Hur gör man för att läsa felkoder på en 90 års modell? Ansluta en pc på något sätt?
Jag är rätt nybliven ägare och har ännu ingen manual alls.
Läsa felkoder på 90års modell?
vi kan börja med detta....... 
Sooner or later, nearly every Third Generation F-Body owner will have to deal with an engine management system problem, whether their ride is carbureted or fuel injected. People may bitch about the increased complexity of these newer systems, but I look at it this way: when was the last time your pre-1980 car or truck actually told you what was wrong with itself? All of this diagnostic stuff isn't so scary once you understand how the whole thing works.
Although a scanner is the best way to perform these diagnostics (because of the far more detailed information you receive), you can retrieve codes for practically nothing - just grab a paper clip, and connect two terminals on the Assembly Line Diagnostic Link (ALDL) connector. This connector is normally located under the dashboard on the driver's side. In some cases the ALDL will be behind a small plastic panel that must be pried off. The terminals you are interested in are terminals A and B, which are the top right two terminals on the connector.
Turn the key to the "on" position (engine not running), and have a paper and pen ready to write down the codes. NEVER CRANK THE ENGINE WHILE THE JUMPER IS IN PLACE - THE ECM COULD BE FATALLY DAMAGED!! The "CHECK ENGINE" light will flash in a series of numbers, telling you whatever codes it has stored. For instance, the diagnostic always begins with a code 12. To indicate a code 12, the CHECK ENGINE light will blink once, pause for about 1 second, then blink two times. Each code (including the first one) is repeated three times before the ECM moves on to the next code. The ECM will pause about 1½ seconds between codes. All GM codes are two digits. There are additional functions served by the ALDL, but here we will only cover the stored trouble code retrieval procedure.
After the codes have been retrieved, and the problem(s) fixed, reset the ECM by disconnecting the negative battery cable for at least 10 seconds, then reconnect it. This should clear all of the codes. Also remember that some codes are the result of one-time glitches, and may not reappear. Before getting into a lot of diagnostics, it may be worth your while to reset the codes first, and then see if they reappear.
The following is a list of most of the codes that you might find while diagnosing your F-Body, and a brief explanation for each. It is certainly not a complete list of all GM codes, just the ones that apply mainly to F-Bodies, nor do they include the most detailed explanations possible. It is important to remember that a trouble code does not necessarily indicate a problem with the actual component. Many times the component will cause an error because of other problems. For instance, a bad vacuum leak could cause codes referring to either the MAP sensor or the Oxygen sensor, even if they are not actually malfunctioning. Also keep in mind that the ECM can't catch everything - a faulty TPS may not trigger a code, but can nonetheless cause many driveability problems, as well as cause trouble codes related to other sensors, but not to itself. The codes will not always indicate the exact problem, but will almost always point you in the right direction.
NOTE: Many of these code listings contain hyperlinks that will take you to a more detailed explanation of the sensor and/or system as well as more advanced diagnostic information.
Code Explanation
12 Diagnostic Mode. This should always be the first code that appears in the sequence. It does not indicate any problems, only that the ECM is now in Diagnostic mode.
13 Oxygen Sensor circuit. This code will usually be set when there is an open condition in the oxygen sensor circuit, or when oxygen sensor voltage is steady between .33-.55 volts after the engine has been running at least 2 minutes and the engine speed is above 1200 rpm.
14 Coolant Temperature Sensor (CTS) circuit shorted. This code is normally set when the sensor indicates an engine temperature of over 266º F, which would indicate a shorted sensor. Either the sensor itself has shorted internally, or the yellow CTS wire has shorted to ground.
15 Coolant Temperature Sensor (CTS) circuit open. After the engine has been running at least two minutes, if the ECM sees a voltage of greater than 4.8 volts in the yellow CTS wire, it will consider it to be an open in the CTS circuit. This usually indicates a broken wire or connection anywhere along the CTS circuit.
16 System/ECM voltage too high. Not all systems use this code. The charging system should limit the system voltage to no more than 16.0 volts. If the voltage level exceeds this value, severe damage to the entire electrical system in general, and the ECM in particular, could occur. Usually, the ECM will disable all solenoids under its control in order to protect itself from damage.
21 Throttle Position Sensor (TPS) voltage high. If the manifold vacuum is above 16.75 in/Hg, engine RPM is less than 1600 (indicating a closed throttle condition), but the TPS voltage is greater than 2.5 (indicating a wide open throttle), the ECM will set this code.
22 Throttle Position Sensor (TPS) voltage low. The ECM sets this code when either the reference voltage (gray wire) or the signal voltage (blue wire) falls to 0, indicating either an open in the wiring harness or a problem with the sensor itself.
23 Manifold Air Temperature Sensor (MAT) reading low. Set when the ECM senses a temperature of below -31º F after the engine has been running for more than 4 minutes, and the vehicle is not moving. Usually caused by either an open in the sensor itself, or an open in the harness.
24 Vehicle Speed Sensor (VSS) circuit. The ECM sees a vehicle speed reading of 0, with the following conditions present:
• Engine RPM is over 1500
• The transmission is not in park or neutral
• ECM has not previously stored codes 21,23,33,34
• TPS is less than 2% open
• These conditions have been present for over 4 seconds
25 Manifold Air Temperature Sensor (MAT) reading high. Set when the ECM senses a nearly impossible manifold air temperature of over 258º F. Usually caused by an internal short within the MAT, or a harness wire shorted somewhere.
32 EGR control failure. This is a very common code. For this code to be set, the following conditions must be present:
• TPS indicates a throttle position anywhere between idle and Wide Open Throttle (WOT)
• ECM demands greater than 48% duty cycle from EGR.
• ECM has not previously set codes 21,22,33,34
• Coolant temperature is higher than 176º F
• These conditions have been present for over 4 seconds
With these conditions met, if the ECM demands a duty cycle of less than 100% (in other words, if it commands the EGR valve to open), and it does not sense a subsequent drop in the voltage on the dark green ECM wire, it will assume an EGR failure. 2.8 V6 engines are different in that the ECM will demand an increase in the duty cycle to open the EGR, and will look for a voltage drop in the white ECM wire.
TBI equipped cars trip this code when Block Learn Cell 10 reads greater than 140, or if the difference in values between cell 10 and the closed throttle value are too great. This indicates that the Block Learn function has enriched the air/fuel mixture beyond the acceptable parameters in response to extra oxygen found in the exhaust that should have been replaced by EGR gases.
TPI equipped engines generate this code when the ECM fails to get a reading from the EGR temperature switch. This switch is located at the base of the EGR on F-Body engines, and on the EGR tube on Corvette engines.
In any case, before you get bogged down in all kinds of hair-pulling electrical gremlin hunting, check the EGR control solenoid. Some engines use a type of solenoid that has a small air filter (the filter looks like the old Q-Jet fuel filters) under a black plastic cap. If it's very dirty, replace it, and your problem might magically disappear.
33 Mass Air Flow (MAF) sensor equipped vehicles: The ECM is sensing an impossibly high airflow reading from the MAF. The MAF read an airflow of 20 gps (grams per second) either with the key on and the engine off, or the engine running less than 1300 RPM, and the TPS at less than 8% open.
Manifold Absolute Pressure (MAP) sensor equipped vehicles: MAP sensor voltage high. TPS indicates less than 2% throttle opening, but manifold vacuum is less than 8 in/Hg (A/C off) or 5 in/Hg (A/C on), indicating that the MAP thinks that manifold vacuum is low (pressure is high) - in other words, it thinks that the throttle is wide open.
34 MAP sensor voltage low: This code is essentially the opposite of code 33; the ECM is receiving signals from either the MAF or MAP that there is an extremely low amount of air flow through the manifold when every other indication is that air flow should be high.
35 Idle Speed Error: The ECM has sensed an idle speed that is ±300 RPM from the desired value. Can be caused by either a faulty Idle Air Control (IAC) motor, or by one or more of the following conditions:
• Carbon fouled IAC pintle bore (common)
• Idle mixture off
• "Hunting" idle caused by another problem
36 Mass Air Flow (MAF) sensor burnoff failure. TPI only. After vehicle shutdown, a burnoff relay is activated which heats up the MAF sensor wire in order to burn off any deposits that may have collected on it. When this occurs, the ECM will sense 12 volts in the relay ground wire. When it does not see this voltage, it assumes that the relay has failed, or there is an open in the circuit.
41 CALPAK fault. This code generally indicates a fault or failure within the CALPAK, which is the portion of the MEMCAL that contains the detailed information about the power train of the vehicle. This could also be caused by faulty CALPAK connections to the ECM, or by an ECM failure.
42 Electronic Spark Timing (EST) circuit. This code is set when the ECM does not receive any pulses from the ignition module for more than 200 milliseconds, indicating a fault either in the module itself, or a problem in the harness.
43 Detonation (Knock) sensor circuit. This code could indicate a problem with the knock sensor, the ESC module, or the harness that connects the knock sensor, ESC, and ECM. This code is set when the ECM fails to sense the signal voltage on the black ESC wire for over five seconds. The ECM also performs a knock sensor test once per startup by deliberately advancing the timing to the point where the engine has to knock. If the ECM does not receive a timing retard signal in response to this test, it will assume a failure and trip the code.
44 Oxygen sensor circuit - exhaust too lean. This code is set when the oxygen sensor output voltage is below .2 volts for longer than 60 seconds, after the engine has entered closed loop operation. Possible causes include:
• Low fuel pressure
• Plugged injectors
• Oxygen sensor wire grounded (often melted against the exhaust manifold)
• Exhaust restriction (plugged converter or muffler)
• Faulty oxygen sensor
45 Oxygen sensor circuit - exhaust too rich. This code is set when the oxygen sensor output voltage is above .7 volts for longer than 30 seconds, assuming that the TPS is not at WOT (wide open throttle). Possible causes include:
• Excessively high fuel pressure
• Worn or leaking injectors
• TPS failure
• Defective canister purge valve
• Ignition wires interfering with the sensor circuit (induced voltage)
51 MEMCAL or ECM failure. The MEMCAL supplies the ECM with information concerning the exact vehicle and engine combination, including "limp home" data.
52 CALPAK error or failure. In this case, the ECM does not recognize the correct data from the CALPAK. This code could be caused by a defective MEMCAL (the CALPAK is part of the MEMCAL), bad connections, or a faulty ECM.
53 System voltage too high. If the ECM senses a voltage greater than 17.1 volts at the ECM power supply terminal for more than 2 seconds. This voltage level will fry the ECM quite easily. The most common cause is a defective voltage regulator, or intermittent shorts in the supply wire.
54 Fuel pump voltage low. The ECM will set this code if it senses less than 2 volts being supplied to the fuel pump. Check the fuel pump relay, as well as the fuel pump harness for opens or corrosion.
55 ECM failure. Pray that you never see this code. The ECM has experienced a catastrophic failure, and it's last mortal act has been to set this code. Before installing the new ECM, try to find out what killed the old one, if anything. Improper solenoid and relay resistance values can easily damage the delicate ECM circuits.
61 Oxygen sensor performance problem. In order to function properly, the oxygen sensor must have an extremely fast reaction time - within milliseconds. Over time, or due to contamination by either leaded gas or old RTV silicone vapor, the reaction time of the sensor can deteriorate. If the ECM picks up on this sluggishness, it will set this code.
..........sen finns det scantools oxå men det bästa är om man kan koppla ihop en dator med bilen, finns elschema på min hemsida eller så har jag kablar om man inte vill bygga en själv.
Sooner or later, nearly every Third Generation F-Body owner will have to deal with an engine management system problem, whether their ride is carbureted or fuel injected. People may bitch about the increased complexity of these newer systems, but I look at it this way: when was the last time your pre-1980 car or truck actually told you what was wrong with itself? All of this diagnostic stuff isn't so scary once you understand how the whole thing works.
Although a scanner is the best way to perform these diagnostics (because of the far more detailed information you receive), you can retrieve codes for practically nothing - just grab a paper clip, and connect two terminals on the Assembly Line Diagnostic Link (ALDL) connector. This connector is normally located under the dashboard on the driver's side. In some cases the ALDL will be behind a small plastic panel that must be pried off. The terminals you are interested in are terminals A and B, which are the top right two terminals on the connector.
Turn the key to the "on" position (engine not running), and have a paper and pen ready to write down the codes. NEVER CRANK THE ENGINE WHILE THE JUMPER IS IN PLACE - THE ECM COULD BE FATALLY DAMAGED!! The "CHECK ENGINE" light will flash in a series of numbers, telling you whatever codes it has stored. For instance, the diagnostic always begins with a code 12. To indicate a code 12, the CHECK ENGINE light will blink once, pause for about 1 second, then blink two times. Each code (including the first one) is repeated three times before the ECM moves on to the next code. The ECM will pause about 1½ seconds between codes. All GM codes are two digits. There are additional functions served by the ALDL, but here we will only cover the stored trouble code retrieval procedure.
After the codes have been retrieved, and the problem(s) fixed, reset the ECM by disconnecting the negative battery cable for at least 10 seconds, then reconnect it. This should clear all of the codes. Also remember that some codes are the result of one-time glitches, and may not reappear. Before getting into a lot of diagnostics, it may be worth your while to reset the codes first, and then see if they reappear.
The following is a list of most of the codes that you might find while diagnosing your F-Body, and a brief explanation for each. It is certainly not a complete list of all GM codes, just the ones that apply mainly to F-Bodies, nor do they include the most detailed explanations possible. It is important to remember that a trouble code does not necessarily indicate a problem with the actual component. Many times the component will cause an error because of other problems. For instance, a bad vacuum leak could cause codes referring to either the MAP sensor or the Oxygen sensor, even if they are not actually malfunctioning. Also keep in mind that the ECM can't catch everything - a faulty TPS may not trigger a code, but can nonetheless cause many driveability problems, as well as cause trouble codes related to other sensors, but not to itself. The codes will not always indicate the exact problem, but will almost always point you in the right direction.
NOTE: Many of these code listings contain hyperlinks that will take you to a more detailed explanation of the sensor and/or system as well as more advanced diagnostic information.
Code Explanation
12 Diagnostic Mode. This should always be the first code that appears in the sequence. It does not indicate any problems, only that the ECM is now in Diagnostic mode.
13 Oxygen Sensor circuit. This code will usually be set when there is an open condition in the oxygen sensor circuit, or when oxygen sensor voltage is steady between .33-.55 volts after the engine has been running at least 2 minutes and the engine speed is above 1200 rpm.
14 Coolant Temperature Sensor (CTS) circuit shorted. This code is normally set when the sensor indicates an engine temperature of over 266º F, which would indicate a shorted sensor. Either the sensor itself has shorted internally, or the yellow CTS wire has shorted to ground.
15 Coolant Temperature Sensor (CTS) circuit open. After the engine has been running at least two minutes, if the ECM sees a voltage of greater than 4.8 volts in the yellow CTS wire, it will consider it to be an open in the CTS circuit. This usually indicates a broken wire or connection anywhere along the CTS circuit.
16 System/ECM voltage too high. Not all systems use this code. The charging system should limit the system voltage to no more than 16.0 volts. If the voltage level exceeds this value, severe damage to the entire electrical system in general, and the ECM in particular, could occur. Usually, the ECM will disable all solenoids under its control in order to protect itself from damage.
21 Throttle Position Sensor (TPS) voltage high. If the manifold vacuum is above 16.75 in/Hg, engine RPM is less than 1600 (indicating a closed throttle condition), but the TPS voltage is greater than 2.5 (indicating a wide open throttle), the ECM will set this code.
22 Throttle Position Sensor (TPS) voltage low. The ECM sets this code when either the reference voltage (gray wire) or the signal voltage (blue wire) falls to 0, indicating either an open in the wiring harness or a problem with the sensor itself.
23 Manifold Air Temperature Sensor (MAT) reading low. Set when the ECM senses a temperature of below -31º F after the engine has been running for more than 4 minutes, and the vehicle is not moving. Usually caused by either an open in the sensor itself, or an open in the harness.
24 Vehicle Speed Sensor (VSS) circuit. The ECM sees a vehicle speed reading of 0, with the following conditions present:
• Engine RPM is over 1500
• The transmission is not in park or neutral
• ECM has not previously stored codes 21,23,33,34
• TPS is less than 2% open
• These conditions have been present for over 4 seconds
25 Manifold Air Temperature Sensor (MAT) reading high. Set when the ECM senses a nearly impossible manifold air temperature of over 258º F. Usually caused by an internal short within the MAT, or a harness wire shorted somewhere.
32 EGR control failure. This is a very common code. For this code to be set, the following conditions must be present:
• TPS indicates a throttle position anywhere between idle and Wide Open Throttle (WOT)
• ECM demands greater than 48% duty cycle from EGR.
• ECM has not previously set codes 21,22,33,34
• Coolant temperature is higher than 176º F
• These conditions have been present for over 4 seconds
With these conditions met, if the ECM demands a duty cycle of less than 100% (in other words, if it commands the EGR valve to open), and it does not sense a subsequent drop in the voltage on the dark green ECM wire, it will assume an EGR failure. 2.8 V6 engines are different in that the ECM will demand an increase in the duty cycle to open the EGR, and will look for a voltage drop in the white ECM wire.
TBI equipped cars trip this code when Block Learn Cell 10 reads greater than 140, or if the difference in values between cell 10 and the closed throttle value are too great. This indicates that the Block Learn function has enriched the air/fuel mixture beyond the acceptable parameters in response to extra oxygen found in the exhaust that should have been replaced by EGR gases.
TPI equipped engines generate this code when the ECM fails to get a reading from the EGR temperature switch. This switch is located at the base of the EGR on F-Body engines, and on the EGR tube on Corvette engines.
In any case, before you get bogged down in all kinds of hair-pulling electrical gremlin hunting, check the EGR control solenoid. Some engines use a type of solenoid that has a small air filter (the filter looks like the old Q-Jet fuel filters) under a black plastic cap. If it's very dirty, replace it, and your problem might magically disappear.
33 Mass Air Flow (MAF) sensor equipped vehicles: The ECM is sensing an impossibly high airflow reading from the MAF. The MAF read an airflow of 20 gps (grams per second) either with the key on and the engine off, or the engine running less than 1300 RPM, and the TPS at less than 8% open.
Manifold Absolute Pressure (MAP) sensor equipped vehicles: MAP sensor voltage high. TPS indicates less than 2% throttle opening, but manifold vacuum is less than 8 in/Hg (A/C off) or 5 in/Hg (A/C on), indicating that the MAP thinks that manifold vacuum is low (pressure is high) - in other words, it thinks that the throttle is wide open.
34 MAP sensor voltage low: This code is essentially the opposite of code 33; the ECM is receiving signals from either the MAF or MAP that there is an extremely low amount of air flow through the manifold when every other indication is that air flow should be high.
35 Idle Speed Error: The ECM has sensed an idle speed that is ±300 RPM from the desired value. Can be caused by either a faulty Idle Air Control (IAC) motor, or by one or more of the following conditions:
• Carbon fouled IAC pintle bore (common)
• Idle mixture off
• "Hunting" idle caused by another problem
36 Mass Air Flow (MAF) sensor burnoff failure. TPI only. After vehicle shutdown, a burnoff relay is activated which heats up the MAF sensor wire in order to burn off any deposits that may have collected on it. When this occurs, the ECM will sense 12 volts in the relay ground wire. When it does not see this voltage, it assumes that the relay has failed, or there is an open in the circuit.
41 CALPAK fault. This code generally indicates a fault or failure within the CALPAK, which is the portion of the MEMCAL that contains the detailed information about the power train of the vehicle. This could also be caused by faulty CALPAK connections to the ECM, or by an ECM failure.
42 Electronic Spark Timing (EST) circuit. This code is set when the ECM does not receive any pulses from the ignition module for more than 200 milliseconds, indicating a fault either in the module itself, or a problem in the harness.
43 Detonation (Knock) sensor circuit. This code could indicate a problem with the knock sensor, the ESC module, or the harness that connects the knock sensor, ESC, and ECM. This code is set when the ECM fails to sense the signal voltage on the black ESC wire for over five seconds. The ECM also performs a knock sensor test once per startup by deliberately advancing the timing to the point where the engine has to knock. If the ECM does not receive a timing retard signal in response to this test, it will assume a failure and trip the code.
44 Oxygen sensor circuit - exhaust too lean. This code is set when the oxygen sensor output voltage is below .2 volts for longer than 60 seconds, after the engine has entered closed loop operation. Possible causes include:
• Low fuel pressure
• Plugged injectors
• Oxygen sensor wire grounded (often melted against the exhaust manifold)
• Exhaust restriction (plugged converter or muffler)
• Faulty oxygen sensor
45 Oxygen sensor circuit - exhaust too rich. This code is set when the oxygen sensor output voltage is above .7 volts for longer than 30 seconds, assuming that the TPS is not at WOT (wide open throttle). Possible causes include:
• Excessively high fuel pressure
• Worn or leaking injectors
• TPS failure
• Defective canister purge valve
• Ignition wires interfering with the sensor circuit (induced voltage)
51 MEMCAL or ECM failure. The MEMCAL supplies the ECM with information concerning the exact vehicle and engine combination, including "limp home" data.
52 CALPAK error or failure. In this case, the ECM does not recognize the correct data from the CALPAK. This code could be caused by a defective MEMCAL (the CALPAK is part of the MEMCAL), bad connections, or a faulty ECM.
53 System voltage too high. If the ECM senses a voltage greater than 17.1 volts at the ECM power supply terminal for more than 2 seconds. This voltage level will fry the ECM quite easily. The most common cause is a defective voltage regulator, or intermittent shorts in the supply wire.
54 Fuel pump voltage low. The ECM will set this code if it senses less than 2 volts being supplied to the fuel pump. Check the fuel pump relay, as well as the fuel pump harness for opens or corrosion.
55 ECM failure. Pray that you never see this code. The ECM has experienced a catastrophic failure, and it's last mortal act has been to set this code. Before installing the new ECM, try to find out what killed the old one, if anything. Improper solenoid and relay resistance values can easily damage the delicate ECM circuits.
61 Oxygen sensor performance problem. In order to function properly, the oxygen sensor must have an extremely fast reaction time - within milliseconds. Over time, or due to contamination by either leaded gas or old RTV silicone vapor, the reaction time of the sensor can deteriorate. If the ECM picks up on this sluggishness, it will set this code.
..........sen finns det scantools oxå men det bästa är om man kan koppla ihop en dator med bilen, finns elschema på min hemsida eller så har jag kablar om man inte vill bygga en själv.