99 & up 7.3L Power Stroke Engine and DrivetrainDiscussion of the 99 & up 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.
What would cause a PCM to go out? About a year and a half ago, I had one go out and when we took it out of the truck a buddy of mine (who used to be a Ford mech) said that they hardly ever go out but there was evidence that the previous owner had a chip in it and that sometimes causes problems. I had it rebuilt by Ford and now it seems like I've lost another one. A different buddy let me borrow a scanner and it's not able to connect to the PCM, just like last time. I have an Edge Evolution programmer connected to the data link connector but I don't ever use it for anything but temp reading and a tach.
Could that be the problem? Is there any other way to check and see if it's dead? All my fuses are good and I don't know what else to try. The buddy who worked for Ford had a Ford scanner and it read that the PCM was bad but the regular scanner just says it won't connect.
__________________ Mike
Member #4,587
1999 F350 XLT crewcab 3 inch body lift, 8 inch suspension lift. Edge Evolution programmer. AFE cold air intake. 37 inch tires. Pics are in link below.
1996 F350 XLT crewcabdually, (RIP) pulled a 50+3' step deck trailer and 30' cow trailer.
Pictures of it's death can be seen in link below.
What are the symptoms, other than not starting and not connecting? I guess the best way to check the pcm is to try it in another truck, but other than that, it is checking all the critical input/outputs to see if they are there. The biggest ones would be the power and grounds.
__________________ Tom
99.5 PS CC 4x4 SRW ZF-6
Triple Pillar Gauges; Fuel pres, Pyro, Boost
AE, Alldatadiy, and half a clue
- AKA "The Big White Truck"
When I turn the key on, I can hear the fuel pump come on and there is fuel in the bowl. It turns over and cranks fine but there isn't a sputter or cough of it trying to start and I'm not getting smoke of any color out of the tailpipe. Batteries are fine and I don't have a multimeter so I can't check the gpr but I turned the key on last night to see if there was a change in light output after the gpr would have normally shut off and there was no change. Unfortunately, I'm not very good at electrical stuff but I've checked connections and all the fuses under the dash and in the power distribution box and they all seem fine. Last time the pcm went out we confirmed it by putting another pcm in but the guy doesn't have access to them anymore, so that avenue won't work.
Added: Just checked and I've got power to the gpr but not to the other big post when the key is turned on so the gpr isn't coming on but now I'll have to try jumping the posts to see if that does any good.
__________________ Mike
Member #4,587
1999 F350 XLT crewcab 3 inch body lift, 8 inch suspension lift. Edge Evolution programmer. AFE cold air intake. 37 inch tires. Pics are in link below.
1996 F350 XLT crewcabdually, (RIP) pulled a 50+3' step deck trailer and 30' cow trailer.
Pictures of it's death can be seen in link below.
What about the Wait to Start light? Does the tach move while cranking?
__________________ Tom
99.5 PS CC 4x4 SRW ZF-6
Triple Pillar Gauges; Fuel pres, Pyro, Boost
AE, Alldatadiy, and half a clue
- AKA "The Big White Truck"
I don't know if it's a light bulb issue or what but this truck didn't have a WTS light when I got it 2 years ago and I've just never messed with it, since it's just a dummy light. No movement of the tach at all. Ive read where some folks say that means it's a CPS issue but others say that it doesn't necessarily have anything to do with it.
__________________ Mike
Member #4,587
1999 F350 XLT crewcab 3 inch body lift, 8 inch suspension lift. Edge Evolution programmer. AFE cold air intake. 37 inch tires. Pics are in link below.
1996 F350 XLT crewcabdually, (RIP) pulled a 50+3' step deck trailer and 30' cow trailer.
Pictures of it's death can be seen in link below.
No movement on the tach CAN be the cps, which will prevent the truck from trying to start, or it could be a bad pcm. It would be a wise thing to try the cps first.
__________________ Tom
99.5 PS CC 4x4 SRW ZF-6
Triple Pillar Gauges; Fuel pres, Pyro, Boost
AE, Alldatadiy, and half a clue
- AKA "The Big White Truck"
No tach movement AND no smoke are both symptoms that you could have a bad CPS. It's a quick check if you already have a spare (you should always have a spare) CPS.
__________________
2002 F350 XLT, CC, SB, 4x4, Auto, AIC, DiabloSport Predator, BD X-Monitor, Kenwood TM-V7A, Pioneer 7400MP3, Infinity 5.25" Components, Infinity 10" Sub in a Q-Logic Box, Heated Mirrors, Gentex/Mito Auto Dimming Mirror, Rear ID Bar, Uniden PC78 Elite CB, Clifford Matrix RS3 Alarm/Remote Start, Keypad Entry, Homemade "Tymar", custom, muffler back exhaust, 6 Whelen LED's in rear window, 6 Whelen Strobes in the Front, Rears still not installed...
Just tried it with a new CPS and no difference. Still just turns over and this time I even tried it after having the block heater on for several hours.
__________________ Mike
Member #4,587
1999 F350 XLT crewcab 3 inch body lift, 8 inch suspension lift. Edge Evolution programmer. AFE cold air intake. 37 inch tires. Pics are in link below.
1996 F350 XLT crewcabdually, (RIP) pulled a 50+3' step deck trailer and 30' cow trailer.
Pictures of it's death can be seen in link below.
What is the oil level in the engine? I blew an o-ring and consumed oil like it was free and the HPOP got starved and truck would not start. Probably not your issue but something to check.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
Linear Mode
