HELP ASAP: Blowing PCM fuse

[-Matt-]

My marauder has been blowing the 15 amp (pcm memory?) fuse. Its the lower most left fuse in the fuse box under the hood. Something is shorting out and causing the fuse to blow, causing complete car shutdown and no restart. It has blown twice in 3 days. Its at the ford dealer right now (it has a ESP) but they cant see any rubbed or bad harnesses. Does this sound familiar to anyone? What did the notorious harness rubbing the firewall problem cause? Search comes up with nothing. Please help.

Love you

-Matt-

[RacerX]

To the left of the row of relays???

[fastblackmerc]

Check the harness that is behind the drivers side cam cover. It may be rubbing on the bolt back there.

[-Matt-]

To the left of the row of relays???

yes... there are two 15amp... its the bottom one

[RacerX]

#19 is second from the bottom left and is PCM and fuel injectors. Short at an injector??? Check for harness rubbing on all injector wiring.
#21 is at the corner, bottom left and is supposed to be empty. If there's a fuse there, you may need to try to follow the new wiring coming from there out of the fuse box and see where it goes.

[-Matt-]

no not the corner.... bottom row, second from left... most bottom left of used fuses. I think its the one you listed for PCM/Fuel Inj.

[RacerX]

Yep! That's #19, PCM and Fuel Injectors! I'd look at the injector wiring...

[-Matt-]

The harness rubbing the coil cover problem.... what was that affecting for people?

[-Matt-]

...or effecting... whatever

[musclemerc]

There is a steel mount for the wiper cowl just to the left of the brake booster, sometimes the harness will short out from rubbing against the mount.

[fastblackmerc]

There is a steel mount for the wiper cowl just to the left of the brake booster, sometimes the harness will short out from rubbing against the mount.

As stated in post #3.

[RacerX]

If all the wiring and harnesses look ok, you may want to pull all the injector connectors and measure resistance with an ohm meter across each injector connector. See if there's one a lot lower than the others. Just another option if other ideas fail.

[-Matt-]

What i was asking is that those that had the bundle rubbing, was it causeing their PCM to mess up too?

[Blk Mamba]

Mine was the wire bundle crushed, not rubbed through, it took out the knock sensor, cops, radio freq. resistor, among others. You couldn't see it from the outside of the wire bundle, my mech. opened it up, and re-worked the wiring harness with a spare harness, and routed it away from the cam cover. My post from two, and a half years ago tells it all, if you can find it. 500 dollars, priceless.

[-Matt-]

Why would it just now start doing this?

[RacerX]

There's always movement and vibration in an engine compartment. But you know that, rhetorical question, I know. :( Hope you find it and get it fixed.

[fastblackmerc]

Why would it just now start doing this?

The engine moves, the body moves. Over time it's worn thru the harness.

[-Matt-]

now, possibly a different problem, when the cars running and you slam the hood, the car shuts off, but doesnt blow the fuse. The fuse hasnt blown yet today.

[LANDY]

Why would it just now start doing this? too much power. lol

[LANDY]

now, possibly a different problem, when the cars running and you slam the hood, the car shuts off, but doesnt blow the fuse. The fuse hasnt blown yet today.
inspect around the hood hinges.

[fastblackmerc]

inspect around the hood hinges.

There shouldn't be any wires or harness near the hood hinges.

Sounds like a bad connection somewhere.

[Blk Mamba]

I parked mine in the yard, washed, waxed, & detailed it, and 2 hours later was going out, and it wouldn't start

[fastblackmerc]

it wouldn't start

Didn't crank over or cranked but didn't start?

[Baaad GN]

I don't understand the problem, it's a ford, wait a few minutes and let it dry!

[Michael]

Hello Matt,

Check relay C 1016 (PCM power relay) in the battery junction box, it is the third one down centrally located in the box, it is rectangular not square I believe? Maybe swap it with another. It may be effecting other circuits also.

[Blk Mamba]

Didn't crank over or cranked but didn't start?


Didn't crank, so I put in a new starter, to no avail, all in all it was a week at the dealership.

[fastblackmerc]

Didn't crank, so I put in a new starter, to no avail, all in all it was a week at the dealership.

How old is the battery?

[-Matt-]

Hello Matt,

Check relay C 1016 (PCM power relay) in the battery junction box, it is the third one down centrally located in the box, it is rectangular not square I believe? Maybe swap it with another. It may be effecting other circuits also.

Hey Michael!

You think the relay could be causing this circuit to short and that fuse to blow?

Side note: drove it all day today, so far no problems

[Michael]

Normally a relay will just stop making contact and not send power though it, which would be an open circuit, but some may be built different and causing shorting togather like when your hood was closed, poping the fuse.

I would say it is not the relay, but it is easy to swap with another just to rule out.

Fuse 19 goes a few places so look closely at those circuits with the car running wiggle harnesses, if it dies or stumbles your getting close.

[-Matt-]

Fuse 19 goes a few places so look closely at those circuits with the car running wiggle harnesses, if it dies or stumbles your getting close.

Already tried that for two days.... nothing

[Michael]

As you have found out intermittent problems are a pain in the who-ha.:)

It will probably get worse and will then be able to find it.

Are you stock? Is there anything you have modified that could be interfearing. The circuit controls the maf, pcm, heated oxygen sensors, evapritive emmissions (EVAP), and canister vent valve.

The pcm relay I refered to earlier is before the fuse, so it is not likely the problem.

Can't say I can help much more, maybe Zack knows something (not sure if thats a bad word :)), You are a member at chicago SVT?

Good luck, post up if you get it solved.:burnout:

[-Matt-]

As you have found out intermittent problems are a pain in the who-ha.:)

It will probably get worse and will then be able to find it.

Are you stock? Is there anything you have modified that could be interfearing. The circuit controls the maf, pcm, heated oxygen sensors, evapritive emmissions (EVAP), and canister vent valve.

The pcm relay I refered to earlier is before the fuse, so it is not likely the problem.

Can't say I can help much more, maybe Zack knows something (not sure if thats a bad word :)), You are a member at chicago SVT?

Good luck, post up if you get it solved.:burnout:

I have a few upgrades...

http://mercurymarauder.net/forums/showthread.php?t=62897

[Michael]

Very nice set up Matt, I apparently was living under a rock at the time to miss your thread.:)

About the only other thing I can offer is may be you taped into the junction box pcm circuit acidentally for power, and are overloading the circuit. Or something is chaffing under the battery junction box.

What was your horsepower to the wheels, I did not see it after page 7?

[-Matt-]

477.... highest dyno'd marauder stock block

[CBT]

There shouldn't be any wires or harness near the hood hinges.

Sounds like a bad connection somewhere.

So where does the wire for the hood light run then.

[fastblackmerc]

So where does the wire for the hood light run then.

It comes out of the insulation about 8-10 inches from the strut & hinge.

[-Matt-]

acting up again today... must be something to do with rain/moisture. Shut down a dozen times... acts like it is running out of fuel but the whole car (PCM?) surges on and off.

[LeoVampire]

acting up again today... must be something to do with rain/moisture. Shut down a dozen times... acts like it is running out of fuel but the whole car (PCM?) surges on and off.

Some where you have exposed wires that are shorting out from all that I have read on this thread.

Once she is dried out get a squirt bottle of water and start testing the wiring harnesses with it and see if you can localize the problem so repairs can be made.