connect the RXD and TXD pins together (solder would be the preferred method), then connect that circuit to the ALDL pin M, then connect the ground pin on the converter board to the ground pin in the ALDL connector (pin A). I can see TP trying to initialize the hardware but always returns 'not connected'. with the Uber-easy DIY USB ALDL Cable posted: RobertISaar.

When does TP connect to hardware - bottom screen where it says hardware not connect. From what I read the 1 baud pins share the same line to the ECM, so the difference between each circuit as far as I can tell, is if you need to 'send' data. ' What I did was make the circuit without Q1,D1 and R3. However, if the faster (and bi-directional) 8192 baud ALDL data stream is to be read, then the complete circuit as shown here is required. ' Note that Q1, D1 and R3 are not necessary if only 160 baud ALDL data is to be read. I just tried a simple read-only ALDL to RS232 circuit and same thing, not connecting. I could use a diagram for a known good circuit to convert the ALDL to RS232.ДЄpplication: 1992-93 truck 2.5 L4 TBI вЂњAвЂќ е…ѓ8 So, now it seems the ALDL to RS232 circuit I made is not connecting the ECM to the Parallax converter. It passed the test so the Parallax converter is working, also tried it without the jumper wire between pins 2 and 3 and got a failed response from the cable test. Opened up TP and went into the plugin config and used the test cable option. Now he has gone away with work for a few weeks and I cannot get the cable working. I was looking at getting an ALDL cable, but a mate who is a tech head said just make one (its very easy) and got me some bits. I connected pins 2 and 3 together on the Parallax RS232 connector to create a loop back route. Been wanting to get into fault checking, data logging etc on my VS commodore V6.

Diy aldl cable