Cheap ebay kkl cable fix?

[Baja juan]

You know how the cheap blue "kkl cables" you buy on ebay sometimes work a few times and then die?

There seems to be two general types. Some have only a ch340 and lm339 and a led. These take power from the usb to light the led, so the led will be on if connected to usb, but not connected to car. Lets call these type 1.

Some have more advanced architecture. They have some switching transistors and a lot more "stuff" inside. In them the led is powered from the car. Lets call them type 2.

Usually you would think type 2 is better, but unfortunately type 2 cables sometimes have problems connecting to older k-line things. For example 1990s climate modules or some Seat ecus. Its not usually a problem because how often do you want to connect to a 1990s climate module? But still a problem.

Type 1 however connects to everything with no problems.

However type 1 are also the ones that work a few times and then die for no reason.

After some diagnosis i decided that its the lm339 that dies. Sure enough, if you take a dead kkl cable and change the lm339, the cable will work again! I repaired many type 1 cables like this.

Some sellers who sell "better" kkl cables say that the really cheap ones (type 1) died because they "have no regulator" or something. I just always assumed that was a chinglish mistranlstion and means nothing (like most things on ebay!) But now im thinking, maybe the lm339 does not like a car electric system? Maybe there is too much garbage when starting/running the engine etc and because the lm339s are the cheapest ones and not protected, it takes one big spike from the starter or somthing and itll kill the lm339.

Maybe its possible to protect the lm339 by clamping the connections from the car to something like 5v or 9v?

Has anybody ever tried that?