Ef að service engine ljósið er kveikt hjá ykkur þá er hérna góð leið til að komast að því hvað er að með einni bréfaklemmu 1985-1994 Full Size GM vehicle, Service Engine Soon Diagnosis.
People may think that if the Service Engine Soon lamp is glowing on their car, then that means that they must take their car in to a car dealership, or a mechanic to figure out what is wrong with it. This is not true. I will be showing you how to pull codes from the computer on your car, yourself!
The first thing you need to do, is to find the ALCL link (otherwise known as The Assembly Line Communications Link). On 1985, through 1991 GM cars, this is usually located just below the area where your radio is. It's inset from the black, sound insulation panel (above where your feet are in your car). On newer vehicles (older than 1994 though) you most likely find the connector right below the steering column!
This is what the connector looks like: Below the connector, are descriptions of what each port is used for.
A- Ground
B- Diagnostic Terminal
C- A.I.R. (if used)
D Service Engine Soon Lamp Illumination
E-Serial Data (special tool required)
F- TCC (if used)
G-Fuel Pump
Now, to pull codes from your vehicle, you will need to make a little jumper (I use a paper clip) and connect the ports A, and B. This will set the computer into a self-diagnostic cycle. You will hear the fans under the hood turn on, if you are succesful. Also, the codes that you are wanting to pull in the first place, will be flashed using the "Service Engine Soon" lamp.
The First Code that you will see, will be a code 12. This code is only to show you that you have sucessfuly sent the computer into its diagnostic cycle. The Code 12 will be repeated 3 times. after code 12 has been repeated 3 times, there will be a long pause, (approx 5 seconds) if there are any other codes, then they will be displayed. If there are not any more codes, then the computer will flash the code 12 again
Code 12
1 flash, pause, 2 flashesDiagnostic
This Code will flash whenever the diagnostic terminal is grounded with the ignition switch turned on and the engine is not running.
Code 13
1 flash, pause 3 flashesOxygen Sensor
Check the wiring and connectors from the oxygen sensor. Replace the oxygen sensor
Code 14
1 flash, pause, 4 flashesCoolant Sensor Circuit
(high temperature)
If the engine is experiencing overheating problems, have those fixed before continuing. Check all wiring and connectors associated with the coolant temperature sensor. Replace the Coolant temperature sensor.
Code 15
1 flash, pause, 5 flashesCoolant Sensor Circuit
(low temperature)
See above, then check wiring connections at the ECM
Code 16
1 flash, pause, 6 flashesSystem High Voltage
If the voltage is above 17.1 volts for more than 2 seconds, the Service Engine Soon light will illuminate. Have the charging system checked
Code 21
2 flashes, pause, 1 flashThrottle Position Sensor
Check for a sticking, or mis-adjusted throttle position sensor
Code 22
2 flashes, pause, 2 flashesThrottle Position Sensor
check TPS adjustment. Replace the TPS sensor
Code 23
2 flashes, pause, 3 flashesManifold Air Temperature
Check the MAT sensor, wiring, and connectors for a possible open circuit. replace the MAT sensor
Code 24
2 flashes, pause, 4 flashesVehicle Speed Sensor
This code can only appear when the vehicle is in motion, if it appears when the car is not in motion, ignore it. Check ECM connections, any other problems should be diagnosed by a qualified mechanic.
Code 25
2 flashes, pause, 5 flashesManifold Air Temperature
Check the voltage between the MAT sensor and the ECM. voltage should be above 4 volts
Code 26
2 flashes, pause, 6 flashesQuad Driver Circuit
Have the car checked by a dealer
Code 27
2 flashes, pause, 7 flashesGear switch Diagnosis
Have the car checked by a dealer
Code 28
2 flashes, pause, 8 flashesSame as code 27
Code 29
2 flashes, pause, 9 flashesSame as code 27
Code 31
3 flashes, pause, 1 flashPark/nuetral switch
Check all connectors, and for a faulty switch
Code 32
3 flashes, pause 2 flashesEGR System
Check vacuum hoses and connections for leaks and restrictions. Replace the EGR solenoid or valve
Code 33
3 flashes, pause, 3 flashesMAF Sensor
Have the mass air flow sensor replaced
Code 34
3 flashes, pause, 4 flashesMAF Sensor
Check for loose or damaged air duct, misadjusted minimum idle speed and cacuum leaks. Inspect the MAF sensor
and the electrical connections
Code 38
3 flashes, pause, 8 flashesBrake Input Circuit
Check brake light switch connections, adjust OR replace switch
Code 39
3 flashes, pause, 9 flashesTorque Converter Clutch
Check ECM connections, check for faulty Torque Conver Clutch solenoid
Code 41
3 flashes, pause, 1 flashCam Sensor
Check for faulty connections, or a faulty cam sensor. Maybe also indicate a problem with the vehicle's timing chain.
Code 42
4 flashes, pause, 2 flashesElectronic Spark Timing
check for faulty connections, or a faulty ignition module
Code 43
4 flashes, pause, 3 flashesElectronic Spark Control
Check for a faulty knock sensor, or Mem-Cal
Code 44
4 flashes, pause, 4 flashesLean Exhaust
Check the ECM wiring connections. Check for vacuum leaks at the hoses and intake manifold gasket
Code 45
4 flashes, pause, 5 flashesRich Exhaust
Check the evaporative charcoal canister and its components for the presence of fuel
Code 46
4 flashes, pause, 6 flashesPower Steering pressure switch
Check for faulty connections, or a faulty switch
Code 48
4 flashes, pause 8 flashesMisfire Diagnosis
Check the ignition and fuel systems
Code 51
5 flashes, pause, 1 flashProm or Mem-Cal
Make sure the MEM-Cal or prom is properly installed in the ECM. Replace Mem-Cal or prom
Code 52
5 flashes, pause, 2 flashesCal-Pak
Check the Cal-Pak to insure properation. replace the Cal-Pak
Code 55
5 flashes, pause, 5 flashesECM
Check for faulty connections. Replace the ECM
Code 63
6 flashes, pause, 3 flashesEGR Flow Check
Have vehicle serviced by a dealer
Code 64
6 flashes, pause, 4 flashesSame as Code 63
Code 65
6 flashes, pause, 5 flashesSame as Code 63