Working on the 2004 Ford Crown Victoria P71

[brianl703]

Because it needed a new windshield (cracked) and the low beams were not working anymore, which I thought was due to the LCM failure for which there is a recall, the Virginia safety inspection lapsed last year so I haven't driven it at all.

Today I had a new windshield installed.

And after the guy was done, it cranked but wouldn't start.

I plugged a scantool in and looked at the fuel pressure PID, was sitting at 30PSI. Cranked it and it dropped to 0PSI.

Then sprayed some carb cleaner into the throttle body then cranked it again and it ran a good 10 seconds off the carb cleaner.

Then looked at the headlights and noticed that someone had broken the locking tabs off the headlight connectors. Pulled one of the headlights out to check that the low beam filament was still intact and checked with a multimeter to make sure.

Put it back and tested the low beams again and that one was working now! Then plugged in the other headlight and that one works now too!

Then made arrangements to have it towed out my driveway tomorrow to get a new fuel pump installed.

Then did some reading and grew a brain and realized that I didn't check the fuel pump relay.

Went outside and swapped the fuel pump relay with the AC compressor clutch relay (the same style relay), then tried starting it.

It started right up.

Then called the towing company to cancel the tow for tomorrow.

I'll drive it to the shop tomorrow (well, today, it's 3:27am here) for a safety inspection and while I'm waiting for that, go get lunch at Hector's, a good Mexican restaurant across the street (Hint: If you're opening an auto repair shop, a good location is within walking distance of a restaurant...)

As far as the LCM goes, a long time ago when I first got this car, it was a total beater (still pretty much is) and the low beams weren't working which I fixed by removing the LCM and re-soldering the relay on the circuit board. So I may just not bother with the LCM recall, Ford's fix is to add an external module of some sort that bypasses the relay inside the LCM.

And I'll just order two of the Motorcraft headlight connector pigtails and pull the terminals out of them and use the connector shells to replace the broken ones (they are the same). That way I don't have to splice any wiring, since there is nothing wrong with it.

 

[SwampSurvivor]

I worry about burning out the LCM on my 2001 Grand Marquis. I had to end up adding a separate powered trailer lighting circuit so I didn't burn it out. I can't adjust interior light brightness, so at night the digi dash is at FULL blast. Don't know if that's an LCM issue or not.

Just need to get the cylinder 5 misfire figured out

 

[dogememe]

I worry about burning out the LCM on my 2001 Grand Marquis. I had to end up adding a separate powered trailer lighting circuit so I didn't burn it out. I can't adjust interior light brightness, so at night the digi dash is at FULL blast. Don't know if that's an LCM issue or not.

Just need to get the cylinder 5 misfire figured out

I hope your misfire isn't the same cause as my 2-valve 5.4. Funny enough even though it's the same head I never had any problems with plugs popping out on the 4.6 on my 3 Vics I owned. Just luck I guess.

 

[brianl703]

I worry about burning out the LCM on my 2001 Grand Marquis. I had to end up adding a separate powered trailer lighting circuit so I didn't burn it out. I can't adjust interior light brightness, so at night the digi dash is at FULL blast. Don't know if that's an LCM issue or not.

Just need to get the cylinder 5 misfire figured out

On the 2004 Crown Vic the LCM does control the dash brightness. It has some sort of microprocessor in it that reads the value of the dashboard dimmer control (which is a variable resistor). And, when you turn the dashboard dimmer control to full bright to turn on the dome light, it recalibrates itself and sets that resistance reading as full brightness. (The recalibration is triggered by the dome light switch in the dimmer control). So if your dashboard dimmer control were worn out and had a high resistance at that position (should be a low resistance as I recall) I suppose it could mess up the recalibration and then the dimming won't work.

Do the other dashboard lights (switches and radio if still the stock radio) dim with the control or do they too remain at full brightness?

Might want to test your dashboard dimmer control with a multimeter (preferably an analog one or one that has a bargraph) to see if it has any bad spots or is maybe completely open circuit...

 

[SwampSurvivor]

I hope your misfire isn't the same cause as my 2-valve 5.4. Funny enough even though it's the same head I never had any problems with plugs popping out on the 4.6 on my 3 Vics I owned. Just luck I guess.

I also have a 2 valve 5.4. I'm waiting for one of them to spit a plug. The plugs looked good, though. No spit plugs. If I hold the pedal to the floor and crank it, you can hear one cylinder has nothing. But sometimes it doesn't and sometimes it runs great. I'm hoping for maybe a valve spring or lash adjuster - something that wouldn't either be a new engine or pulling a head off. It runs great otherwise, uses no oil and gets decent MPG.

On the 2004 Crown Vic the LCM does control the dash brightness. It has some sort of microprocessor in it that reads the value of the dashboard dimmer control (which is a variable resistor). And, when you turn the dashboard dimmer control to full bright to turn on the dome light, it recalibrates itself and sets that resistance reading as full brightness. (The recalibration is triggered by the dome light switch in the dimmer control). So if your dashboard dimmer control were worn out and had a high resistance at that position (should be a low resistance as I recall) I suppose it could mess up the recalibration and then the dimming won't work.

Do the other dashboard lights (switches and radio if still the stock radio) dim with the control or do they too remain at full brightness?

Might want to test your dashboard dimmer control with a multimeter (preferably an analog one or one that has a bargraph) to see if it has any bad spots or is maybe completely open circuit...

Everything remains full brightness all the time. Mine just has the up/down brightness rocker button and then push on the headlight switch for dome light. What's weird is, sometimes, it will dim on it's own if I have the lights on during sunset time. Then once it's dark out, back to full brightness.

The autolamp function appears to work along with the wipers turning on the headlights.

 

[brianl703]

Everything remains full brightness all the time. Mine just has the up/down brightness rocker button and then push on the headlight switch for dome light. What's weird is, sometimes, it will dim on it's own if I have the lights on during sunset time. Then once it's dark out, back to full brightness.

The autolamp function appears to work along with the wipers turning on the headlights.

I'd test that rocker switch. If I remember correctly, it just has 3 terminals, common, brightness up, and brightness down.

 

[SwampSurvivor]

I'd test that rocker switch. If I remember correctly, it just has 3 terminals, common, brightness up, and brightness down.

Apparently the switch itself is worn out. I pushed REALLY hard on it last night and they adjusted. It was very nice to drive without the dash lights cranked to 11. The headlights are bad but worse when the cluster is blindingly bright

 

[Quantico]

My 02 grand marquis had a sticky valve on number 5. Assume it was intake. Techron fixed it if you kept adding it. I sold the car as it got some rust that looked too icky for a family car to me.

 

[brianl703]

Went outside and swapped the fuel pump relay with the AC compressor clutch relay (the same style relay), then tried starting it.

It started right up.

So it started right up after I swapped the relay, I drove it 5 miles to the shop (safety inspection) and 5 miles back home.

I then left it parked till last month, when I tried starting it, it again cranked but wouldn't start.

Troubleshooting lead to me try powering the fuel pump directly with a 12V bench supply, which went into overcurrent at 10A and limited the voltage to 7V.

Conclusion: The pump has locked up and must now be replaced.

Ordered a new Carter fuel pump assembly (hanger, pump, and sender), now just need to get it installed.

I guess if a fuel pump is gonna die it's best it dies in the driveway!