Reading JDM stock ECU fault codes

[JoeLanger]

Might be useful for standard FD users

Nice to have all the info in one place, courtesy of wstrhom on rx7club.com or this thread here: http://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-read-fd-trouble-codes-851414/

Copied below for convenience:

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1) Disconnect the battery for about 30 seconds to discharge the airbag system's "back-up power supply" capacitor. This will clear old PCME stored faults. Reconnect the battery.

2) Place a jumper wire (a paper clip will do) between the "TEN" and "GND" terminals of the Diagnostic Connector.

(Cars with no 'CEL') connect the positive end of the LED, with a 500 ohm resistor in series to the 'B+' terminal. the negative side of the LED should go to the 'FEN' terminal. Now use the LED as your CEL. I used some pre-wired LEDs from ebay (5 for 99p) that then didn't need the resistor in the line.

3) If the engine is known to run, however badly, start the engine and run it for about a minute. If it will not start, attempt to start it for a few seconds. Next, with the engine off, turn the ignition key to the "ON" position.

4) Observe the CEL. If there are no current stored trouble codes, the CEL will turn on for 2-3 seconds and then go off. If there are stored codes, the CEL will display flashing code(s) identifying the trouble area. (If the CEL stays on, possibly the jumper wire or paper clip is not making a good connection.)

The flashes are read as follows:
1) A break between repeats of the code(s) lasts 4.0 seconds. During this time the CEL will be off.

2) The code(s) can display "tens" digits and "ones" digits. A "tens" digit is 1.2 seconds long. A "ones" digit is 0.4 seconds long. If the code number is greater than "10, the "tens" digit(s) will display first, followed by a 1.6 second break, followed by the "ones" digit(s). Example: Code #34, an Idle Air Control Valve electrical fault, would be displayed as three 1.2 second flashes followed by a 1.6 second break, followed by four 0.4 second flashes, followed by a 4.0 second break, followed by a repeat.

3) If more than one failure is present, the code numbers will be indicated in numerical order.

The FD trouble code chart in the 1994 Workshop Manual lists the following codes:

02 No Crankshaft Position Sensor "Ne" signal
03 No Crankshaft Position Sensor "G" signal
05 Knock Sensor - open or short circuit
06 Vehicle Speed Sensor - no signal
09 Engine Coolant Temperature Sensor - open or short circuit
11 Intake Air Temperature Sensor - open or short circuit
12 Throttle Position Sensor (Full Range) - open or short circuit
13 Manifold Absolute Pressure Sensor - open or short circuit
14 Barometric Absolute Pressure Sensor (in PCME) - open or short circuit
15 Oxygen Sensor - <0.55 volts for 25 secs in closed loop zone
16 EGR Function Sensor - open or short circuit
17 Oxygen Sensor - no voltage change for 120 secs in closed loop zone
18 Throttle Position Sensor (Narrow Range) - open or short circuit
20 Metering Oil Pump Position Sensor - open or short circuit
23 Fuel Thermosensor - open or short circuit
25 Solenoid Valve, pressure regulator control - open or short circuit
26 Metering Oil Pump Stepping Motor - open or short circuit
27 Metering Oil Pump - open or short circuit or sticking of MOP sensor
28 Solenoid Valve (EGR) - open or short circuit
30 Solenoid valve, split air bypass - open or short circuit
31 Secondary Air Bypass Valve - open or short circuit
32 Secondary Air Switching Valve - open or short circuit
33 Solenoid Valve, port air bypass - open or short circuit
34 Solenoid Valve, Idle Air Control - open or short circuit
37 Metering Oil Pump - low battery positive voltage
38 Solenoid Valve, Accelerated Warmup System - open or short circuit
39 Solenoid Valve, Relief 2 - open or short circuit
40 Solenoid Valve, Purge Control - open or short circuit
42 Solenoid Valve, Turbo Precontrol - open or short circuit
43 Solenoid Valve, Wastegate Control - open or short circuit
44 Solenoid Valve, Turbo Control - open or short circuit
45 Solenoid Valve, Charge Control - open or short circuit
46 Solenoid Valve, Charge Relief - open or short circuit
50 Solenoid Valve, Double Throttle Control - open or short circuit
51 Fuel Pump Relay, Speed - open or short circuit
54 Air Pump Relay - open or short circuit
71 Injector, Front Secondary - open circuit
73 Injector, Rear Secondary - open circuit
76 Slip Lock Up Off Signal (PCMT) - open or short circuit
77 Torque Reduced Signal (PCMT) - open or short circuit

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Can you make this a sticky Phil so it's easier to find for FD:OCers in the future.

 

[welshkid]

Cheers for this!
Any idea how to read the ABS fault codes too? I seem to remember a guide but can't find it. Think the process is similar but different pins are used.

 

[Efini-dan]

@bazjim this is what you need to do. If you don't have a CEL light on the dash, you can jump another two pins in the diagnostic port with an LED and a inline resistor and this then flashes any codes up.

Ill see if i can find out the resistance of the resistor needed as ive forgotten myself.

 

[initialDean]

I actually did this yesterday lol

 

[ascari]

What version, OBD-I or OBD-II, does a JDM 2000 FD have? I've tried searching, but nothing appears conclusive.

 

[initialDean]

What version, OBD-I or OBD-II, does a JDM 2000 FD have? I've tried searching, but nothing appears conclusive.

neither I dont think ?

 

[MKZ7212]

Cheers for this!
Any idea how to read the ABS fault codes too? I seem to remember a guide but can't find it. Think the process is similar but different pins are used.

be good to know this also, don't think my ABS has ever worked

 

[ascari]

neither I dont think ?

the '94 FSM show OBD as the SAE standard for diagnostics. i presume this is the same as OBD-I, so I wonder if they upgraded to OBD-II in later models.

 

[initialDean]

the '94 FSM show OBD as the SAE standard for diagnostics. i presume this is the same as OBD-I, so I wonder if they upgraded to OBD-II in later models.

No OBD2 as far as I know... I have a 2002 and its not got one. you have to do the wire/led thingy as above

 

[ascari]

No OBD2 as far as I know... I have a 2002 and its not got one. you have to do the wire/led thingy as above

interesting, how are you checking for OBD2?

 

[initialDean]

interesting, how are you checking for OBD2?

I just know it doesnt have one..... IF by OBD2 you mean one of these connections

 

[ascari]

I just know it doesnt have one..... IF by OBD2 you mean one of these connections

View attachment 14819

i think you've confirmed just OBD1 is supported, thanks!

 

[welshkid]

be good to know this also, don't think my ABS has ever worked

I figured this out. Will write it up this week, it mirrors some of the mx5 systems.

 

[bazjim]

Hi guys if you search my posts I will shortly be selling a code reader that connects directly to the standard JdM port on all rx7s and will read off a standard ecu.
It will also do the following
Runs the cooling fans
Runs the fuel injectors with engine off
Check all buttons on the dash
Clutch engagement sensor
Break pedal sensor
Throttle pedal sensor.
I’ve put on a video of it working in basic form.

 

[welshkid]

be good to know this also, don't think my ABS has ever worked

In the diagnostic port, Bridge with a jumper wire TBS to GND, you don't need an LED etc
Then ignition on, And you ABS light should flash a pattern on the dash.

As above long flashes count as 10's, short flashes as 1's, add them all up and it gives you your code (there may be multiple)

Images are from a RX7club post I found.

THe above worked on my 94/95 JDM car, not sure if it carries across all years and models, but worth a check

 

[MKZ7212]

In the diagnostic port, Bridge with a jumper wire TBS to GND, you don't need an LED etc
Then ignition on, And you ABS light should flash a pattern on the dash.
View attachment 14823

As above long flashes count as 10's, short flashes as 1's, add them all up and it gives you your code (there may be multiple)
View attachment 14824

Images are from a RX7club post I found.

THe above worked on my 94/95 JDM car, not sure if it carries across all years and models, but worth a check

Great info thanks. Do you know how to clear the codes once done? And if this is only relevant for the stock ECU or does it read from the ABS ECU?

 

[welshkid]

Great info thanks. Do you know how to clear the codes once done? And if this is only relevant for the stock ECU or does it read from the ABS ECU?

No worries, it should be reset by pressing brake pedal 10 times in less than a second (with the bridged connection still in)