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Code 542 (fuel pump secondary circuit fault)?

Tiny
EVANDER GAMBLE
  • MEMBER
  • 1994 FORD CROWN VICTORIA
  • 4.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 144,188 MILES
My car mysteriously stopped working on me overnight. Tried to crank my vehicle but ol Nelly wouldn't fire up. I did the (KOEO) key on ignition off test and the code 542 came up. I replaced the fuel pump circuit relay, the fuel pump fuse, and the entire sending unit that came with motor. I ordered the part from rock auto, and it was OE. Alas to no avail. I keep getting the same code and my car still won't fire up. I'm really feeling this one in the soul. I really need help getting my car rolling again.
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Monday, January 22nd, 2024 AT 8:56 PM

20 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

First, I attached some diagnostics related to the code. Take a look through them and let me know if you have questions. Note: the manual indicates specifically which possible faults have set the code.

Also, the first thing I recommend is to try resetting the inertia switch. It is located in the trunk of the vehicle on the left side (driver's side). Try that and let me know if it helps. Also, the last pic below shows the switch location.

Let me know what you find or if you have other questions.

Take care,

joe

See pics below.
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Monday, January 22nd, 2024 AT 9:21 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
I tested all the wires to see if there were any openings. And everything was running hot. I'm not sure if there were specifics, I had to dig and research for diagrams. Now my car only shows that there is a 512 (kam) keep alive memory failure. Does that mean I need to get a new PCM for the fuel pump motor to behave properly? Also, if you could send schematics or anything of use would be greatly appreciated. My old girl has been sitting for a month now...
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Monday, February 5th, 2024 AT 3:30 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Do you hear the fuel pump prime? It has been a while since I worked on this model year, but as I was sitting here, a thought popped into my mind. If the EEC relay or fuse has failed, you will lose spark and fuel to the engine. Have you checked those? (See pic 3)

Also, the keep-alive memory can be related to the EEC. Check in the under-hood fuse box for these two components. I remember the engine would be running fine, someone would turn the engine off and it wouldn't restart.

Also, I attached diagnostics below for the new code (KAM). Let me know if you are comfortable performing them. See pics 1 and 2.

Let me know what you find. If you are looking for a specific wiring schematic, let me know and I'll do my best to get it to you.

Take care,

Joe

See pics below.
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Tuesday, February 6th, 2024 AT 8:19 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
So, I was told that the 512 code appeared because I disconnected the negative battery terminal on the car, and it disappeared. So, I'm still left with code 542. Not sure what to really say about hearing the fuel pump prime never really listened to it while it was working. As far as schematic diagrams I need something that'll let me know the voltage across each wire that is associated with the fuel pump motor system. That way I can accurately determine where the short is located. As far as the inertia switch, I reset it and Power was still going to the part. Of course, the pink n blk wire is an open switch so it wasn't receiving any power. I encountered the issue when I turned the engine off and my car didn't start back up but I could still read codes from EEC with my odb1 scan tool. Someone told me it could affect fuel pump relays and such, but I'd like to hear multiple sources.
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Tuesday, February 13th, 2024 AT 3:22 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
So I was told that the 512 code appeared because I disconnected the negative battery terminal on the car and it disappeared. So I'm still left with code 542. Not sure what to really say about hearing the fuel pump prime never really listened to it while it was working. As far as schematic diagrams I need something that'll let me know the voltage across each wire that is associated with the fuel pump motor system. That way I can accurately determine where the short is located. As far as the inertia switch I reset it and Power was still going to the part. Of course the pink n blk wire is an open switch so it wasn't receiving any power. I encountered the issue when I turned the engine off and my car didn't start back up but I could still read codes from eec with my odb1 scan tool. Someone told me it could effect fuel pump relays and such but I'd like to hear multiple sources.
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Tuesday, February 13th, 2024 AT 3:22 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

I'm not sure which wires you are referring to when you say black and pink. Do me a favor. Look at the diagnostics I attached below. I suspect you have already done this, but I need to know which direction to go at the end of pic 2.

Let me know.

Joe
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Tuesday, February 13th, 2024 AT 5:57 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
My apologies I meant inertia switch.
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Monday, February 19th, 2024 AT 1:54 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

By chance, were you able to perform the aforementioned test on the inertia switch?

Let me know.

Joe
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Monday, February 19th, 2024 AT 8:09 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
I replaced the inertia switch and tested new one. I noticed the fuel pump connector was jelled up pretty bad. I think the grease on there wasn't any good anymore. Not sure if that has anything to do with it, Cleaned it off though. What sound am I supposed to be looking for when I turn the key over?
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Saturday, March 30th, 2024 AT 1:29 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Has anything changed with the new switch? As far as a sound, the directions indicated to check the resistance. Did that check good?

Let me know and I hope you have a good Easter!

Joe
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Saturday, March 30th, 2024 AT 9:02 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
I checked the resistance on the new inertia fuel pump switch. It measured more than 5ohms. Nothing has changed. I'm in the process of cleaning out the tank. My Ol lady put sugar in it. So anyway, I already changed out the sending unit, the relays, and switches. Including the inertia fuel pump switch. I used multimeter and test light witch voltmeter to check resistance and continuity. Like I said it was an overnight magical die move on me. Anyway, upon removing tank I realized there was jell in the connector, so I cleaned it with alcohol and a nylon brush. In the process of reinstalling the tank now.
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Tuesday, April 9th, 2024 AT 11:00 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Thanks for the update. Make sure there is power to the pump and a good solid ground. Let me know how things turn out for you or if I can help in any way.

Take care,

Joe
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Tuesday, April 9th, 2024 AT 7:03 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
Hey there Joe, I'm still having issues. I'm pretty sure it's probably a grounding issue because I hot wired the dg/y from fuse relay to the blk/pink wire on fuel pump to force it to kick on. End result I could hear fuel being sprayed from the injectors while car key wasn't even in the ignition. So I abandoned that ideas in fear it may explode or something crazy. Please help me out man. Not sure where to look for the grounding problem. It died on me overnight and ever since then it hasn't turned over anymore. I'm running low on options and I need the car more than ever because it's the only vehicle I have.
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Friday, April 12th, 2024 AT 7:58 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Sorry to hear you are still having problems. If you were able to force the pump to run, the ground is likely not the problem unless you ran a separate ground for it. The ground will be a black wire and mounted to the center (rear portion) of the trunk area and mounted on the rear support.

So, we need to start from square one. We know the power supply, a 20-amp fuse in the under-hood fuse box, is good and has power at all times. We know the inertia switch is good and reset. What I need to confirm is if the dark green wire with a yellow tracer has power when you first turn on the key. That is the power supply at the inertia switch. Check that and confirm for me, if there is power in, confirm power out from the inertia switch via the pink wire with a black tracer.

If there is no power getting to the inertia switch, we need to go back to the fuel pump relay and see why it isn't sending power. If there is power to and from the inertia switch, there has to be an open between the pump and switch.
'
I attached a pic of the schematic below so that you have a reference. Let me know what you find. Based on what is found, we will then move to either looking for an open circuit in the wiring or have to go back to the relay to see why it isn't working.

Let me know what you find.

Joe

See pic below.
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Saturday, April 13th, 2024 AT 6:42 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
The pink and blk wire don't have power to it. I tried using jumpers on the relay but to no avail. The wires on the diagram you sent all run hot except pink and blk going to and from inertia switch. One wire coming from connector to fuel pump read 7.3 volts.
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Thursday, May 23rd, 2024 AT 12:22 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Are you checking the pink/black wire at the pump? Which wire at the connector shows 7.3V?

Also, power to the inertia switch should come from a dark green/yellow wire. Is that not present?

Joe
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Friday, May 24th, 2024 AT 6:57 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
Pink/black wire has no voltage going into the fuel pump and inertia switch. The entire wire has no voltage reading. That is the one I hotwired from, the green/yellow wire from the fuel pump relay to the connector of the fuel pump on the pink/black wire. I got 12.3v after hotwired. The wire that gives me 7.7v is a yellow wire with a white Traver. This is the order list on the connector established for each wire.
The numbers are on each port of connector to fuel pump
21) Grey and red tracer. No voltage
42) yellow and white tracer. 7.7v (key on engine off)
42) pink and black tracer. No voltage (12.3v after hot wire)
44) solid black. (Usually ground)

The green and yellow wire 12.3v under hood and in trunk.
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Tuesday, May 28th, 2024 AT 7:09 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

If the pink/black has no voltage unless it is hotwired, go back to the inertia and see if the dark green wire with a yellow tracer has power. If it does (without being jumped), the inertia switch is bad.

Also, I assume continuity to ground was checked via the black wire.

Let me know.

Joe

See pic below.
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Wednesday, May 29th, 2024 AT 7:48 PM
Tiny
EVANDER GAMBLE
  • MEMBER
  • 20 POSTS
There wasn't any continuity. I used blk wire with blk lead on multi meter on each slot and the first one on the opposite end ringed out.
When I used red lead in the ground. (Black wire) Each slot ringed out. When I pushed in the inertia switch the pink/blk wire read 12.6v. I attached image of connector.
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Thursday, May 30th, 2024 AT 8:29 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
If you got power to the pink/black wire when you pressed the inertia switch, it sounds like the switch itself is faulty. Once it is reset, you should have power without pressing the reset button.

Let me know.
Joe
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Friday, May 31st, 2024 AT 8:24 PM

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