where to get CEL codes and how to get them???

[TI-CAVA]

a friend of mines 93LE has the CEL light on, but i want to know how do i pull the code and how to identify it, and know whats wrong with the car. apreciate all the help thanks!

[ganda1f]

A '93 should be an OBD1. Then you can get it without a scanner.
In the diagnosis connector in engine bay, jumper the TE1 and E1 terminals. Turn on the ignition, do not start the car. CEL will flash the 2 digit codes that are stored in ECU. Flash the first digit, short pause, second digit. Then longer pause and it will flash next code if there are several stored, or the same code if it is just one.
Rapidly flashing CEL means there are no codes.

Haynes manual has the list of all codes for OBD1.
Post the code when you get it. I am sure someone can look it up for you.

[TI-CAVA]

thanks will do!

[p1u1n1x1]

Thanks a lot, I've never owned an OBD1, that worked like a charm!

[ganda1f]

Here are the codes listed in Haynes manual. Numbers are not consecutive, some codes probably just do not exist:
12. RPM signal. No rpm signal to ECU within several seconds after engine is cranked.
13. RPM signal. No rpm signal to ECU with engine speed above 1500 rpm.
14. Ignition signal. No ignition signal to ECU.
16. ECU control signal. Problem between the engine controls and transmission controls inside the ECU.
21. Main oxygen sensor. Problem in sensor circuit.
22. Coolant temperature. Open or short in sensor circuit.
24. Intake air temperature sensor. Open or short in sensor circuit.
25. Oxygen sensor or circuit. Excessively lean air/fuel ratio has been indicated by the oxygen sensor circuit.
26. Oxygen sensor or circuit. Overly rich air/fuel ratio has been indicated by the oxygen sensor circuit.
27. Sub-oxygen sensor. Open or short in sensor circuit.
31. MAP sensor. Open or short in sensor circuit.
41. Throttle position sensor. Open or short in sensor circuit.
42. Vehicle speed sensor. No speed signal for 8 seconds when the engine speed is 3000-5000 rpm and the transmission is in gear.
43. Starter signal. No starter signal to ECU until engine speed reaches 800 rpm with the vehicle not moving.
51. Switch condition signal. No throttle position signal, gear selector signal or air conditioning signal to ECU.
52. Knock sensor signal. Open or short in sensor circuit.
71. EGR system. EGR temperature signal is too low.

[TI-CAVA]

ok i have a 12 and a 51, wich are RPM sensor and TPS, but the connectors are nice and clean, solid conection, TPS is original, Distributor assembly not original.... what should i aim for here?

thanks

[ganda1f]

You could measure resistances on the TPS. Disconnect the TPS, there should be 4 terminals. If I remember correctly these are VCC (reference 5Volt), VTA (Voltage throttle angle), IDL (Idle switch) and E (Earth). With closed throttle there should be continuity between IDL and E, but not otherwise.
Measure the resistance between VTA and E. It should be lower with closed throttle and increase as the throttle opens up.

But let me double check it. I don't have the Haynes manual at hand right now.

Remember to DISCONNECT the TPS before measuring resistances, or else you will be sending current to the ECU in ways that might potentially fry it.

You could also measure the reference voltage between VCC and E terminals supplied by the ECU and verify that it is 5V.

Code 12 could be due to ECU not seeing the Ne signal (generated in the distributor) which it needs to operate the igniter. Bad sensor/distributor or a wire issue.

[TI-CAVA]

thanks, will check, also the car is an AT, and it hessitates a lot to build power and for starting acceleration, could this be bc of the faulty sensors?

[ganda1f]

If the TPS is faulty and it feeds misinformation to the ECU (like TPS says the throttle is open although it is not, or the other way around) then the injectors may send bursts of fuel or cut down the fuel delivery. Obviously the engine will not run right, lack of power, hickups, all sorts of misbehaviour.

To check the TPS you will need feeler gauge (0.40 and 0.90mm, or 0.016 and 0.035in.) to insert between the throttle stop screw and the stop lever.

The measured resistances should then be:
throttle closed: 0.2-6.0kOhm between VTA and E2
.40mm: 2.3kOhm or less between IDL and E2
.90mm: infinity(no continuity) between IDL and E2
throttle fully open: 3.3-10.0kOhm between VTA and E2
Always 4.0-8.5kOhm between VC and E2 regardless of throttle position.

The terminals are top-to-bottom: VC, VTA, IDL and E2.

If the resistances are not right, one can try to adjust the TPS. Mark the current position of the TPS so you can come back to its original setting.
Insert a 0.70mm or 0.028in feeler gauge and measure resistance between IDL and E2. Loosen the TPS mounting screws and slowly rotate the sensor clockwise until resistance reads infinity. If it reads infinity from the beginning I would assume one should rotate it anti-clockwise to find the spot where it just starts to read infinity. Tighten the screws and recheck the resistances. If still wrong, replace the sensor.

Code 12 could also be set if there is a problem with the crankshaft position sensor or circuit.

Now that you mentioned it is an automatic transmission, code 51 could also be the neutral start switch.

As for code 12, if the ECU fails to see the signal from the distributor or the crankshaft position sensor while cranking, it won't operate the igniter. So the car should not even start.
You said it hesitates, so I assume it does start. Have you tried resetting the ECU and see what codes come back?

[lancelantier20]

wat do you do if the you get no code am i just completely screwed ????

[Kiwi-Corolla]

Originally Posted by lancelantier20

wat do you do if the you get no code am i just completely screwed ????

If no codes are detected then your check engine light should flash continuously (at 0.26 second intervals) when you've got the E1 and TE1 terminals of the diagnostic box jumped. If your check engine light doesn't flash when you've jumped the ports, then wiggle the paper clip or piece of wire around a little as the terminals are filled with grease from factory and it can sometimes be a difficult to get a good connection. If however you mean that you're experiencing problems with your engine but it's not showing a code then it could be something malfunctioning that wouldn't trigger the CEL to go off, such as spark plug wires, distributor, fuel pump, injectors etc.