1990 GMC C1500 Check engine light

MNO221

MEMBER
1990 GMC C1500
V8
2WD
AUTOMATIC
255,000 MILES

My check enigne light comes on after I have driven for a while. Once I stop its goes out, when I start back up and drive for a while it comes back on. How do you do a diagnostic test on a 90 GMC P-U, or any ideals.
Lloyd.

Monday, March 23rd, 2009 AT 4:54 PM

6 Replies

RASMATAZ

MECHANIC
75,992 POSTS

The CEL coming On the computer has identifed a problem within the engine management system. You need to pull the code/s. Below is how you do it and comeback with the code/s

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Monday, March 23rd, 2009 AT 5:01 PM

MNO221

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49 POSTS

If I did it right there was three codes:

32
43
12

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-1

Monday, March 23rd, 2009 AT 5:19 PM

RASMATAZ

MECHANIC
75,992 POSTS

Diagnostic Trouble Codes - 1990
Chevrolet
13 Open Oxygen Sensor Circuit
14 Coolant Temperature Sensor (High Temp Indicated)
15 Coolant Temperature Sensor (Low Temp Indicated)
21 Throttle Position Sensor (Signal Voltage High)
22 Throttle Position Sensor (Signal Voltage Low)
23 Manifold Air Temperature (MAT) Low Temp Indicated
24 Vehicle Speed Sensor (VSS) Circuit
25 Manifold Air Temperature (MAT) High Temp Indicated
32 Exhaust Gas Recirculation (EGR) Circuit
33 Manifold Absolute Pressure Sensor Circuit (High Sig.)
34 Manifold Absolute Pressure Sensor Circuit (Low Sig.)
42 Electronic Spark Timing (EST) Circuit
43 Electronic Spark Control (ESC) Circuit
44 Oxygen Sensor Circuit (Lean Exhaust Indicated)
45 Oxygen Sensor Circuit (Rich Exhaust Indicated)
51 Faulty PROM
52 Fuel CALPAK Error or Missing
54 Fuel Pump Circuit (Low Voltage)
55 55 ECM Error

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Monday, March 23rd, 2009 AT 5:23 PM

MNO221