Hi, I lost my ALDL data connection, cannot connect at all now, was working perfectly for the longest time. Swapped ecm, did some other troubleshooting. Finally tested ground on pin A of ALDL port, getting 185k ohm between pin A and a known good ground.

Does anyone know where this ground comes from (to pin A)? I'd like to find out why I'm not getting good continuity here. Almost forgot to mention, complete continuity when key is off or backwards, but 185k ohm to ground when key on. Does this run through the ignition switch? Please help, I cannot trace the wire very far as it goes up and under or rather behind the radio pod, it seems.

Thanks,
Ben

 

You sasid ya did a ecm swap.Did you change from 165 2 730 ecm by chance?If so, the connector close to the ecm that goes to the dash harness has a different pinout.I did the 165 2 730 swap & had the same problem.I just connected the term. on dash harness side to a known good ground,& no problems since.

 

Car was originally CC Qjet, swapped to FI, '727 few years ago, I've been able to datalog for that period of time until this weekend, when it suddenly stopped being able to connect.

Anyhow, now it has good continuity to ground again, when key is on, but still not connecting...