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1997 F-350 No Start Condition, Code 542 (Fuel Pump/ECM Related)


Micro Machine Manager
That didn't take long. I am lucky if I have 10 miles on this thing since purchase in August. That's a whole different story on why I wasn't driving it and will be settled in a court, but that's not the problem.

So the rear tank doesn't fill because it likely has the midship filler neck installed and is causing problems. That's on the shop on the 18th, and hoping I can DRIVE it there. However, I just bought a new battery cuz the Die Hard from 11/20 was nearly dead with a 11.8v or less pull. Got a mid-grade NAPA battery plus my plat oil filter and a new drain plug seal for $134, not too bad, Triple ! gave 20% to the cause.

Now I can Triple A Tow this thing, but I'd prefer to drive it the 2 miles to the bloody shop.

It has power. Things turn on. Some eejit before me put a 20 amp fuse in slot 13 on the inside, which is a 15 amp. I sacrificed my handy work at the stereo station and pulled its fuse to get the proper fuse in place -- the old fuse came out in 2 parts, although I think the continuity on the metal was still good. HAH! Never seen that before. Probably gonna change all the fuses soon, maybe with the fancy smancy light-ups when things go awry.

So, Code 542 came up right away, saying open circuit fuel pump or EEC/ECM issue.

Now I have yet to open the relays in the engine and put a light to it, etc. Is there a proper voltage test to determine the supply is right or a way to verify the relay is not broken inside? I know most of the time folks say, "Jus switch'm in the box, they're all the same." Isn't there a diagnostic though for a more scientific electrical or mechanical check?

I also found a great video that went through the Trifecta. They hot wired the rear fuel tank pump and verified it worked, plus checked the Inertia Safety Switch behind the passengers front panel and reset it, and then pulled the fuel selector switch out and verified it was bad, so they hot wired that too but STILL had a problem. Now this was on a 300-6, not a f350 460, but I believe it's pretty much the same overall. What they found was they still didn't have control at the engine fuse box on the relay for the fuel pump, so they pointed at an odd-shaped relay that was actually for the ECM! I had no idea. I feel (think) I need to check this on my f-150 too. Anyway, it had bad contact and had wiggled lose, so they cleaned it off, inserted it and everything worked as advertised.

Any thoughts on this probably being the right set of solutions?

Incidentally, the Fuel Selector Switch was replaced by the previous owner by the shop that did the new fuel tanks, differential seal, pinion seal, bunch of drive control stuff and new filler necks for the tanks. I'm thinking the FSS is good and we're at the relays. I've fussed around the Inertia Safety Switch on my f-150 and doubt it's tripped, but I can check that too on this one. Highly doubt it's tripped and even if it is, even more doubt on it being the culprit of the problem since I've not impacted anything recently in the 10 miles it was driven. The most impact it's had was the battery making a nice thud into its new home.

Oh yeah, battery block holders -- where should I get them? This engine bay thinks it's cool to just let it bounce around and hope for the best. Thinking I'd like to get her strapped in on the platform with some good rubber grips, but don't even know what to call them! Rubber battery bump stops? Rubber Baby Buggy Bumpers? I dunno. I just don't have any holding this new one or the previous battery down. :ROFLMAO:


Micro Machine Manager
Looks like all system components between my 91 f250, 92 f150, and 97 f350 are interchangeable, so I have relays, fuel selector switches, etc to swap and try. Unsure about the PCM/ECM Relay/Fuse. Going to look at in the 3 vehicles and see if a part number matches between them as well.

Hopefully just a little jiggle will get this the right way. I may have to check the Inertia just in case.

Found that Battery Holder Clamp at Rock Auto for about $4, so no need to answer that question. Dorman type.


Micro Machine Manager
Another Question: Could I have sprayed something on the frame rail with PB Blaster that shorted part of the fuel pump wires, etc?

I was underneath PB and Penetrating Oil on multiple bolts that I plan on knocking out now or later (removing towing hitch framework, old straps for old cat/mufflers, etc). I sprayed numerous drive train joints and shackle locations so they would have some give if I need to change any of those things out later as well. Did about 2 cans of french fry undercoating so far on strategery points.


Micro Machine Manager
My one test light on me was corroded on the inside, so couldn't do much. Did pull the PCM Power Relay Diode (nomenclature, found) F2TF-14A604-AA part #. Apparently hard to find if it goes bad.

Unsure how to test it yet, as power should only go one way. I guess I could reverse-connect it and test the outlet end for power and see if it inhibits it. I know things but having done them is another task on its own.

Got my new HF tester set so I'll try to check power again in relays. I swapped relays and still inop on the fuel pump. Need to check inertia safety switch since maybe it is tripped, just need to be sure. Can hot wire that and eliminate the guesswork, have done on the f150 before when the fuel selector was bad. Thinking maybe I'll want to pull my FSS out of my f250 and put it in just to see if that's an improvement.


Master Ford Tech
Your multi meter should have a diode test selection. I know you said the rear tank doesn’t fill but if you flip the FSs to rear tank can you hear the pump run?


Micro Machine Manager
Your multi meter should have a diode test selection. I know you said the rear tank doesn’t fill but if you flip the FSs to rear tank can you hear the pump run?

Yeah, I figured one of my multimeters will have that (I have solar-installation grade electronic equipment, but am not ever doing diagnostics on diodes in general). I'll figure that part out, something about a resistance check on current should determine whether it's good or not.

As for rear pump, nope, it does not make the priming sound. I had the same scenario (wound up being Fuel Selector Switch and an engine ground issue) in F-150, so know what I'm listening for. No pump runs when selecting either.

Still need to double-check the inertia safety switch and look at the FSS. Maybe a wire came off from the mechanic's install. Maybe the part is bad. I have "working" ones, but any good way to bench test a Fuel Selector Switch once I have it out? Or maybe see which of the wires is the power supply to the switch and see if no power is coming through the wires when I turn on accessory power pre-ignition.


Micro Machine Manager
I went way overboard on this.

Glad I didn't go Inertia Safety Switch first.

Popped out the instrument cluster bezel and swapped an old Fuel Select Switch for the "new" one. Truck started right up on the fuel tank that can be filled.

LED'd the instrument cluster (left in place, tilted and swapped out with seeing-eye hands) so it's running brighter (or in some places, now is running as the bulbs were bad) plus did the bed light. Cab Dome Light has the fuse-lights. Need to figure out what part number those are and if there are LEDs for them! Anyone know about a 97 F-350 cab dome light led #? There's a left and right reading light on switch and center comes on if you open the door.

Changing headlight bulbs out to LEDs shortly. Still need to do glove box and cigarette tray as LEDs to minimize voltage draws from mistakes (I'm prone to forgetting things).

No luck dropping the hitch assembly, but did find a 13mm wrench wedged up in there. Yay! It looked like someone had welded it there as a replacement to a support, but nope it was on a bolt top side to the back hitch assembly and was just chilling. Any pointers on super-rusted hitch assembly removal, appreciate that as that's next. They're 7/8 and 13/16 bolts holding her in. Super rusted. Might have to grind and knock'm out?