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Computer Codes

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Before you can look up your trouble code you have to get the code from your car's computer. This is a very easy operation that doesn't require any expensive tools, all you need is a small piece of wire stripped on both ends. Then, with the car off, you take the wire and you plug into slots A and B in your ADL connecter. The connector should be located under your steering column. To find the A and B connecters is easy, just look the only
group of to clips in a corner. Keep in mind that you are looking for slots that have metal clips on the inside! Then, after you have the wire hook up, turn the key over to the run position, don't start the car! If you picked the right connectors, your fan will start and your check engine light will start to flash. If your fan does not start but your check engine light does flash, then you have a bad fan and you need to get that replaced or you risk overheating in stop and go traffic.

With the check engine light flashing, you need to count how many times it flashes in succession. The first code you will always get (unless you have a bad computer, then that's the cause of your problems) is a code twelve. For this code, the light will flash once, then pause for awhile and then flash twice. Then it will pause for a longer period of time than was between the 1 and the 2. It will repeat all codes 3 times so you will be sure
to have it right. Then it will move on to the next code stored into memory. If you keep getting a code 12, then the system doesn't have any codes stored. If this condition exists but you get a check engine light when you drive, you may need to bring your car in for a more detailed analysis.

With the information that you gain from this chart, you can greatly help out the mechanic and some times save your self from getting ripped off.
Also, it can help you identify a problem that is easy to fix such as a bad oxygen sensor that you can replace yourself!

 

 

12 No reference pulses to the ECM. This is not stored in the memory and will only flash when the fault is present (not to be confused with the code 12 discussed earlier)
13 Oxygen sensor circuit. The engine must run for at least 5 min. before this code will set
14 Shorted coolant sensor circuit. The engine must run for at least 2 min. for this code to set
15 Open coolant sensor circuit. The engine must run fat least 5 min. for this code to set.
21 Throttle position sensor circuit. The engine must run up to 25 sec. below 800 rpm, before this code will set.
22 Throttle position sensor (voltage low)
23 Intake air temp. sensor (high)
24 Vehicle Speed Sensor (VSS) circuit. The engine must run for at least 5 min. at road speed for this code to set.
25 Intake air temp. (low)
32 EGR system (1990-91)
32 Altitude Compensator circuit
33 MAP sensor
34 Vacuum sensor circuit. Then engine must run for at least 5 min. below 800 rpm for this code to set
35 Idle speed control switch circuit shorted. Over 1/2 throttle for at least 2 sec.
41 No distributor reference pulses to the ECM at specified engine vacuum. This code will store in memory
42 Electronic Spark Timing (EST) bypass circuit grounded
44 Lean oxygen sensor indication. The engine must run at lest 5 min in closed loop at part throttle and road load for this code to
set.
45 Rich system indication. The engine must run at least 5 min in closed loop at part throttle and road load for this code to set.
44&45  (at same time) Faulty oxygen sensor circuit
51 Faulty calibration unit (PROM) or installation. It takes 30 sec. for this code to set.
54 Shorted M/C solenoid circuit and/or faulty ECM
55 Grounded Vref (terminal 21, faulty oxygen sensor or ECM