Code 543


PFC Laird

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so I got this 94 ranger 2.3l that sputters while accelerating (or taking off, makes it kind of daunting to pull out into traffic) it's throwing this code 543 for secondary fuel circuit fault. I've just replaced the fuel pump and it's still running the same.

Could it just be a bad ground by the ECM that would cause this?

Edit: on a less serious note does anyone know what code 10 is? it's not in the book for my code reader and i can't seem to find it in google anywhere.
 


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AgPete139

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CODE 10 INFORMATION:

This is taken from ExplorerFOrums, which is taken from MuscularMustangs:


Here is an article from http://www.muscularmustangs.com/test1.php with a lot of good troubleshooting information.

Checking your Ford Mustang computer codes.
2 Digit Codes 3 Digit Codes.
TYPES OF CODES.
NOTE: Some people have problems distinguishing the different codes. READ THIS SECTION CAREFULLY.
There are drawings of the code formats at the end of this section.

FAST CODES.
Fast codes contain the fault information output in the normal slow codes but are output about 100 times faster.
These are the first things output on a Key On Engine Off test.

HARD FAULTS.
Hard faults are problems that the computer has located RIGHT NOW. Examples are a sensor out of range or a broken wire (open circuit).
Hard faults are the FIRST set of slow codes output in a Key On Engine Off test. BEFORE the SEPARATOR pulse.
In a Key On Engine Running test, there are ONLY HARD FAULT codes. These are output right after the fast codes.

SEPARATOR PULSE.
The separator pulse is a single pulse that indicates the END of hard fault codes and the BEGINNING of memory codes.
It will show up as a code 10 on most digital testers.

MEMORY CODES.
Memory codes are problems that the computer has noticed in the past. If for example there was a loose wire to a solenoid that only lost contact while driving but was making contact while testing the system there would be NO HARD FAULT CODE. The code would show up IN MEMORY. The same would happen for a sensor that only went out of range occasionally. Memory codes come out AFTER the separator pulse.
NOTE: The computer will erase the memory after a certain number of engine re-starts if the problem does not repeat itself. The number of re-starts varies from 20 to 80 depending on the year of the vehicle. The later models keep memory longer.

ENGINE ID.
The engine ID in a running test is a series of pulses equal to one half the number of engine cylinders. A 4 cylinder engine ID is 2 pulses, a 6 cylinder ID is 3 pulses and an 8 cylinder ID is 4 pulses. A diesel ID is 5.

GOOSE CODE.
A "GOOSE" code (also called a dynamic response test) is output during an engine running test. This is a single pulse to signal you to quickly move the throttle approximately 1/2 way down and release. NOTE: Not all engines give a "GOOSE" code.

CODE FORMATS.
Codes are output as a series of pulses. The following charts show the (approximate) timing of the various code pulses.
NOTE: Two digit codes are shown. Three digit codes have similar timing. It just takes a little practice to distinguish between two and three digit types.




TESTS.
NOTE: Vehicle should be fully warmed for all tests.

HOOKUP.
See figure below. EEC IV vehicles have two connectors for self testing the system. They are located on the firewall or the left or right front fender. The large connector contains the self test output (STO) and ground (SIG RTN). The small pigtail is the self test input (STI).



1. Make sure engine is fully warmed. If in doubt, run engine at 2000 rpm for 2 minutes.
2. Turn ignition off and wait 10 seconds for system to shut off. Make sure A/C is off and transmission is in Park (automatic) or Neutral (manual).
3. Hook up light and jumper (or a tester if you have one). Turn key to ON (do not start engine).
4. Fast Codes are output (ignore fast light flashes).
5. Read hard faults.
6. Separator Pulse.
7. Read memory codes.
8. See code explanations and check components as necessary.
Use FIRST CODE OUTPUT and retest after any repairs are made.

KEY ON ENGINE RUNNING (KOER) TEST.

1. Make sure engine is fully warmed. If in doubt, run engine at 2000 rpm for 2 minutes.
2. Turn ignition off and wait 10 seconds for system to shut off. Make sure A/C is off and transmission is in Park (automatic) or Neutral (manual).
3. Hook up light and jumper (or tester if you have one).
4. Make sure vehicle is safe to run and start engine.
5. Engine I.D. should be output.
6. Step on brake and turn steering wheel 1/4 turn.
7. If a "Goose" pulse is received, move throttle quickly 1/2 way down and release.
8. Fast Codes are output (ignore).
9. Read codes.
10. See code explanations and check components as necessary.
Use FIRST CODE OUTPUT and retest after any repairs are made.

CYLINDER BALANCE TEST.
NOTE: This test is only available on Sequential Fuel Injection (SFI) Engines.
Start an engine running test and press the accelerator lightly within 2 minutes after the last code is output. The PCM will cancel each cylinder in turn and measure the RPM drop. If any weak cylinders are noted their number will be output as a multiple of 10 (e.g. 30, 40). The output is the actual cylinder number, not the number in the firing order. NOTE: Will not always pinpoint bad injectors.

WIGGLE TEST.
Engine running or engine off tests
Hook up for a self test but do not hook up the self test trigger. Turn key to on. Hook up the trigger, wait 10 seconds and disconnect. Hook up trigger again . Tap suspected sensors (be careful if engine is running), wiggle the wiring harnesses etc. IF the PCM picks up a fault the self test output will pulse and a memory code will be stored (The value of this is questionable. I NEVER located a problem with it. - JT).

MEMORY ERASE.
To erase the memory disconnect the self test trigger while the codes are being output. You COULD also disconnect the battery but then the PCM forgets some important running characteristics.

OUTPUT STATE TEST.
Run the KOEO test all the way through and leave the test hooked up.
Cycle throttle 3/4 open and closed while watching tester, light or voltmeter. Self test output will switch with every throttle activation. On some testers (like my old pocket testers) the light will only pulse every other push. But the outputs still switch EVERY time.
Solenoids (EGR etc.) will switch on or off with every throttle activation (push throttle they're on, push throttle they're off). You should be able to hear clicks as the solenoids switch states. The test will work for most solenoids: AIRB, AIRD, BOOST, EGR, EVR (NOTE: EVR does not click but vacuum cycles).
 

AgPete139

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Essentially, it's a separator pulse.
 

AgPete139

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From MrShorty:

"KOEO 543 can mean a couple of different things. Based on the other symptoms, I believe it points to an intermittent break in the fuel pump circuit between B+ and the point where the PCM monitors the fuel pump circuit. Get a wiring diagram and go through it and see if you can find the break. The fact that it's intermittent could make it more difficult.
That said, I'm going to add a couple of other things, in case the break in the circuit isn't obvious. A 543 can be either a KOEO code or a continuous memory (CM) code, both of which are output during the KOEO test. If there is any doubt in your mind on how to distinguish between the two codes, resolve it now. There are some significant differences in diagnosing a KOEO 543 and a CM 543. If you feel confident in stating that it's a KOEO code, it may be important, given the intermittent nature of this fault, to note if the test was performed at a time when the engine would/wouldn't start. At the beginning of the KOEO test when the computer clicks the relays, note if you hear the fuel pump run or not."



In my opinion, I'd check for corrosion at the fuel pump relays, all fuel pump connections (including the power and ground for the PCM), and the relays.
 

Crazyer_310

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So did this ever get fixed? I'm having the same problem except it's not all the time, it does it randomly, and mine is the same everything just that its stick shift
 


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