Bits Of C4 Corvette Info




To recover ECM codes from the 1984 through 1993 Corvette, place a jumper (paper clip works fine) as shown below between pins "A" and "B" on the ALDL (Assembly Line Diagnostic Link) connector. This connector is located under the dash just to the right of the steering column and has space for 12 pins although not all of the cavities will be populated.
84_93_code_display.JPG


Turn the ignition switch to "On" but do not start the engine.
Depending on the model year, either the "Check Engine Light" or the "Service Engine Soon" will begin to flash.

As the code display sequence begins, you will see a flash followed by a pause and then two flashes. This is the indication for the number "12". The number 12 is a delimiter intended to show where the ECM code display starts and stops.

Code 12 will flash three times and then any stored codes will flash. When all codes have been displayed or if there are no stored codes, the number 12 will again flash three times.


So my interpretation of what you provided is:
#1: DTC 33, MAF is not connected to the ECM (corroded pin/use electrical cleaner), or trace for a bad wire).
#2: DTC 36, Mass Airflow Burn Off Circuit (common issue)

Fix the MAF and verify by disconnecting the battery+ 20 seconds. IGN ON/RUN-IGN OFF. IGN/ON, no START. Once Code 33 is not thrown, and if 36 is still showing:

1. Repair broken wiring
2. Replaced relays
3. Replaced MAF
4. Replaced ECM

After RUN...then IGN OFF, the MAF burnoff RELAY applies 12V to the MAF sensor wire (glows red to burn off deposits) During a very short cycle the ECM (in closed loop mode) reads the MAF output voltage values and resets the IAC. A read outside the values sets code 36, and burnoff will not occur. Then the MAF output can deteriorate (Code33) and affect performance.

I suggest you first scan and post the P Code(s) for proper repair sequence. If you have the ability, another first step is to make sure the MAF output voltage values (for your specific year), are within limits. Last resort is to shotgun #'s 1-4 above. There is a replacement ECM that may solve your problem (1227165 added a jumper for a second MAP input).
 
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yeah its going to require work,
yes its going to require you to learn how to do all the minor repairs and buying a SHOP manual and a few tools is mandatory unless,
you have an unlimited checking account
balance

 
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