Ok, trying to identify what this wire does. Light tan wire on 91 tpi car. It has the 730 ecm. Thanks

 

IIRC it is in the "F" position and is the TCC solenoid monitor.
Goes to "F6" in the ECM and also to the solenoid in the trans.

 

Sorry but I had my wires crossed
The tan "might be" the ALDL "M" pin for data.
The TCC was tan with black stripe.
I only have my 90 schematic, not a 91 and my G body is slightly different.
I would confirm the colors at the ECM side pins to be sure.

 

You may be right. The car has a 1227730 ecm but was originally a tbi car. The tan wire on my aldl is on the M pin. The orange is on E pin. When i pulled the ecm to look at the harness connections, there is no tan wire anywhere near the serial data output of the ecm. There is an orange wire though. Looks like the same size orange wire that goes to the aldl connector on E. Orange wire on the ecm end goes to Ba8 on the ecm , which is correct. There is 3.63 v on that wire at the aldl side also. Still cannot data log this car though? Any ideas?

 

http://www.chevythunder.com/199092_f...227730_ecm.htm Ok, check out that link, that is the pinout for the 90-92 7730 ecm. Notice the tan wire going to the airbags that splits from the orange serial data wire. Could someone have wired this car wrong? I have a tan wire going to pin M and an orange going to pin E. I have tried connecting directly to ecm orange wire too. Datamaster stills says, your cable is working correctly but no pcm is detected. WTF??

 

Ok, found out that the tan wire in pin M is for the SIR system (airbags). Datawire. There is also a purple wire on pin K for the SIR system.