose and potentially fix the problem was thousands of dollars. He decided not to have it fixed but he did mechanically maintain the vehicle with receipts to prove it. The front cameras failed soon after.
Fast forward to 2025. Using an OBD II tool I had, the error codes indicated a faulty right side BSM ECU. The cost of a new module was around $1,200. eBay cost for a used one was $84. I bought 2. I took the rear bumper off.
Before taking off the rear bumper make sure you have replacement fasteners on hand. Especially for the wheel arches.
Here’s what I bought on Amazon $10.92
GOOACC - GRC-33 240PCS Bumper Retainer Clips Car Plastic Rivets Fasteners Push Retainer Kit Most Popular Sizes Auto Push Pin Rivets Set -Door Trim Panel Fender Clips for GM Ford Toyota Honda Chrysler
Rexka 20pcs Wheel Flare Moulding Clips DYC101420 Compatible with Land Rover Freelander Ranger Rover LR3 LR4 $8.99
Installed the eBay replacement module on the right side and it didn’t work. I bought the GAP IID tool and it did not detect the right side BSM. It did show the left side module was fine.
What I hadn’t realized is that the BSM ECU’s are flashed at the factory as right or left. I unfortunately purchased 2 left side BSM’s on eBay (they don’t specify which side they came off the donor vehicle).
When I swapped the original right side BSM, which was working, with the old left side BSM it was detected by the GAP IID tool. So, I knew that original right module was bad. But then I thought perhaps the mirror glass display LED’s were bad as well so I purchased an aftermarket mirror glass. But that didn’t work. I’ll get back to the aftermarket mirror glass a bit later.
I emailed the folks at GAP IID and they told me the module had to be flashed from a Side Object Detection Left (SODL) to a SODR. They sent me a series of flashes for the module which resulted in it becoming a right-side module. But it still didn’t light up the mirror glass led’s. I kept the original mirror glass so I thought why not try it out. It worked! The aftermarket led’s were not recognized by the BSM. Not sure why yet.
Flashing a module requires caution. The battery voltage has to be above 12.7. The only way to maintain this level is a power supply that is designed to flash modules. These power supplies are relatively expensive. I bought this one:
AUTOOL Flash Reprogramming Power Supply 120 Amp, Car Battery Charger with Battery Repair Mode, Flash Reprogrammer & Adjustable Power Supply w/ 6.5ft Cables, HD Display
$389.99
I plan to do some of my own programming on this vehicle so I will get some continued use of it.
Let me say that the folks at GAP IID were outstanding!! I received one updated flash after 9 PM one evening. After a few flash attempts the module appeared in the tool.
The Blind Spot Monitor now works!
I now better understand how these ECU’s function. There are 31 on my vehicle. I can now take off the rear bumper in about 10 minutes.
I learned how the Car Configuration File (CCF) works after making some changes using the GAP IID tool. I learned that there are 3 copies of the CCF stored in 3 different modules on the vehicle for redundancy.
Another thing I learned. I asked ChatGPT to help me with this problem. At one point it told me the way the BSM module determined what side of the car it was on was it used the Led’s in the mirrors. It used the Led’s in the right mirror to determine if the module was on the right side of the vehicle.
This made some sense to me because when I looked at the wiring diagrams, the modules are directly connected to their respective left and right side led’s. But obviously that was wrong. ChatGPT also told me the GAP IID tool couldn’t be used to flash the BSM module! Ha! Wrong again!
I use ChatGPT for a number of things but this is another example of how it can steer you wrong. ChatGPT answers are plausible banality. Answers that are plausible but not verified. Sometimes it responds with hallucinations, sometimes folklore, sometimes correct. But how can you trust the response? Beware of those machines offering advice! They don’t care if they give you the wrong answer. In fact they always provide an answer. They never say, “sorry I don’t have an answer to that”, unless you want to build a bomb.
Now onto my Park Assist problem!
