Built the one transistor winaldl cable twice, using completely new componets each time. Both times no data was transfered. I tried using the serial 12 volts on each, and a external 12 volts on each.
I have an associates in electronics engineering, so my ability to build a cable should not be in question.

Laptop:
The laptop I used was a IBM Thinkpad PII 300 Mhz. The laptop has com ports 2 and 3 free. I tried both.

Transistor:
I used a 2N2222A transistor in both cases.

Resistors:
I used 10K ohm resistors. They were 1/4 watt and 5% tolerance. I tried using a resistor on the cars aldl connector. This only led to high idle with no data transfer.

Cable: 3 foot long.

Car: 91 RS 305 TBI Automatic

I checked each cable 4-5 times. I even broke out my fluke multimeter and checked all the connections. I am clueless to why my car won't transmit data.

 

check that the com port on the computer works...

try plugging in a old mouse or some other serial device and see if the computer can see that.... it may be a prob with the com port.

only other thing i could suggest would be to look at the serial output on a scope or somthing and see if its putting out data..

 

also try setting the speed of the COM port to the speed of the stream.

if i remember, there are two possible data channels on an ALDL, 160 bits/sec and 8192 bits/sec. make sure you're using the right one for your car.

 

I have done both, no dice.

Wondering if someone cut the wire to the data terminal...

 

I know you said you have an associates in electronics engineering, but are you sure the transistor is in correctly? Thats about the most common problem people have with the home made cables...components installed incorrectly.

 

I thought the one transistor interface only suited the 160 baud ALDL (that's what my '808 uses). Are you sure you don't need the 2 transistor interface?

Have you check the output of the transistor with the car running to see if you're getting data onto it?

John

 

I thought the one transistor interface only suited the 160 baud ALDL (that's what my '808 uses). Are you sure you don't need the 2 transistor interface?

What ECM do you have?

Have you check the output of the transistor with the car running to see if you're getting data onto it?


John

 

The one transistor job is working on my 165 (TPI) ECM.
I was powering the laptop directly from the cigarette lighter and had some intermittent data x-fer issues. Plugged a small inverter into the cigarette lighter and used the wall-wort. Works perfectly that way.
If the idle is coming up, that means the 10Kohm state has been entered. I had to disconnect the IAC when driving with the laptop connected and logging.

May want to ohm-out the data wire from the ALDL to the ECM connector.

 

The cable is correct, been over it many times.

My car is 160 baud. I have TBI.

The cars cable checks out. Looks to be my laptop...

Thanks everyone.

 

Try using 110 power for the laptop, I and others had troubles using the battery in the laptop to power the cable and laptop, you either get a partial data stream or no data stream.