Help a newb out? IRCM - CCRM - PCM - code 543

[NogginBopper]

Hey guys,

I'm getting a 543 error code indication "fuel pump secondary failure, battery to PCM"

A friend of mine linked this error to my 1994 explorer xlt needing its IRCM replaced.

1.) Does an IRCM = a CCRM?

2.) I haven't been able to find either of those parts on any sort of schematic/diagram online or in my FSM and am wondering if they even exist for my year.?

3.) I'm guessing what would be a IRCM/CCRM in later models (2nd generation and less old) = a PCM for my XLT?

Am I horribly failing to locate the IRCM/CCRM or am I on the right track with the PCM here?

Thanks for your help!

 

[MrShorty]

I find a lot of references to IRCM's (Integrated Relay Control Modules) to several of Ford's cars, but none to trucks, so I don't think our Explorers use an IRCM to get power to the PCM and fuel pumps. We have individual EEC and fuel pump relays in the power distribution box.

A KOEO or CM 543 indicates some kind of break in the fuel pump circuit, and the fuel pump relay is probably as good as any place to start (the fuel pump fuse might be a better first place to start). Get into the power distribution box, check the fuse, then check to see if the fuel pump relay is closing when it should.

 

[NogginBopper]

Hey,

Thanks for your prompt response.

I've swapped out power distribution box relays to no avail.
the fuel pump usually turns on and cold starts fine, but won't reinitialize for a restart. It just cranks at that point.

The above, of course, comes after it's initial symptoms (over the course of the prior month) of randomly dying/turning off on 3 separate occasions, all at different speeds. It also decides to not turn over when its in a bad mood. I'm guessing the fuel pump wasn't turning on for the cold start, but I wasn't paying enough attention during that point of the diagnostic phase.

I've put in a new Fuel pump (its an airtex, that's bad right?), breached the inertia switch, and am now down to a OBD-1 code 543 which references a PCM. Since I haven't been able to locate a PCM in my vehicle, I'm assuming the code meant to say ECM/ECC, as that's what the relay schematic shows in my distribution box.

I'm hoping I'm on the right track here, as my next step is replacing the ECM.
Could it be a faulty wire/connection in the fuel pump circuit?
How easy would it be to test for something that?
Pardon my newb questions, but I'm electrically challenged.

 

[MrShorty]

Being electrically challenged can make it difficult to diagnose these things, because cars these days rely so much on electricity/electronics. I would encourage you to use these situations to become more familiar with how DC electronics works. The fuel pump circuit is a fairly simple DC circuit and is probably a good one to learn on.

The ECM may very well be bad, but that is not the next step I would take based on what you've described here. Part of the challenge in diagnosing a problem like this is that it is intermittent, so you have to be looking for the problem when it occurs. My approach would be to get a wiring diagram and poke around to become familiar with the fuel pump circuit and identify some "access points" where I could quickly and easily check the voltage. I would carry this wiring diagram and voltmeter around with me in the car. Then, when it stalls/won't start, I can start probing different places in the fuel pump circuit to see where there is power and where there isn't.

My Explorer did something very similar. Turns out there was a loose connection somewhere between the fuel pump fuse and the fuel pump relay. It was fixed with a length of wire, a couple of butt splices, and a little electrical tape (a lot cheaper than "guess and check" by replacing the PCM).

 

[NogginBopper]

Thanks for the help. I'll be updating with any results as soon as i find a legit wiring diagram. Sorry for the delayed response.