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What does this mean?

SwaintaN

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93 ext, stock engine but the snorkel.

Ok had a few questions, a friend of mine got a Snap On Solus Pro code reader for 80-2008 vehicles, all of them so while working on mine he played around and stuck it in the eec and checked it out (the check engine light WAS NOT ON) but got these codes and meanings:

543- Fuel Pump Circuit Open Battery to Eca

556- fuel pump relay circuit open

What do those mean exactly; how do i fix it?
 
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MrShorty

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Assuming that expensive scanner makes the distinction, did it say if they were KOEO or CM codes? Both codes indicate a fault in the fuel pump circuit. A KOEO code indicates that the fault was present at the time the test was performed. A CM code (without the KOEO code) indicates that the fault occurred at some time in the past (and is likely an intermittent fault or possibly someone ran the engine with the fuse/relay disconnected to depressurize the fuel system or something like that).

If they are KOEO codes and the engine runs, that suggests the problem in the wiring that leads from the fuel pump circuit to the PCM, rather than the main fuel pump circuit.

For a long time, I used to get an occasional CM 543 (or 542, can't remember which) without a KOEO 542/543. One day the engine wouldn't start, because the fuel pump wasn't coming on. Turned out there was a loose connection between the fuse and the relay. I could never figure out the source of the CM 542/543 because the problem was intermittent, and didn't occur when I was in a position to look for it.

In any case, the fuel pump circuit isn't very complicated. If the fault will occur when you are looking at it, it should be pretty easy to track down with a voltmeter and a wiring diagram.
 
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SwaintaN

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not sure what KOEO and CM reads but this is what I can tell you he did.

First it was a memory read.

Then ;lol is this what KOEO stands for? He had Key On Engine Off, it read the codes, we cleared the codes cause we put in a new relay. It reset pcm?! Then he ran it with key on engine off again, no codes.

Then it was running test, key on engine on. Once it ran all its test doing that then we shut it off, scanned it again as key on engine off. no codes.

But the Snapon Solus Pro had a memory bank in it, so he went back to see what the codes were and we wrote them down. Then of course got bored and did all the other cars in the driveway.
 
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MrShorty

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not sure what KOEO and CM reads but this is what I can tell you he did.
you might review my "notes on pulling EEC-IV codes" thread in the EEC-IV forum. Even using the expensive scanner, the test protocols/and desgnations are the same.

It sounds like he did both the KOEO (key on engine off) and KOER (key on engine running) tests. Where they went away and didn't come back when he cleared them, they appear to be CM (continuous memory) codes. This suggests to me that they are either old codes (from previous work) that needed to be cleared or the fault is an intermittent one. If you think the latter may be the case, you might take the time to inspect the fuel pump circuit and see if you can find any obvious loose connections. If you don't, I'd probably periodically run the KOEO test to see how frequently those codes come back and otherwise keep an eye on it until it fails in such a way that it can be tracked down.

Edit: Just read through your other thread describing the power distribution box (PDB) issues. I would bet these codes are a result of whatever problem you had there, that seems to have cleared itself up for the time being.
 
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SwaintaN

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yeah we went and got it this morning. started right up, no hesitation on gas pedal, i did find ONE wire last night that seemed to be a little loose, but it went to the ABS relay. pushed it in firmer.

CM is what he said the codes were, that the test was KOEO but the codes ran CM, never kicked another code after testing and driving.

And sorry didnt know we had a forum for that.
 
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