Renault Master key issues, faulty coil - immobilizer light blinking fast

[txuko]

Hi, I have had my van parked for a long while and when I tried to start it I found that immobilizer light was blinking fast which means it's not detecting my key. I replaced batteries etc without any luck until I poked with the multimeter and found that the coil somehow was gone, no resistance across it. Ordered a replacement key from Aliexpress just in case, but first I tried replacing the coil with a similar one; original was 14.5mm by 4.5mm but I could only find replacements for they keys aliexpress sells which are slightly smaller so had to add a short wire to the pad, shitty job but it should do the trick.

In any case, the immobilizer is still not detecting the key so I am wondering what I should do now, would it work if I replace the IC that contains the encrypted key between the key fobs?
https://i.ibb.co/QY22Zj9/IMG-20240601-115026-1.jpg


unfortunately I don't have specific car tools but I tried to use an rfid reader and I could see some data using psk but I am going to guess it's encrypted. The new key on the left seems to have some connection points, Is there otherwise a way of dumping the IC using common electronics tools/protocols like SPI, I2C, etc ? I can't seem to find much info on the datasheets for those parts.

Thanks for your help
Best regards
https://ibb.co/c2GGPXJ
https://ibb.co/c2GGPXJ

[askkey]

Hi, I have had my van parked for a long while and when I tried to start it I found that immobilizer light was blinking fast which means it's not detecting my key. I replaced batteries etc without any luck until I poked with the multimeter and found that the coil somehow was gone, no resistance across it. Ordered a replacement key from Aliexpress just in case, but first I tried replacing the coil with a similar one; original was 14.5mm by 4.5mm but I could only find replacements for they keys aliexpress sells which are slightly smaller so had to add a short wire to the pad, shitty job but it should do the trick.

In any case, the immobilizer is still not detecting the key so I am wondering what I should do now, would it work if I replace the IC that contains the encrypted key between the key fobs?
https://i.ibb.co/QY22Zj9/IMG-20240601-115026-1.jpg


unfortunately I don't have specific car tools but I tried to use an rfid reader and I could see some data using psk but I am going to guess it's encrypted. The new key on the left seems to have some connection points, Is there otherwise a way of dumping the IC using common electronics tools/protocols like SPI, I2C, etc ? I can't seem to find much info on the datasheets for those parts.

Thanks for your help
Best regards
https://ibb.co/c2GGPXJ
https://ibb.co/c2GGPXJ

Your original key is like Clio MK1 key with Philips Crypto 1st gen transponder (HITAG 1). What you ordered from aliexpress is a key with an NXP 26 type transponder that is set to emulate an ID46 PCF7946 (HITAG 2) transponder precoded for a Clio MK2 (most likely). So neither will you be able to program it to the car, nor will you be able to use the coil of that PCB on your original key as the induction value is different. The 1st gen transponders use quite a unique coil so you will have a lot of trouble in finding one with the correct value. So swapping the IC won't work as well because the issue with the coil would still remain. Also you won't be able to transplant an original coil from a different working key as the 1st gen coils are glued to the PCB so they are nearly impossible to remove in working condition.

The good news is that the data is not encrypted in any way, so a competent locksmith with the right tools should be able to read the tranponder data from your keys and write them to a separate ID13 transponder which will be able to start the car when placed in the key shell once the faulty coil is removed (that is how I do it when one is brought to my workshop).

[txuko]

Thank you so much for the detailed response, really appreciate it. I will try to find someone who can do that for me :five:

[kemaster]

Your original key is like Clio MK1 key with Philips Crypto 1st gen transponder (HITAG 1). What you ordered from aliexpress is a key with an NXP 26 type transponder that is set to emulate an ID46 PCF7946 (HITAG 2) transponder precoded for a Clio MK2 (most likely). So neither will you be able to program it to the car, nor will you be able to use the coil of that PCB on your original key as the induction value is different. The 1st gen transponders use quite a unique coil so you will have a lot of trouble in finding one with the correct value. So swapping the IC won't work as well because the issue with the coil would still remain. Also you won't be able to transplant an original coil from a different working key as the 1st gen coils are glued to the PCB so they are nearly impossible to remove in working condition.

The good news is that the data is not encrypted in any way, so a competent locksmith with the right tools should be able to read the tranponder data from your keys and write them to a separate ID13 transponder which will be able to start the car when placed in the key shell once the faulty coil is removed (that is how I do it when one is brought to my workshop).

Just for the record. His original chip is Atmel U9280M, not hitag1. And using id13(megamos) is not the correct one.

[askkey]

Just for the record. His original chip is Atmel U9280M, not hitag1. And using id13(megamos) is not the correct one.

Well, if I program the data read to a Sokymat T5Nova emulating an ID13 it starts the car. Hitag1 is directed more to the gen of the transponder, not the manufacturer. For the older tranponders separate manufacturers didn't have their own dedicated solution so manufacturers like Philips (now NXP) and Sokymat were using the same basic solution at the time, only different fab production facilities (similar like the old x86 CPUs back in the late 70s and 80s)
I doubt he will be able to order a brand new IC for the key nowadays so the manufacturer is irrelevant. And even if he did, his issue is still in the coil.
For the record.

[txuko]

I have managed to start the van by swapping the capacitor with a 220pF part that should work with the 7.2mH coil that I bought. you were right regarding the obscure impedance, acording to the capacitor I removed from the PCB (1.86nF), the original inductor should be something around 0.87mH that I can't seem to find available anywhere.

I'll try to get somebody to make a copy now that it works in case it's not consistent. Hope it helps someone else on my situation.

[kemaster]

Well, if I program the data read to a Sokymat T5Nova emulating an ID13 it starts the car. Hitag1 is directed more to the gen of the transponder, not the manufacturer. For the older tranponders separate manufacturers didn't have their own dedicated solution so manufacturers like Philips (now NXP) and Sokymat were using the same basic solution at the time, only different fab production facilities (similar like the old x86 CPUs back in the late 70s and 80s)
I doubt he will be able to order a brand new IC for the key nowadays so the manufacturer is irrelevant. And even if he did, his issue is still in the coil.
For the record.

I also copy onto T5 or 7930/35 but don't understand what you mean emulating id13. Agree - better to consider compatibility with Philips/NXP HITAG Family than actually being part of it.

@ txuco - glad you found how to sort it out.