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OBD1 and OBD2

6K views 21 replies 3 participants last post by  Toddnos 
Toddnos said:
...the one I bought isnt virgin, and it dosent work right.
Who knows what it is chipped for........Turbo? Nitrous? who knows. Now in addition to the cost of the ecu, i have to pay for it to be re chipped.
If you open up your ECU, and look right next to the "Chip", you'll see a component marked "J1". This is a jumper to enable the "chip" section of the circuit board. If you cut this jumper, the ECU will return to stock, and ignore all the "chip" stuff on the board. In the OBD1 ECUs, when you chip them, the stock program stays on the board, and the J1 jumper enables the "chip".
 
It will cause no damage whatsoever. When the time comes to use the chip again, you just need to join the 2 ends of the wire you just cut, and put a dab of solder on it, and the chip will once again be enabled.

Depending on who did the chipping, and what parts they used, your jumper could be just a loop of wire, with or without insulation on it, or it could be a small resistor looking component with 1 black stripe on it. If its the resistor looking device, just cut at 1 end where the wire come out of it.
 
Well 7,800 could be 7,200 with a really out of whack tach. If you look at the circuit board, with the end where the connectors go in closest to you, on the left side of the board, at the end furthest from you, there is a block of plastic standing up on its edge. Its about 1" high and about 1 1/2" long. That is the PA sensor. If your ECU is chipped, the 1st component closer to you is a flat chip with 28 pins on it. If your ECU is not chipped, you'll see a white line outline of the 28 pin chip, and it will say in white characters "27C256".

If there's a chip there, just to the left of it is where J1 is supposed to be. I'll try and find a pic for you.
 
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