Originally Posted by RSWORDS

When your "Check Engine" light comes on in your 92-93 truck, you can get the trouble codes of it yourself by using your ignition. Simply turn the key (without starting the truck) "on, off, on, off, on" and leave it in the on position. The codes will be displayed by the check engine light blinking. The light blinks out the first digit of the code, stops for a second, then blinks out the next digit, all the codes only have 2 digits. If the code in your truck was say code number 15, it would be displayed as one blink, a pause, then 5 blinks. If there is another code that one would be displayed after the 1st. When all the codes have been displayed code number 55 will come up. This code means all the codes have been read.

11 No Crank Speed sensor signal during cranking
12 Battery connection disturbed within the last 50 starts
15 No signal from VSS (Auto or Cruise Control equipped only)
22 Coolant temp sensor shorted or open (Auto only)
23 Air temp sensor shorted or open
24 TPS shorted or open (Auto only)
33 A/C clutch relay shorted or open
34 Cruise control shorted or open (cruise control equipped only)
41 Generator field not switching properly
42 ASD relay (charging circuit supply) shorted or open, or no ASD voltage at PCM
45 OD solenoid shorted or open (Auto only)
46 Charging system voltage too high
47 Charging system voltage too low
53 Internal PCM failure
62 same
63 same