Help. I recently replaced the battery in my truck and the new battery had the posts flipped (hot on the side where gnd use to be...). Some idiot (me) out of habit, reversed the battery cables and I fried the scanner. I've checked all the truck fuses back to the fuse block and they are good, so I don't understand why it would not have blown one of them first. Is there an internal fuse in this scanner? Is this a fixable issue or is it fried? I don't mind tearing into it as the warranty is long expired. Thanks a bunch for any insight!
BCD396T/BC996T: Dead BCD996T from reverse polarity
- Thread starter bfolk
- Start date
tvengr
Well Known Member
Does your scanner power cable have a fuse? Is it blown? Some scanners have a reverse polarity protection diode which will blow the cable fuse if polarity is incorrect. It should have a 2-amp fuse. If you are using the cigarette lighter adapter, there should be a fuse inside the plug.
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If it made to the polarity diode inside the scanner , you can try clipping the diode and it should power on , but you'll need to replace the diode.
Ubbe
Member
The newer BCT15x uses diodes in series that stop any wrong polarity voltage reaching its circuits but older scanners could use a diode to ground that shortcircuit any wrong polarity, and there's also a zener diode in BCT15x that shortcircuit at 18V but then a fuse that powers the scanner should have blown. Perhaps the fuse in the truck have a too high rating like 15A or 20A then the diod burns up and then probably also the copper foil on the circuit board to it. There's no fuse inside the scanner. There's always a coil at the DC input and can sit before or after the diod so that could act as a fuse if the wire used are thin enough.
You have to open up the scanner and look at the components closest to the DC jack and do resistance measurements of the DC input to ground and check the coils input to output resistance, its usually a big component and perhaps have shrink tubing over it.
/Ubbe
You have to open up the scanner and look at the components closest to the DC jack and do resistance measurements of the DC input to ground and check the coils input to output resistance, its usually a big component and perhaps have shrink tubing over it.
/Ubbe
Obviously, you learned your lesson. Depending on the year of your truck, if you never turned the ignition on, no fuses would have been blown on the truck. If the 996 was hard wired to the battery (such as a cigarette lighter lead or directly to the battery you'd have blown a fuse or reverse polarity protector diode or worse in the 996.
Unless you let the blue smoke out of the 996, it believe it should be fixable.
Unless you let the blue smoke out of the 996, it believe it should be fixable.
freqseeker
Member
You're lucky if the scanner was the only casualty! Reverse polarity and cross jumps can fry a lot of modules in modern vehicles.
