Classic FAST Diag Codes

[RonRed89]

All,

Trying to diagnose some interesting behavior when cold starting my '89 Vette with a FAST Classic B2B. Car is randomly not starting up while cold, but acts completely normally if it gets warm. We're checking a number of things including the FP, IAC, TPS, Injectors and haven't found anything meaningful yet. This tune as it sits has been running on the car for a number of years without issue.

I am seeing something in the dash that I wanted to ask about which is related to DIAG codes on the ECU itself. Does anyone have a table of these codes (DIAG A, DIAG B). If the ECU is trying to point us towards the problem with these codes, it'd be helpful to know.

Right now, DIAG A = 755 and DIAG B = 0.

Anyone know what this means?

Thank you,

Ron

 

[HighPSI]

The codes are probably useless. As the firmware changed over the years, code numbers would show up that were meaningless

 

[RonRed89]

Thank you, Cal. I think we have narrowed the problem down to either an IAC issue or a possible failed sideband O2. I'm going to post up about it shortly.