Hello folks, I finished making my 1 transistor circuit tonight and hooked it up to my car, then the problems, I have an 87 IROC with 305, I put the 10K between A and B and nothing happened, when I did this the circuit would not send data to the laptop, I have a green LED wired in to the data stream to show me when data is sent, with the resistor the led stays on constantly VERY dim, without the resistor it is nice and strong and blinks when data is sent, the software also tells me it's recieving data without the A and B jumped, but it can't link. says Chksum 0/64. Any ideas? The interface I"m using comes from here and I'm using a General Purpose Switching circuit/amplifier circuit transistor (2N4401). this is the circuit I built.




Should I be using a 2 transistor interface?
Thanks In Advance


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1987 IROC-Z T-Tops wait... GUTTED MAF!

I have a 7747 ecm and I don't use the 10K resistor between A and B. Of course, my situation is a little different.

I too have an LED an it flickers brightly like you described. I used the same diagram but used a 2N2222A transistor. I don't know if there's any difference.
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'92 Astro, GM crate 350, Performer TBI intake, MSD 6AL, 3.42's, 2.5" exhaust, Flowmaster 40 2 chamber, B&M 2nd stage shift kit, 255 60 R15 tires on AR-727's, Polished & Bored TBI, Custom EPROM in progress

[This message has been edited by V8Astro Captain (edited October 14, 2001).]