I'm still new to this, so forgive me if some of the questions are dumb. I have an ALDL to serial adapter, which I'm trying to get to work with a USB to serial cable (laptop doesn't have serial), and WinALDL. No matter what com port I set the "virtual" serial port to use, WinALDL won't connect. I've read about people having problems with certain USB to serial adapters, and I was curious if anyone can suggest one. I'm not yet too interested in doing any changes to the PROM, I'm trying to view the sensor readings to get the car running better. Also, I'm a little confused as to which pin I should connect the adapter to. The ALDL pinouts I've looked at show pin "E" as 160 baud data, and pin "M" as 8192 baud data. WinALDL says it's a 160 baud reader, so I assumed pin "E". However, when I was looking over the wiring diagram for my car, it shows that both pins "E" and "M" are actually the same circuit going to the ECM. I assume my car is only 160 baud then? Lastly, remember reading that on MAF TPI cars, you have to jumper pins A and B with a 10K resistor, to get the ECM to start transmitting data. Is this also correct?

Edit, forgot to mention, engine is an 88 305TPI, MAF, 1227165 ECM.

 

You are correct about pins E & M being the same on that vehicle. Try the 10K between A & B. I know it is required for 8192 baud ALDL, but it may also be required for the 160 baud ALDL. You may want to try a different logger. WinALDL will only work at 160 baud which is mostly worthless. That ECM will also connect at 8192 baud which makes datalogging worthwhile.

Oh, with WinALDL try both 2400 and 4800 baud for connecting at 160. Sometimes one speed works while the other doesn't.

RBob.

 

Thanks for the info, RBob. I'm having some ECM troubles at the moment, and all of the 5 volt ECM stuff (including aldl diag ports) are dead. However, can I test my ALDL cable on my truck? It's a 1995 Chevy pickup, with a 350TBI in it. Some of the pages I've come across list it as 8192 baud only, yet it's on the "supported vehicles" list on the WinALDL site. Is there any harm in trying it?

 

If your ALDL cable supports 2-way communications you could test it on the truck. However, WinALDL won't work on the truck. As you found it is 8192 baud only. The '7165 ECMs are unreliable, if you can find a couple in a JY it is probably worth grabbing them.

RBob.