Help PCM
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Help PCM
I have a RV which when vin searched is classed as a F550 Super Duty. I have many codes coming up, I've tried clearing and they come back. I have changed the Valve cover assembly with all solenoids, plus both O2 sensors and codes come back. I have purchased a VXDIAG tool to help with the scanning and reprogramming with no luck. Sure need a clue as to if its the PCM or something else. Followed the wiring harness and other than a couple of wires reading off the same pin, am not sure what to do next. Here is the list of codes:
P0135
P0155
P0743
P0750
P0755
P1747
These codes were shown before and after new parts installed...
P0135
P0155
P0743
P0750
P0755
P1747
These codes were shown before and after new parts installed...
Fleet Mechanic
Joined: Oct 2017
Posts: 1,704
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From: Southwest Ohio
How does it shift? Does it drive smoothly or is there shifting and/or transmission issues that can be felt?
Any signs of rodent chewing anywhere? Have you checked up underneath the dash?
— Dave
Any signs of rodent chewing anywhere? Have you checked up underneath the dash?
— Dave
Hotshot
Joined: Jan 2004
Posts: 19,760
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From: St Louis
It would help if you COMPLETELY identified what you're working on. Can't look anything up without basic info like year and model, at a minimum. Posting the first 11 digits of the VIN would be best.
BTW, wouldn't be surprised if it's simply a blown fuse.
BTW, wouldn't be surprised if it's simply a blown fuse.
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Pcm
My husband shifts manually because rpms too low, won't go and more than 2300 rpms. Runs super rough and barely moves when you step on the gas. Our dash has a beautiful hinge so we have it up while doing our tests and absolutely no mice evidence.
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Ok, it's a 99 Rexhall Rexair but like I said the vin at Ford for parts and stuff falls under F550. 3FCNF53S0XJ Here is partial and have tested every fuse.
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
Your VIN says that Ford built an F53 stripped motorhome chassis with a weight range of 19-26K The coach builder took it from there.
Your fault codes indicate that the power feed from fuse F3 under the hood is missing at the O2 sensors and at the transmission (probably more but that's all your code reader reported).
Visually inspect fuse F3.
If no apparent fault, inspect the pins of it's socket looking for retaining pins that might be spread open causing a "no connection" condition.
Put the fuse back in and measure both test points on the fuse with your meter with the ignition switch set to RUN and to START. You should measure battery voltage both times.
If you measured battery voltage both times, then there is an open circuit somewhere between the fuse's load contact and the underhood loads. RD/YE wires.
If battery voltage was NOT read, then there is an open circuit between the line side of F3 and pin 87 of the PCM Power Relay.
Your fault codes indicate that the power feed from fuse F3 under the hood is missing at the O2 sensors and at the transmission (probably more but that's all your code reader reported).
Visually inspect fuse F3.
If no apparent fault, inspect the pins of it's socket looking for retaining pins that might be spread open causing a "no connection" condition.
Put the fuse back in and measure both test points on the fuse with your meter with the ignition switch set to RUN and to START. You should measure battery voltage both times.
If you measured battery voltage both times, then there is an open circuit somewhere between the fuse's load contact and the underhood loads. RD/YE wires.
If battery voltage was NOT read, then there is an open circuit between the line side of F3 and pin 87 of the PCM Power Relay.
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Wow, you were spot on as of right now, checked fuses again and found the one you said was in fact blown. It started right up and when stepped on gas it sounded awesome...thank you very much projectSHO89
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