GM Service Manual Online
For 1990-2009 cars only

DTC

Description

12

DTC 12 Diagnostic System Check

21/31

DTC 21/31 Courtesy Lamps Feed Shorted to Ground

22/32

DTC 22/32 Courtesy Lamps Return Shorted to Battery

23/33

DTC 23/33 RAP Feed Shorted to Ground or Battery

24/34

DTC 24/34 Seatbelt Indicator Shorted to Ground or Battery

25/35

DTC 25/35 Security Indicator Status

41

DTC 41 Last Message Received Valid

42

DTC 42 Last Message Received Invalid

43

DTC 43 Last Message Received with Sumcheck Error

44

DTC 44 Last Message Received with Encryption Error

45

DTC 45 Receiver Processing in 20 Second Lockout

55

DTC 55 Begin Configuration Display